Sclerotinia blight has been confirmed in a peanut field in Surry County, VA. According to the Sclerotinia advisory, the current risk for Sclerotinia in Virginia is HIGH and scouting for the disease is recommended. Cool temperatures and high humidity favor disease development. Signs and symptoms of Sclerotinia blight include rapid wilting and death of infected branches, bleaching of stems, and white, fluffy fungal growth on stems, leaves, or pegs. Once Sclerotinia is identified in a field, a fungicide spray such as Omega is the best way to limit further development of the disease. For more information see the Peanut-Cotton Infonet (http://webipm.ento.vt.edu/cgi-bin/infonet1.cgi) or contact Dr. Hillary Mehl, Extension Plant Pathologist at the Tidewater AREC (hlmehl@vt.edu).
Author Archives: Hillary Mehl
Southern Rust on Corn in North Carolina
Southern rust, a potentially devastating disease of corn, has been reported from several counties in North Carolina. At this time, southern rust has NOT been reported in Virginia. Samples of corn plants suspected to be infected with southern rust should be submitted to your local extension office or the disease clinic at the Virginia Tech Tidewater AREC (contact Dr. Hillary Mehl). Signs of the disease are pustules filled with powdery masses of orange spores (see attached photo). Typically the disease has little impact on Virginia corn since it arrives too late in the season to affect yield, but if southern rust is confirmed in Virginia prior to corn reaching the dent stage (R5), fungicide applications may be warranted. Updates will be provided as more information is obtained.
Sclerotinia blight advisory
Sclerotinia blight has been confirmed in a peanut field in Surry County, VA. According to the Sclerotinia advisory, the current risk for Sclerotinia in Virginia is HIGH and scouting for the disease is recommended. Cool temperatures and high humidity favor disease development. Signs and symptoms of Sclerotinia blight include rapid wilting and death of infected branches, bleaching of stems, and white, fluffy fungal growth on stems, leaves, or pegs. Once Sclerotinia is identified in a field, a fungicide spray such as Omega is the best way to limit further development of the disease. For more information see the Peanut-Cotton Infonet or contact Dr. Hillary Mehl, Extension Plant Pathologist at the Tidewater AREC.
Scab advisory
Some parts of Virginia have entered a moderate risk of scab, and a few localized areas have a severe risk (check your area using the Scab Risk Assessment Tool at www.wheatscab.psu.edu). This is the result of increased humidity, and the forecasted rain may increase infections of flowering heads by the scab fungus. The following recommendations were made on the Head Scab Prediction Center Website (www.wheatscab.psu.edu) by Nathan Kleczewski from the University of Deleware:
“Fields entering flowering are at the highest risk for scab. The best fungicides for scab are Prosaro, Caramba, and Proline. Do not apply products containing a strobilurin (e.g. Aproach Prima, Quilt, Stratego, Headline, Quadris, etc) as strobilurins have been associated with elevated DON levels when applied to the head and scab occurs. There is a 5-6 day window after the majority of a field is flowering and conducive weather occurs to make a fungicide application and maximize efficacy. Ground rigs should have nozzles angled at least 15 degrees in the forward direction and apply at least 10 gallons per acre, with 15-20 being optimal. Aerial applicators should apply at 5 gallons per acre. Shoot for 300 to 350 micron droplet size. Prosaro, Caramba, and Proline will control foliar diseases.””
These same recommendations apply to Virginia.
Foliar diseases of wheat also have the potential to increase at this time. Several fungicides have good to excellent efficacy in control of multiple diseases. Remember to avoid strobilurin containing fungicides for the reasons described above.
The attached document gives information on wheat growth stages, scouting for diseases, and fungicide efficacy for control of various wheat diseases.
If you have any questions or concerns feel free to contact me.
Hillary L. Mehl, Ph.D.
Assistant Professor of Plant Pathology
Virginia Tech Tidewater AREC
6321 Holland Road
Suffolk, VA 23437
Telephone: (757) 657-6450, ext. 423
email: hlmehl@vt.edu
Additional information: wheat-disease-update-2014-pdf
Head scab advisory
If your wheat is flowering, it may be at risk for head scab (Fusarium head blight, FHB). FHB is caused primarily by the fungus Fusarium graminearum. Infection of wheat heads with this fungus can result in significant yield loss and contamination of the grain with deoxynivalenol (DON or vomitoxin). Risk of FHB can be determined using the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/). As of today (May 5) many areas in eastern and central Virginia have a moderate FHB risk; portions of the Eastern Shore (Accomack County) have a high risk. Early flowering is the best timing for fungicide applications. Prosaro, Proline, and Caramba are the most effective products to reduce FHB and DON. If a strobilurin is applied at or after heading, and IF scab infections occur, DON levels are likely to be elevated compared to a triazole or even an unsprayed check. Information on FHB can be found in the Virginia Tech Extension publication “Managing Fusarium Head Blight in Virginia Small Grains” (http://pubs.ext.vt.edu/3102/3102-1535/3102-1535.html). Additional information: fhb-virginia-tech-pdf
Applied Research on Field Crop Disease Control – 2013
A summary of the field crop disease management trials conducted at the Tidewater Agricultural Research and Extension Center in 2013 is attached. Additional information: appl-res-field-crop-dis-2013-pdf
Virginia Soybean Rust Update: September 26, 2013
This week Asian soybean rust was confirmed in Isle of Wight County. Please see the attached update for details. Additional information: virginia-soybean-rust-update-9-26-13-pdf
Soybean Rust Update: September 19, 2013
Since the announcement that Asian soybean rust (SBR) was found in the sentinel plots at the Tidewater AREC, we have been receiving lots of inquires about what the risk is to the soybean crop and whether or not it is prudent to spray. Attached I have provided a somewhat lengthy description of the status of SBR in Virginia and the factors growers should consider before deciding whether or not to spray. Please contact me if you have any additional questions or concerns regarding the status of soybean rust in Virginia (Hillary Mehl, Extension Plant Pathologist: hlmehl@vt.edu). Additional information: virginia-soybean-rust-update-9-19-13-pdf
Soybean Rust found in Suffolk, VA
On September 17, 2013 soybean (SBR) rust was observed and confirmed on soybean leaves (10/34 leaflets, 2% leaf coverage) collected from one of the Tidewater AREC sentinel plots on September 5. Suffolk is the only county in Virginia thus far with confirmed soybean rust, but we will now intensify our scouting efforts throughout the soybean-growing regions of the state.
So far in 2013, SBR has been confirmed on soybeans in 185 counties/parishes in 10 states in the U.S. (AL, GA, FL, MS, LA, SC, AR, NC, TN, and VA) including two counties in North Carolina and one county in SE Virginia.
Soybean sentinel plots and commercial fields are monitored annually for early detection of SBR and tracking of disease spread. Data are used to make recommendations for timely applications of fungicide sprays for control of SBR. Since August, soybean leaflets from sentinel plots at the Virginia Tech Tidewater AREC in Suffolk, VA have been evaluated on a weekly basis, and as in prior years, the first report of SBR in Virginia was from one of these sentinel plots. Other diseases in soybeans at this time include Cercospora blight, brown spot, frogeye leaf spot, and anthracnose.
Risk of yield loss in soybean is minimal if SBR is detected following the R6 development stage. However, growers with soybeans that have not yet reached the R6 stage should consider spraying fungicides for control of SBR (triazole or pre-mix fungicide). This is particularly relevant for late-maturing/double-cropped soybean.
Updates will be emailed weekly as we track the progress of SBR spread and disease development throughout Virginia.
NOTE: I would like to introduce myself as the new Extension Plant Pathologist (replacement for Dr. Pat Phipps) at the Virginia Tech Tidewater AREC in Suffolk, VA. My focus is plant disease management in field crops for the state of Virginia. My contact information is the following: Hillary L. Mehl, Ph.D.
Assistant Professor of Plant Pathology; Virginia Tech Tidewater AREC, 6321 Holland Road, Suffolk, VA 23437; Telephone: (757) 657-6450, ext. 423; Cell: (530) 906-0807; email: hlmehl@vt.edu