Alyssa Koehler, Extension Field Crops Pathologist; akoehler@udel.edu
The small grains planting window will be here soon. To get a head start on disease management for next spring, here are a few factors to consider.
Variety
Variety selection is one of the most important pieces of integrated disease management. In the case of wheat, varieties may have varying levels of resistance to powdery mildew, leaf rust, stripe rust, Fusarium head blight, and other diseases. When selecting your varieties, consider what diseases have been an issue in the past and, when possible, select resistant varieties to reduce the risk of disease developing in 2020. Fusarium head blight is typically the disease of biggest concern in our area. While there is not complete resistance, there are FHB resistance genes available in many lines to help reduce disease severity and the amount of mycotoxin (DON) that accumulates in the grain. The University of Maryland conducts an inoculated misted nursery trial to test varieties for FHB/DON. In this trial, the fungal pathogen is added to the field prior to flowering and plants are misted daily to create the perfect environment for disease development. Wheat plants in this trial are under a “worst case scenario” for disease, so FHB index and DON levels tend to be much higher than would be seen in a natural field setting, but this allows for separation of varieties to see which have the lowest levels of disease and DON content. 2019 results can be found at https://psla.umd.edu/sites/psla.umd.edu/files/_images/Wheat%20and%20Barley%20FHB%20ratings%202019.pdf
Planting Date
While we do not often see Hessian flies, planting after the Hessian fly-free day helps to reduce the chance of issues with viruses like Barley Yellow Dwarf Virus (BYDV). Aphids spread BYDV, so if you are planting before the Hessian fly-free day, make sure to have a variety with tolerance to BYDV and follow IMP practices for aphid management. Early planting can also allow for infection and overwintering of several foliar fungal pathogens that could lead to more disease the following spring.
Stands and Nutrition
High plant populations tend to create favorable environments for disease due to reduced airflow and increased canopy humidity. High levels of fertilizer promote lush, rapid growth that can favor disease; keeping fertility balanced reduces the chance of disease development.