Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu
Barley is almost all out and wheat harvest is underway in many parts of the state. From what I hear and see, this looks like it will be a year without many mycotoxin associated issues. This is in line with the dry, hot weather we had before and during flowering as well as what was predicted by the scab forecast model around critical flowering periods. Although there are some subtle differences in scab levels in fields with different management practices, all fields that have been assessed are well below the critical 10% field index where we may start to see levels of DON above 2 ppm. Again, this falls in line with the weather and the scab forecasting model.
Now is a good time to direct you to an updated factsheet on selecting varieties for managing scab. Selecting a good, moderately resistant variety is the first, most important, cost effective, and best management practice for managing scab. The factsheet provides a quick synopsis on scab and also gives the last set of results from the misted nursery at UMD http://extension.udel.edu/factsheet/moderately-resistant-wheat-varieties-for-vomitoxin-don-suppression-in-wheat/. In the table you will notice that I have arranged the varieties by DON levels. This is because this is the most important characteristic we are looking at for managing scab. You will also note the column labeled ISK. This is a visual estimate of the amount of head bleaching and infected kernels in a variety, calculated from severity, incidence, and FDK values weighted for importance. Green values are the most resistant, followed by yellow. Another misted nursery can be found at Virginia Tech, although there isn’t a great deal of overlap in varieties.