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, hlmehl@vt.edu). 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. Additional information: southern-rust-on-corn-jpg
Category Archives: Disease
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 (http://webipm.ento.vt.edu/cgi-bin/infonet1.cgi) or contact Dr. Hillary Mehl, Extension Plant Pathologist at the Tidewater AREC (hlmehl@vt.edu).
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.
Late Blight found on Potato in Carteret Co., NC
Please review the attached disease alert regarding the discovery of late blight in NC. Additional information: lateblightalert062014-doc
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