Anthracnose is capable of surviving in infected plant debris and in the soil. When present, it can invade plants early in life, and may not manifest until maturity. It is encouraged by high temperatures, and heavy rainfall. You will notice small dark spots on leaves, initially. Prune or stake as necessary, to improve sunlight passage, and ventilation.
Cercospora leaf spot starts out in a similar way. You will first notice a darkening of the leaves. This is typically followed by the formation of circular spots. In humid weather, these coalescing spots may be covered with areas of steel blue to light bluish-purple fuzz. Be sure to use clean tools, when planting, or pruning. Crop rotation can help, also. Just like anthracnose, cercospora can live over the winter in the debris.
Gummy stem blight is commonly found in squash, pumpkins, cucumbers, watermelons and other field-grown cucurbit crops. It can occur at any growth stage, from seedlings to mature plants. This disease on fruits, in the field or in storage, is called black rot. It affects all parts of the plant, except for the roots. Leaves appear dark yellow or reddish-brown, with lesions in various shapes. Begin at leaf margins and extend rapidly back into the leaf blade, causing curling and death of the entire leaf. Fruit symptoms vary among crops. Commonly, you will see rotting areas on the skin. Lesions may appear very watery, gushing yellow liquid, and may cause fruit to hook as it grows. You may notice something similar developing on the vine itself. Again, garden with clean tools, rotate crops, and be sure to buy seeds from reputable suppliers, as effective measures of prevention.
All of these problems can be taken care of with a liquid known as Mancozeb Flowable. You can put it in a pressure sprayer, and use it once every ten days, or so.
These are all very common problems, among fruit and vegetable growers. There are lots more that belong in this category. If you have suggestions on preventing, and treating these thorns in the green thumbs of our readers, please be sure to share your ideas!