Posts Tagged ‘soybean rust’

Soybean Rust Risk Assessment (ZedX, Inc. & PSU)

Friday, May 11th, 2012

Bob Mulrooney, Extension Plant Pathologist;

The lower than normal rainfall observed has limited spread of soybean rust throughout the Southeast and South-central U.S. Soybean rust was recently identified in kudzu in Leon County, Florida on April 17. However, at this early point of the growing season, and with minimal infection across the South, the risk of long distance soybean rust spread to the north is minimal. The map below shows areas currently positive for soybean rust in northeastern Mexico and throughout the Gulf Coast area of the United States. A relatively mild winter likely contributed to more conducive overwintering conditions for rust on kudzu along the Gulf Coast. A drier last 30 days across the Southcentral along with drought conditions across the Southeast has made further rust spread unlikely in these areas.

Early-Season Soybean Rust Situation

Thursday, March 29th, 2012

Bob Mulrooney, Extension Plant Pathologist;

While we are a long way from dealing with soybean rust (SBR), it is still a major threat to soybean production in the South. The incidence of SBR in the last two years has been low to almost non-existent (last season). However 2012 is looking different possibly. We have had a record warm winter which extended to the deep South as well where soybean rust has to overwinter on other live hosts, primarily kudzu. In 2012 soybean rust has been found in Cameron County, TX, Baldwin County, AL, Iberia Parrish, LA and now the most recent find has been in Gadsden County, FL. This is the northern panhandle region where most of the soybeans in FL are grown. The Florida find is the earliest (March 22) that soybean rust has been detected on kudzu in FL. Besides the warm weather, they have had much more rain than in previous years, which has also favored the fungus. The panhandle of FL has only had 70 hours below freezing all winter compared to most years when they see more than 200 hours each winter. The early season is promoting early kudzu growth which could mean increasing levels of rust on kudzu that moves to soybeans that produces spores that have the potential to blow north in storm fronts, tropical storms and hurricanes.

I am not predicting anything here, because it is way too early, but the scenario is developing that we have the potential for soybean rust increasing after record low levels of the past two years. One year the South had a late freeze that killed the kudzu and the fungus along with it, which greatly slowed and reduced soybean rust that year. You can’t predict what will happen, but the forecasters do not forsee that happening this year. If you want to keep up with soybean rust development the ipmPIPE ( is continuing this year despite reduced federal funding Thanks to industry partners, the website will continue for 2012.

Soybean Disease Update – September 23, 2011

Friday, September 23rd, 2011

Bob Mulrooney, Extension Plant Pathologist;

Soybean Vein Necrosis Virus
I just wanted to add a brief summary for our WCU readers that soybean vein necrosis virus has been seen in all three counties in Delaware and apparently is widespread in the surrounding states of PA, MD, and VA. We see it everywhere we look now but I am not sure how much effect it is having on yield at this point. Researchers in other parts of the country are also working on it and have a few more years experience with it. It is premature to say too much about it other than we now know what is causing the symptoms we have seen this year and probably last year as well, but did not know what it was. By the time the winter meetings occur hopefully I will be able to share more hard facts about the disease and control options for our region.

Early symptoms of soybean vein necrosis virus (SVNV) from DE

Soybean Cyst Nematode
Do not ignore soybean cyst nematode. Soil sampling after harvest before any fall tillage is recommended for fields to be planted next season to soybeans following this year’s crop. Do not plant SCN susceptible varieties without soil testing first. Soil sample bags and information sheets are available from the county Extension offices for $10/ sample bag.

Soybean Rust Risk Assessment (ZedX, Inc. & PSU)
Despite recent heavy rainfall along the Atlantic Coast and throughout the Northeast from the remnants of Lee and Hurricane Irene, source inoculum in the Southeast was likely still too low to cause widespread transport and deposition of spores further north. Soybean rust was, however, identified in extreme southwestern Georgia for the first time this season. Due to the ongoing drought in Texas and Oklahoma, the slow progression this season in the Southeast, and the fact that the primary soybean production season is in the later stages, it is unlikely that soybean rust will spread as far as it has in years past. As such, the risk area will remain rather minimal in spacial coverage (see map below). Double crop soybeans along the Gulf Coast could still be at risk for soybean rust as the season progresses, but even double cropped soybeans are at a minimal risk.

The above image displays the current threat level of soybean rust. The yellow “wait” areas are considered slightly at risk, orange “watch” areas are at moderate risk, and red “warn” areas are at great risk or already identified positive for soybean rust. Risk areas are estimated based on meteorological factors affecting spore transport and deposition and factors conducive for further development within the canopy such as temperature and moisture. Biological factors such as host plant and crop phenology are also considered. Risk assessment maps are produced by the PSU Ensemble Field Crop Rust Forecasting Program.

Soybean Disease Update – June 24, 2011

Friday, June 24th, 2011

Soybean Rust Report
There is very little soybean rust activity to report. It has been very dry and hot in the Gulf Coast region where soybean rust overwinters. It has only been found on kudzu so far this season. The risk of soybean rust is very low now even for the southeast. I continue to monitor soybean rust development in the south and will provide a report periodically as the season progresses.

Septoria Brown Spot
Septoria brown spot is one of the earliest fungal diseases that we see on soybean and can be found on the unifoliate leaves and the lower trifoliate leaves when it is present. Badly infected unifoliate leaves will usually fall from the plant and we will not see this disease again until the soybeans canopy and conditions would be favorable for infection. Most seasons this disease is not yield limiting.

Septoria brown spot on unifoliate leaves of soybean.


Agronomic Crop Disease Updates – September 17, 2010

Friday, September 17th, 2010

Bob Mulrooney, Extension Plant Pathologist;

Corn harvest is underway so be sure to check corn fields for lodging potential by squeezing the lower nodes or pushing on the stalks. A simple way to do this is to walk through the field and, keeping your hands at chest height, push stalks 8-10 inches from vertical. If 10-15% of the stalks lodge, schedule the field for early harvest before a strong wind results in severe lodging. Drought conditions during grain fill put substantial stress on corn plants. In many fields, it is likely that the corn crop responded by cannibalizing stalk reserves to fill the grain. This results in a weakened stalk and greater susceptibility to stalk rot.

Small Grain
Be sure that you plant wheat varieties with high levels of disease resistance. Select varieties with high levels of resistance to powdery mildew, leaf rust and stripe rust. Seed should be treated with Baytan, Raxil, Dividend or other labeled product to protect plants from loose smut and common bunt. Varieties that are susceptible to powdery mildew should be treated with Baytan, Dividend or other seed treatment that will protect them from early infection.

Do not ignore soybean cyst nematode. Soil sampling after harvest before any fall tillage is recommended for fields to be planted next season to soybeans following this year’s crop. Do not plant SCN susceptible varieties without soil testing first. Soil sample bags are available from the county Extension offices for $10/ sample bag.

Soybean Rust Update
Nothing new has developed north of the North Carolina find on August 30. Florida had its first soybean rust detection on soybeans on September 14. Needless to say, soybean rust is not going to be an issue in most of the US this season.

Soybean Rust Found in North Carolina

Friday, September 3rd, 2010

Bob Mulrooney, Extension Plant Pathologist;

Steve Koenning, Extension field crops pathologist reported that “Asiatic soybean rust has been identified this morning (8/30) from a research plot at Kinston, NC, in Lenoir County. There were none to very few pustules on any of the leaves inspected, and none were sporulating. We are not sure how the spores got there, or where they came from, since the nearest rust that has been reported so far has been is southern Georgia, and that is 270 (Murphy, NC) to 570 (Elizabeth City, NC) miles away from our North Carolina soybeans.” It was confirmed today by ELISA testing that the rust that was found is Asiatic soybean rust.

This is unusual and not at all in line with the prediction models that have been issued so far. We will continue to monitor this find and see what happens, but with the hot dry weather the spread of any soybean rust is highly unlikely. Most of our soybeans are mature enough that this find should have no impact on DE soybean production. We will see what the current hurricanes might bring us but the amount of soybean rust in the South right now has been the lowest since this monitoring effort began.

To see the ipmPIPE website for more information on soybean rust see:

Soybean Rust Update – August 20, 2010

Friday, August 20th, 2010

Bob Mulrooney, Extension Plant Pathologist;

It looks like most soybean areas in the US may escape soybean rust this season. It has yet to be seen on soybeans in the South. To date it has only been observed on kudzu.

The linked pdf file shows the 30-day Soybean Rust Risk Outlook.

Soybean Rust Update – July 16, 2010

Friday, July 16th, 2010

Bob Mulrooney, Extension Plant Pathologist;

Soybean rust was reported on kudzu in the county of Leon, Florida on July 13, 2010. Soybean rust was reported July 3 in two counties in Alabama and one county in Florida. On June 28, soybean rust was found in one county in Florida. Rust has also been confirmed recently on soybean in the northern portion of the state of Tamaulipas in Mexico. Rust develop has been very slow this season. Conditions are dry in the South and there was not much overwintering on kudzu since the cold winter went so deep into the South.

Soybean Rust Update

Friday, June 25th, 2010

Bob Mulrooney, Extension Plant Pathologist;

Soybean rust was confirmed June 10, in the US for the first time this season on soybean in Hidalgo County, Texas. Rust has also been confirmed on soybean in the neighboring Mexican state of Tamaulipas. Rust was just detected in Mobile AL on kudzu on June 23. Conditions for soybean rust are still very unfavorable in the Gulf States. If you are interested in the movement of soybean rust consult the ipm PIPE website at

Soybean Rust Update – June 4, 2010

Friday, June 4th, 2010

Bob Mulrooney, Extension Plant Pathologist;

It is the first week of June and there is no active soybean rust in the US. This is very unusual compared to past seasons. The cold winter in the South killed back kudzu and reduced most of the overwintered spores in that region. Dry weather again in the South is not providing the conditions needed for infection. Only time will tell what this season’s rust scenario will be. The southern states continue to monitor for rust using the established sentinel plot system that is in place.