Answer: Your description of the problem points to two different possibilities: bacterial wilt or leaf blight. Bacterial wilt begins with long white or pale yellow-green streaks on the leaves that eventually turns brown. The stalks may exude a sticky, yellow sap when cut. Wilt is spread by flea beetles and most commonly strikes early sweet corn. Leaf blight symptoms include brown to gray-green spots on the lower leaves, and may disfigure the ears. Both are fungal diseases best avoided by rotating crops and planting resistant varieties. You can take your chances that the ears will mature, or you can rogue the infected plants to help stop the spread of the disease, but there are no fungicides available for control of these problems.
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