Plant Fungal Diseases

Evaluation of fungicides for management of foliar diseases on watermelon, 2015

Evaluation of fungicides and Melcast forecasting program for watermelon disease management, 2014

Evaluation of fungicides for management of foliar diseases on watermelon, 2014

Field evaluation of triploid cultivars for resistance to Fusarium wilt of watermelon in Maryland, 2014

Evaluation of fungicide programs for management of downy mildew of cucumbers – Trial 2, 2016

Evaluation of fungicide programs for management of downy mildew of cucumbers – Trial 3, 2016

As soybeans begin the pod fill growth stages, heat and drought stresses can trigger the development of many disease symptoms. Currently we are seeing many instances of stem diseases in soybean. Many pathogens are associated with stem diseases in soybean, and many produce very similar foliar symptoms, which is why diagnosis from foliar symptoms alone typically leads to a misdiagnosis. Submit questionable samples to the UMD Plant Diagnostic Lab for proper identification. Common soybean stem diseases and their symptoms/signs are outlined below.

Another disease we might be seeing now and in the next week or so is late blight. The weather conditions of the past week have been favorable for its development: cool (for summer temperatures) daytime and nighttime temperatures along with ample moisture.

Gummy stem blight (GSB) was found in an Eastern shore muskmelon field in the last few weeks. It is a cucurbit disease caused by the fungal pathogen Didymella bryoniae. This fungus is favored by cool to warm, rainy weather. It can infect a host at any stage of growth and affects almost all parts of the plant including leaves, stems and fruits.

To no one’s surprise this week has seen a great number of problems pop-up in tomato fields throughout our area. The first of course has been disease with bacterial and fungal diseases spreading. The fungal pathogens usually can be contained with timely (as difficult as that is) fungicide applications. Bacterial spot or speck on the other hand can be much more difficult to control once it gets started and the weather remains wet and warm. In figure 1 on the right hand side is a row of tomatoes that had been sprayed with fungicides and copper for the last several weeks. Bacterial spot has ravaged this row.