Late blight has been confirmed in North Carolina on potato. Few details are known right now regarding the intensity of this outbreak, but, it is focused around the Elizabeth City, NC area. Potato and tomato growers, particularly those in the SE part of the Commonwealth should be diligent about scouting their crops and consider protective fungicides. Please let us know if you have further questions and we will continue to update everyone as we learn more.
The Virginia Tech Tidewater AREC (TAREC) maintains the Peanut-Cotton Infonet website (webipm.ento.vt.edu/infonet/) which provides growers in southeast Virginia with daily weather data (e.g. air and soil temperatures, rainfall, relative humidity), peanut leaf spot and Sclerotinia advisories, peanut heat units, cotton degree days, and a frost advisory. Four weather stations located in Suffolk, Capron, Skippers, and Waverly are maintained by the TAREC Plant Pathology program. Thanks to funding from the Virginia Peanut and Cotton Boards, we have been able to upgrade our equipment which should improve the overall reliability and consistency of data transfer from our weather stations. The new equipment has been installed and we are receiving data, but we are temporarily unable to post the data to the Infonet website. This technical issue should be resolved by next week, but in the meantime daily weather data will be sent out as an email to extension agents and posted to the Virginia Ag Pest Advisory Blog. We apologize for the inconvenience, and we are working hard to get the Peanut-Cotton Infonet website up and running for the season. If you have any questions or concerns feel free to call the TAREC Plant Pathology lab at (757) 657-6450 ext. 428 or email Dr. Hillary Mehl (hlmehl@vt.edu).
Please find below the current weather data for Suffolk, Capron, and Skippers. The Waverly data will be available shortly.
Wheat in the southeastern portions of Virginia will start flowering soon if it has not already. Wheat is susceptible to scab (Fusarium head blight) from early flowering until approximately 10 days after first flower. An online scab risk assessment tool (www.wheatscab.psu.edu) provides information on relative risk of wheat infection by the scab fungus which also has the potential to contaminate grain with DON (vomitoxin). The risk model is based primarily on relative humidity during the 15 days prior to flowering since high moisture favors inoculum production by the scab fungus on crop residues. However, the model also takes into consideration variety resistance to scab. No wheat varieties have complete resistance (immunity) to scab, but commercially available varieties vary in their susceptibility. Current variety rankings for scab resistance can be found here:
Wheat variety rankings for scab resistance
If you do not know the relative susceptibility/resistance of your variety, it is probably best to err on the side of caution and assume that your wheat crop is susceptible or at least moderately susceptible to scab. Currently, the predicted scab risk for wheat that is flowering in Virginia is low for all but the most susceptible varieties. Dry weather is predicted after the current storm passes through, so scab risk will likely remain low to moderate over the next week. However, it is prudent to be prepared to apply a fungicide for scab management as the wheat crop approaches the flowering growth stage. Keep in mind the best management tactic for minimizing yield and quality losses to scab and DON is to plant resistant varieties and to make a properly timed fungicide application when wheat is in the susceptible growth stage (flowering) and weather conditions favor dispersal of the scab fungus.
If a fungicide is applied for scab, strobilurins should NOT be used as they may increase DON (vomitoxin) contamination of the grain if applied after flag leaf. Foliar diseases are starting to increase in some fields in Virginia, but if the wheat is at or near flowering, a strobilurin or premix fungicide containing a strobilurin is not recommended. Fungicides recommended for scab also provide very good to excellent control of common foliar diseases of wheat (see last week’s post), so a scab fungicide application may provide the added benefit of controlling leaf spots and rusts. The triazole fungicides Prosaro, Proline, and Caramba are the most effective fungicides for scab and should be applied at early to mid-flowering and up to one week later. For maximum efficacy, fungicides for scab and DON control should be applied with nozzles angled at a 30 degree angle from the horizontal using both front and back facing nozzles. This will ensure that the product is applied to the grain head rather than the leaves or the ground.
Growers, agents, and consultants can subscribe to the U.S. Wheat & Barley Scab Initiative’s (USWBSI) FHB Alert system at http://www.scabusa.org/fhb_alerts. Region-specific scab alerts that provide growers with updates during critical times are sent as emails and/or text messages.
As the wheat crop approaches flag leaf emergence and heading growth stages, it is time to start thinking about disease management. When conditions are conducive to disease development (e.g. high humidity, warm temperatures) foliar fungicide applications may be necessary to protect wheat yield and quality.
Wheat diseases observed in Virginia so far in 2015 have included viruses (which cannot be managed with fungicides), powdery mildew, and leaf blotch. Disease severity thus far has been relatively low in most areas but an increase in disease can be expected with warm, humid weather. Leaf blotch, for example, has been observed on the lower leaves where it is unlikely to impact yield, but once the flag leaf emerges, this leaf surface, which feeds the developing grain, should be protected from disease if symptoms are observed on the lower leaves and conditions are conducive to disease development. Once heading and flowering occur, the developing grain need to be protected from infection by the Fusarium head blight (scab) fungus if scab risk is high. Factors contributing to scab development and proper timing of fungicides for scab management will be discussed in a later post.
Each year plant pathologists from throughout the U.S. update the following wheat fungicide efficacy table based on the most current data. Efficacy ratings for each fungicide listed in the table were determined by field testing the materials over multiple years and locations. Efficacy is based on proper application timing to achieve optimum effectiveness of the fungicide as determined by labeled instructions and overall level of disease in the field at the time of application. Judicious use of an appropriate fungicide for the target disease can protect both yield and quality of the wheat crop.
We captured a kudzu bug in a Southampton County, VA sticky trap this week. Please see the map for more details. Kudzu_bug_traps_22_Apr_2015
Our kudzu bug trap operators provided first reports in three more counties since last week’s report: Isle of Wight, Lunenburg, and Nottoway. Please see the attached map for all locations reported so far in Virginia for 2015. Kudzu_bug_traps_13_Apr_2015
We just received confirmation that kudzu bug adults have been found in two counties, one on a trap at the VT Tidewater Ag Research and Extension Center in Suffolk, and several on the side of a building in Mecklenburg County (see the attached map). These adults are the overwintering population getting active as the weather warms. They are about a month later than our first reports in 2014–the first in that summer emerged the first week in March in Chesapeake. This winter has been pretty cold and wet compared to some and could have caused this delay. Most likely more reports will start coming in soon. Updates will be posted. Kudzu_bug_traps_7_Apr_2015
Dr. Ames Herbert’s annual research summary booklet for cotton and peanut entomological research in 2014 is now available on the Virginia Cooperative Extension “Publications” website: http://www.pubs.ext.vt.edu/ENTO/ENTO-109/ENTO-109.html
Please see the attached report by Dr. Herbert (Virginia Tech) and Dr. Kennedy (North Carolina State University) regarding thrips resistance to neonicotinoid insecticides. NeonicThripsResistance
Dr. Dominic Reisig (Entomologist, North Carolina State University) has shared these slides showing (1) corn trade names, their Bt protein(s), and their effectiveness against corn earworm and fall armyworm; and (2) corn seed treatment trade names, their active ingredient(s), and their effectiveness against billbug, white grub, and wireworm. In these two attached tables, P = Poor, F = Fair, G = Good, VG = Very Good, E = Excellent, and NL = Not Labeled. Please click on the pdf document at the end of this sentence to access the tables: corntraits
