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Spring is a busy time on the farm requiring many different tasks be completed in a short time frame; one of the tasks that can easily be overlooked is scouting small grain fields. As we prepare for the first application of nitrogen remember this is a perfect time to scout for foliar diseases like powdery mildew and the leaf blotch diseases. Green up is the time to look for powdery mildew. The fungus responsible for powdery mildew typically colonizes wheat in the fall when the plants are small. You should be able to see the powdery white fungus if present on plants close to the crown. Powdery mildew is one of the common diseases of wheat in our region, although typically not a major concern unless it gets out of hand. It is good to scout for its presence early, but treatment if needed should wait until wheat begins jointing. Powdery mildew will not begin active growth until after green up and begins rapid growth around jointing. Fungicide applications will have no activity on dormant fungi at this time. If you spot powdery mildew now, you may not need to apply a treatment if weather conditions become warm and dry later. This is your cue to keep an eye on the crop especially when the flag leaf emerges.
A similar strategy should be used with the leaf blotch diseases if encountered now. Delay fungicide applications if needed until jointing. The strategy is to protect the flag leaf. If the disease is present at low levels and weather conditions do not favor disease development a fungicide treatment may not be necessary. Also remember if a fungicide application is needed at flowering for fusarium head blight, these fungicides will also have activity on powdery mildew and leaf blotch. Several species of fungi can cause leaf blotch. Initial infections typically occur in the fall as seedlings emerge. Symptoms of leaf blotch first appear between veins of lower leaves. Initially yellow, water-soaked flecks are observed. The flecks then enlarge to become dry, yellow (eventually red-brown), oval-shaped lesions, often surrounded by yellow haloes.
