Asked September 27, 2016, 5:00 PM EDT

Are fruits and vegetables edible if the leaves have powdery mildew on them (but not seen on the fruits and vegetables)?

Boulder County Colorado

3 Responses

Thank you for your question.

Vegetables and fruits from plants infected with fungal powdery mildew are still edible; Although severely infected plants may have reduced yields, shortened production times, and fruit that has little flavor.

Cultural Practices to prevent powdery mildew:

Some plants are highly susceptible to powdery mildew and will almost certainly be infected by the end of summer no matter what you do. Never compost plants infected by powdery mildew. Plant in sunny areas as much as possible, provide good air circulation, and avoid applying excess fertilizer.

Is the soil affected by the mildew? Can I plant in that soil next spring? A nearby pear tree had some blite, could that affect the plants in the garden bed? Do I need to sanitize my garden gloves and tools?

Hi again,

Powdery mildew is not a soil born disease. Most commonly powdery mildew over-winters on plant debris left in the garden.

Interestingly enough, these fungi are more abundant in semiarid areas, than in areas of high rainfall where other diseases thrive. Unlike other fungi, powdery mildew spores do not require standing water for germination. However, high humidity, shady locations, and crowded planting, and/or poor air circulation do promote spore germination. The spores are easily transported by the wind and, as with most fungal spores, they are everywhere in the environment.

Cultural practices and sanitation can decrease the incidence of many plant pests and diseases. Healthy plants can often resist pest attacks by themselves. In addition to planting in sunny areas as much as possible, provide good air circulation, and avoid applying excess fertilizer. A good alternative is to use a slow-release or organic fertilizer. Overhead sprinkling may help reduce powdery mildew because spores are washed off the plant. However, overhead sprinklers are not as efficient as drip or furrow irrigation and could contribute to other pest problems.

Removing infected plants and keeping them out of the compost pile is the best sanitation practice.

Thank you,