Apple Pest Report: Thursday, June 28, 2007 Vol. 15 No. 13
Contents
Apple scab Not-fire blight Fire blight Flyspeck Black rot Codling moth Apple maggot European red mite Two newer miticides Japanese beetles & Rose chafers Pear psylla Early-season hail Food safety Spray Spreadsheet Census of Agriculture
Apple Scab
Second generation scab infections originating from the final primary scab infection period on June 1-5 will have had enough time to develop visible spots on leaves starting around Friday-Saturday, June 29-30. This is a couple of days later than the dates forecasted last week. The apple scab growth model estimates that high temperatures above 85F on Tuesday and Wednesday June 25-26 were too hot for lesion development to progress on those days. The number of visible scab lesions increased after June 14 when 1 st generation lesions from the final (and severe) primary scab infection period began to appear. The hot dry weather on June 25-26, and generally dry conditions overall, have been ideal for suppressing spore development by existing scab lesions and preventing spread of secondary scab to young leaves and fruit. If you thoroughly scout your orchard after June 30 and do not find scab then it is reasonably safe to assume that scab control was effective. This means that can switch to a more relaxed fungicide schedule based on keeping flyspeck, sooty blotch, and other summer diseases in check.
If you already are battling active scab, or find it appearing in the next week, this is a critically important time to control it because young fruit are sensitive to infection and there is still plenty of tender young foliage. As fruit grow larger and as trees reach terminal bud set in mid-July, there will be decreased potential for scab to spread. Where scab lesions are found, fungicide protection should be maintained during the first 4 weeks after the lesions appeared. For orchards where scab lesions started appearing around June 14, this requires protection until at least July 12. It is too early to reliably forecast the earliest date for a fungicide application to last through July 12. As a preliminary estimate, a full-dose protectant fungicide application (but not sulfur) on or after June 27 should last until around July 12 for preventing secondary scab. Recommended spray intervals for secondary scab protectant fungicide applications based on rainfall at Highmoor Farm and vicinity are online at
http://pronewengland.org/AllModels/MEmodel/me-Monmouth-SecondaryScabSpray.htm.
Not - Fire blight
A Maine orchard observed this week had what at first appearance looked like fire blight blossom blight on most of the trees in a 1 acre planting. Many branches per tree were affected with a significant portion of the blossom clusters killed. The cluster leaves were dark colored, but the dead fruitlets were not brown-black. Their degree of collapse seemed to reflect loss of vascular support from their supporting cluster, but was not as extensive as if the fruit themselves were infected. There was no sign of fresh or dried ooze. None of the infections progressed beyond the spur-branch junction and into shoot growth. “Blossom-only” blight is atypical, but has been observed before elsewhere, and I saw it once a few years ago in Maine. But this damage didn‟t quite match a fire blight diagnosis. One missing symptom was no dried ooze on any of the dead tissues. One of the plant pathologists to whom I sent photos for help in diagnosis noted that the color of the dead tissues was not as dark as is usually the case with fire blight. There is another bacterium that can cause blossom cluster death such as observed here, and without bacterial ooze. However, further investigation found a more likely nonpathogenic cause.
Overall foliage was thin, with some leaf spotting and considerable fruit russet. Finding out the spray history provided evidence that fire blight was not the cause. Bordeaux mix + captan was applied at Pink and early Bloom. Symptoms may have started even before the May 28 fire blight infection period. Foliage was much thinner in the weeks immediately after the Bordeaux-captan applications. Thus, it appears that the damage to the blossom clusters was caused by spray burn. Specifically, by phytotoxicity of Bordeaux mix applied much later than the ¼” recommend cutoff, and exacerbated by an incompatible mixture with captan.
Fire blight
If present, shoot blight arising from the May 28 blossom infections would be visible by now. Shoot blight arising from overwintered fire blight cankers could begin appearing around July 3. So far it looks like the May infection period did not lead to any serious fire blight infections in Maine, but continued monitoring for at least one more week is advised. If fire blight strikes do appear, a quick response helps to limit severity on affected trees and to reduce spread to other trees. Pennsylvania is reporting one of their worst fire blight outbreaks in many years.
Flyspeck and Sooty blotch
The stretch of dry weather has pushed back the expected date for when 2nd generation flyspeck spores become available from border row host plants. The estimated date at Highmoor Farm is July 4. The estimated end of the 50 leaf wet hour limit for postinfection control is July 10.
Black Rot
Black rot is present at a low level in many Maine orchards every year. It commonly occurs as branch cankers on older trees. While it can lead to loss of productive branches or even whole trees, it rarely causes extensive losses. Black rot also causes leaf spotting and can, but usually doesn‟t, cause fruit rot. Black rot leaf spots are easily confused with spray burn. One way to distinguish the two is the pattern of their location. Spots caused by phytotoxic affect of concentrated spray on leaf tissue will be heaviest where spray coverage is best, and fairly consistent throughout the orchard. Black rot leaf lesions are often concentrated below a mummified fruit or below a branch canker. The spots are caused by spores carried down by rain in a cone shaped area. Leaf spots themselves are not a significant source of spores for further spread. Wood cankers and mummified fruit are source of spores. If you are using captan, Topsin, Flint or Sovran for scab protection those fungicides also help prevent spread of black rot. Those fungicides will not kill black rot in wood cankers. The only way to control that black rot is sanitation pruning and removal of fruit mummies. If pruning is not an option, then maintaining fungicide coverage will at least help keep the black rot from spreading. The most important times for this are 1) from Petal fall until about 40 after Petal fall (i.e. until about July 5-10) when unpollinated or thinned fruit that would otherwise drop can become infected to create mummy fruit, and 2) in August as fruit near maturity. You can use the secondary scab protectant fungicide intervals recommended for protection against secondary scab as a guide for protection against the spread of black rot. See http://pronewengland.org/AllModels/MEmodel/me-Monmouth-SecondaryScabSpray.htm
Insects and Mites
Codling moth 1st generation egg hatch should be about 30% complete by June 28. In most orchards, insecticide protection against plum curculio is adequate to control 1 st generation codling moth. The lack of residual insecticide protection for plum curculio in organic orchards can allow codling moth to be a significant pest. Prolonging Surround coverage into July may provide additional protection against late season plum curculio egglaying, and will help suppress 1st generation codling moth infestation. Other options for organic blocks are targeted applications of Bt or Entrust, both of which can be reasonably effective against codling moth. To kill 1st generation larvae before they can enter fruit, protective residue should already be in place and should be maintained until at least July 9. Apple maggot flies will soon be emerging, mating, developing eggs, and looking for host fruit in which to lay eggs. It takes about 10 days after emergence for the female flies to begin egglaying. Early ripening cultivars are most at risk in July. Larvae can hatch from eggs in less than 7 days. At the end of the season, the latest cultivars can be heavily damaged when alternative fruit egglaying sites are removed from the orchard. Monitoring traps can help you minimize the number of apple maggot insecticide sprays by knowing when there is enough pest pressure to require starting or renewing protection. To hang traps, choose trees along the edge of the block closest to an abandoned orchard or wooded area. If there are no abandoned apple trees or woods in the vicinity, choose the southern edge of the block. Placing traps in trees of early-harvested cultivars is best for detecting the earliest activity in the orchard. Placement in late ripening variety trees is best for monitoring late season activity. Traps should be located at least 30 feet away from each other. Place the traps at 6 feet or more above the ground, or at least as high as you can and still check them efficiently. Place traps in the outer portion of the canopy in an area with numerous fruit. Position the traps so that they are visible from outside the tree, and so that they are surrounded by fruit and foliage. Remove all foliage within 12 inches of the trap. Trap effectiveness is enhanced if they are open to sunlight and if there are fruits located within 2 feet, preferably below the trap. As fruits grow, branches may bend and the traps may need to be repositioned.
Flagging tape placed one or two trees away from the trap is useful to help relocate the traps. Do not place the flagging so close to the trap that it might interfere with the trap effectiveness. Use at least 1 trap per 4 acres. Do not use less than 3 traps per block even in very small blocks.
The threshold for unbaited traps is 1-2 AM flies per trap. I do not recommend use of odor baits that increase trap catches. While they do provide a more sensitive monitoring system, using unbaited traps is simpler, less expensive, and can achieve the same management objective of knowing when to start and when to renew insecticide coverage against AM.
After an insecticide application with one of the top-rated materials, you can ignore trap catches for 14 days or 2 inches or rain, whichever comes first. Then clean off traps and begin checking again at least twice a week to see if the threshold is exceeded again. If using one of the second-tier insecticides listed, or less than a full rate of one of the top-rated insecticides, a shorter “ignore trap capture period” of 7-10 days or 1 inch of rain, whichever comes first, is recommended. Continue checking traps until residue from the last spray lasts until August 31 for cultivars harvested in September, and until September 10 for fruit that will be harvested in October. Effective insecticide options for control of apple maggot flies before they can lay eggs include Imidan, Assail, Calypso, a pyrethroid. Assail and Calypso are both neonicotinoids. Of the two, Calypso may be a little better against plum curculio (for which the control period is over for this year), while Assail may be preferable for apple maggot control. The pyrethroid insecticides are relatively inexpensive to purchase, but are detrimental to beneficial arthropods that provide natural control of leafminer, aphids, leafhoppers, codling moth, European red mite and twospotted spider mite. These and other species are potential pests that often do not require targeted management intervention during the summer because natural control and insecticide directed at other pests keeps them in check. By decreasing natural control, pyrethroids can cost more money in the long run than the initial savings of the lower purchase price. SpinTor, Sevin, or Avaunt are not quite as effective against apple maggot as the top-rated materials listed above, but are still probably good enough for most orchards, especially if applied with the tighter interval mentioned above. European red mites have been very low in monitored blocks so far this year. Apparent mite populations usually increase at the end of June and early July as 2nd generation mites become full sized adults. Until July 15 the recommended treatment threshold is 59% of middle-aged leaves with living hatched mites present. The sequential sample system on the Apple Pest Monitoring Pocket Guide minimizes the time required to check for mites down to little more than time required to walk across the block to collect leaves. http://pronewengland.org/INFO/PROpubs/AppleScoutCard-2007web.pdf
In addition to Portal (same active ingredient at Fujimite) mentioned last week, Envidor is another miticide registered in Maine but not mentioned in the 2007 New England Tree-Fruit Pest Management Guide. The following two entries are adapted from the 2007 Pennsylvania Tree Fruit Production Guide. Envidor (spirodiclofen) is a nonsystemic foliar miticide belonging to the chemical class of tetronic acids. Envidor mode of action is classified as lipid biosynthesis inhibitor and is active by contact against all developmental stages of mites including eggs and female adults. Adult males are not affected. The product is registered for use on pome and stone fruits. Envidor is registered for the control of European red mites, twospotted spider mites, peach silver mites, and rust mites. Only one application is allowed per growing season. (Ed. – Envidor is not known to be cross resistant with any other type of registered apple miticide. It has a 12 hour REI and 7 day PHI. The label calls for application in a minimum of 100 gallons per acre.) Portal (fenpyroximate) belongs to the phenoxypyrazole class of acaricides. Its mode of action is a mitochondrial electron transport inhibitor (METI) blocking cellular respiration. This mode of action is similar to the mode of action of two other acaricides, Nexter and Kanemite. Therefore, no more than one application of compounds from the METI group is recommended per season. Portal is active on larvae, nymphs, and adult mites as well as on pear psylla, leafhoppers, and mealybugs. It halts feeding damage and oviposition within hours after application, and the mortality of mites occurs within 4 to 7 days. Portal is registered for use on the pome fruit group but not on stone fruit. Portal can be applied up to 14 days before harvest but no more than one application per season is recommended. Similarly, as with all other acaricides, excellent coverage is necessary to achieve good mite control. (Ed. – Portal is not known to be cross resistant with any other type of registered apple miticide. It has a 12 hour REI and 7 day PHI. Japanese beetles begin attacking apple tree foliage and occasionally fruit starting in early to mid July, continuing through August. Insecticides applied for apple maggot and codling moth (except for Bt and growth regulators) will also control Japanese beetle. Sevin is a good option against Japanese beetle. Because new adults may arrive, repeat application may be necessary. Rose chafers are a closely related species that cause similar damage and are subject to similar controls. Rose chafers are already out in force in some central Maine locations.
Pear psylla –The top-rated insecticides for summer control of pear psylla are Actara, Calypso, Esteem and Nexter. It is too late in the season to make best use of Agri-Mek against pear psylla. Nexter is not effective against apple maggot or apple maggot, but is an excellent miticide. Esteem is fair against codling moth but is not effective against apple maggot. While Cornell rates Assail a step below Calypso against pear psylla and equal against apple maggot, Penn State rates at it as equal to Calypso for pear psylla, and better than Calypso against apple maggot. They are both rated as good against codling moth. Cornell rates pyrethroids, summer oil, Proclaim, and Surround as Fair against pear psylla.
Other News
Early season hail A Maine retail orchard suffered extensive hail on Friday June 22, but the dense young fruit were only slightly dented, not cut. Cut fruit are not acceptable for wholesale use, and are tough to keep from rotting before attempting to sell them for retail or pick-your-own. But I seemed to recall that another Maine orchard had early season hail dents a few years back that turned out to be not too bad by the end of the season. I posed a question to the apple-crop listserv to see what others who had experienced similar situation could report about the eventual effects of the early season hail dents with regard to retail sales. Here are excerpts from some of the replies. 1) From an apple rower who had early season hail damage last year: “I figured we'd be buying apples wholesale. They actually turned out not as bad as we thought. Some varieties faired better than others. If I remember the Big Red Gala cracked pretty badly. The hail didn't crack them, however, the bruise that formed didn't grow with the skin, and it caused the apples to crack. Out of our 10 trees of Big Red Gala, I only had a few worth taste testing. The rest were a loss. But others like the Jonathan really made it through. As a very smart grower told us: Don't mark them down as hail damaged apples, mark them up as "Ice-Kissed" apples. If Florida can do the Sun-Kissed, why not?
2) We had a similar situation at the Hudson Valley Lab last year at about this time or a little earlier. The dents ended up producing a bit of corking beneath the skin. Thus, they looked a bit like a stippen or bitter pit lesion at harvest. 3) In early July 2001 we experienced a pretty good hail storm on our 25 acres of apples. All fruit had at least dents, many multiple skin pierces. Crop insurance adjuster called it 100% loss. We sell all of our crop retail, mostly PYO. It was heartbreaking for the entire season to look at all those damaged fruit every day. We spent the next month thinning out as many torn fruit as we could. That was a good move. At harvest we explained to all customers that the fruit had been "Kissed by Mother Nature". We found that most (99%) customers were content, though they did not purchase as much fruit as they would have. I felt we had already sustained a loss of volume, and an increase in expenses, and so could not afford a loss on price, and so we raised our price 15% over the last year‟s price. That turned out to be the best decision we made, as our dollar sales that year were the best in 20 years. I know it is counter intuitive, but the numbers do not lie. Be upfront with your customers. They have a stake in your continuing in business. Remind them of that! 4) We had bad hail damage several years ago, just about this time of year. The hail mostly caused denting, as in the orchard in your post. Even our blueberries were dented! We continued with our sprays and tree maintenance. We were able to sell all the apples, at a very reduced price of course. I often say we never sold so many apples as we did that year. We are 100% retail at our farm store and farmers' markets. People just love cheap apples.... I advertised the 'Hail Sale' in the papers. We did sort out the few apples that were undamaged and sold them at our usual prices. So, it was a loss, but not a total loss. 5) We experienced early season hail last year and the year before. Last year was probably more serious. We sell our crop PYO, retail, wholesale, and peel many of the apples. Sounds like the grower you're asking for is more retail than us. We still wholesale approx 25-30%. The hail marks were noticeable at harvest, but manageable. Most of the effect was small scabbed over marks, many of which were in the acceptable USDA fancy grade allowance. We didn't need to discount our pricing based on the hail damage. We didn't make any special effort to go out and thin off what
was damaged. In comparison to years where we've experienced later hail, the impact was much less. I have learned in the past that if you do wholesale, it's best not to tell the buyers you've had hail. Let the grading process cull out the fruit that doesn't meet the account's standards. I thought being up front with the buyer would help, but all it did was predispose him to an expectation of lower quality, and their inspecting of our loads was much more rigorous. Of course, how much information is disclosed to your buyer is specific to each operation, and in some cases full disclosure might be called for. I don't know if any of this helps, but my experience has been don't lose hope. As you mentioned, at retail your customers tend to be quite understanding. If warranted by the amount of damage, then lower prices are seen favorably and maintains your customer base...and it still gives you a better return than cider price. 6) We know what it's like as we had hail damage 3 consecutive years when the apples were about 1 1/2" diameter. Only 3 minutes of hail and the apples looked like they had been rolled in gravel. The marks on Gingergold and Grimes Golden were the most unsightly. We did some thinning and found foliage had protected at least some of the crop. The damage was usually only skin deep and I would demonstrate that to customers. We sold the damaged apples at a reduced price. 7) An old saying is that is always darker immediately after a storm. An apple orchard will appear that way too. Unfortunately, many times it does not get any better. The number and size of the dings determine the ultimate result and if not too bad, there can be considerable recovery value. One of best ploys I know of for pick your own blocks is to let the public know that apples were KISSED BY GOD. Then they will sort out the best when picking. In this area of a frozen-out crop, we could use the cider apples. 8) Those dents will leave a dead and pithy spot in the apple just under the surface. Not number 1 grade. I'm sure no two hail storms are exactly the same. In the last 25 years we've had early hail three times. I think it pays for farm market orchards to go through the trees and hand thin most of the hail marks out. The remaining fruit will be larger and higher quality. And it‟s easier to sort bad apples out now so you don't have an awful time at harvest. Of course if you've got 70% plus damage, save your time - go fishing.
9) One inch diameter fruit is the threshold for the „what you see is what you get‟ hail. The first rule I have is to make decision for at least a week, allowing the fruit to grow and show the number and depth of hits. The second rule is to be objective. Hail is an emotional event that needs clear headed dollars and cents evaluation. If the leaves of the trees are tattered, and you can see damage pretty easily, the wholesale fresh value is going to be very limited. The US extra fancy grade allows about two „bb‟ pellets for red varieties, and one for yellow/green varieties. If the orchard is able to sort their own fruit, retail it and have a cider outlet the decisions are easier. If the fruit is packed by someone else and is wholesale oriented, the „standing in the light of truth‟ is critical. Often with multi-hit hail on red/partial red varieties the smaller hits blend with fruit shape and color and some of the fruit slides into the grade. Green and Yellow varieties are very difficult. There will be times when the hail looks better, times it will be terrible. It varies with the growth, color and lighting…. 10) The fruit will attempt to heal over the dents. Since they're less than halfway to their selling size, they have plenty of time to heal. In some cases, the resulting healed fruit will still be saleable as #1 fruit. In fact, the dents may not be noticeable at all to the untrained eye. If the dents are really bad, some fruit may be graded into seconds, or "culls" but could still be saleable to those on a budget or looking to freeze peaches, make jam, etc.
Food Safety There was another discussion on the "apple-crop" email list this week about grazing sheep in apple orchards. Of course, putting grazing animals near fruit raises serious concern about the risk of E. coli contamination. The excerpts below are from a message by Ronald Gaskill, a Congressional liaison for the American Farm Bureau Federation. They provide an insider view about the critical need for all fruit growers and cider makers to reduce the risk of E. coli contamination at every step of fruit production, harvest, and postharvest handling: "In response to the growing number of cases over the past decade where fresh produce has been implicated as the source of food borne contamination and resulting human illness, especially last fall's incident with E. coli in leafy greens that resulted in three fatalities and hundreds of sick
people, there is a very real threat that Congress will enact a law requiring producers of fresh produce to adopt or eliminate certain cultural practices that potentially compromise the safety of fresh fruits and vegetables. They don't care that there are differences in growing spinach and tree fruit; it's all consumed direct from the plant without an intermediate heat treatment. We're doing our best to keep the debate logical from the perspective of producers and I think we're being effective thanks in large part to growerinitiated state-level fresh produce safety programs in California, Florida and Virginia that demonstrate both a legitimate concern and a meaningful response. But purposely introducing ruminant animals into a fresh produce environment, particularly when the source of the virulent strain of E. Coli 0157:H7 has been directly traced to ruminant animals, is the exact wrong action to be taking at this critical time. ..."One grower's initial problem becomes a much bigger problem for the entire grower community. As it regards the safety of fresh produce, the grower community doesn't have any more strikes left; there will be regulation after the next major incident. I urge all growers of fresh produce to do all they reasonably can to be sure they're not the next unwitting victim of unintended consequences. Examine your practices with a view of their possible impact on contamination of the product you raise, especially if you sell it direct to consumers. Irrigation water, human sanitation, animal waste, and packing line wash water are not the exclusive, but the most usual sources of contamination."
Penn State Spray Record Spreadsheet Penn State Extension has a spray record spreadsheet files online for free at http://adams.extension.psu.edu/Agriculture/Grower%20Resources.htm#SpraySheet I have only looked at this briefly, but it seems to me that even if you do not want to use the Excel file to enter your spray data, the sheet listing apple pesticides, their EPA numbers, REI and PHI requirements could be a useful reference.
2007 Census of Agriculture From the USDA: All agricultural operations, large or small, are important to U.S. agriculture but it is often difficult for the National Agricultural Statistics Service (NASS) to reach the smaller producers. This is unfortunate because census data are used by local communities, businesses, government agencies and others to make critical decisions about the future of farming and rural America. Extension and other groups who work with small scale farmers can help improve the Census data by encouraging farmers to sign up to receive a Census Data Form and to complete and return the Data Forms to NASS by early February 2008. People can sign up by calling 1.800.892.1660 between 8am and 4:30 pm MT, or online at www.nass.usda.gov/counts. NASS will „finalize‟ the mailing list in early August so sign up time is limited.
I will be out of the office next week. Next issue will be in about two weeks. Sincerely,
Glen
What we call the secret of happiness is no more a secret than our willingness to choose life. Leo Buscaglia In complying with the letter and spirit of applicable laws and pursuing its own goals of diversity, the University System shall not discriminate on the grounds of race, color, religion, sex, sexual orientation, including transgender status or gender expression, national origin, citizenship status, age, disability, or veteran's status in employment, education, and all other areas of the University System. The University provides reasonable accommodations to qualified individuals with disabilities upon request. Questions and complaints about discrimination in any area of the University should be directed to the Executive Director of Equal Opportunity, The University of Maine, Room 101, 5754 North Stevens Hall, Orono, ME 04469-5754, telephone (207) 581-1226 (voice and TDD).