Wet Weather and Disease Development in Cool Season Crops

Many growing regions have been hit hard with heavy rains, hail and high humidity over the past few weeks. These conditions have been ideal for the development of diseases, such as leaf blights and entry of decay (rot) organisms, in most cole crops, roots, bulbs and leafy vegetables. In addition to the downpours or hail causing splashing of soil-borne diseases and pelting injury on foliage, heavily saturated soils allow for the hasty spread of root and bulb diseases. With little relief from this wet, humid weather, the risk of prolonged leaf and root wetness, and hence incidences of infection remain high. It is essential to do as much as possible to avoid significant losses due to disease development. So, be on the look out in your fields for any signs or symptoms of infection, remove excess surface water by digging trenches and catch basins, if needed, and practice proper field sanitation techniques to avoid the risk of spread or contamination.

Figure 1. Hail damage, onions

Figure 2. Rhizoctonia infection, broccoli

Figure 3. Leaf blight, carrot