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ASIAN SOYBEAN INFECTED AREAS SOYBEAN RUST - Identifi ed in

Prior to the November 10, 2004 Michigan soybean producers should scenario because we have several announcement of a positive be aware of the recent soybean rust months before the 2005 growing identifi cation of the Asian soybean identifi cation in Louisiana, but NOT season to make management plans. rust in two different fi elds in become alarmed. The U.S. soybean Never before has there been such a Louisiana by the Animal and Plant industry will survive! There is no need unifi ed effort of industry, government, Health Inspection Service (APHIS) to panic. We have the knowledge to and academia to prepare for such a of the United States Department of manage the disease. The timing of disease. Agriculture (USDA), North America the recent infestation is a best-case was the only soybean producing continent unaffected by the disease. Bacterial Pustule Since this initial fi nd, not surprisingly, additional fi elds of in the south as well as another host plant are Brown Spot reported to have been infected. Asian soybean rust, , originated in tropical and subtropical regions of and and most likely spread to several African countries via wind currents. In 2001, the disease was fi rst identifi ed in South America and subsequently has moved to regions further north in that continent. It is believed this year’s active hurricane season, most likely , brought the windborne spores into the U.S. Rust causes early Soybean Rust Disease leaf defoliation of soybean plants resulting in fewer pods and seeds; therefore, less yield. The primary symptom when looking for rust is brown-colored spots on the soybean leaf. Early rust detection can be diffi cult because the lesions Cercospora Leaf Spot can resemble other foliar disease like brown spot, bacterial pustule or Frogeye Leaf Spot bacterial blight; however, if observed closely with magnifi cation, you will see tiny bumps within the lesion. An indication the diseased leaf may be soybean rust would be when the SOYBEAN RUST – Winter Survival pustule opens it most likely will have Because of Michigan’s freezing winter conditions and no known host species a circular pore rather than a linear surviving the winter, soybean rust spores are not likely to over-winter in crack at the top of the lesion more Michigan. With alternate host plants being abundant and surviving winter in the common with bacterial pustule. The southern U.S., this is most likely where spores will survive. lesions are generally found on the Since the spores are dependent on southerly winds to be transported to Michigan underneath side of the lower leaves during the summer and need proper moisture and temperature conditions once then progress up the plant as the lower they arrive, rust will most likely vary from year to year. leaves die. SOYBEAN RUST – Fast Facts • Since the rust spores do not infect • When properly applied, fungicide • Early season soybean rust will be the soybean seed, there should be no applications by either ground or found on lower leaves and “move” effect on seed supplies for the 2005 aerial methods are believed to be upwards as lower leaves die. planting season. equally effective. • If infection occurs, the “best-case • Early detection is a must along with • Research suggests row widths do not scenario” in Michigan would involve an aggressive fungicide control affect soybean rust incidence/sever- late season infection necessitating a program. ity. single fungicide application. • Soybean rust resistant varieties are • Most experts estimate fungicide • When soybean rust has been not yet available commercially. and associated costs for Michigan confi rmed, the proper fungicide • Cell infection is quick, easily in growers to be at $20-$25/acre. application will be most effective 9-10 days and cycles of spores can • Yield reduction caused by soybean within a couple of days after rust continue for up to 15 weeks under rust is reported to be anywhere from confi rmation. ideal conditions although not likely 10% - 80% with Michigan losses at • Be knowledgeable because some to occur in Michigan. the lower percentage. fungicides are preventative while • Six hours of moisture is needed with • Soybean rust spores are reported to some are curative. a temperature range of 59-82o F for have been transported by the wind • With the approval of at least six germination. currents up to 100 miles per day. additional active fungicides under • Soybean rust spores can penetrate • In the southern U.S., there are EPA’s section 18 permit, fungicide the leaf cells directly, not need- at least twenty reported species shortages are not expected. ing “assistance” from leaf damage, of alternative hosts for the over- insects, etc. wintering of rust spores.

Fungicide Options for Asian Soybean Rust (Phakopsora pachyrhizi)

SOYBEAN RUST – Trade Name Manufacturer Active ingredient (ai) Resistance management Quadris® Syngenta Crop Export Concerns Protection Inc azoxystrobin See guidelines for strobilurin fungicides Bravo® Syngenta Crop Based on the history of soybean rust Protection Inc chlorothalonil See guidelines for chlorothalonil fungicides in other soybean exporting countries, Echo 720® Sipcam Agro Inc chlorothalonil See chlorothalonil experts predict the recent soybean Headline® 2.09EC BASF Corporation pyraclostrobin See guidelines for strobilurin fungicides rust identifi cation in the U.S. will not Pristine® BASF Corporation pyraclostrobin + See guidelines for strobilurin + affect soybeans and soybean product 38%WDG boscalid carboxamide combination fungicides exports. Many importing countries These fungicides have received Section 18 approval in most states including Michigan have been purchasing soybeans from Tilt® Syngenta Crop South America with very few import 3.6EC Protection Inc propiconazole See triazole fungicides concerns because of soybean rust PropiMax™ presence. 3.6EC Dow AgroSciences propiconazole See triazole fungicides Bumper® 41.8EC Makhteshim-Agan propiconazole See triazole fungicides Folicur® SOYBEAN RUST – 3.6F Bayer CropScience tebuconazole See triazole fungicides Human/Animal Concerns Laredo™ 25EC Dow AgroSciences myclobutanil See triazole fungicides Laredo™ Soybean rust spores pose no health 25EW Dow AgroSciences myclobutanil See triazole fungicides concerns to either humans or animals. Stratego® Bayer CropScience propiconazole + See guidelines for strobilurin The rust spores attack the foliage of 2.08F trifl oxystrobin and for triazole fungicides the soybean plant causing early defo- These fungicides have not yet received Section 18 approval liation and affect the seed yield but do Domark™ Sipcam Agro not directly attack the seed to cause 125SL USA, Inc. tetraconazole See triazole fungicides food/feed concerns. Graph taken from www.planthealth.info/rust/rustfungicide.htm as of January 6, 2005. “We are using a new mailing list. Please notify us of NON-PROFIT duplicate mailings to help save valuable checkoff funds.” U.S. POSTAGE PA I D Ithaca, MI Permit No. 35

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SOYBEAN RUST – SOYBEAN RUST – Checkoff Efforts Grower Education • Growers should avail themselves throughout the winter of any grower For many months prior to the meetings addressing soybean rust. November 10th rust identifi cation rust resistance in maturities adaptable • Pay particular attention to management in Louisiana, the soybean checkoff to Michigan environments. Much of information which you can use in program has been involved in soybean this germplasm screening involves making 2005 planting decisions. rust efforts on behalf of Michigan material unique to Chinese production. Symptoms, detection, history, etc. are growers. These many efforts include: Since the rust is present in , interesting but do you need that for rust information coordination of the planting decisions? private and public sector, literature we are free to artifi cially inoculate, • Review and understand the fungicides development and distribution, training evaluate, and experiment with the and how they control the rust. Are they for the detection and verifi cation of soybean rust. The provinces of preventative or curative? soybean rust, and an intense effort Fujian in southern China and Jiangsu • Understand fungicide use for effi cacy, to identify unique Chinese soybean in central China are ideal for rust application timing, methods, rates, germplasm for genetic resistance to evaluation because of “good” rust nozzle type, spray pressure, adjuvant rust. growing conditions as well as having a use, gallonage and, of course, fi ne cooperator in the Academy. Most experts economics of control. agree the ultimate Even though some Michigan • Understand and plan for the importance adaptable germplasm has been of immediate reaction needs both for goal is to identify unique soybean identifi ed as having some “resistance “fi rst detection” confi rmation of rust level”, much evaluation is still needed. and for proper fungicide application. germplasm with genetic resistance Optimistic estimates of germplasm • Know who to contact in different Dr. Dechun Wang resistance are 8-10 years away – but situations before you need their help. to the multiple races of soybean rust. By virtue there is hope! Through your support DEVELOP A PLAN OF ACTION. of the soybean checkoff, we have a • With immediate response needed, who of “developed networks” between Dr. Dechun Wang, Michigan State good start on resistance germplasm is the CORRECT contact to show your screening. suspected diseased leaf to? University Soybean Geneticist and his • Investigate the availability of any web- comrades at the Nanjing Academy of Be sure to check out the various web based in-season soybean rust mapping Agriculture Sciences in the Chinese sites listed below. Most are being service to help you calculate the risk province of Jiangsu, we are in the updated regularly. and potential spore arrival date for your third year of germplasm selection for area. SOYBEAN RUST – Reference Information For additional information on soybean rust, visit any of these web sites: • www.planthealth.info • www.ipmcenters.org/newsalerts/soybeanrust • www.unitedsoybean.org/producers_rustguide.pdf • www.ncpmc.org/soybeanrust • www.cornandsoybeandigest.com • www.tifton.uga.edu/sumner/tifton/spray/soybeansprayernozzles.htm • www.soybeanrustinfo.com In addition, most likely a USDA-based web site will be available • www.aphis.usda.gov/ppq/ep/soybean_rust for the 2005 season that will predict soybean rust occurrence based • www.aphis.usda.gov/lpa/issues/sbr/sbr.html on climatic conditions and reported rust identifi cation.