Solutions for Powdery Mildew

300Powdery_mildew-phlox_Univ_KentuckyPowdery mildew is a common problem in the summer garden. It can infect vegetables, roses, perennials, shrubs and trees. Although there are many varieties of this mildew, it usually presents itself as white or powdery gray spots on leaves, although it can also grow on stems, flowers and even fruit. Although it may look bad, it rarely kills a plant.

So before I suggest how to tackle the problem, first understand why it occurs. Powdery mildew is caused by spores located in the soil or garden debris that are then carried by the wind or splashing water to leaves. High night humidity levels often trigger the growth of mildew spores but there are other conditions that spark outbreaks (see below).

Here are a few ways to prevent or reduce powdery mildew:

espoma_Gard-Fungicide*BEFORE the problem begins, apply an organic fungicide to leaves of plants that are commonly infected. Espoma’s Earth-tone Garden Fungicide is highly effective, even on early and late tomato blight. Espoma carries a whole line of organic products for pest control.
*Purchase disease resistant plants. Some perennials that are particularly susceptible to PM are Monarda, Phlox, Heliopsis, Coreopsis, Rudbeckia fulgida (Black-Eyed Susan)
*When watering the garden, water at ground level (i.e. with soaker hoses) versus using overhead sprinklers. Water in the morning, not at night.
*Allow plenty of air circulation around plants
*Give plants sufficient sunlight, at least six hours a day
*Don’t over-fertilize plants, stimulating lots of new growth that can be more susceptible. Instead, use a slow-release, organic fertilizer like Espoma’s Plant-tone or Holly-tone.

For more ways to organically control this problem, check out the web site, written by my friend, Joe Lamp’l.