Docstoc

soy.rust.intro.jan.1.. - Extensi

Document Sample
soy.rust.intro.jan.1.. - Extensi Powered By Docstoc
					Soybean Rust – Don't
Panic!


 www.extensionplantclinics.msstate.edu



             Alan Henn
             Extension Plant Pathologist
             Mississippi State University
             662.418.9697
                            Rust lesions   Soybean
                            may be         rust
                            present on     infecting
                            leaves,        cotyledons
                            petioles,      of soybean.
                            and stems.
Most Soybean rust lesions
will be present on the
lower side of the leaf.



     Soybean rust symptom
     expression as influenced
     by soybean cultivar
 Premature defoliation          Decrease in weight of seed
 Increase in number of         per plant
unfilled pods per plant         Decrease in 100- seed weight
 Decrease in number of          Decrease in seed germination
normal pods per plant
 Decrease in number of seeds
per plant




                                               Spray skip




            Note more Severe symptoms in
            the
            lower canopy where moisture is
 Soybean Rust, Other Hosts
               LEGUMES (Papilionoideae) :
               Phaseolus lunatus (lima and butter
                  beans)*
               Phaseolus vulgaris (green beans, kidney
                  beans)
               Vigna unguiculata (cowpeas)*,
                  Peas
               Cajanus cajan (pigeon peas),
                  Kudzu
               Crimson and white, sweet clover
               Pachyrhizus erosus (yam bean, jicama)*

               ORNAMENTAL PLANTS:
               Hyacinth bean,
               Royal poinciana

Bacterial Blight
Disease most likely
to be confused with
Soybean rust
         Known to Be:
 Highly adaptable
 – variable strains
 Spreads easily
 Wide host range –
especially for a rust
 No known resistant
germplasm
   Reported Yield Losses
     Historical              New Reports
Country Yield             Country   Yield loss (%)
  loss(%)             6   Uganda         40
Australia       60-   0
  70                  -   Zimbabwe       40-60
India           66    7   South Africa        10-80
                      0
Indonesia    81           Nigeria        100
Japan        15-40
                          Brazil              10-80
Philippines     30-
  80                      Paraguay       30-80
South China     10-       Argentina Not determined
  50
Taiwan       12-80        Bolivia    Not determined
Thailand        10-
 Risk Analysis Predictions
       for the USA
 Southeastern
and Delta states
can expect
losses of 50%
while Mid-
Western states
can expect
losses of 10%


 Weather driven    Clyde Levy, Zimbabwe, Spray Skip
risk model
   Virulence Diversity of
          P. pachyrhizi
 In Australia, 8 isolates were separated into
6 races using wild Glycine species as the
differentials.
 Native populations of wild Glycine spp.
showed differential responses.

 In China, 9 isolates that had a susceptible
reaction on soybean were separated into 6
phenotypes using asparagus bean, kidney
bean and short podded yam bean.
GENE ACCESSION FOUND LOST
Rpp1  PI200492 1960-62 1966
Rpp2  PI230970 1972-74 1978
Rpp3  PI462312 1973-75 1977
Rpp4  PI459025 1980-83 2004
 Soybean Rust Distribution




Hawaii,   2004                            1902
1994                               1934
                            1997
              2003          1998
           2001
          2000       2001
   Synoptic Scale Airflows                                        Ultraviolet Radiation
     Govern Transport
     Direction and Speed
                               Turbulent
                             Transport and          Survival of Spores
Turbulent Diffusion                                                             Temperature and
                             Dilution in the          While Airborne
 and Wind Shear                                                                 Relative Humidity
 Govern Dilution              Atmosphere




                                         Conceptual
                                          Model of                           Dry Deposition Due
 Vertical Distribution of                 Soybean                               to Wind and
                                                                                 Turbulence
   Spores in Canopy
                                            Rust                                            Wet
                                                                                        Deposition
Canopy Density
  & Structure Escape of Spores            Transport               Deposition of
                                                                                          Due to
                                                                                             Washout
                                                                  Spores into a
 Wind &
 Turbulence
                from Canopy                Process                Soybean Crop                  by
                                                                                           Precipitation
    Time of Spore
    Release                               By Scott Isard,
                                          Roger Magarey,                                  Temperature &
Soybean Plant
                                                                                           Leaf Wetness
   Growth
                 Spore Production
                                           Bob Griffen           Colonization of
  Stage of                                                        Soybean Crop            Soybean Crop
  Disease
                                                                                          Growth Stage
  Weather
                         Calendar Showing Relative P. pachyrhizi
                            Source Strength in South America
                   108
                                                                   Equatorial Brazil
                                 Very high risk                    Southern Brazil
Spore Production




                                                                   Composite
                   106
                                   High risk

                   104
                                 Moderate risk


                   102
                                    Low risk


                    0
                         J   F      M      A       M J J A         S    O     N D
                                                  Month of Year
                    Divided year into 6 two-month periods based on spore production in
                             South America and U.S. soybean growing season
                 Release from
                   Current
                 Source Area
                   in South
                   America

                          (22 years)


                                        0
Height of SBR                                    End of SBR
    spore                                        major spore
  production                                     production
                                        1
 (mid-March)                                      (mid-May)




                  Spore Concentration
                                        10



                                        100



                                        1,000
   Start of
second peak of                                   Second peak
  SBR spore                                      of SBR spore
  production                                      production
                                        10,000    (mid-Aug)
  (mid-July)
                 Distribution
                 after First
                    Week




                                       0
Height of SBR                                   End of SBR
    spore                                       major spore
  production                                    production
 (mid-March)
                                       1         (mid-May)




                 Spore Concentration
                                       10



                                       100



                                       1,000
   Start of
second peak of                                  Second peak
  SBR spore                                     of SBR spore
  production                                     production
                                       10,000    (mid-Aug)
  (mid-July)
                  Distribution
                 after Second
                     Week




                                        0
Height of SBR                                    End of SBR
    spore                                        major spore
  production                                     production
 (mid-March)
                                        1         (mid-May)




                  Spore Concentration
                                        10



                                        100



                                        1,000
   Start of
                                                 Second peak
second peak of
                                                 of SBR spore
  SBR spore
                                                  production
  production
  (mid-July)                            10,000    (mid-Aug)
                 Distribution
                 after Third
                    Week




                                        0
Height of SBR                                    End of SBR
    spore                                        major spore
  production                                     production
 (mid-March)
                                        1         (mid-May)




                  Spore Concentration
                                        10



                                        100



                                        1,000
   Start of
second peak of                                   Second peak
  SBR spore                                      of SBR spore
  production                                      production
  (mid-July)                            10,000    (mid-Aug)
The Bringer of Spores
Rust as of November 30, 2004
      What Will Happen Here?
 The next few years will probably be different
from later years as pathogen becomes
established
 Modified by temperatures, free moisture
 Modified by hosts
  Much depends upon overwintering hosts
  If overwinters in frost-free zone – one pattern
  If can overwinter in a host – e.g. Crimson Clover-
  another pattern
Different spray timings likely for each
        Yearly Entry Model
Rust blows in each year
  Time of arrival is weather driven
 Sentinel plots – provide spray advisories
for people in the area AND downwind
Southern Corn Leaf Blight Model
Southern Corn Leaf Blight Model
Southern Corn Leaf Blight Model
           Occurrence of Soybean Rust in China



                                               Occasional occurring area
               45 N
                                               Frequent occurring area

                                               Severe epidemic area




             30 N




              20 N
                      High elevation
                      rust year round
                                                                           Overwinterring
(modified from Tan et al, 1996, Soybean Rust, China Agricultural Press)
Also see: Pivonia and Yang, 2004. Plant Disease 88:523
Next year-2005 growing season
We do not know to what extent rust has
infected alternative hosts in areas such as
South Florida and the Caribbean where it
can over winter.

We have been unable to detect rust in many
alternative hosts from these areas.

Therefore, we believe that rust may or may
not be a problem in the U.S. in 2005.
            Scenario One
If this scenario happens, the severity of the
disease would depend on wind currents etc
and the disease would have to built up.

If this scenario happens, the disease would
be more severe in the Southern United
States and would be a problem 1 or 2 years
out of 5 in the Midwest and Northern United
States
            Best Guess?
Rust will probably not be severe in 2005
because the fungus has not built up in
alternative hosts in areas where these
hosts are not killed by winter. (South
Florida, Caribbean, etc
Rust will built up in these areas and after
2005 or 2006 rust will be blown into the
Southern United States every year.
    Scenario 2: Overwinter
            Model
Rust overwinters in native hosts
surrounding soybean fields
   Host releases spores in spring which infect other
   alternative hosts e.g. garden beans, peas, kudzu
Soybean cotyledons might be infected
Spray preventatively at flowering
Role of sentinel plots changes to
confirmation
Situation if Overwinters in Native Plants:




               Soybean field




 Spores constantly bombard Soybeans.
 Flowering turns them susceptible,
 disease occurs
      Scenario Two-Unlikely
The fungus is able to over winter in
alternative hosts such as crimson clover,
vetch in the United States.
If this scenario happens, the disease would
spread from the alternative hosts and rust
would be a problem throughout the United
States.
This scenario is unlikely because the
fungus does not over winter in China on
alternative hosts.
Management
Rust Control and Management

Cultural practices such as row spacing,
seeding rates etc... have little effect.
No resistant varieties for 6-8 years
(conventional breeding projection)
 Resistance will probably depend upon genetic
  manipulation of the soybean genome using the
  results of the sequencing projects of the
  Phakopsora genome
          Some thoughts
It is an advantage to grow short season
varieties (IV and early V) because fewer
fungicide sprays are needed.
It may be an advantage to plant early
because the early planted beans are
maturing in July and August when it is hot
and weather conditions are not favorable
for rust development.
    Soybean Rust Management
          Suggestions
 Economic threshold – NONE
 Fungicide treatments – 0-4/season
 Timing of fungicides – based on sentinel crops,
local reports, and weather – OR Spray based on
plant stage
   Sentinel Crops – kudzu, soybeans or other leguminous
   plants
 Cost of Fungicide Treatment of
           Soybeans
ASA estimate ~ $15/acre/treatment

Survey results by USDA:
Fungicide cost -- $6-32/acre (average ~ $10)
Application cost:
 By ground -- $2-10/acre (average ~ $4.50)
 By air -- $4-12/acre (average ~ $6.50)
Fungicides Registered in U.S. for
  Soybean Rust on Soybeans
       (Section 24 label)

    Azoxystrobin (Quadris)
    Chlorothalonil (Bravo and Echo)
    Pyraclostrobin – Headline
 Fungicides Requested to Control
Soybean Rust on Soybeans under
Quarantine Exemption (Section 18)
         by South Dakota and Minnesota
Propiconazole (Tilt, Propimax, Bumper) – Granted
4/23/04
Tebuconazole (Folicur) – Granted 8/27/04
Myclobutanil (Laredo) – Granted 3/25/04
Trifloxystrobin + propiconazole (Stratego) –
approved but not yet received in MS
Tetraconazole (Eminent) – Probably not avail. next
year
Pyraclostrobin (Headline) – section 3 granted
Pyraclostrobin + Boscalid (Pristine) – May not be
available
   Other foliar fungicides
    registered in U.S. on
          legumes
         (some for organic use?)
 carbonic acid, monopotassium salt (Armicarb) –
soybeans, lima beans, green beans, dry beans
 cinnamaldehyde (Cinnacure) – soybeans (for rust)
 coppers – soybeans, lima beans, dry beans, green
beans
 harpin (messenger)– soybeans, dry beans
 hydrogen peroxide (Rezistox) – dry beans (for rust)
 neem oil – soybeans (for rust)
Fungicides Registered in U.S. for
  Rust On Other Legumes (lima
  beans, green beans, kidney beans,
  cowpeas, pigeon peas, and others)
 Azoxystrobin (Quadris)
 Chlorothalonil (Bravo and Echo)
 Pyraclostrobin (Headline)
 Maneb (Manex) on dry beans
 Myclobutanil (Laredo, Rally) on green beans
 Pristine (Pyraclostrobin + Boscalid)
Fungicide: Delay

                   The more
                   effective
                   the
                   fungicide
                   the greater
                   the time
                   between A
                   and B
      Pathogen Growth and
           Fungicides
You are fighting a delaying battle – delay until
 the environment turns unfavorable
Delay through the use of fungicides
                        Fungicides are best used
                          preventively, before
                       pathogen infection, though
                        some fungicides do have
                          some post-infection
                         activity, esp. imidizoles
   Reducing / Delaying Inoculum
    Using Fungicidal Chemicals
Protective fungicide: kills germinating spores, multiple points action




Penetrant fungicides: single point of action and prevent new infection
The azole group have some “curative” ability – maim fungus in plant
but in doing so the a.i. used is no longer available for further work
Relationship Between Fungal Infection and Fungicide Efficacy
                      Plant and Infection Status:
 Healthy:    Infection:      Latent Infection:       Symptoms and
                                                      Sporulation:
 Uninfected Spore lands,       Plant infected
                                        VISIBLE Disease symptoms appear
 plant       germinates,
           INFECTION                but no             SPORULATION
                                        SYMPTOMS and new spores are
             infects plant       symptoms
                        Latent period
                                5 – 8 days          produced – 16 wk

      Fungicide Efficacy in Relation to Fungal Infection:

 All             Some fungicides have           Some few fungicides
 fungicides      some ability to attack and     can kill actively
 work best       either kill or limit further   growing/fruiting
 applied         growth of the fungus           Called: “Eradicative or
 preventively    inside the plant; publicists
                 call “Curative”                Antisporulant”


     Fungicide Classes Active Against Infection Status
Chlorothalonil    Imidizoles
Strobulurins
Imidizoles
      Topicals: chlorothalonil
           Bravo, Echo
Provide a barrier between the plant and
the pathogen
 must be present prior to the pathogen propagule
landing/germinating on the plant
  reapply every 7 – 14 days

Kills multiple pathogens multiple ways
Pathogen resistance not known
Avoid mixing with oils, EC’s, alcohols, or
materials with xylene - crystals dissolve,
can enter through leaf cuticle & result in
phytotoxicity
      Penetrants: all other rust
            Fungicides
Kill small groups of pathogens with a single
     mode of action; Resistance known
Most need to be present before disease
 Penetrate into the plant tissue through leaf
surface
   Some move both up (xylem) and down (phloem) in the plant
 (true systemics)(Ridomil) - others move only upward
 (acropetal penetrants)(Quadris)
    Some move locally in the plant, usually by
  xylem, (locally systemic)(Headline)
    Some land on one side of leaf and move to protect
  the opposite side (translaminar)
    Some penetrate into the tissue and move cell to cell
                  Strobilurins
 Pyraclostrobin (Headline), Azoxystrobin
(Quadris), Trifloxystrobin part of Stratego)
 Preventative application is KEY
  Provide control of germinating spores prior to
  infection
  Little control of existing infections once in plant
Offer residual control to prevent new infection
  New foliage requires new application on some
                        Distribution of Azoxystrobin
                       within Grape Leaves Over Time




M:\MAMOSS\GRAPHS.PPT
               Headline Movement
           Locally Systemic/Translaminar
    Bean/Uromyces phaseoli vs. Wheat/Puccinia recondita

                         treated area




                        protected area
F 500 –
64 ppm                                   F 500 - 25 ppm

 (inoculation: 4 dat, assessment: 10 dpi)
                                  Quadris



           Quadris


                                                                            This chemical
                                                                            may be in the
                                                                            approval
                                                                            process
Application of azoxystrobin & cyproconazole made to middle region of wheat leaf only
(picture taken 7 days afterwards demonstrating some rust pustules developing in former
treatment area of cyproconzaole vs. few to none in azoxystrobin. Cyproconazole is/was
recognized as the longest residual DMI at the time of this trial).
     The Imidazole Problem
EPA has been very reluctant to register members
of the imidazole (triazole) family for ANY food use
Concerns: 1) long-lived secondary breakdown
residue – and 2) endangered species
Task Force in effect called the Triazole task force
to review these concerns – hopefully report this
spring
Myclobutanil and Propiconazole both OK'ed for
residue ~ 1 yr ago – thus Section 18 approvals
Many other azoles have no residue data!
 Approved Imidazoles:
Propiconazole
  Propimax
  Tilt
  Bumper
Myclobutanil
  Laredo
Tebuconazole
  Folicur
Propiconazole Mode of Action
   Uptake by leaves, crowns, and roots
   Systemic Action: acropetal
   translocation so it will protect old and
   new growth
   Demethylation Inhibitor (DMI - also
   known as a sterol inhibitor)
   As sterol inhibitor, it prevents fungal
   cell wall & hyphal development
   Fungicide Resistance Action
       Committee (FRAC)
                 www.frac.info

 For Strobilurins (azoxystrobin, pyraclostrobin,
trifloxystrobin)
  used alone in only 1/3 of applications
  used in mixes in only 1/2 of applications
 For Triazoles (propiconazole, tebuconazole,
myclobutanil, tetraconazole)
  alternate with other chemistries if possible
         What and When
If the crop is already infected with rust, use
an active ingredient ending with “zole” (or
myclobutanil) especially tebuconazole
If the crop is not infected or exposed, use a
strobilurin, or use a strobilurin as the
second application – 20 days after the first
If light disease pressure or late arrival, 3rd
spray not needed– otherwise strobulirin or
your choice unless previous spray was an
azole
      Soybean Phenology
Planting to first bloom, about 50 days after
emergence
R1-R3 requires 18-22 days, regardless of
group
R3 – R5 14 days (seed fill) – This application
will probably pay for itself
R5 – seed fill 21 – 30 days
                          Scenarios
Scenario                               Soybean Stage Action*, **
1 No rust detected                     R3 – R4         S
2 Rust detected downwind               R3 – R4         M
3 Rust detected in sentinal plots but not in field
                                   R1               M or Z
                                   R3               M or Z
4 Rust established in area             R1              Z + S (if dis.
                                                    Minimal) else Z+ C




 * S = strobilurin, M= mix of strobilurin and azole, Z = azole.
 ** If ca 10 days is needed use chlolothalonil such as Echo
                     Spray Needs
 Complete canopy coverage – COVER ALL
 REPRODUCTIVE GROWTH
 Be paranoid about spray skips
 Short season beans
need fewer sprays
than long season
beans



Compare to complete season long control in Irish potatoes for Late blight
               Spray Needs
Adjuvants help penetrate canopies
  80% nonionic surfactant, 0.125% Headline
MORE WATER CARRIER IS BETTER:
 Air: at least 5 gal/A
 Ground: At least 15 gal/A (More is better)
 May need to provide ground spray coverage for
 aerial skips due to obstructions such as power
 lines
Mato Grosso




Primavera do Leste, MT: 21.02.03
      Some Final thoughts
Rust is manageable, however rust control
will add $30-50 per acre to the cost of
growing soybeans.
Rust control must began before the disease
is severe in your field.
Rust has been managed in other areas
where it is present and it can be managed
in the United States.
Fungicidal Control of Soybean
     Rust in Zimbabwe
              Strip not protected by fungicide




       Photo courtesy of USDA/APHIS
       No Fungicides       With Fungicides




Photo courtesy of Clive Levy, Commercial Farmer’s
Union of Zimbabwe
Complete Season Long Spray
    Cover: Irish Potato




 Image courtesy of Steven Johnson, ME Cooperative Extension

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:52
posted:9/25/2010
language:English
pages:64