Category Archives: Disease

Wheat Disease Update – April 30, 2018

Posted on by

As wheat starts flowering in the region, it is time to consider whether or not to make a fungicide application for Fusarium head blight (FHB). Currently, risk is low in most parts of Virginia. There are a few exceptions, including portions of the Eastern Shore, where risk is moderate to high.

The most effective fungicides for control of FHB and DON are Caramba (metconazole), Prosaro (prothioconazole + tebuconazole), and Proline (prothioconazole). Less expensive triazoles such as Tilt (propiconazole) and Folicur (tebuconazole) will provide some control, but if FHB risk is high these fungicides are unlikely to prevent unacceptable levels of DON contamination. Keep in mind that fungicides containing a strobilurin should not be applied after the flag leaf stage since they can increase DON contamination.

Current FHB risk in Virginia and the surrounding region. Green, yellow, and red indicate low, moderate, and high risk, respectively. FHB risk can be monitored using the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/).

To maximize their effectiveness, fungicides for FHB and DON control should be applied at early flowering or up to one week later. Fungicides that control FHB and DON will also control foliar diseases including powdery mildew, leaf rust, stripe rust, and leaf blotch. Stripe rust has been found in NC and was recently reported from a single field in Warsaw, VA so be sure to scout susceptible varieties for this disease. For specific wheat disease management recommendations or assistance with disease identification, contact Dr. Hillary L. Mehl (hlmehl@vt.edu).

 

Wheat Disease Update – April 19, 2018

Posted on by

Currently the wheat crop in Virginia is near flag leaf emergence, and flowering will start within a couple of weeks. As flowering begins, be sure to monitor the FHB risk in your area using the Fusarium Head Blight Prediction Center website. Currently, most of Virginia has low risk for FHB infection. The exception is the Eastern Shore where risk is moderate to high in many areas, especially on susceptible varieties such as Shirley. Powdery mildew outbreaks have been observed in some fields this season, and incidence of common rust has been sporadic. Stripe rust has been found in North Carolina, but it has not been reported from Virginia. The 2018 Wheat Fungicide Efficacy Table can be downloaded below. Once wheat approaches the heading stage, keep in mind that strobilurin fungicides should no longer be applied. For specific wheat disease management recommendations or assistance with disease identification, contact Dr. Hillary L. Mehl (hlmehl@vt.edu).

2018 NCERA 184 Wheat Fungicide Table

Wheat Disease Update – April 12, 2018

Posted on by

Currently the wheat crop is in the jointing stages, and we are several weeks away from flowering. Currently the Fusarium head blight (FHB) risk is low for most areas of the state except for the Eastern Shore. These conditions may change as the wheat crop approaches flowering, so be sure to continue monitoring the FHB risk tool (http://www.wheatscab.psu.edu/). Moderate to severe outbreaks of powdery mildew have been reported from several fields in the past week. Be sure to scout wheat fields at this time and apply fungicide when disease is first detected. The updated Wheat Fungicide Efficacy Table can be downloaded below. For specific wheat disease management recommendations or assistance with disease identification, contact Dr. Hillary L. Mehl (hlmehl@vt.edu).

 

NCERA 184 Wheat fungicide table 2017_Final

Update on the Boxwood Blight Situation in Virginia and Recommendations for Minimizing Disease Introduction and Spread from the Virginia Boxwood Blight Task Force

Posted on by

Current situation in Virginia, 10/6/17

According to records of the Virginia Boxwood Blight Task Force, to date boxwood blight has been diagnosed in over 70 locations and approximately 30 counties in Virginia. There are likely additional undocumented incidences of the disease, for example, if no sample was submitted for diagnosis through Virginia Cooperative Extension or the Virginia Department of Agriculture and Consumer Services.

Although boxwood blight has been diagnosed in many counties in Virginia, there is no indication that it is widespread throughout any Virginia county. This is not unexpected, based on the current understanding of the biology of the boxwood blight pathogen. Boxwood blight is typically initially introduced into a new location on infected boxwood or other susceptible plants (e.g. pachysandra and sweet box). Holiday greenery containing infected boxwood can also introduce the disease into a new location. However, boxwood blight is not spread long-distance via wind currents. Therefore, one need not panic even if the disease has been found in one’s county. However, if the disease has been identified in one’s neighborhood, then there is a heightened risk of local spread of the disease.

After the initial introduction of boxwood blight-infected boxwood (or pachysandra or sweet box) into a location, neighborhood boxwood plantings are at risk for boxwood blight. There are a number of means by which the sticky spores of the fungal pathogen can move through a neighborhood. For example, they can be spread via contaminated pruning tools, spray hoses, equipment, vehicles, clothing, shoes, or infested leaves spread by leaf blowers. Wildlife (including birds), insects, domestic animals or humans that have been in contact with the spores may also move the infective spores through a neighborhood. Movement of the pathogen by many of these means has been documented in locations in Virginia.

To safeguard Virginia boxwood plantings and production, we call for community awareness and efforts to avoid accidental introduction of boxwood blight into new locations and prevent local spread of boxwood blight:

Specifically, we recommend and stress the following:

  • Purchase boxwood, pachysandra and sweet box only from a nursery that is listed as a member of the Boxwood Blight Cleanliness Programand/or from a retailer who sells only boxwood produced by nurseries in the Boxwood Blight Cleanliness Program.
  • If boxwood blight is suspected, immediately contact your local Extension office, which can submit a sample for confirmatory diagnosis. Where boxwood blight is confirmed, it is strongly recommended to immediately remove and double bag all diseased plants and fallen leaves as well as contaminated soil underneath the planting. The bagged waste should be removed to a designated landfill to mitigate disease spread to other boxwood in the landscape and other properties nearby.
  • Employ only landscape professionals who are aware of how boxwood blight spreads, since boxwood blight can be introduced to properties through landscape maintenance activities. The fungal spores and fallen diseased leaves can be moved on tools, boots, tarps, hoses, clothing and vehicles. Landscape professionals should have a stringent sanitation plan in place to decontaminate tools, equipment, vehicles, clothing, shoes, etc. between landscape locations and other practices that minimize the chance to move the disease through landscaping activities.
  • Adhere to best management practices outlined for boxwood blight, which are detailed in PDFs available at the Virginia Boxwood Blight Task Force website.

Additional Precautions for Landscape Professionals:

  • Landscape professionals are strongly advised to walk through a site before beginning work. This is to identify any potential boxwood blight problems and/or risks. We have heard anecdotal reports from landscape professionals of both serious equipment contamination issues and spread of the disease by unexpected encounters of the disease in a landscape.
  • Landscape contractors should at all times be equipped with a sanitation “kit” for disinfesting tools and equipment and take precautions to avoid moving spores on clothing, boots, hoses, vehicles, etc. Specific recommendations for effective sanitation methods are detailed on the Virginia Boxwood Blight Task Force website (under the “Sanitizers” tab).
  • Landscape companies should ensure their staff are familiar with the symptoms of boxwood blight so that they can recognize the disease in the landscape. Laminated wallet cards with images of symptoms of boxwood blight and information on the Virginia Boxwood Blight Task Force website are available through your local Virginia Cooperative Extension

Resources: the Virginia Boxwood Blight Task Force website and Best Management Practices

Refer to the Virginia Boxwood Blight Task Force website for further information on boxwood blight. We recommend that you familiarize yourself with the appropriate Best Management Practice (BMP) for your situation. The BMPs are available on the website as PDFs.

Eastern Shore AREC Field Day CANCELED!

Posted on by

Due to impending rain Tuesday and Wednesday and already saturated soils, the Eastern Shore AREC field day scheduled for Wednesday, September 13, 2017 has been canceled. Let’s hope Hurricane Irma keeps tracking further west. We certainly do not need any more rain!

Eastern Shore AREC Field DAY: September 13th, 2017

Posted on by

Please join us for Virginia Tech’s Eastern Shore Agricultural Research and Extension Center (ESAREC) 2017 Research Field Day on Wednesday, September 13th. Registration is free, open to the public and will begin at 8:00 AM at the ESAREC complex located at 33446 Research Drive, Painter, Virginia 23420. The field tour will begin at 9:00 AM and conclude with lunch at 12:30 PM.  See the attached flyer for specific projects to be highlighted and more information.

If you would like more information or are interested in sponsoring this event, please contact Lauren Seltzer at 757-414-0724 ext. 11 or email at mlpeyton@vt.edu.

2017 ESAREC Field Day Announcement

Potato Late Blight in North Carolina

Posted on by

The following advisory is posted on behalf of Dr. Steve Rideout:

Late blight was found on potato in Camden and Pasquotank counties in North Carolina over the weekend. We will be processing the samples to determine more information on race/fungicide sensitivity. In the meantime, growers are encouraged to scout their tomato and potato fields for the disease.  Preventative fungicide applications are recommended, particularly near the outbreak area in NC.

If you have questions please let us know.  You can access current recommended materials for late blight in the commercial and homeowner vegetable production guides.  Also, you can visit the following web page for more information on this disease:

https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/ANR/ANR-6/ANR-6_pdf.pdf

This is a serious threat to potato and tomato production in the Commonwealth.  Please let us know if we can help.

Wheat Disease Update – May 2, 2017

Posted on by

Following last week’s rain, the risk for Fusarium head blight (FHB or scab) infections has increased, and the risk is very high even for moderately resistant varieties in certain portions of the state (see FHB Risk Map). Much of the wheat crop is beyond the early flowering stage, but for fields where wheat is currently flowering a fungicide may be needed to protect the crop from FHB infection and DON contamination. Recommended fungicides include Caramba, Prosaro, and Proline. Fungicides are most effective when applied at the start of flowering and up to a week later. The greatest coverage of the heads can be achieved by applying fungicides in 5 gal/A by air and 15 gal/A by ground with a 300-350 um droplet size and nozzles angled forward at least 30 degrees.

FHB risk on May 2, 2017 for moderately resistant wheat varieties. Susceptible wheat varieties that are currently flowering are at high risk for FHB infection throughout Virginia.

Wheat Disease Update – April 20, 2017

Posted on by

Wheat is beginning to flower throughout Virginia, so it is time to make decisions about fungicide applications for both Fusarium head blight (FHB, also known as scab) and to protect the flag leaf as the grains begin to form. Currently, the risk for FHB is low in most parts of Virginia, even for susceptible varieties. The FHB Risk Assessment Tool can be found at http://www.wheatscab.psu.edu. Keep in mind that this is a prediction tool and it will not predict FHB outbreaks 100% of the time. A current screen shot of the website is shown below. Rains are expected over the weekend, but dry weather over the past several weeks has not favored spore production by the FHB fungus, so risk of FHB infection is expected to remain low for wheat that is flowering over the next week. However, now may still be the time to apply fungicides for foliar diseases including stripe rust, powdery mildew, and leaf blotch. The flag leaf must be protected during grain development to maximize yields. Again, due to the dry weather some areas have very little disease, and scouting is still recommended prior to making a fungicide application. However, there have been numerous reports throughout the region of outbreaks of stripe rust (especially on Shirley) and powdery mildew. Do NOT apply a strobilurin or fungicide pre-mix containing a strobilurin after flag leaf emergence (Feekes 9) since this can increase DON contamination in the grain. Prosaro, Caramba, and Proline are the most effective products for reducing scab and DON contamination, and these fungicides will also control foliar diseases such as leaf blotch, stripe and leaf rust, and powdery mildew. A fungicide efficacy table for wheat can be found in a previous post.

Screen shots from the Fusarium Head Blight Risk Assessment Tool (http://www.wheatscab.psu.edu) on April 20, 2017. Currently, risk of FHB infection in wheat that is flowering is low in most parts of Virginia. The exception is along the Eastern Shore where conditions are typically more humid and favorable for spore production by the FHB fungus. For susceptible varieties such as Shirley, FHB risk is moderate to high in some areas. However, for moderately resistant varieties such as Hilliard, the risk is currently low. This illustrates the importance of variety selection in management of FHB and DON contamination in wheat.