In addition to daisies, leafminer can be a problem on chrysanthemum, snapdragons and tomatoes. Avid may still be the best material for most leafminer infestations, but growers should have alternatives ready. Downy mildew on salvia Jan Byrne, Diagnostic Services Downy mildew has been reported as a problem on salvia in several Michigan greenhouses. Both plugs and plants in cell packs were affected. The pathogen is an obligate pathogen, meaning it can grow only on live plant tissue.
Most downy mildews require periods of leaf wetness and fairly cool temperatures to infect.
The pathogen grows on the underside of the foliage and is visible to the naked eye. Look for gray fuzzy looking mold on the lower leaves. Initially the upper surface of the foliage shows only a faint chlorosis. With time the upper surface develops dark, dry looking lesions which are often restricted by the veins. Heavily infected leaves will curl and drop from the plant.