Soybean Rust Alan Henn, Extension Plant Pathologist Mississippi State University May 30, 2004Soybean Rust is one of nine agricultural select agents/toxins (Table 1) designated by congress in the Homeland Security Act of 2002. If introduced into the United States, these agents are thought to be capable of significantly damaging agriculture. Plant pathogens highlighted in yellow (Table 1) can thrive under our climatic conditions and are potential threats to Mississippi agriculture, or in the case of citrus (highlighted in green), Mississippi may provide a bridge for the disease to enter into Florida or Louisiana/Texas.
Soybean rust is not in the United States yet, and there is no reason to panic. What needs to be done is to prepare for its eventual arrival by learning all we can about the disease and how to control it before it arrives. The purpose of this page is to provide access to this information and advise Mississippi growers on how to manage it when it does arrive. This information is provided to you by Mississppi State University Extension and Agricultural Station personnel. Please send comments and suggestions to alan henn, Extension Plant Pathologist.
Table 1. Select Agents /toxins from the Agricultural Bioterrorism Protection Act of 2002.
|
Pathogen |
Disease |
Primary host |
|---|---|---|
|
Librobacter africanus and L. asiaticus |
Huanglongbing/greening phytoplasma disease |
Citrus |
|
Peronosclerospora philippinensis |
Philippine downy mildew |
Corn |
|
Phakopsora pachyrhizi |
Soybean rust |
Soybean, other legumes |
|
Xanthomonas oryzae pv. oryzicola |
Bacterial leaf streak |
Rice |
|
Ralstonia solanacearum race 3 biovar 2 |
Bacterial wilt, brown rot |
Many hosts, esp. solanaceous |
|
Sclerophthora rayssiae var. zeae |
Brown stripe downy mildew |
Corn |
|
Plum pox potyvirus |
Sharka, Plum pox |
Stone fruits |
|
Synchytrium endobioticum |
Potato wart or potato canker |
Irish potato |
|
Xylella fastidiosa |
Citrus variegated chlorosis |
Citrus |
P. meibomiae is
found in the Carribean and Central and South America. Because of its
close proximity to the United States, it is possible that it will be
introduced into U.S. soybean production. Because P. meibomiae
causes few problems on soybeans, its introduction would not be a
problem if it were not so difficult to tell from P. pachyrhizi. A
difficulty that has led to confusion elsewhere. To alleviate this confusion and to advance our
understanding of the disease, USDA-ARS contracted with the Joint
Genome Institute (JGI) to sequence the genomes of both Phakopsora
species. The sequence data is to be made public. These data should
facilitate methods to distinguish between the two species of Soybean
rust and among races of P. pachyrhizi. Information on this initiative
can be found at http://www.jgi.doe.gov/ .
P. pachyrhizi was first discovered in Southeast Asia and has spread -
rapidly at times - through Africa and South America (Figure 1). Some
reported yield losses in various countries which it has infested
appear in Table 2.
In the western hemisphere, Soybean rust arrived in Paraguay in 2001. By 2002 it had spread to neighboring Brazil and Argentina. In 2003 it infested most of the major Brazilian soybean production areas and was discovered in Boliva. As of December 2003, Soybean rust was present in 70% of the norther soybean crop area and in 50% of the eastern soybean crop area.
In Brazil this year, there has been continued cultivation of soybeans
because of good market price. Thus, there was a continuous source of
P. pachyrhizi spores. Late 2003 plantings were showing infections at
growth stages V3-V4, about 20-25 days after planting.
So far, P. pachyrhizi has not been shown to exist in the northwestern
hemisphere - above the equator. Once north of the equator, the
combination of intertropical convergence zone and tropical storms will probably move the rust
spores into North America.
Spread of Soybean Rust
and where it might be a problem in the United States
In China, the latitude
line of 35 degrees north is the limit of frequent SBR disease
occurrence (Figure 2). China experiences frequent, severe epidemics
in its south (below 30° north in latitude), frequent but not
always severe epidemics in the center of the country (between 30 and
37°), and occasional but mild epidemics in the north
(above 37°). Areas
south of this line are frequently affected by SBR, while areas north
of the line may be affected by SBR but only occasionally. In the
U.S., the 35 degree latitude line passes through North and South
Carolina, the southern border of Tennessee, Arkansas, and Oklahoma.
While other epidemiological considerations will change
this observation in the
U.S., it may give us some idea of what to expect.
Introduction of the
pathogen into the U.S. may be purposeful (bioterrorism), by accident,
or by wind currents. The movement of P. pachyrhizi spores on wind
currents is being studied and modeled. Please refer to http://soybeanrust.zedxinc.com
for further information on the
spread of P. pachyrhizi by winds (aerobiology). A power point
presentation may be found on the USDA APHIS wet site
http://www.aphis.usda.gov/ppq/ep/soybean_rust/rsampling5.pps.
In the U.S., entrance of
P. pachyrhizi is expected somewhere around the gulf coast, an environment
closer to Africa and South America and more suitable to the pathogen
than other regions of the U.S. In Africa, several years passed before
SBR reached it full expected range (Figure 1), arriving in South
Africa in 2001. Opinion varies on the time required for SBR to
dominate its expected range in the U.S., but several years would
likely be required for SBR to attain its full intensity and range.
Figure 3 shows the spread of Southern corn leaf blight through the
United States in 1981 (Moore et. al. 1981). It is possible that soybean rust
may spread like Southern corn leaf blight.
Conditions required for
Soybean rust include favorable temperatures and humidities for spores
to germinate, for infection of the host and for the developing
uredinia to produce spores. Researchers have investigated these
requirements, and some found by Dr. X. B. Yang are in Table
3.
It appears that
non-optimal higher temperatures may be overcome by longer periods when
the leaves are wet (e.g. dew periods). Extensive periods of leaf
wetness, almost nightly, occur in the lower canopy of soybeans in the
Mississippi delta. Temperatures themselves, are not unfavorable (http://www.srh.noaa.gov/jan/climate_connection.htm). Such
conditions, and an abundance of alternative hosts (see below) indicate
that the Mississippi delta will probably be a good incubator for
soybean rust.
These data and much more
scouting information are summarized in an informative CD created by
Dr. X. B. Yang and available from the Crop Advisor Institue
( http://www.cai.iastate.edu ). Mississippi State Extension
Service employees may check out a copy from Kathy Nash.
Table 3. Temprature (degrees F) for P. pachyrhizi to germinate and infect. Data from Yang et al. 1991.
Stage of P. pachyrhizi development Temperature range Temperature optimum Moisture Spore germination 46-97 61-75 Infection 52-82 66-75 >= 6 hour dew Uredinia maturation 72-81
Tan lesions contain small
uredinia (generally a raised pustule like area) surrounded by slightly
discolored areas. The young uredinia have a small hole (ostiole) in
their upper surface from which the spores (urediniospores) emerge. As
the uredinia grow, many tan colored urediniospores are released,
giving the surface the appearance of light brown to white raised areas
.
Reddish/brown lesions
cause a larger lesion (dead area) on the surface of the leaf, but
contain few uredinia that usually have few spores visible on the leaf
surface .
Early lesions may be
confused with bacterial pustule (Xanthomonas campestis pv. phaseoli)
or Bacterial blight (Psuedomonas glycinea) or brown spot (Septoria
glycines). The bacterial diseases usually occur on the underside of
the leaves and produce a raised light brown blister within the lesion.
The lesions may vary from small specks to large irregular areas. If no
bacteria or spores are present, the early bacterial/Soybean rust
lesions may be difficult to distinguish from Soybean rust. Spores
will almost always be present.
In older bacterial
lesions may be distinguished from Soybean rust by two characteristics
that may be seen with a powerful hand lens or microscope. The
bacteria emerge through a torn crack in the leaf epidermis whereas
P. pachyrhizi spores emerge through the small roundish ostioloe. In the case
of more advanced Soybean rust lesions, white clumps of spores catch on
top of the raised area in the lesion. Sometimes these will be in
columns. Spores will be present. Further identification needs to be
made by other means, including microscopic and by PCR (Polymerase
Chain Reaction).
Spores can be detected by wiping a clean white tissue, such as Kleenex, on the suspect area. If a tan or brown smear is seen on the tissue than spores are probably present.
The affect of Soybean rust on the soybean plant
P. pachyrhizi infects all
above-ground parts of the soybean plant. Rust pustules may be found on
both sides of the leaves, the stems, pods, and petioles. Although it
may infect the soybean plant as early as the cotyledon stage, it does
not start to cause damage until the plant has started to flower. It
is speculated that changes in the flow of plant nutrients from
vegetative tissues (leaves and stems) to reproductive tissues such as
flowers, pods and seeds induces increased
susceptibility.
Under conducive
environmental conditions, the infection may move quite rapidly,
proceeding from spore through infection to producing new spores within
a few days. Earliest lesions appear where moisture remains the
highest for the longest period - lower leaves of the plant, especially
near low/wet areas such as ditches or along roads and streams.
Many questions remain
unanswered - can we tolerate defoliation inside the canopy while
retaining the canopy leaves? How much defoliation - if any- can be
tolerated? Will our indeterminate cultivars behave differently than
determinate cultivars (more discussion under control).
Genetic Resistance to
Soybean Rust
The Fort Dietrik program
is screening soybean germplasm against a number of P. pachyrhizi races
simultaineously. They are going to reexamine a few lines, but
apparently no notable resistance has been found. There does seem to
be some good resistance in some soybean relatives, but none of this
has been integrated into agronomically acceptible lines.
Breeding work needs to
continue at full pace to provide a long term solution to Soybean rust.
In the meantime, chemical control is the only known
alternative.
Alternative
hosts
Most alternative hosts are in the Legeume family Papilionoideae. This host list will probably increase with new research.
Dr. Victor Maddox, GeoResources Institute, MSU, helped identify those plants with closely related species in Mississippi.
Compiled by Alan Henn, Extension Plant Pathologist, Mississippi State Univeristy,
662.325.4535.
________________________________________________________________________
The USDA in its report "Status of Scientific Evidence on Risks
Associated with the Introduction into the Continental United States of
Phakopsora pachyrhizi with Imported Soybean Grain, Seed and Meal",
dated 23 Feb. 2004 www.aphis.usda.gov/ppq/ep/
soybean_rust/sbr_riskevidoc2_23_04.pdf notes that
P. pachyrhizi has been naturally found on Crotalaria spp.,
Desmodium spp., Glycine spp., Dennedia spp., Lablab
purpureus, Lupinus spp., Macroptilium spp., Melilotus
officinalis, neonotonia wightii, Pachyrhizus crosus,
Phaseolus spp, Pueraria lobata, Sesbania exaltata,
Trifolium incarnatum, Vicia dasycarpa, Vigna spp.
Note that Kudzu (Pueraria
lobata or Pueraria phaseoloides) is an alternative host for
P. pachyrhizi. It produces many spores on Kudzu but does little
damage to it otherwise. In Brazil, where cold weather does not kill
the Kudzu, rust from Kudzu infects soybeans early in their culture.
In Paraguay, soybeans growing close to infected kudzu were showing
rust symptoms this past year at the V3-V4 growth stages or 20-25 days
after sowing.
Kudzu overwintering on
the coast, may provide an inoculum source in Mississippi. Rust may
also hurt the culture of various beans and peas and those in turn may
provide additional inoculum to infest later planted
soybeans.
P. pachyrhizi infects the alternative hosts kudzu, sickle pod, sweet peas and pigeon peas up to one month prior to soybeans in Brazil. While they may act as a indicator for the presence of P. pachyrhizi, they also serve an inoculum reservoir.
Control of soybean
rust
Management techniques that have been investigated in other countries include planting dates, row spacing and use of soybeans in different maturity groups.
Changing planting dates has not worked in Zimbabwae. Climatic conditions caused the plants to enter the reproductive stages at similarl times, despite the various planting dates.
Changing plant spacing (inter-row and densities) has shown no benefit in South Africa, but using different maturity groups may be helpful. In Brazil, narrow soybean row widths have been abandoned in favor of the relatively wide rows between (45 to 50 cm). This allows better penetration of the soybean canopy by soybean fungicides as well as
avoiding a microenvironment conducive to soybean rust.
A key factor in controlling soybean rust is the timing of the first fungicide application. Experience in both Zimbabwae and Brazil has shown that early warning is vital. Some countries have established a network of sentinel soybean plantings (each about 0.5 A) around the country. The sentinel crops are planted about one month prior to the
commercial crops and scouted daily by the cooperator.
Because of their greater maturity, these sentinel crops become infected first, giving area growers warning to start fungicide applications. Some of these sentinel crops are then turned into fungicide demonstration plots.
This season in Mississippi, the SMART program, led by Dr. Alan Blaine, in association with Dr. Gabe Sciumbato of the Mississippi State Delta Research and Extension Center, have established sentinel crops around the state. There was no funding to do this, the expense coming out of their operations monies. These plots are being
monitored at least once/week.
The Brazilians also have not defined a particular growth stage to start spraying. Rather, the first spray depends on when the first infection is detected, on weather conditions, and on the mode of action of the fungicide used (protective or protective/curative).
For indeterminate soybeans, timing of applications in relation to growth stage is much more difficult because the plants continue growing and putting out new leaves and flowers. Thus, indeterminate soybeans may require more sprays with shorter intervals between sprays, because new leaves may be exposed to infection every week.
Fungicidal management
Experience in both Zimbabwae and Brazil has shown that spray skips become rapidly diseased, and very noticeable. Severe localized yield losses result.
In Brazil short season varieties require fewer applications (one) than longer season varieties (2-3). During the 2003-2004 Brazilian growing season, it is estimated that 95% of the acreage required 1.5 – 2 sprays, but selected fields received as many as four. Despite these applications under conducive conditions for disease in Brazil, yield losses approximate 10%. Losses are 50% or greater without applications. As has been observed in Mississippi, Brazilian soybeans treated with fungicides remain green longer -extending the season.
Timing of fungicide applications is critical to effective disease control.
In Zimbabwe: the
recommendation developed is to apply the first spray at first flowering
(R1 growth stage, approximately 50 days after planting), a second
spray
applied 20 days later, and a third 20 days thereafter.
Generally three sprays
work best, but two may be adequate under low disease pressure. Spraying
earlier during reproductive growth is more beneficial than
delayed
applications.
In Brazil: Full canopy
spray coverage is required. Application is made at first detection of soybean
rust in
the region as indicated by the sentinel
crops. The disease normally intensifies during the reproductive
phase,
resulting in a spray around R1. A second spray is
applied
15-20 days later for protective fungicides. If needed a
third spray is made
20-25 days later for protective/curative fungicides, and other sprays
are made if necessary. Because early identification can be difficult, many are
moving to
applications based on soybean growth stage.
Application methods are
diverse in countries infested with Soybean rust. Large growers in
Brazil generally rely on aerial applications of ultra low volumes in
oil. Spray volume is usually less than 10 liters/hectare of which 3.5
liters are oil, 1.5 liters water and the rest fungicide product ( ).
Ground applicators are generally agreed to be more effective. Most
applications in Brazil are made in 70-75 liters of water/hectare ( ).
Cone nozzles are preferred.
Adjuvants have been used with some fungicide products. They have been found to help sprays penetrate the canopy to the lower leaves.
In general, growers in most countries prefer triazole and strobilurin class fungicides (links here to examples) because of their systemic activity. The particular fungicide group used depends upon the developmental stage of the plant and whether or not it has already
been infected by rust. Generally, but not always, the triazole group of fungicides have an 'azole' near the end of the chemical name of the active ingredient whereas strobilurins molst often have a 'strobin'. Both groups of fungicides penetrate into the plant tissue and provide protection against new infection, but some of the triazoles also have some 'curative' ability - able to destroy some of the fungus already infecting the plant.
Some protectant fungicides are also used. If they are, they are often applied in late V5 to protect the lower foliage. This is then followed by a systemic fungicidal applications during R1-R5. Most recently Brazilian growers have started their initial application
using fungicides formulated as mixtures of both a triazole and a strobilurin. This application is followed 20-25 days later by either a triazole or a strobilurin, depending upon infection status of the field.
Over the six years since SBR's introduction into Zimbabwe, several triazole fungicides, a benzimidazole + triazole mix, and a morpholine have been utilized without any evidence of pathogen resistance. The fungicides registered are carbendazim + flusilazole, triadimenol, cyproconazole, tebuconazole, difenoconazole, propiconazole, and triforine - the first two having been used extensively.
Fungicides recommended for control of soybean rust in Brazil include penetrant fungicides applied prior to disease establishment. These are applied at repeated at 10-15 day intervals, if needed. This group of fungicides includes difenoconazole, azoxystrobin and fluquinconazole.
A second group of fungicides are used either before or after disease establishment, since they have some curative ability. These must be reapplied at 20-25 days intervals. This group of curative chemicals always includes a triazole. Active ingredients include epoxyconazole + pyraclostrobin, tebuconazole, flutriafol, azoxystrobin + cyproconazole, trifloxystrobin + propiconazole and trifloxystrobin + cyproconazole.
U.S. fungicides
Several fungicides in the United States already have labels for Soybean rust, Quadris (azoxystrobin) (strobilurin class), Echo (chlorothalonil, a non-penetrating surface protectant needing reapplication every 7-14 days). BASF has applied for a regular label for Headline, containing pyraclostrobin.
The experience of growers in other countries have shown that these fungicides alone are not sufficient, nor will enough quantities be available to meet needs. To meet the expected market demand and needs for fungicides, Section 18, are being applied for by states.
Section 18
Mississippi can add its
name to the soybean rust Section 18 by making a formal request to EPA
in which they reference the MN/SD application and supply a limited
amount of state specific information.
The Section 18 will be
activated when Soybean rust is first identified in the United States.
It will be active for three years.
Fungicides (trade names
in parentheses) listed in the Section 18 are propiconazole (Tilt,
Propimax, Bumper), tebuconazole (Folicur), myclobutanil (Laredo),
trifloxystrobin + propiconazole (Stratego), tetraconazole (Eminent),
pyraclostrobin (Headline), and boscalid + pyraclostrobin
(Pristine).
The active ingredients
propiconazole and myclobutanil have been approved for immediate use if
Soybean rust were found today. The other active ingredients are still
under EPA review.
Mississippi Department of
Agriculture, Bureau of Plant Industry Tommy McDaniels and Extension
Plant Pathologist alan henn are working on this for the state. A copy
of the state application may be found as a Microsoft Word document
here; EPA's approvals (in PDF format) are here for propiconazole, myclobutanil and
tebuconazole.
Much forecasting work
(epidemiology) on soybean rust in the United States has been conducted
by Dr. X. B. Yang. Dr. Yang, was formerly with the USDA, Foreign
Agricultural Service, and is now at Iowa State University
(http://www.ag.iastate.edu/departments/plantpath/faculty_pages/xbyang.html
). During the mid 1990s he became familiar with the devastating
effect of Soybean rust on Chinese soybean production. A map of the
distribution of Soybean rust in China appears in Figure 2. Its occurrence varies with
the location and year (Figure
2).
Soybean rust symptoms
P. pachyrhizi may
cause different colors and severity of lesions, depending upon the
genetics of the soybean host. The lesions are characterized as either
red/brown or tan. Examples of these symptoms may be found on the USDA APHIS web
site: http://www.aphis.usda.gov/ppq/ep/soybean_rust/detection5.html
Soybean rust affects the plant by causing:
-Premature defoliation
-Increase in number of unfilled pods/plant
-Decrease in number of normal pods/plant
-Decrease in number of seeds/plant
-Decrease in weight of seed/plant
-Decrease in 1000-seed weight
-Decrease in seed germination
Active screening of soybean germplasm has been conducted by the
USDA in other countries since the 1980's. Screening continues at
Ft. Dietrick, in a quarantine lab. Additional screening programs are
being conducted by other countries, including Zimbabwae. Promising
lines have been identified by several programs, only to fail
after one
to several years in the field. Apparently new races of P. pachyrhizi
which can infect previously reistant lines develop
rapidly.
P. pachyrhizi does not seem to be a typical rust. Most rusts
have five
life stages:
Stage 0 Spermagonia bearing spermatia (n) and receptive hyphae (n)
Stage I Accia bearing acciospores (n+n)
Stage II Uredinia bearing urediniospores (n+n)
Stage III Telia bearing teliospores (n+n -> 2n)
Stage IV Basidia bearing basidiospores (n)
Only uredinia spores have
been found for P. pachyrhizi. While teliospores have been found mixed
with uredinia below the leaf epidermis, none have been shown to
germinate (be viable) (NPAG data, 2002 draft). Additionally, most
rusts alternate hosts amongst each of the stages and infect very few
hosts in any particular stage (usually only one). In contrast, the
uredinial stage of P. pachyrhizi infects many hosts (Table 4).
Because it is the uredial spore that infects many hosts, and not other
spore types, the term "Alternative" hosts, not alternate
hosts is used.
-------------------------------------------------------------------
Table 4. Known hosts of P. pachyrhizi, the pathogen causing soybean rust. 1
Alysicarpus glumaceus Alyce clover (Naturalized in West Indies and FL?) #
Alysicarpus vaginalis - ***
Cajanus sp. pegeon pea relative
Cajanus cajan Cajan, pegeon pea Widely cultivated in tropical countries - *
Calopogonium muconoides
Canavalia gladiata Gian butterbean, Sword Bean - C
Canavalia maritima
Cassia occidentalis - *
Centrosema pubescens Butterfly pea; W. Indies and Mexico - #
Clitoria ternatea - #
Coronilla varia - ***
Crotalaria anagyroides Rattlebox Tropical northern South America #
Crotalaria dissaromoensis
Crotalaria linifolia
Crotalaria pallida
Crotalaria spectabilis - **
Delonix regia Royal Poinciana Wide-branching tree, indoor cultivated
Desmodium discolor - #
Desmodium rhytidophyllum - #
Desmodium triflorum - #
Desmodium varians - #
Dolichos axillaris - #
Glycine argyrea
G. canescens Soybean relative
G. clandestina Soybean relative
G. curvata
G. cyrtoloba
G. falcata, Soybean relative
G. latifolia
G.latrobeana Soybean relative
G. max Soybean Major agricultural crop in US*
G. microphylla
G. soja
G. tabacina
G. tomentella Soybean relative
Hardenbergi violecea
Kennedia coccinea
Kennedia prostrata
Kennedia rubicunda
Kudzu, Pueraria lobata or Pueraria phaseoloides - name change*
Kummerowia striata
Lalab purpureus Hyacinth bean (Dolichos lablab) - C
Lespedeza bicolor - ***
Lespedeza juncea
Lotus americana - # C?
Lotus major
Lotus purshianus
Lupinus albus - C
Lupinus angustifolius
Lupinus hirsutus Blue lupine (Annual; southern Europe)
Lupinus luteus
Macroptilium atropurpureum Siratro; purple bean Grows wild in Cen. And S. America
Macroptilium bracteatum
Macroptilium lathyroides
Macrotyloma axillare
Medicago arborea Medic (Shrub; southern Europe) - #
Melilotus officinalis Yellow sweet clover Eurasia; naturalized in N. America - - ***
M. Speciosus
Mucuna cochinchinesis Velvetbean relative - C
Neonotonia (Glycine) wrightii Glycine (Old World probably)
Pachyrhizus erosus Yam bean; jicama C. America; naturalized in FL C
Phaseolus coccincus Scarlet runner bean - C
Phaseolus lunatus Butter bean, lima bean Tropical SA: important edible bean*
P. vulgaris Kidney bean; green bean Tropical America; widely cultivated*
Pisum sativum - garden peas
Psophocarpus tetragonolobus
Psoralea tenax - #
Pueraria lobata or Pueraria phaseoloides - name change* Kudzu
Rhynchosia minima Creeping tropical weed #
Sesbania exaltata Colorado River hemp NY to FL; west to southern CA*
S. sericea
S. vescaria - *
Teramnus uncinatus
Trifolium incarnatum - *
T. repens - *
Trigonella foenum-gracecum Fenugreek (Asia & southern Europe; forage)
Vicia dasycarpa - ***
Vicia faba - C
Vigna luteola - ** coastal area
Vigna mungo
Vigna radiata
Vigna unguiculata Cowpea, black-eyed pea Widely planted in warm regions*
______________________________________________________
# Closely related species present in the state
C Cultivated in the state as an ornamental
*Frequent in the State
**Occasional in the State
***Infrequent in the State
1 host list adapted from
USDA-APHIS Strategic plan to minimize the impact of the introduction
and establishment of soybean rust on soybean production in the United
States: Soybean rust: Phakopsora pachyrihizi,
P. meibomiae, and "Status of Scientific Evidence on Risks
Associated with the Introduction into the Continental United States of
Phakopsora pachyrhizi with Imported Soybean Grain, Seed and Meal",
dated 23 Feb. 2004
The best long term hope for management of Soybean rust is
resistant plant cultivars. None are available today, and probably
won't be for another 4-5 years. The sequencing project may help in
the development of transgenic cultivars.
Fungicides have become the management tool of first choice in most countries. Dr. Clyde Levy in Zimbabwae determined that full-canopy spray coverage is essential. All reproductive growth needs to be protected. The fungicide needs to protect both the upper trifoliates and kill the spores in the lower and middle canopy.
The USDA has been conducting fungicide tests in other countries. Some of these results may be found at http://www.ipmcenters.org/NewsAlerts/soybeanrust/
To meet crop protection needs, a special needs request called a "Quarantine Exemption (Section 18)" has been submitted by Minnesota and South Dakota to manage Soybean rust on soybeans when it arrives. This submission, has been approved, and serves as a "master" or "generic" application that other states can reference. The Section 18
application can be accessed at:
http://plantsci.sdstate.edu/draperm/SoybeanRustSection18/
APHIS SBR site and strategic plan - http://www.aphis.usda.gov/ppq/ep/soybean_rust/
APHIS risk maps - http://soybeanrust.zedxinc.com & http://aries.zedxinc.com/sbrust.php
Florida SBR Pest Alert - http://www.doacs.state.fl.us/%7Epi/enpp/pathology/soybeanrust.html
Illinois facts about SBR - http://www.ag.uiuc.edu/cespubs/pest/articles/200213k.html
Iowa State University Crop Advisor Institute module on SBR - http://www.cai.iastate.edu
IPM Centers SBR website (past Working Group meeting summaries, membership, action plan, SBR
fungicide efficacy trials, and useful links) - http://www.ipmcenters.org/NewsAlerts/soybeanrust/
National Pest Alert (States & USDA) - http://www.ncpmc.org/soybeanrust
NC504 SBR Committee - http://www.lgu.umd.edu/project/home.cfm?trackID=3154
Ohio SBR facts - http://ohioline.osu.edu/ac-fact/0048.html
Quarantine Exemption (Section 18) - http://plantsci.sdstate.edu/draperm/SoybeanRustSection18
United Soybean Board SBR guide - http://www.unitedsoybean.org/soybeanrustguide.pdf
Aerobiology of Soybean rust and risk assessment http://soybeanrust.zedxinc.com
Aerobiology of Soybean rust and risk assessment http://aries.zedxinc.com/sbrust.php
Michigan State University Information http:///www.pested.msu.edu/