Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu
Small grains will be planted in the next few weeks. The decisions made at planting can and do significantly impact many diseases of small grains in the ensuing season. The following is a brief review of some of the more important planting decisions growers will make in the next 3-4 weeks that can impact diseases in 2015.
Variety: Variety selection is the most important part of an integrated disease management program. No two varieties are created equal in terms of disease resistance or tolerance. Although it is not often possible to find a high-yielding variety with excellent resistance to all pathogens, it is possible to find some productive varieties with solid disease resistance to common diseases with the potential to reduce yield such as powdery mildew and leaf blotch or to contaminate grain such as Fusarium head blight. When selecting varieties, take into account what diseases tend to be issues in your fields and choose those that will help reduce the risk of severe disease epidemics through resistance. Disease resistance ratings for Mid-Atlantic small grain varieties can be found at the University of Delaware, The University of Maryland, and Virginia Tech Cooperative Extension websites. Seed companies also provide disease resistance ratings.
Planting date: Wheat planted before the Hessian fly-free date has a greater chance to be damaged by viruses such as Barley Yellow Dwarf. If you do plant before the Hessian fly-free date make sure you are planting a variety with tolerance to Barley Yellow Dwarf and follow IPM practices for aphid management. Early planting can also lead to higher levels of infection and overwintering of several foliar pathogens. This can result in more foliar and head diseases in the spring.
Stands and fertilization: Disease issues may occur in fields with excessive plant populations. Planting at excessive rates reduces airflow and increases canopy humidity, which favors the development of many diseases. Excessive fertilization promotes rapid, lush growth that can enhance disease issues. Not only does excessive fertilization result in dense canopies, but it also can cause internal metabolic shifts that influence the overall ability of the plant to defend itself against pests and pathogens.