Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu
I am now seeing some of that powdery mildew and leaf blotches that were lower in the canopy on the flag leaves of susceptible varieties. Some varieties are showing more hypersensitive responses (flecking) than typical. There is a little barley scald out there, but not at significant levels. Rainy, humid weather continues to keep our scab risk at moderate to severe in many parts of Delaware and Eastern Maryland. Remember that the scab risk is an issue for fields entering flower though 5-6 days after the start of flowering. Those with fields that have not yet entered flowering should continue to monitor the Head Blight Risk Assessment Tool at http://www.wheatscab.psu.edu/ and pay attention to the local forecast. If you sign up for alerts you will receive a notice every time I input new commentary.
I am hearing more reports of Pythium and Fusarium issues in early planted corn and Nancy has received a handful of samples in the clinic. This is not surprising given the cool, wet soils that the corn was planted into this year. With soil temperatures increasing I don’t imagine there are many cases where additional intervention (i.e. in furrow fungicides, etc.) are needed. Low lying and compacted areas may continue to give you problems, particularly if we enter another rainy period shortly after replant. Those of you who planted full season beans early should keep an eye out for SDS later in the season, particularly if your field has a history of cyst nematodes. Cool, moist weather early in the seedling stage favor infection and colonization of the SDS pathogen, which produces characteristic disease symptoms later in the season.
Additional notes:
Two new factsheets are available online: Soybean Stem Blight (White Mold) and Sudden Death Syndrome of Soybean. Both are found under the field crops section in the fact sheet database http://extension.udel.edu/factsheet/.
After some prodding, I have started my own Twitter account in an effort to increase your access to up to date field crops disease information. I will post real time disease updates, links to new articles and data, and new blog posts. Follow me at @Delmarplantdoc