Angular to irregular water-soaked spots form on the leaves. When leaves are moist, droplets of bacterial ooze form on the underside of lesions and dry to a white residue. The lesions later turn gray to brown, dry and tear away, leaving large irregular holes. The bacterium overwinters in diseased plant refuse and on the seed coat. Disease is spread by rain and by hands, clothing and equipment.
Avoid working around cucurbits when foliage is wet. Work soil only when it is dry. Do not water with overhead sprinklers. If the disease has been a problem in the past, spray with a copper soap fungicide before the disease normally appears. Once an epidemic has taken hold, sprays are generally ineffective. We recommend Soap- Shield® Flowable Liquid Copper Fungicide.