A fungicide should be applied to the underneath side of the leaf. We recommend Maneb or Bravo.
Downy mildew is a common problem for home gardens.
It occurs on most garden plants including turnips, cabbage, cucumbers, squash and other garden plants. It occurs primarily on the underneath side of the leaf. The first symptom is a yellowing of the upper surface of the leaf. When the leaf if overturned a downy gray growth may be seen on the lower surface. A fungicide should be applied to the underneath side of the leaf.