Soybean rust is a new disease for American soybean growers. Please visit MSU's Michigan Soybean Growers Reference for state and national links to resources. Below, you will find current season advice and reports from MSU Extension faculty and field staff as published in the newsletter, the Field Crop Advisory Team (CAT) Alert. Information will be regularly updated through the growing season.

The following articles are excerpted from the Field Crop Advisory Team Alert newsletters. To read additional issues of the newsletter, please visit: http://www.ipm.msu.edu/fieldCAT.htm

To view information about another new soybean pest, soybean aphid, visit:
http://www.ipm.msu.edu/soybean/aphid.htm

You’ve probably read about the soybean rust found in early March on soybean residue from a bin of soybeans produced in Iowa in 2006, but if you haven’t you can read about it at the link listed here: http://www.plantpath.iastate.edu/soybeanrust/node/394 . Even though it’s early in the season, I thought that I’d start giving you some updates on what is happening with soybean rust so far this year further south.

On April 7-8, record low temperatures in the Florida Panhandle dipped below freezing for several hours. It is not known how this might impact the spread and build up of soybean rust on kudzu, but it will probably slow it down for a while. Before the frost, warm temperatures had increased the growth of kudzu throughout the Southeast. Scouting efforts are already underway on kudzu and emerging soybeans in southern sentinel plots. Soybean rust has been detected on kudzu in nine Florida counties and in five counties each in Georgia and Alabama. In some cases, the infected kudzu has been destroyed and rust in some of those locations is no longer found. Soybean rust was found on soybeans in one county in Texas, but that field has since been destroyed. Sentinel plot scouting will take place again this year in Michigan. We will provide more details to you as the season gets underway.

Editor’s note: see the national tracking web site for soybean rust at: http://www.sbrusa.net/

On July 26, soybean rust was confirmed on soybeans from a sentinel plot in Rapides Parish, Louisiana. This is the first report of rust on soybeans in Louisiana for the 2006 season. So far this year, rust has been confirmed on soybeans in six different counties in four states: Alabama, Florida, Georgia and Louisiana. The rest of the finds have been on Kudzu – 26 counties in five states: Alabama (5), Florida (12), Georgia (5), Louisiana (3) and Texas (1). The movement of rust to other areas has been slow this year due to dry to very dry weather in spore source regions. Last year at this time, there were 14 confirmations of rust in Florida, Georgia, Alabama and Mississippi.

There were 8 samples received from sentinel plots during the reporting week.

The following is a compilation of the reports.

Growth stages: 1 plot=V6, 1 plots=R1 ®R2, 4 plots=R2, 1 plots=R4, 1 plot=unknown.

Plant height: Ranged from 11 to 30 inches with 1 height unknown.

Degree of canopy closure: Ranged from 50 ® 100 percent, 1 unknown, and averaged 89 percent.

Soybean diseases present: Samples had high levels of Septoria and moderate levels of bacterial blight.

Today’s Field Crop CAT Alert contains a pdf on scouting for soybean rust. The second page contains color drawings of soybean R (reproductive) stages. The scouting period for rust begins at R1, when soybeans have at least one open flower at any node, and ends once soybeans reach full seed (R6). Risk levels for soybean rust in Michigan remain very low. So far this year, rust has been reported in 25 counties total, five each in Alabama and Georgia, 12 in Florida, one in Texas (the plot was destroyed earlier this year), and two in Louisiana. Only three of these reports have been on soybeans; the rest have been found on kudzu. The recent positive finds on soybean have been in Decatur County, Georgia (July 10) and Martin County, Florida (June 15).

There were nine samples received from sentinel plots during this reporting week. The following is a compilation of the reports.

Growth stages: 1 plot=V4, 1 plot=V5, 1 plot=V6-V7, 3 plots=R1, 2 plots=R2, 1 plot=unknown.

Plant height: Ranged from 10 to16 inches.

Degree of canopy closure: Ranged from 5 - 90 percent and averaged 60 percent.

Soybean diseases present: There were moderate levels of brown spot (Septoria) present on samples from 4 plots. A sample submitted from Kalamazoo County had downy mildew, this is the first time this season that we have seen soybean downy mildew.

There were 8 samples received from sentinel plots during the reporting week of June 21-28, 2006. The following is a compilation of the reports.

Growth stages: 4 plots=V3, 2 plots = V6, 1 plot=V7, 1 plot=R3.

Plant height: Ranged from 5 to 10 inches.

Degree of canopy closure: Ranged from 10 – 40 percent and averaged 24 percent.

Soybean diseases present: Low levels of Brown Spot (3 plots).

Comments: This is the first week that we received soybean samples. Most samples were in good condition. A few samples had Brown Leaf Spot (Septoria), but the majority showed no signs of pathogens.

Soybean rust has been found on soybeans in southern Florida. The impacts of tropical storm Alberto on the spread of rust haven’t shown up yet, but sentinel plots are being watched closely.

I just returned Tuesday (June 20) from a trip to Florida to visit the North Florida Research and Education Center at Quincy. There is a tremendous amount of soybean rust research going on there. I was taken out to several locations to scout for rust in kudzu. My genial southern hosts didn’t need to caution me twice not to venture into the kudzu too far due to snakes – cottonmouths, rattlers and coral snakes. I spent time looking at soybean rust lesions, spores and symptoms. The workshop offered in July would be a worthwhile educational experience for any professional looking for some hands-on experience with soybean rust. I’ve included their announcement below.

This short course will be modeled after last year's – hopefully without the occurrence of a hurricane this time around.  The program includes hand lens and microscope observation of infected soybeans, field observation of infected kudzu and, we hope, soybeans and tours of current soybean rust field research.

This workshop will be offered without a registration fee, thanks to the generosity of the North Central Soybean Research Program.  We do have a space limitation of 100 people, so we plan to offer the spaces on a first-come, first-served basis.

For a registration form, visit:
http://www.ipm.msu.edu/cat06field/pdf/sbrreg.pdf

Scouting in Michigan sentinel plots has started, but is off to a slow start due to the weather. Soybeans are still fairly small. No rust has been detected.

Further south, soybean rust is still being found on kudzu in Florida, and was found on kudzu in Georgia yesterday. There have been no finds on soybean yet in either location. Soybeans are at early bloom (R1-R2) in Florida.

This year, spore traps will be installed in two Michigan soybean rust sentinel plots. The spore traps, provided by Syngenta Corporation, collect wind-blown spores. Additional spore traps are located throughout the sentinel plot network. Positive spore trap information does not imply that soybean rust infection has taken place. Only plant samples are used to determine a positive occurrence of rust. The data from the Michigan spore traps will not be released to the public unless there is a positive confirmation of soybean rust in the North central region. The spore traps are being used in the Michigan sentinel plots primarily to evaluate their potential as a research tool. All the spore trap samples will be processed at the University of Arkansas.

One of the challenges in using wind traps is that currently, identification of the rust spores obtained is done solely on the basis of visual identification. The spores are collected on a glass slide coated with petroleum jelly. It is difficult to separate the spores from the petroleum jelly to permit the use of analytical methods to confirm that they are positively Asian soybean rust. Researchers at The Ohio State University are working on a screening process that uses a fluorescent antibody that reacts with only Asian soybean spores, to fluoresce under ultra violet (UV) light.

Antibodies are coupled with molecules which fluoresce under ultra violet (UV) light, to improve detection of specific antigens. After the cells (rust spores) are mounted on a slide, fluorescent labeled antibody is placed on the slide and given time to bind to the cells. Antibody that doesn’t bind is washed off. The slide is viewed under a microscope using UV light. Fluorescence indicates the presence of the antigen-in this case, Asian soybean rust spores. Additional testing of the procedure is underway to make sure that the antibody only binds to (and fluoresces with) soybean rust, and not with other spores.

An updated fact sheet on where to get information about soybean rust forecasts, models and information can be found at: http://www.ipm.msu.edu/cat06field/pdf/6-8sbrinfo.pdf

Sentinel plot scouting in Michigan started this week. No rust has been reported. Soybean rust continues to move slowly down south. In Georgia plots were scouted for soybean rust, but none was observed on any of the samples. Most of their soybean sentinel plots are at the V5-V7 growth stage, with a few scattered plants at first bloom (R1). Weather continues to be hot and dry for most of the state with a few scattered thunderstorms. Previously infected sites that were destroyed are still not showing any new signs of infection. There have been positive finds of soybean rust on kudzu in north Florida. Although there hasn’t been any recent rain, high humidity has provided sufficient dew to allow sporulation and infection. All of the soybean sentinel plots are still negative. Some have started to bloom (R1).

Despite a report of “rust-like” spores caught in a spore trap at a Texas location, there was no soybean rust in a sentinel plot and three commercial fields in the area. There has been no rust observed on sentinel plots, commercial fields or kudzu patches. Sentinel plot scouting is underway in Louisiana. No soybean rust has been found.

Soybean rust update
Diane Brown-Rytlewski and Willie Kirk
Plant Pathology

The following article is from the May 25, 2006 Field Crop CAT Alert.

Soybean rust website expands to include soybean aphids
Christina DiFonzo, Entomology

The following article is from the April 6, 2006 Field Crop CAT Alert.

Soybean rust fact sheet insert
Diane Brown-Rytlewski
Plant Pathology

The following article is from the April 6th 2006, Field Crop CAT Alert.

Last year, a series of fact sheets about soybean rust were developed. Those fact sheets have undergone major revisions to provide additional information that has been requested. Fungicide Application Technology for Soybean Rust-2006 is avaiable as a pdf at: http://www.ipm.msu.edu/cat06field/pdf/sbr_aptechnology.pdf

The keys to successfully using fungicides to control soybean rust are applying the fungicide at the right time, achieving good canopy penetration and good leaf coverage. The fact sheet gives guidelines for selecting the correct spray volume, droplet size, ground speed, nozzle pressure, boom height and nozzle type to achieve good penetration and coverage of the soybean canopy.

Latest news on soybean rust
Diane Brown-Rytlewski
Plant Pathology

The following article is from the March 2 2006, Field Crop CAT Alert.

Last year, the national sentinel plot system worked very well to track the spread of soybean rust in the United States. This year, there will again be a national sentinel plot network, with a higher proportion of plots in the southern states, where soybean rust is found early in the season.

Work is underway now to determine locations for this year’s 20 plots in Michigan.

So far this year, rust has been found on kudzu in Florida, Alabama and Georgia, although some of the sites have since been killed by frost or removed. For an up-to-date report on scouting for rust in the sentinel plots, visit: http://www.sbrusa.net

National Soybean Rust Symposium

The following article is from the September 8, 2005 Field Crop CAT Alert.

The American Phytopathological Society (APS) will hold a national forum of leaders in state and federal government, grower organizations, researchers, educators, crop consultants, agribusiness, food industry and others to review the United States soybean rust strategic plan and coordinated framework in light of knowledge acquired during the first crop season with Asian soybean rust in North America.

The technical program will include discussion of the latest information on:

• Detection and prediction systems for soybean rust - how well did they work in 2005?
• Fungicide efficacy and application studies.
• Pathogen genetics - what does the sequence say?
• Host resistance - sources of partial resistance to soybean rust.
• Marker assisted selection - what's in progress?
• Pathogen biology - epidemiology, additional hosts, inoculum sources.

Confirmed soybean rust detections have occurred in eight Florida counties, four Georgia counties, one Alabama county and one county in Mississippi. Infection loci are small and spread appears to be minimal despite weather conditions favorable for spread over the last two weeks. Intensive scouting is occurring throughout the southern states and includes commercial fields and kudzu patches as well as sentinel plots.

More information is available at http://www.sbrusa.net/

• Soybean – Manganese deficiency; Downy mildew (two samples)
• Sugar beet – Cercospora leaf spot
• Wheat – Take-all

Asian soybean rust sentinel plot scouting report for June 30-July 6
Jan Byrne and Steve Gower, MSU Diagnostic Services
Sandy Perry, SBR Sentinel Plot Coordinator

Although no Field Crop CAT Alert was published on July 7, 2005, a soybean rust update was submitted.

There were 13 scouting reports filed from the 20 sentinel plots during the reporting week.

• Low pH injury on corn
• Cercospora leaf spot on sugarbeets
• Bacterial leaf spot on sugarbeets
• Corn nematodes
• Mesotrione carryover on soybeans

Soybean rust has now been confirmed on soybeans in the following locations: Baldwin County in Alabama, Marion County in Florida (June 29) and Seminole County in Georgia. The Alabama and Florida finds were in sentinel sites, while the Georgia find was on volunteer soybeans that have since been destroyed. Six counties in Florida have now reported soybean rust on kudzu. The latest find is in Leon County in Northern Florida. Intensive scouting is continuing throughout eastern North America from the Gulf coast to southern Ontario wherever soybean is grown with no new finds.

Soybean rust fact sheets provide information for growers

The following article is from the June 16 , 2005 Field Crop CAT Alert.

Five new fact sheets containing Asian soybean rust recommendations are now available for Michigan growers.

The fact sheets can be found online by clicking on the agriculture link at: www.msue.msu.edu. They are also available at any county Michigan State University (MSU) Extension office.

The fact sheets focus on scouting for soybean rust, modeling and forecasting web sites for soybean rust, an introduction to fungicides, soybean rust fungicide application strategies and fungicide application technology for soybean rust.

“The most critical steps for reducing the adverse impact of soybean rust are monitoring the disease’s progress, applying the proper fungicides at the right time and providing adequate canopy penetration and leaf coverage when applying fungicides,” says Mike Staton, MSU Extension educator for Van Buren and Berrien counties. “These fact sheets contain all the information soybean growers need to meet these objectives in a concise and usable format.”

The fact sheets were produced by the MSU Department of Plant Pathology, the MSU Extension Field Crops Area of Expertise Team and the MSU Integrated Pest Management (IPM) Program.