Gummy Stem Blight
About the Disease: The Gummy Stem Blight diseases as well as the black rot disease are quite similar. In fact the causative agent for the Gummy Stem Blight is the same as the black rot.
Symptoms: This mainly involves the infection of the stems and the leaves of the plant. The main symptom that is observed is that the leaves turn brown in color, especially at the edges. In plants like cucumber or squash, you can find that the leaves have a brown wedge. The disease spreads from the leaf edges to the leaf tissues fully. In the melon plants, usually the browning will progress and discoloration of leaves is seen. This is mainly present in between the veins or it forms brown spots.
Around all these leaf spots, you can observe the yellow colored halo. This is a characteristic feature in all the plants affected by this disease. The old spots will dry out and form cracks throughout the length of the plant. The winter squash can get affected with the black rot infection but it might not get affected by the stem blight disease. The fruit rot in its initial stages look as though the plant is soaked and finally the fruit turns completely black in color.
On the regions of the stem, tan lesions will start to develop. The stem is the most affected region. On the stem, you can also observe the black pimples, which are raised from the stem surface. The other common feature in the stem is the gummy exudates. This is the main reason for naming this disease as the gummy stem blight disease. With the yellow halo on the leaves and the black fruits, the plant totally looks ugly.
Pathogens: Didymella bryoniae is the causative agent for this disease
Time of Occurrence: This disease mainly occurs in the wet weather.
Conditions Favoring Disease: The spores of the fungus get dispersed by the action of wind. The main condition that can favor the progression of the disease is the wet weather. The high humidity will also favor the disease to develop.
Disease Management: When you are planning to cultivate the plants, the seeds that are purchased must be clean ones. The resistant varieties need to be cultivated. The pest management has to be properly done, in order to eradicate the growth of the pests. Instead of trying out the sprinklers, drip irrigation can be done. Crop rotation is also a good option to prevent the disease.