A good example is early blight of tomato. This fungus disease is correctly named since it gets off to an early start following spring rains. Early blight is generally one of the most severe tomato problems faced by home vegetable gardeners each season, and for top yields of high quality fruit, early blight control is essential. Early blight-resistant tomato varieties aren't available, so gardeners have to use a combination of disease management practices.
Early blight shows up as a leaf blight on the lower part of plants.
As the disease progresses, leaves turn yellow, wither, and drop from plants. Tomato plant severely infected by early blight produce low yields of undersized fruit. Generally, fruit also show signs of sun-scald since leaves aren't present to protect fruit from direct sunlight. Early blight tends to be more severe when periods of rainy weather are experienced after transplants are set. Plants are more likely to become infected by the blight fungus under these conditions.