Research: Current Projects 2000 Projects Cotton Production Bioremediation Efforts for Sticky Cotton Vern J. Elliott 31 Biological Control of the Cotton Aphid Kris Godfrey and Michael McGuire 34A Remote Sensing in Cotton at Shafter, 2000 Glenn J. Fitzgerald and William R. DeTar 37B Approved Pima Variety Trials Robert Hutmacher 39 Establishing Updated Guidelines for Nitrogen Fertility in Upland (Acala) Cotton Robert Hutmacher 40 SJV Acala and Pima Testing Program Dick Bassett & Shane Ball 43 Management of Key Cotton Arthropod Pests with Insecticides and Acaricides Larry Godfrey & Kevin Keillor 44 Interaction of Cotton Nitrogen Fertility Practices and Cotton Aphid Population Dynamics in California Cotton Larry Godfrey, Jorge Cisneros, Kevin Keillor, & Bob Hutmacher 45 California Upland Cotton Advanced Strains Variety Trials Robert Hutmacher 46 Upland Cotton Varietal Response to Short-Season Versus Long-Season Management Practices Robert Hutmacher, Steve Wright and Brian Marsh 52 Narrow-Row (Double-Row 30 Inch and Double-Row 40 Inch) by Variety Trial Robert Hutmacher, Bill Weir and Brian Marsh 53 Evaluation of Bollgard II Cotton for Lepidopteran Control & Performance under Commercial Productions Brian Marsh 54 Agronomic Test of Improved Fiber Quality Pima Germplasm Richard Percy 55 Root-Knot Nematode Management in Cotton Pete Goodell, Phillip A. Roberts and Chuck Haas 56 Cotton Weed Control Brian Marsh 83 Development of High Yielding, Pest Resistant Blackeye Bean Varieties for California Jeff Ehlers, Tony Hall and Blake Sanden 84 Potato Late Blight Screening Nursery Ron Voss and Joe Nunez 86 Importation of Peristenus spp. for the Biological Control of Lygus Hesperus C. Pickett 87 Root-Knot Nematodes (Meloidogyne javanica) in Field & Vegetable Crops Phil Roberts 88 Nightshade Control in Blackeyed Beans and Annual Morningglory Control in Blackeye Beans David Bayer and Ernie Roncoroni Project: Bioremediation Efforts for Sticky Cotton Project Leader: Vern J. Elliott (661) 746-8003 (661) 746-1619 FAX USDA ARS Shafter Research and Extension Center Objective: The Problem. Sap feeding cotton pests like aphids or whiteflies can excrete a sticky, sugar rich liquid onto open cotton bolls. This sticky cotton as it is called, poses serious difficulties at the textile mill. Machinery can be fouled to the point that the cotton cannot be used. Consequently, sticky cotton is difficult to sell and a production area can get a bad reputation that will hurt sales for years to come. Although insect management can reduce the chances of sticky cotton, no effective treatment currently exist to remove the sugar contamination once it occurs. Our work is focused on applying special strains of yeast to consume the sugar on the cotton fiber and reduce the stickiness. If successful, this research would allow sticky cotton to be cleaned up in the module and permit trouble free processing at the gin or mill. This would give California cotton growers an important tool to protect the well deserved reputation for quality cotton. The Plan Bioremediation offers a possibility of eliminating stickiness by using microorganisms to consume the sugars. Yeasts have several characteristics that would be useful in a bioremediation agent for sticky cotton. Yeasts readily consume sugars, grow over a range of temperature and moisture levels, and withstand drying. Honeydew is a sugar rich mixture that is somewhat variable in composition depending on which insect is present. The predominant sugars found on sticky cotton are melezitose, trehalulose, sucrose, fructose, glucose, and trehalose . Other unique sugars such as bemisiose can also occur. Consequently, it is important to identify strains of yeast with the enzymes needed to break down these different sugars. The present research was initiated to survey the ability of various plant associated yeasts to utilize the sugars found in honeydew. Methods Used Naturally occurring yeasts were collected from cotton leaves, lint, and from other plants growing in the San Joaquin Valley of California. A sub-sample of 250 strains was selected to evaluate the ability of these yeast to metabolize some of the sugars found in insect honeydew. The yeast were grown on Bacto YM agar for 48 hr to condition them physiologically, then suspended in sterile water. Solutions of sugars (either sucrose, glucose, fructose, melezitose, or trehalose) were prepared in a solution of Bacto yeast nitrogen base, filter sterilized, then dispensed into 96 well microplates. Two controls of either water or the nutrient base without added sugar were also tested to check for growth on stored nutrients. Trehalulose was not available at this time and therefore will be evaluated in later tests. Each strain by sugar combination was tested in two replicates. Plates were incubated at 28° C and growth was determined by periodically measuring turbidity over a 48 hour period. Growth rate was measured by calculating the change in turbidity over time. Results of the Study All the sugars evaluated could be degraded to some degree by many of the strains tested (Fig 1). When assessed across all 250 strains, sucrose supported the highest average rate of growth followed closely by glucose and fructose, then melezitose and trehalose. Essentially no growth occurred in water or the nutrient base controls. The distribution of growth rates on any given sugar was positively skewed with some strains showing much higher rates than the average. When ranked by the maximum rate, fructose and glucose supported the highest rate followed closely by melezitose and sucrose. The maximum rate on trehalose was considerably lower. Many strains could utilize more than one sugar and within the same strain, growth rates on the different sugars tended to be correlated (Fig 2). These results indicate that the naturally occurring yeast population in the San Joaquin Valley will be a suitable source for selecting bioremediation agents for whitefly and aphid honeydew. The positively skewed distribution indicates that selecting strains for rapid rates of utilization will be successful. Trehalulose has yet to be tested but given its prevalence in honeydew, it is likely that strains will be found that can degrade this sugar. Ultimately, selected strains will have to be tested for the ability to reduce or eliminate stickiness as measured by the thermal detector test and lint processing trials. Conclusions These studies show that the yeasts living on cotton and other plants can breakdown the sugars tested. More importantly, some strains with greater rates of utilization have been identified. It was also encouraging that we found yeasts strains capable of breaking down several different sugars. These will be valuable as biocontrol agents. Project: 31 Biological Control of the Cotton Aphid Project Leaders: Kris Godfrey, Environmental Research Scientist, CDFA Biological Control Program, 916-262-1185 Michael McGuire, Research Leader USDA, ARS Shafter Research and Extension Center, 661-746-8001 Objective: The cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), is a persistent concern in cotton production in the San Joaquin Valley. Over the last 4 years, researchers at the California Department of Food and Agriculture - Biological Control Program and the USDA - Agricultural Research Service at Shafter have been conducting studies in an attempt to construct a natural enemy complex that would complement the existing natural enemy complex, thereby reducing cotton aphid densities. From these studies, 2 introduced parasites, Aphelinus near paramali and Aphel. gossypii Timberlake (Hymenoptera: Aphelinidae), have been identified as the initial components for the new natural enemy complex. In addition, studies are continuing on a fungus, Neozygites fresenii (Nowakowski) Batko (Zygomycetes: Neozygitaceae), to determine what role, if any, it will play in the new natural enemy complex. The research conducted this year has 2 aspects: establishment of the 2 introduced parasites across the San Joaquin Valley, and efficacy testing of the fungus. To establish Aphel. near paramali (ANP) and Aphel. gossypii (AG), a system of parasite nurseries was established in Kern, Merced, and Madera Counties. In Kern County, 6 parasite nurseries were established, and in Merced and Madera Counties, 2 nurseries were established in each county. Beginning in June in Kern County and July in Merced and Madera Counties, the nursery sites were visited once per week to assess aphid densities. Once aphids were found, releases of ANP and AG mummies began. From July 17 through August 24, 3,000 ANP and 7,200 AG mummies were released in Kern County. From July 19 through August 30, 2,500 ANP and 5,300 AG mummies were released in Merced and Madera Counties. Sampling of the aphid populations began 2 weeks after the initial release of parasites. To date, black mummies characteristic of aphelinid parasites have been recovered in all counties. In Kern County, both ANP and AG adults have been recovered, and in Merced and Madera Counties, only ANP adults have been recovered. The parasite releases and sampling will continue until cotton harvest. After harvest, habitats near the cotton field will be examined for aphids and parasites. Another biological control we are currently examining, in cooperation with scientists at the University of Arkansas is a fungus called Neozygites fresenii that attacks cotton aphids. In Arkansas, this fungus occurs naturally and causes widespread crashes of aphid populations and removes the need for insecticide applications. In September of this year, we have released the fungus in plots infested with aphids. Since most insect pathogenic fungi are dependent on moisture to spread, our experiment involved three irrigation treatments; in furrow, overhead sprinkler and no irrigation. Measurements of fungus establishment and spread will be made until defoliation. In related research, efforts are currently being made to obtain at least 2 new species of aphid parasites, Aphidius colemani Viereck (a strain from Chile) and Lipolexis oregmae (Gahan) (Hymenoptera: Aphidiidae), for testing in cotton in the San Joaquin Valley. It is anticipated that these parasites may be available late in the year. Project: 34A Remote Sensing in Cotton at Shafter, 2000 Project Leaders: Glenn J. Fitzgerald, Physical Scientist, (661) 746-8009 William R. DeTar, Agricultural Engineer, (661) 746-8011 USDA-ARS, Shafter, CA http://pwa.ars.usda.gov/uscrs Objective: Remote sensing can be an important tool for detecting within-field variability in the crop and soil. When flown regularly during the cropping season, this information can show temporal changes in crop and pest development. The Shafter Airborne Multispectral Remote Sensing System (SAMRSS) is the principal tool used to acquire remote sensing data for cotton research at Shafter. This is the third year SAMRSS has been flown in a light aircraft. Over 20 flights will be made in 2000 to characterize cotton dynamics in research plots and cooperating growers fields. Funding for flights was provided for a second year by a NASA EOCAP grant. SAMRSS consists of four digital cameras, three of which have special filters that allow only green, red, or near infrared light into each of the cameras. The particular wavelengths were chosen because they contain important information about plants, soils, and water. The fourth camera is a thermal camera that measures heat from the earth's surface. This camera can measure canopy temperature which is important in water stress studies. When water evaporates from a surface is takes heat with it causing the surface to cool. Thus, a healthy, transpiring plant has cooler leaves than the surrounding air. Conversely, as a plant undergoes water stress, the temperature of its leaves increases. Thus, if canopy temperature can be measured with remote sensing, it could become an input to an irrigation scheduling model for an entire field. During 2000 the remote sensing project at Shafter continued investigations on early detection of spider mites and water stress in cotton. Once images are acquired and stored on computer they are processed and analyzed. An image processing procedure was developed and tested on data collected in 1998 and 1999 and was found to consistently show mite damaged areas within the Shafter research plots. This will be implemented on 2000 data to test the ability of the procedure to detect mites for a third season. Additionally, in 2000 there was a heavy aphid infestation in the research plots. A procedure will be tested to detect these pests as well. Other work being performed at Shafter includes a cooperative effort with Opto-Knowledge Systems, Inc. (OKSI) for development of hyperspectral imaging technology in cotton. Hyperspectral remote sensing involves special instruments capable of acquiring images of cotton in dozens or hundreds of wavelengths. Thus it might be possible to develop, a spectral "signature" for mite damage that could be detected even before the human eye can see damage. This same technology could be used for water stress and other stresses in cotton. The figure at the end of this article shows an example of this technology. Spectra of mite damaged and healthy leaves are compared showing that there are distinct differences. These differences could lead to the ability to identify mite damage through hyperspectral imagery. This project was funded by a grant from Cotton Incorporated. A new project was begun, called Ag20/20 that will showcase the application of remote sensing technology to the management of a cotton farm. A 3800 acre farm near Lemoore was flown on over 20 dates in 2000 using the SAMRSS package and some flights had the OKSI hyperspectral imager on board. Although the images have not yet been analyzed, it may be possible to provide the grower with variable rate gypsum recommendations when combined with ground data collected from one of the fields on the farm. Other possible uses of this technology include, irrigation scheduling, pest detection, measurement of soil variability, and mid-season yield estimation. Additionally, geographic information can be added to the imagery from data acquired with global positioning systems (GPS) from locations identifiable in the images. Thus, anomalies seen in the images can be located on the ground. This could improve scouting and sampling efforts since maps and GPS receivers could be provided to field scouts to locate areas of interest located in the imagery. They could then pinpoint problems on the ground. Plans for the future include: 1) Continued development of a mite spectral "signature" that will allow detection of mites in any field from remotely sensed imagery and associated image processing techniques, 2) Continued development of a water stress model allowing estimation of water stress and canopy temperature from remotely sensed images, 3) Comparison of SAMRSS imagery with satellite, film-based infrared, and an inexpensive digital camera to determine the advantages and disadvantages of these technologies for the agricultural community. Click here to view spectrum of a mite damaged portion of a leaf compared to a healthy leaf. Project: 37A Approved Acala Varieties Evaluations: Multi-County Evaluations in the San Joaquin Valley Project Leader: Bob Hutmacher, UCCE Extension Agronomist, UC Shafter REC & Agronomy & Range Science, UC Davis Cooperators: B.L. Weir, Farm Advisor, UCCE-Merced County R.N. Vargas, Farm Advisor, UCCE-Madera County Dan Munk, Farm Advisor, UCCE-Fresno County B.A. Roberts, Farm Advisor, UCCE - Kings County S.D. Wright, Farm Advisor, UCCE-Tulare County B.H. Marsh, Farm Advisor, UCCE-Kern County M. Keeley, R. Delgado, S. Perkins, L. Banuelos, J. Wroble, T. Martin-Duvall Objective: Eight county test sites were selected for the 2000 Approved Acala trials. Weather during the March 10 through March 23 period was unsuitable for planting, with inadequate heat units for good probability of germination/ emergence. Soil temperatures and heat units improved after that period, and all plantings in these trials occurred between March 30 and April 26. Six of the tests are large-scale evaluations at grower sites in Kern, Tulare, Kings, Fresno, Madera and Merced counties. At these locations, most trials are 1300 foot run lengths, although some are as short as 800 feet and others as long as 2600 feet. Four replications were used at all locations. In addition, there are two smaller tests at both the University of CA Shafter Research and Extension Center and the West Side Research and Extension Center. Even in these smaller tests, plot sizes remain 300 feet in length by four rows in width. At the six large-scale county grower locations, a total of thirteen Approved Acala varieties were planted at each of the test sites. The Acala varieties included in the test include Maxxa, GTO Maxxa, DP-6211, Phytogen-33, DP-6207, SJ-2, GC-500, BR-9605, C-166, C-144 (Ultima), and three new releases for this year (GC-505, GC-507, and C-176 (Riatta RR). At the West Side REC and Shafter REC locations, two non-Acala CA Upland varieties (DPL Nucotton-33B, Stoneville BXN-47) will also be grown in this test (in addition to the thirteen Approved Acalas) for comparison purposes. Data collection includes the following: plant population evaluations and varietal comparisons in incidence of foliar symptoms of Verticillium. In addition, during the past few weeks, field evaluations have been done to compare crop progress in nodes above white bloom (NAWF). This data has been collected across all field replications, but has not been analyzed. Evaluations for incidence of Verticillium wilt symptoms was done on two additional dates during August and early September, and earliness will again be measured on as many varieties as possible (all if personnel and resources allow, fewer if necessary) as nodes above white flower, nodes above cracked boll, efficacy of defoliation following harvest aid applications, and timing of 30 to 50 % open boll. Plots in these large-scale trials will be harvested by commercial pickers, and weights determined using in-field weighing boll buggies. In the smaller trials at the Research and Extension Center locations, modified commercial pickers able to pick into sacks will be used, and individual plot weights will be determined on full row lengths. In both types of trials, six pound samples will be collected in all field replications at harvest, and samples analyzed for seed weight, gin turnout, with subsamples of lint sent to the USDA Classing Office for HVI analysis. Results will be reported at county meetings, annual meetings of the UC cotton group, at the annual Workgroup and Cotton Incorporated meetings. In addition, the information will be presented in the annual variety trial issues (yield and quality) of the CA Cotton Review Newsletter, and on the web site for cotton maintained by the University of CA (cottoninfo.ucdavis.edu). Basic yield results from the multiple locations in the 1999 Approved Acala Variety trials are as follows in Table 1. More complete results, including fiber quality data are available in the Variety trial information contained at the above-mentioned web site or in January and February issues of the "California Cotton Review". Project: 37B UCCE Approved Pima Variety Trials Project Leader: Bob Hutmacher, UCCE Extension Agronomist, UC Shafter REC & Agronomy & Range Science, UC Davis Cooperators: Ron Vargas, Bill Weir, Steve Wright, Bruce Roberts, Dan Munk, Brian Marsh, Mark Keeley, and Raul Delgado Objective: 1999 Studies The objectives of these studies with Pima are to evaluate approved varieties under different environmental conditions and management. The studies are part of a regional Beltwide Pima variety evaluation that includes Texas, New Mexico, Arizona and California, and are supported in part through the California Crop Improvement Association. Two UCCE Research Center test locations were used in the 1999 trials, the West Side and Shafter Research and Extension Centers of the University of California. The West Side location is in a clay loam soil with an soil profile largely unrestricted to rooting to a depth of 6 feet or more, while the Shafter location is a sandy loam soil with surface infiltration problems which limit mid- and late-season irrigation water penetration and effective rooting depth to 2 to 3 feet in the mid- to late- season. In order to provide a reasonable limit on the number of varieties in the tests, the entries include newly-approved varieties for the current year, varieties released last year that are in their second year of testing, plus the top 4 or 5 previously-approved varieties (in terms of planted acreage). The new varieties are the focus of the tests, but they only remain in the tests for the first two years following release unless that variety moves into the top 4 or 5 varieties in planted acreage. Released varieties also may not show up in the tests if the seed companies request that the variety is for a special market and don't want it in multiple location testing, or when inadequate seed supplies exist for large-scale testing. Objectives were also to evaluate varieties under different environmental conditions and management. The number of test locations was expanded considerably in 1998 and 1999 in response to increasing Pima plantings and the need for a broader base of information on varietal performance. Pima variety trials had limited financial support in 1999, supported largely from general research funds of UCCE Specialists and Farm Advisors, and in part through grants from the California Crop Improvement Association. In 2000 the Supima Association provided some supplemental funding to assist in running these trials. Two test locations (UCCE Shafter and West Side Research and Extension Ctrs.) were used with 8 varieties in the 1999 trials, plus four additional locations where growers agreed to include 6 varieties. The four large-scale test sites were on grower-cooperator locations in Kern, Kings, Fresno and Merced counties. Approved Pima varieties included in the tests are shown in Table 1. Results for the six varieties grown at five locations are shown in Table 1, data for the eight varieties at two locations (West Side and Shafter REC) in Table 3, and yields at the Fresno County saline site are in Table 3. Fiber quality information from the trials is shown in Table 2. This project gives growers a continuously-updated comparison of newly- available varieties versus those varieties which have been available for one or more years. This data base has been significantly improved by increasing the number of test locations to include 6 sites, instead of the 3 locations used in 1996 or 2 locations used in 1997. Grower confidence in the utility of these tests has been improved with this marked increase in number of locations, and we hope to continue this expanded testing in the future. Across all locations and varieties, 1195 lbs of lint per acre were produced in the Pima Approved Variety Trials this year, compared with 791 lbs/acre (1998), 1703 lbs/acre (1997) and 1256 lbs/acre in 1996 trials. Planting dates in 1999 trials ranged from April 12 to April 27, and plants in most locations suffered from delayed development and flowering due to cool conditions that prevailed into mid-June. Pest problems (lygus in some locations, spider mites in three sites) were causes of moderate early and mid-season losses in at least three locations. Data from multiple years should be considered in making variety choices, as one year's data may not represent long-term performance. For instance, CH-252 performance in yield tests has been similar to S-7 in many locations and numerous years prior to 1999, but 1999 yields were significantly lower. 2000 Studies Four county test sites were selected for the 2000 County Approved Pima Variety trials in addition to the two UCCE Research Center sites. Test plots were planted between March 28 and April 16. Four of the tests are large- scale evaluations at grower sites in Kern, Kings, Fresno, and Merced counties. At these locations, trials range from 800 foot runs to 2600 foot run lengths. Four replications were used at all locations. In addition, there are two smaller tests at both the University of CA Shafter Research and Extension Center and the West Side Research and Extension Center. Even in these smaller tests, plot sizes remain 300 feet in length by four rows in width. Project: 39 Updated Guidelines for Nitrogen Management in Acala Cotton Project Leader: Bob Hutmacher, UCCE Extension Agronomist, UC Shafter REC & Agronomy & Range Science, UC Davis Robert L. Travis and Bill Rains, Agronomy and Range Science, UC Davis Cooperators: B.A. Roberts, B.H. Marsh, Bill Weir, R. Vargas, S. Wright, D. Munk, M. Keeley, R. Delgado, S. Perkins, L. Banuelos, J. Wroble, T. Martin-Duvall Objective: The response of Acala cotton in California to a range of applied N treatments are under investigation in a multi-year, multi-site experiment. Goals are to identify crop growth and yield responses to applied nitrogen and to provide information to better assess the utility of soil residual N estimates in improving fertilizer management. Results obtained during the first four years of this project have shown positive responses to increases in applied N across the 50 to 200 lbs N/acre range in only 10 out of 31 test sites (8 locations by 3 years, 7 locations in fourth year). These findings indicate that while it is still true that 50 to 60 lbs N are needed per bale of cotton produced under CA conditions, more efforts should be put into identifying plant N requirements that can be met from residual soil N, rather than solely from fertilizer N applications. Incentives to consider adjusting nitrogen management practices for cotton and other CA crops come from several areas of concern. It has been recognized for many years that mid and late-season nitrogen management has an impact on progress toward defoliation and harvest. High nitrogen levels can increase problems with some late-season pests (silverleaf whitefly, aphids) that can influence lint quality. Higher than desired nitrogen levels during bloom and early boll filling can also promote vegetative development at the expense of fruit retention under some conditions. An additional area of concern in recent years has been the fate of nitrogen applied in excess of plant requirements. If plants grown in the rotation sequence do not have deep enough roots to intercept applied and residual nitrogen, its eventual movement through the soil profile has been shown to cause nitrate contamination of shallow groundwater in a wide range of conditions Materials and Methods. In the first full year of the multi-site studies (1996), the fertilizer treatments ranged from a low of 50 lbs total N/acre to 200 lbs N/acre. Four treatments of 50, 100, 150 and 200 lbs N/acre were applied in late May (prior to the first within-growing season irrigation), and in three supplemental treatments (50, 100 or 150 lbs N/acre initially applied), a second N application of 50 lbs N/acre was applied in June just prior to the second (pre-flower) within- season irrigation. In 1997 to 2000, the experiments were simplified down to four basic treatments (50, 100, 150 and 200 lbs N/acre) due to the lack of crop growth and yield responses to split-application treatments as well as grower concerns over the practicality and expenses involved in split applications and potential for damage to plants associated with getting application equipment in prior to the second irrigation. Soils were sampled at five locations per replication to a depth of 8 feet at all sites for analysis of soil NO3-N, NH4-N, PO4-P and K. Samples were collected in 1 foot increments to a depth of 4 feet, and then in twofoot increments to 8 feet depth. While there were four field replications used in determining yield, growth and petiole nutrient responses to treatments, only the first three field replications were used in soil tests. Elemental analyses were conducted on both KCl extracts (which were frozen after collection until analyzed) as well as on composite, air-dry samples run to complement data from soil extracts. Petioles were collected at intervals representing a range of growth stages at all sites. Results and Summary of Data Soil Nitrate-N Levels - Treatment Effects. Soil samples were collected to a depth of 8 feet in May (or in several cases, April) (post-planting) in all years of the trials. This data is far too extensive to go over here. In addition, there are recognized limits in interpreting this type of data, since values change over time with processes such as mineralization and denitrification. However, these changes in soil NO3-N over time still represent a general index of soil changes in N status resulting from crop uptake and other processes / losses during the growing season. Soil data varies quite widely across years and site, but some generalizations can be discussed. Soil NO3-N levels in the upper 2 feet of the profile at the Spring 1998 sampling ranged from a low of 37 lbs N as NO3-N per acre at the Shafter REC site to 103 lbs N as NO3-N per acre at the Madera County site in spring of 1998, with an 8-location average of about 65 lbs N as NO3- N/acre. The range in soil sample spring nitrate levels was even greater in 1999 and again in 2000, with the highest N site having over 200 lbs N as NO3-N available in the upper two feet of the profile ( in a field where cotton planting followed corn). Soil NO3-N levels in the upper 2 feet of the profile at the Spring 1999 sampling ranged from a low of 36 lbs NO3-N per acre in the low N treatment at the West Side REC to a high of 241 lbs NO3-N per acre at the Madera County site. Most other sites in the spring upper 2-foot sampling in 1999 ranged from about 45 to 110 lbs NO3-N per acre in the upper 2 feet of soil (data not shown). Data in general has indicated that most net depletion of soil NO3-N was seen in the upper four feet of the soil profile. It could be argued that this depletion could result from leaching losses as well as denitrification, but the measured presence of significant root mass at depths down to 6 to 7 feet indicates that plant uptake is another reason for net depletion even at the 4 to 8 foot zone. Most other sites had root activity primarily in the upper 3 to 4 feet of the soil profile. As levels of applied N increased at most sites, soil NO3-N levels in the 4 to 8 foot zone of the soil profile generally increased. If the cotton or subsequent crops cannot access this N source, it would be subject to leaching losses if moved further by water moving through the soil profile. Lint Yields. It is important to get a multi-year, multi-location perspective in analyzing lint yields across these nitrogen treatments (yield tables on following page). Some generalizations are possible for each year. 1996 Moderate yields across all sites. In all but one of the eight field sites used in 1996, there were no significant effects of nitrogen treatments on lint yields 1997 more locations showing significant yield reductions with N applications of 50 to 100 lbs N/acre Yield responses to applied N were not observed in locations with low initial soil NO3-N levels 1998 a very difficult production year, with cool and wet spring conditions, delayed growth, and abnormal progression of crop development associated with early cool conditions, hot late summer conditions which influenced flower and boll retention, and a cool fall which delayed progress toward defoliation and harvest. Yields were extremely low in fields across most of the San Joaquin Valley. Under these low yield potential conditions, less N is required 1999 Much higher yields at most study sites in 1999 put a higher N "load" on the plants (higher need for N to meet fruit development requirements) Future Plans - Related Studies. This field project was again conducted in 2000 in order to strengthen the data set and complete the field portion of this project. Project: 40 SJV Acala and Pima Testing Program Project Leader: Dick Bassett & Shane Ball, Cotton Specialists Jim Bergman & J. Scott Perkins, Ag. Techs. (661) 746-8028 Objective: Acala Six of the entries in the regular large-scale tests completed the third year of testing and thus were eligible to be considered for approval as SJV Acalas (Table 1). Five of them were ultimately approved by the SJV Cotton Board in March. Three are transgenics, the first such cottons to enter the testing program. Two of these contain the gene for resistance to Roundup herbicide. These are CPCSD's C-176, which has a Maxxa background, and Germains GC-9646. These have been renamed and will be marketed as Riata and GC- 546RR respectively. The third transgenic is GC-9645, renamed GC-545BG. It contains the BT gene for worm resistance. The two non-transgenics that were approved are GC-9642 (renamed GC-507) and GC-9643 (renamed GC-505). The C-176 (Riata) significantly out yielded the standard in 1999, but not in 1998. Very few measurable differences were found in growth and fruiting characteristics, fiber quality or spinning performance when compared to the standard. The two Germain transgenics were below the Maxxa yield at most locations, but both possessed excellent quality traits, especially the GC-9646 (GC-546RR). The latter variety is characterized by a shorter, more determinate growth and fruiting pattern. The two conventional cottons, GC- 9642 and GC-9643, lint yields were the same as Maxxa, although there were response differences in 1998 and 1999. The fiber and yarn quality characteristics were equal to or slightly better than Maxxa. The DP6100RR was inconsistent in yield performance and was not approved by the SJV Board, primarily over concerns about substantial reductions in yarn strength, especially when spun into the fiber count yarns. Pima The UA-5 fell below the S-7 yield when averaged over all test sites, but the difference did not reach statistical significance (Table 2). Any yield deficits are primarily a result of a lower lint percent and gin turnout. It grows taller, is more indeterminate and somewhat later maturing than the S-7. This may account for its relatively poorer showing in the 1998 shortened season than in the other two years. The more vigorous, indeterminate growth characteristics make it less susceptible to the premature bronzing and leaf senescence that often occurs with the S-7 and similar types. Overall fiber and yarn qualities are improved. The slightly lower micronaire is a result of improved fineness, rather than immaturity. These fiber characteristics translate into a stronger and more even yarn. Project: 43 Management of Key Cotton Arthropod Pests with Insecticides and Acaricides Project Leader: Larry D. Godfrey, Entomology, UC Davis (530) 752-0473 Kevin Keillor, Shafter REC & Entomology, UC Davis (661) 746-8032 Objective: INTRODUCTION: Insecticides and miticides represent a large portion of the budget required to grow cotton in the San Joaquin Valley. Lygus bugs, cotton aphids, spider mites, and silverleaf whiteflies are key pests of SJV cotton. In addition, Lepidopterous larvae, particularly beet armyworm, appear to be an increasing problem. Research-based, unbiased information needs to be available to growers and PCAs so that they "get the most bang for the buck" in pest control activities. These pests, depending on the year, reduce cotton yields up to 15% with each individual pest inflicting as high as 4-6% loss. Losses from arthropod pests and costs of control were on an increasing spiral from 1994 to 1997; however, from 1998 through 2000 these values were more moderate. Insecticides are an important part of integrated pest management programs. However, in order to refine and to advance IPM programs, research on the role of insecticides needs to continue. Three primary areas are of importance 1.) incorporating new insecticides into IPM programs including the effects of these materials on non-targets, efficacy on pests, yield impacts, etc., 2.) efficacy of registered materials on pest populations as a means of forewarning the development of resistance and determining the cost- effectiveness of products, and 3.) the impacts of registered materials on natural enemies in order to thoroughly evaluate product fit into effective IPM programs. Changes in registration guidelines, such as the Food Quality Protection Act, also alter the availability insecticides and this hastens the need for additional research. RESEARCH AND EDUCATIONAL OBJECTIVES: 1.) Develop an expanded database on the current efficacy of labeled/recommended insecticide and acaricide products on key insect and mite pests of cotton in the San Joaquin Valley and record the impact of these products on beneficial arthropods with the objective of providing better guidelines on pesticide use. 2.) Evaluate the effectiveness of new candidate insecticide/acaricide products on key San Joaquin Valley cotton pests, the impact of these new compounds on populations of beneficial arthropods, and devise strategies for utilization of these new products. 3.) Provide outreach to growers, PCAs, UCCE personnel, and others in the cotton industry through appropriate field days, meetings, and publications. PROJECTS: Replicated field plots were established to evaluate the effect of registered and experimental compounds on cotton aphids at the Shafter Research and Extension Center. Similar studies on spider mites and lygus bugs were conducted at the West Side Research and Extension Center. Aphid treatments were applied on 3 August on plots measuring 6 rows by 70 feet (4 replications of each treatment). Pretreatment aphid populations averaged 76.6 per leaf. Efficacy was evaluated at 3, 7, 14 and 21 days after treatment. Selected treatments were re-applied and further evaluations were conducted. Treatments examined included registered materials (e.g., Provado, Lorsban, Furadan, Thiodan, Vydate), experimental materials (Actara, Fulfill, Calypso, Assail), and Bollwhip (a neem based product). Post-treatment populations were as high as 377 aphids per leaf. Data are being summarized and analyzed at this time. Project: 44 Interaction of Cotton Nitrogen Fertility Practices and Cotton Aphid Population Dynamics Project Leader: Larry D. Godfrey, Entomology, UC Davis (530) 752-0473 Jorge Cisneros, Entomology, UC Davis (530) 752-0473 Kevin Keillor, Entomology, UC Davis (661) 746-8032 Bob Hutmacher, Shafter REC & Agronomy & Range Science, UC Davis Cooperators for Complementary Studies Conducted in Grower Fields: Pete Goodell, UC IPM Project, Kearney Agricultural Center Brian Marsh, UCCE Kern County Bruce Roberts, UCCE Kings County Steve Wright, UCCE, Tulare County Dan Munk, UCCE, Fresno County Ron Vargas, UCCE, Madera County Bill Weir, UCCE, Merced County Objective: During the last 10 years, the cotton aphid (Aphis gossypii) has developed from a non-pest to one of the most significant insect pests of California cotton. This insect pest has joined lygus bugs, spider mites, silverleaf whitefly, and beet armyworms as a key arthropod pest of California cotton. The most significant cotton aphid outbreaks occurred in 1997; an estimated 3.5% yield loss occurred which was estimated at $34 million in crop loss and an additional $38 million in control costs were incurred to "manage" this one insect pest. Cotton aphid infestations damage the cotton crop in several ways. On vegetative stage cotton, aphid feeding stunts the plant growth. However, only the highest, most prolonged early-season infestations result in a yield reduction or delay in crop maturity. During the mid-season (July to mid-August) cotton aphids reduce cotton lint yields since the aphids act as a significant sink, competing with the bolls, for carbohydrates. The late-season infestations (mid-Aug. to Sept.) are problematic because the aphids deposit honeydew on the exposed cotton lint, which reduces the lint value. Reasons for this change in pest status of cotton aphid are unclear; however, one of the most noticeable changes in cotton production over the last 10-15 years is the use of a plant growth regulator instead of irrigation and nitrogen deficits to limit early-season cotton vegetative growth. This has allowed cotton production practices in the SJV to evolve to higher nitrogen fertilization and irrigation inputs. Host plant conditions including high nitrogen and adequate moisture are generally optimal for aphid population growth and development. Insecticide use patterns (some of which directly or indirectly affect aphid populations), cotton varieties, the crop mosaic in the SJV, and other factors may also be acting upon aphid populations. Several species of insects have been shown to respond positively to higher levels of nitrogen, and similarly, small plot studies have shown more cotton aphids in highly nitrogen fertilized plots compared with low fertility areas. The idea of balancing the amount of nitrogen needed for optimal cotton yield with the level required to mitigate cotton aphid population build-up is the goal of this project. Utilizing cultural control measures such as nitrogen management could play an important role in cotton aphid management. Biological control, predators and parasites, of mid- and late-season aphid outbreaks is only moderately effective. Relying on insecticides for aphid control adds undesirable production costs and also promotes the development of insecticide resistance in this aphid pest. Therefore, additional non-chemical control measures would fill an important void. Objectives 1) Study the influence of cotton nitrogen fertilization practices on cotton aphid population dynamics and seasonal buildup in cotton. 2) Identify specific crop carbohydrate and N status associated with higher aphid densities during specific crop growth stages. Projects Two specific studies were conducted at the Shafter REC in each of 1999 and 2000. In addition, the REC was included as a location in the "grower field" strip tests evaluating the effects of nitrogen on cotton yield as well as on cotton aphid populations. Nitrogen Effects on Aphid Biology: Cotton aphid reproduction, survival, and development were studied under treatments of 0 (=20 lbs. residual in soil), 50, 100, 150, 200, and 250 lb./A nitrogen (ammonium sulfate fertilizer) in 1999 and 2000. There were also treatments of 200 lb./A nitrogen split in 4 applications (applied every two weeks), an alternate source of nitrogen (200 lb./A of urea), and a "balanced" fertilization (200 lb./A nitrogen + 100 lb./A K2O) in 1999. In 2000, the nitrogen rate treatments studied in 1999 were used, as well as several combinations of nitrogen and potassium were studied. Cotton aphids from a laboratory colony were placed on to five to eight plants in each plot on July 16 and July 10 in 1999 and 2000, respectively. These aphids were enclosed in single-leaf cages and were monitored daily for their survival, fecundity, and generation time. Results from detailed studies on the effects of nitrogen on cotton aphid levels showed that, for the first generation of aphids exposed to the conditions, the aphids from high nitrogen plots, especially the ones reared on plants fertilized with ammonium sulfate only, produced significantly more offspring and had shorter generation times, i.e., the time needed to go from a new- borne aphid to an adult, than the aphids from low nitrogen plots. Generation times ranged from 12.3 days (0 lbs./A nitrogen) to 9.3 days (250 lbs./A nitrogen). Similarly, the number of offspring per adult averaged 1.7 and 5.3 with the low and high nitrogen regimes, respectively. Conversely, potassium seemed to have a detrimental effect on the aphid processes. Thus, aphids from the treatment that had the "balanced" fertilization (200 lb./A nitrogen + 100 lb./A K2O) had a lower fecundity and longer generation time than individuals from the two highest nitrogen treatments (200 and 250 lb./A of ammonium sulfate). No differences in aphid survival were found among treatments; however, the overall survival was low (about 33%). Data from 2000 are still being summarized. However, the initial results suggest that the aphids developed faster (~6 days from nymph to adult in the high nitrogen) and produced more offspring (more than 20 per adult) in 2000 than in 1999. This corresponds with the aphid outbreak observed in the natural field population in 2000. Nitrogen X Insecticide Aphid Study: In a second study at the REC, nitrogen rates ranging from 0 to 200 lbs./A were set-up and at the onset of aphid build-up, insecticide treatments of Capture and Provado (and an untreated) were placed in each nitrogen treatment plot. In 2000, a 200 lb./A nitrogen + 150 lbs./A K2O was added. After establishing the fertility by insecticide combinations, aphid populations were monitored weekly via leaf samples. For the nitrogen by insecticide study, at 3 weeks following the insecticide application, in the untreated plots, aphid numbers increased slightly across the increasing nitrogen levels (10.9 to 24.8 aphids per leaf from 20 to 200 lbs./A N). Aphids populations in 1999 did not develop until late August/early September. At this time, the applied nitrogen rates had undoubtedly been greatly altered and/or depleted by the growing crop. This probably muted the effect. Provado controlled the infestation which is in agreement with its activity spectrum. At 0 to 100 lbs./A N, the aphid population was 50-75% higher in the Capture-treated plots compared with untreated. However, at 150 and 200 lbs. N/A, there were 3 and 4 times, respectively, more aphids in the Capture plots compared with the untreated. In 2000, the naturally- occurring aphid population in the nitrogen by insecticide plots was much higher than in 1999 and populations developed earlier (treatments were applied on 26 July). Data are still being collected and results are being summarized/analyzed but some treatments averaged as high as 350 aphids per leaf. Large Plot Strip Tests: Replicated field studies were set up and managed by the Cotton Agronomist and Cotton Farm Advisors in grower fields and contributed to the overall goals of the REC studies. The treatments were set up in strips, generally 8 rows wide x the field length (up to 1/4 mile long) x 4 blocks. Target nitrogen rates in these studies were 50, 100, 150, and 200 lbs. N/A; the lowest rate utilized the residual soil nitrogen and therefore varied across locations. The three highest rates were the residual plus the appropriate amount of applied N generally in June. Field sites were located in Tulare Co., Fresno Co./West Side Research and Extension Center, Kings Co., Merced Co., Madera Co., and Kern Co. (Shafter Research and Extension Center and in a grower field). Planting dates varied across locations but were generally in mid-late April in 1999 and early April in 2000. Cotton aphid populations were sampled at weekly intervals from each plot from July to September. A ten-leaf sample, fifth main stem node leaf from the top, was used. Aphids were counted with the aid of 50X magnification. Aphid number, separated into color morphs and winged vs. unwinged aphids, was recorded for each sample. In the grower field strip studies, cotton aphid populations were generally low in 1999 and moderate in 2000, but levels responded to nitrogen regime. Populations generally built-up late in the season at a time when the nitrogen levels had likely largely equilibrated or at least were greatly altered compared with the treatment regimes. In 1999, aphid populations developed in six of the eight sites. The highest aphid density was ~33 per leaf. However, at all the six sites with aphids, there was a trend with more aphids at the higher nitrogen levels; a 3-4X range was commonly seen from the 50 to 200 lbs./A treatments. Similarly, the percentage of leaves with aphids also responded positively to nitrogen level. Project: 45 California Upland Cotton Advanced Strains Variety Trials Project Leader: Bob Hutmacher, UCCE Extension Agronomist, UC Shafter REC & Agronomy & Range Science, UC Davis Cooperators: Mark Keeley, Raul Delgado, Scott Perkins, Shafter & West Side REC staff, Brian Marsh, Dan Munk, Steve Wright, Bruce Roberts, Bill Weir, Ron Vargas Objective: Project Summary A series of variety trials (both large-scale grower fields, plus two or three screening trials in small plot studies) were done on CA Upland cotton varieties in the San Joaquin Valley. This report only covers the "Advanced Strains" variety trials on the CA Upland varieties, with these trials conducted only at the West Side and Shafter REC locations. Overall goals of the project are to identify field performance in yield and quality of varieties seed companies are bringing in to the SJV region. This information is designed to supplement that provided by the San Joaquin Valley Cotton Board (for Acala and Pima entries in the Approved variety trials) plus the UCCE Farm Advisor tests on Approved Pima and Approved Acala entries. The "Advanced Strains" trials supplement the "Large-Scale CA Uplands Variety Trials" , providing an opportunity for field trials with varieties where there is little prior performance information in the San Joaquin Valley. Seed availability is often quite limited on some of these varieties, so the plot sizes and seed requirements are small enough to allow testing to begin prior to large-scale seed increases. The tests do not overlap those underway in other SJVCB or UCCE trials. Data collected includes the following: final mapping will be done on select varieties at all locations, with all yields machine-harvested and weighed. In- season and final mapping includes data on height, number of nodes, vegetative nodes, percent bolls at positions 1, 2, 3 and greater, identification of the 95% zone for yield production, percent retention of fruit in the first five fruiting branches, and the number of bolls per plant. Yield data and a six pound seedcotton sample will be collected in all plots in 2000 as in 1999. Seedcotton samples will be ginned at the UC Shafter Research and Extension Center gin to determine gin turnout, lint percentage and seed weights. Results will be tabulated by locations and statistically analyzed using analysis of variance and mean separation procedures. Summaries of data will be done by individual locations and over locations. Verticilium wilt incidence will be evaluated in 25 plants per field replication in the as many varieties as time and labor allows. As we did following the 1999 season, results of the trials will be reported in winter meetings of the UCCE Specialist and Farm Advisors, and will be printed in the CA Cotton Review (January or February issue) as well as in county newsletters and meetings. Plans for 2000/2001 are to include the yield, final mapping and lint quality data in a web site that will be more accessible for grower and industry review, with this information posted as soon as possible after February 1 each year. This posting on a UCCE web site was initiated in 2000. Following is some information collected in the Advanced Strains trials in 1999 (Table 1 for yield summaries, Table 2 for lint quality summary). This is similar to the type of information we will continue to collect in 2000 and 2001. The data shown concentrates on yield and quality information, and does not show data collected in mapping work, Verticillium wilt evaluations or evaluations of earliness and ease of defoliation (that work will be reported elsewhere for the 2000 data after analyses are complete. Project: 46 Upland Cotton Varietal Response to Short-Season Versus Long- Season Management Practices Project Leader: Bob Hutmacher, UCCE Extension Agronomist, Shafter REC & Agronomy & Range Science, UC Davis Steve Wright, Farm Advisor, UCCE Tulare County Brian Marsh, Superintendent, Shafter REC and Farm Advisor, UCCE Kern County Cooperators: Mark Keeley, Raul Delgado, Scott Perkins, Lalo Banuelos Objective: The introduction of some potentially widely-different varieties which were developed in environments outside of CA in most cases represents a real challenge in terms of identifying the most suitable management practices for best results under SJV conditions. These "newly-available" varieties are now available in CA under the designation "CA Upland". These varieties in many cases represent an opportunity of unknown proportions to CA cotton growers. Tests on grower fields in 1998 were largely planted very late under the governor's emergency exemption, so may or may not truly represent the potential of these varieties in improving grower profitability. It was considered vital that we get some UCCE testing programs underway in 1999 and beyond that will begin to answer some questions regarding management approaches with these varieties. Information is needed by the growers to make some hard decisions on variety choices. It is important that at least some of these tests occur under well-controlled conditions so that assessments can be made of the likely range of varietal performance in both yield and quality characteristics. Varietal evaluations important to the growers and industry include not only yield, but quality characteristics of the new variety choices with potential to impact both the reputation of CA SJV cotton and potentially the impact of the premium price now paid to growers of "Approved Acala" varieties approved by the San Joaquin Valley Cotton Board. The evaluations begun at the WSREC and Shafter REC in 1999 began an evaluation of the impact of combinations of two planting dates, two irrigation treatments and two growth regulator regimes on growth, yield and quality responses of three cotton varieties (one approved SJV Acala and two CA Upland varieties) representing some of the range of expected differences in growth habit and estimated maturity. Data from this project will eventually be described in the CA Cotton Review, and will also be mentioned in crop advisory updates printed in handouts at Production meetings. Data will also be presented at cotton field days at both the Shafter REC and West Side REC. Project results will also be featured in oral presentations at the Cotton Workgroup meetings in December, and in the session and Proceedings of the jointly-sponsored CA Cotton Growers Association Winter Meeting / UCCE Winter Production Management Seminar when adequate data is available for presentation. Protocol Used: Some of these varieties can be classified as having the potential to be "early- maturing", "medium season", or "full-season" varieties. While years like 1998 can demonstrate the utility of "short-season" varieties in making a good crop within the constraints of a limited growing season, there are many years in CA where the growing season duration is much greater than in 1998. We feel that it is important to identify the "plasticity" of some varieties representative of part of the range of growth habits, maturity classes under management practices covering a range of strategies, including: (a) conditions typical of a shorter growing season requiring a more compressed fruiting period (perhaps more water stress and earlier or higher rates of growth regulator) (b) long-season management where goals may be to build a larger framework / more fruiting sites, with a different management scheme involving less water stress / more growth regulator application which are started later, and, if boll load warrants, consideration of additional foliar fertilizer applications during flowering to "push" the plant under long-season conditions (c) with two planting dates, two irrigation / fertilizer regimes and two growth regulator treatments and the eight combinations (2 x 2 x2 ), there can be a range of conditions in between the extremes mentioned in (a) and (b) above 1999 Results/2000 experiment. In both 1999 and 2000, this test was replicated at both the Shafter and WSREC locations. Both fields were planted on 40 inch row spacing. Trials initiated in 1999 at the West Side and Shafter REC's begin to look at the impact of combinations of two planting dates (mid-April versus early May), two irrigation treatments and two growth regulator regimes on growth, yield and quality responses of three cotton varieties (one approved SJV Acala (Maxxa) and two CA Upland varieties (Germains GC-204 (early-mid- maturity) and DPL Nucotton 33B (mid-maturity)). These varieties represent at least some of the range in expected differences in growth habit and estimated maturity across the CA Upland varieties when compared with an Acala standard. The following points are worth noting in the 1999 results: · Irrigation treatments with variable irrigation amounts and timing were achieved at both field research sites, resulting in different timing and degrees of water stress across treatments (IRRIG TRT #1 was irrigated at the standard -16 bars first irrigation / -18 bars subsequent irrigation for leaf water potentials in UCCE recommendations) - (IRRIG TRT #2 was irrigated the same for the first irrigation, but subsequent irrigations were delayed to achieve about 2-3 bars lower leaf water potential prior to irrigations) · Growth regulator treatments differed in the timing and amount of mepiquat chloride applications, based upon the use of 4th-5th internode length measurements for the timing in short-season management versus first bloom timing in longer-season management treatments · Plant monitoring data showed some differences in factors such as plant height and node development across treatments, with varietal interactions, but the data has not been fully analyzed at the time of preparation of this proposal · Differences in yield were seen across treatments, with the most consistent yield improvements with the earlier planting date, with planting densities approximately 40,000 to 45,000 plants per acre instead of 75,000, and with earlier irrigation termination (under 1999 conditions). Results from primary treatments for each variety at the Shafter REC and West Side REC locations are shown in Table 1, showing lint yield averages for all three varieties individually. Data for the West Side REC location showed more dramatic differences with planting date, irrigation and plant density treatments than at the Shafter REC location. Lint yields were generally significantly better with the earlier planting date in all three varieties, and with the delayed irrigation in the two CA Uplands but not with Maxxa. Plant density impacts were more complicated, with higher densities resulting in reduced yields in the earlier planting date treatments at high yield locations, but in similar or higher yields under the lower yield potential conditions at Shafter or with delayed plantings. 2000 project results. Very good plant populations were achieved in both field trial locations this year, which provided adequate numbers of plants to allow thinning to the two planned plant populations (40,000 to 45,000 plants per acre versus 70,000 to 75,000 plants per acre). For 2000, the three varieties utilized in the study include Maxxa (an Acala standard variety for comparison purposes), Germain's GC-204 (a relatively short-season/mid-season variety - changed from 1999); and DPL Nucotton-33B (a mid-season variety grown on quite a few acres in CA in recent years). Project: 52 Narrow-Row (Double-Row 30 Inch and Double-Row 40 Inch) by Variety Trial Project Leader: Bob Hutmacher, UCCE Extension Agronomist, UC Shafter REC & Agronomy & Range Science, UC Davis Bill Weir, Farm Advisor, UCCE Merced County Brian Marsh, Superintendent, Shafter REC and Farm Advisory, UCCE Kern County Cooperators: Mark Keeley, Raul Delgado, Scott Perkins Objective: Studies were initiated in 1999 and continued in 2000 to evaluate the responses of three cotton varieties (two CA Upland and one Acala) to several different combinations of row spacings and plant density. These studies were initiated as an extension of studies initiated by Dr. Bill Weir and representatives of San Juan Ranch (Daniel Burns) and Bowles Farms (Ken Van Loben Sels) at farm sites in Merced County. Preliminary studies have been done in 1998, 1999 and 2000 on private farms in Merced and Madera County, and these sites at the West Side and Shafter Research and Extension Centers were set up as locations for trials under conditions where a fairly high level of control over inputs and pest control measures could be handled. Shown in Table 1 is the 1999 data at the West Side REC, while Table 2 has 1999 data for the Shafter REC location. 1999 Results. In the West Side REC trial in 1999, the plant populations achieved were lower than the design plant populations. In the 1 row / bed planting configuration, the planting rate called for a final plant population of about 45,000 plants per acre, while an average of 33,100 plants per acre were achieved (averaged across all three varieties). In the 2 row per bed configuration where a final plant population of 75,000 plants per acre was the target population, an actual average population of 54,700 was achieved. At the Shafter REC trial in 1999, the plant populations achieved were also somewhat lower than the design plant populations, although not as low as at the WSREC location. In the 1 row/bed planting configuration, the planting rate called for a final plant population of about 45,000 plants per acre, while an average of 41,500 plants per acre were achieved (averaged across all three varieties). In the 2 row per bed configuration where a final plant population of 75,000 plants per acre was the target population, an actual average population of 59,200 was achieved. In both 1999 and 2000, the double-row and single-row plantings at the West Side REC location were all on 40-inch beds, while the trials done at the Shafter REC were on 30-inch rows. All of the field trials in the Merced County grower locations were on 30-inch beds. In the 1999 trials at Shafter REC, double-row plots out yielded single-row in each variety by 8% or more, while yield differences were not significant at the West Side REC site. 2000 Results. Identical field setups were used for these trials in 2000, and data collection and plans for harvest and lint quality evaluations are the same as in 1999. Final plant mapping will again be done to help analyze affects of treatments on boll distribution on a plant basis. Results of these studies will be reported either in CA Cotton Review articles or at the Winter UCCE Production meeting held annually in February of each year. Project: 54 Agronomic Test of Improved Fiber Quality Pima Germplasm Project Leader: Richard Percy, Research Geneticist USDA-ARS, 602-379-4221 Bob Hutmacher, UCCE Extension Agronomist, UC Shafter REC & Agronomy & Range Science, UC Davis Objective: Sources of superior fiber strength and length exist within extra-long staple Gossypium barbadense germplasm. However, these sources lack heat tolerance, are later maturing, have lower yield potentials, or are otherwise unadapted to the southwestern United States. A breeding project was initiated several years ago to incorporate superior fiber length and strength into a heat tolerant, earlier maturing, higher yielding Pima background, and to widen the genetic base of Pima germplasm. A Sea Island cotton, St. Vincent, and an Egyptian cotton, Giza 70, were hybridized with an early maturing Pima strain, P62. Progeny of these hybridizations were intercrossed among themselves and crossed to another source of high fiber strength, 8810. Selected progeny of this second round of hybridization are now being evaluated in replicated testing to identify superior lines for release to private and public breeding programs. In 1999, ten progeny lines were evaluated in replicated tests at Maricopa and Safford, AZ. Preliminary analyses of results indicate that the lines possess fiber that is 4-5 g/tex stronger and a tenth of an inch, or more, longer (approx. 1.48-1.55 inches) than Pima S-7. Fiber yield among the 10 lines varied from 110% to 66% of Pima S-7 when averaged over the two locations. The majority of lines tested were equal to, or shorter than, PS-7 in plant height. All lines exhibited heat tolerance superior to the Sea Island St. Vincent and Giza 70 parents and comparable to PS-7 at Maricopa, AZ. Some deficiencies were noted within the lines, among these being lower lint percentages. Two or three of the lines exhibit tight, non-fluffed lint within the boll and weak stems. All lines are being evaluated for yield, fiber quality, and agronomic characteristics at Shafter, CA in 2000. The best three or four germplasm lines will be determined using data collected at the three test sites in Arizona and California in 1999 and 2000. The USDA-ARS, the Arizona Agricultural Experiment Station, and the California Agricultural Experiment Station will jointly release the best lines to public and private breeding programs in the winter of 2001. Project: 55 Root-Knot Nematode Management in Cotton Project Leader: Peter B. Goodell, IPM Advisor, Statewide IPM Project, Kearney Ag Center Phillip A. Roberts, Professor, Nematology, UC Riverside Chuck Haas, SRA, Kearney Ag Center Objective: Cotton is susceptible to attack by root-knot nematode, causing an estimated 1.2% loss of yield (25,000 bales) in 1999. Chemical control has been limited through the restrictions on fumigants and the lack of long-term control with contact nematicides. Our project has investigated non-chemical alternatives to management of root-knot nematode in Acala cotton and is developing information on the impact of root-knot nematode on Pima yield. Root-knot nematode can be managed in cotton using non-chemical approaches, specifically rotation to non-hosts and use of host plant resistance. We demonstrated that rotation with alfalfa or black-eye bean reduced root-knot nematode populations (Figure 1) and raised yields compared to continual Maxxa rotations (Figure 2). The introduction of root-knot nematode resistant Acala cotton in 1996 provided a new tool in the management of this pest. During the period 1997 through 1999 we demonstrated the value of NemX cotton in protecting yield (Figure 3). In addition, the resistant variety does not allow the population to build during the growing season. The impact of root-knot nematode on Pima production is not very clear. Pima cotton (Gossypium barbadense) is a different species from Acala upland cottons (G. hirsutum) and information about this Pima and root-knot nematode is limited. We have initiated trials comparing two varieties under different root-knot nematode populations. These trials have already demonstrated that Pima S7 yield is as susceptible as Maxxa and allows populations to build during the growing season (Figure 1). Our investigations will also look at the interaction of Fusarium, root-knot nematode, and Pima cotton. Project: 83 Development of High Yielding, Pest Resistant Blackeye Bean Varieties for California Project Leader: Jeff Ehlers, Botany and Plant Sciences, UC Riverside (909) 787-4332 Tony Hall, Botany and Plant Sciences, UC Riverside (909) 787-4405 Blake Sanden, UCCE Kern County (661) 868-6218 Objective: Introduction Blackeye bean is an important rotation crop of cotton systems in California with production on about 40,000 acres in the State, most of which is in the San Joaquin Valley. 'Blackeyes' are the largest single market class of dry beans produced in California. Varieties with high yield, heat tolerance, excellent grain quality, and resistance to root-knot nematodes, Fusarium wilt, lygus bug and cowpea aphid are needed in order for blackeye production to remain competitive with lower-cost producers in Texas and elsewhere. As there are no private companies breeding blackeyes in the US, so it is appropriate that the University of California be involved in the genetic improvement of this crop. There are no private companies breeding blackeyes in the US, so it is appropriate that the University of California be involved in the genetic improvement of this crop. The University of California, Riverside (UCR) has a breeding program to develop improved blackeye varieties and complimentary production systems for California growers. Since 1995, the Shafter Research and Extension Center has been a key testing site for evaluation of breeding lines being developed by the UCR program, and for evaluation of agronomic practices (e.g. row-spacing x variety trials) and of the heat tolerance and delayed leaf senescence traits. Results Varietal development and testing: 'California Blackeye No. 27' (CB27), developed by the UCR blackeye breeding program under the experimental designation H8-8-27, was released in May 1999 following several years of field performance testing at the Shafter Research Station and other locations. CB27 possesses high yield potential, excellent grain quality and also heat tolerance, broad-based resistance to root-knot nematode (Meloidogyne incognita and M. javanica) and resistance to two races of Fusarium wilt (Fusarium oxysporum) (Table 1). We consider the Shafter Research Station to be a key site at which to evaluate yield potential of blackeye lines under development by the breeding program at UCR. In 2000, we are evaluating 32 new blackeye breeding lines for yield potential and seed quality in replicated trials, and have a breeding nursery with 140 lines from which selections will be made. Effects of heat tolerance and delayed leaf senescence (DLS) traits on single-flush yield and agronomic performance: The DLS and heat tolerance traits in cowpeas were discovered and described by this project some years ago. The DLS trait enhances plant survival under certain stress conditions that cause many plants of non-DLS lines to die after the first flush of pods is produced ('early cut-out'). Consequently, the DLS trait can increase yields of long-season blackeye crops. Both heat tolerance and DLS have now been incorporated into advanced blackeye breeding lines, but assessments of the traits individual and combined effects on yield in a wide genetic background under field conditions had not been investigated. In this experiment, conducted at both Riverside and Shafter, we compared the first- flush grain yields and other agronomic traits of 40 lines, ten lines each of the following four types: heat tolerant with DLS, heat tolerant without DLS, heat susceptible with DLS, and heat susceptible without DLS. All lines were derived randomly from a single cross between a heat tolerant, non-DLS parent (H8-9) and a heat susceptible, DLS parent (8517) and had been developed and characterized for either expression/non-expression of DLS and heat tolerance in several evaluations over the last four years. The interaction of the DLS and heat tolerance traits was not significant for either yield, harvest index, pods per peduncle, 100 seed weight, or seeds per pod. Heat-tolerant lines produced substantially greater average yields than the heat-susceptible lines at the hotter location (29.6 vs. 21.6 sacks/ac at Shafter) and similar yields at Riverside. Heat-tolerant lines also had a higher harvest index, more pods per peduncle, and greater seed weight than heat- susceptible lines. Average grain yields of lines with DLS were 3-4 sacks/ac lower than senescent lines, suggesting there is a yield penalty on the first- flush. This penalty is more than made up for in double-flush production fields where CB46 cuts-out and the DLS lines consistently produce two flushes of pods. Evaluation of growth habit x production system interactions. We completed a two-year study in 1999 at the Shafter REC to evaluate yield responses of new compact and viny plant type blackeye breeding lines and varieties in the production systems used by blackeye growers in San Joaquin Valley. Growers typically use one of three planting systems, i.e. single planted row on 30" raised beds, single planted row on 40" raised beds, or two planted rows on 40" raised beds. Within-row spacing is generally 3-4 plants per foot, resulting in different total plant densities for each system. Past research, conducted before the development of compact blackeye varieties such as CB46 and CB27 had not shown yield response to changes in planting density or row spacing. With the development of compact blackeyes, a re-examination of variety x row spacing effects was warranted. We evaluated the agronomic performance of 6 lines with contrasting plant habit (3 compact lines- CB46, CB27, and H36, and 3 viny lines- CB5, H8-8- 1N, and UCD 8517) under the three planting systems used by growers in the San Joaquin Valley. Plots were harvested after a single pod flush had occurred (about 100 day growing season). Briefly, compact lines produced higher grain yields in both years (two year avg. yield of 3076 lb/ac) and had higher harvest indices (two year avg. of 48 %) than viny lines (two year avg. yield of 2698 lb/ac) and harvest index (42%) over the three production systems. The compact plant type appears to be higher yielding as a consequence of better partitioning of assimilates into grain. In both years, compact varieties produced their highest yields (two year avg. yield of 3226 lb/ac) at the intermediate density (single-row 30" bed) and high density (double-row 40"bed) systems, while viny varieties produced their highest yields at the lowest density (single-row 40"bed) spacing (two year avg. yield of 2817 lb/ac). Future Plans The Shafter REC provides a representative high-yielding environment to test breeding lines being developed by the UCR breeding program. We hope to continue this effort as well as agronomic/management studies that compliment new blackeye varieties that are being developed. Project: 84 Potato Late Blight Screening Nursery Project Leader: Ron Voss, Vegetable Specialist, UC Davis Joe Nunez, UCCE Kern County Objective: Problem and Significance: Late blight of potatoes was a major problem in Kern County spring potatoes in 1994, 1995, and 1998. This has become a problem in the past few years not only for Kern County potato growers, but for potato growers worldwide. New strain of the fungus has entered Kern County, just as it has in other parts of the country. The introduction of the new strains of Phytophthora infestans has made the control of late blight more difficult. The old strain, A1, was satisfactorily controlled with the use of systemic fungicides. The presence of the newly introduced A2 strain has hampered control of late blight because it has shown resistance to the standard fungicide treatment. The presence of both mating types has also produced new genetic recombinations that are superior in their ability cause disease. Besides being resistant to the previous standard late blight fungicide, these new strains are more aggressive and cause infection over a wider range of environmental conditions. The new strains found in Kern County potato fields are superior from the previous strains that growers had to deal with in their ability to overwinter, produce many generations of asexual spores (sporangiaspores), resistance to metalaxyl, and ability to cause infection at higher temperatures. Because of the increased virulence of the new strains growers need to adopt new control strategies. Genetic resistance has been one area of late blight control strategies that has been ignored in the past. This has probably been largely due to the fact that highly efficacious fungicides were available. With the introduction of the new strains however, identifying potato varieties that demonstrate resistance or tolerance to late blight has become increasingly important as a method of reducing pesticide use. A late blight screening nursery has been conducted at SREC since 1998 to identify commercial and breeding lines that may have some genetic resistance. These studies have shown that differences do exist among some of the commercial lines and breeding materials. Project: 86 Importation of Peristenus spp. for the Biological Control of Lygus Hesperus Project Leader: C. Pickett, J. Ball, D. Mayhew, K. Casanave, U. Kuhlmann , D. Coutinot , L. Ertle , and K. Hoelmer Biological Control Program, California Dept. of Food & Agriculture, 3288 Meadowview Road, Sacramento, California CABI Bioscience, Delemont, Switzerland USDA-ARS European Biological Control Laboratory, Montpellier, France USDA-ARS Newark, Delaware Objective: Lygus hesperus is the number three ranked pest nationwide on cotton and a key pest of cotton in California. New, imported parasitoids capable of attacking L. hesperus nymphs could significantly reduce early season populations infesting cotton by attacking overwintering populations of this pest residing in alfalfa and other non-crop plants within the cotton agroecosystem. Past and present surveys have found parasitism completely lacking in nymphs of Lygus hesperus sampled from central California grown alfalfa. An attempt to establish nymphal parasites of Lygus hesperus in California in the 1970's failed, either due to poor syncronization between host and parasite or loss of habitat. Bill Day and others in eastern United States, however, have successfully imported a nymphal parasitoid that attacks Lygus lineolaris, a close relative to Lygus hesperus. Peristenus digoneutis has increased parasitism from 15% to 50% two years following establishment. Lygus numbers have decreased by 75% in alfalfa. We propose importing exotic species of Peristenus spp. collected from Lygus infesting alfalfa in southern Europe. Populations of Peristenus collected from areas with climate similar to central California and released into alfalfa managed for parasitoid survivorship will maximize their chances for permanent establishment. Foreign exploration has been conducted in Europe over the past 3 years. Three populations of adult and immature Peristenus stygicus (i.e., parasitized nymphs) have been released multiple times into each of 7 release sites in central California, from Kern to Yolo county. Three sites are in the Sacramento region and four in the southern San Joaquin Valley. The alfalfa fields are either small plots maintained specifically for our project, or commercial forage alfalfa. One of these is at the UC/USDA Shafter Field Station. The first releases were made in the Sacramento region summer 1998. The first releases of parasitoids at the southern sites occurred this summer, beginning in April. This year a total of 12,269 adult parasitoids and 15,900 exposed nymphs were released in the 7 fields. Peristenus cocoons were recovered in May from our Sacramento site, showing the population released in summer 1999 successfully overwintered and persisted in our plot. They were recovered in higher numbers in an August sample. Parasitoids have been recovered this August from 3 of 7 release sites. Recoveries have been found in 3 out of 4 of our own managed alfalfa plots. A surprisingly high level of parasitism (24%; n=25) was recorded at the UC Kearney Agriculture Ctr. Site where parasitoids were released for the first time this summer. Project: 88 Nightshade Control in Blackeye Beans Project Leader: Dave Bayer, Professor, UC Davis Ernie Roncoroni, SRA IV, UC Davis, (530) 752-2173 Blake Sanden, UCCE Kern County Carol Frate, UCCE Tulare County Objective: Tall morningglory (Ipomoea purpurea) and ivy-leaf morningglory (Ipomoea hederacea) continue to be serious problem in some areas of the blackeye bean growing areas of the Southern San Joaquin Valley and is appearing in more fields each year. Both tall and ivy-leaf morningglory over grows the blackeye bean plants making harvest difficult and reduces blackeye bean yields in areas of heavy infestation. Current registered herbicides for use in blackeye beans are not satisfactorily controlling either species of morningglory. A Pesticide Research Authorization from the State of California for weed control trials in blackeye beans allowed the use of non-registered and experimental herbicides such as Frontier, Authority, Pursuit and Raptor to be evaluated alone and in combination with currently registered herbicides for weed control. The Shafter Research and Extension Center site is of major importance because it is located in the major blackeye bean growing area. The field was divided into four 40-inch rows by 25 feet long plots and replicated 3 times in a randomized complete block. Preplant incorporated treatments (Table 1.) were applied May 22, 2000 using a hand held CO2 backpack sprayer. Herbicides were applied, to the entire plot, in 20 gallons of spray solution per acre using 80015 nozzles at 30 psi. Immediately after the last herbicide application all beds were reshaped using a power incorporator bed shaper. Two rows of 'California Blackeye 27" were then planted per 40 inch bed. The post plant surface treatments of Authority or Aim were then applied. Prior to the post emergence treatments on June 22, 2000 all plots were evaluated for morningglory control. Post emergence treatments were also made in 20 gallons of spray solution per acre. Herbicides were applied over the top of the blackeye beans to evaluate both morningglory control and injury to the beans. A second evaluation was made August 2, 2000. Attempt at a third evaluation on August 24, 2000 showed that our individual plot size was too small and that morningglory from one plot had spread throughout surrounding plots. The preplant treatments of Sonalan and Dual Magnum + Prowl (Table 2.) gave satisfactory early control of the morningglory. The addition of Pursuit + Crop Oil Concentrate to Dual Magnum, Dual Magnum + Prowl or Frontier gave added morningglory control. Only Raptor at the .047 lb ai + 1 quart of COC per acre caused any visual damage to the blackeye beans. This injury was noted as a loss of early flowers, which delayed the blackeye pod set. The soil active herbicides such as Authority and Pursuit were tested at reduced rates for weed control and to reduce herbicide residuals. At the end of the normal growing season the blackeye beans will be harvested and then the area will be tilled and planted to selected winter vegetable and agronomic crops to evaluate carry-over of the soil active herbicides in Kern County soil.
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