Bt should be applied when first instar larvae are present in the field. Bt takes time to work and is best on larvae control. Rotate the garden plants and sites. Early maturing varieties may help lessen the time plants have to tolerate them. Surrounding the vegetable production area with a mix of wildflowers helps maintain a population of predatory insects.
Diseases Keep plants healthy.
Rotate vegetable plants and sites. Space vegetables further apart to allow more air flow. Plant to take advantage of the prevailing winds so air flow is increased down the row. Don't go into the garden when plants are still wet. Sanitation is important.