POWDERY MILDEW
PM spores can spread very easily The best way to handle PM is by taking the proper steps to prevent an infection in the first place. Keep in mind that PM fungal spores can travel easily through both the water and the air. •
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Try to avoid planting where shade is prevalent and air circulation is low. These types of areas are almost always the most active sites for PM infections. To prevent PM from occurring and spreading, water plants at ground level and not from above. If there is a small portion of a plant that is in the beginning stage of infection watering from above the plant can certainly cause it to spread. When planting several plants in a group or row, make sure to give them plenty of space so the air readily flows through and around the plant foliage. Pruning and thinning plants often will also help increase air circulation, allowing the surfaces of the plant to dry out faster when they do get wet. Clean up any plant debris on a regular basis, whether infected or not, to prevent the fungal spores from populating them. PM fungal spores can lay dormant through the winter and become active in the spring. Another reason to keep the areas underneath and around the plants as clean as possible to avoid a nasty surprise. For another level of preventative protection, foliar applications of calcium carbonate and silicon supplements can help strengthen and fortify the plant cells, making them less susceptible to a PM attack.
When a PM infection does become a moderate to severe problem, there are additional steps one can take to eliminate the problem and stop it from spreading. The first step is to remove any infected areas of growth immediately. Do not add the infected plant parts to a compost bin or pile. Most home compost piles do not reach the high temperatures needed to properly kill the spores and once you add such compost to the ground soil the spores can easily infect nearby plants. Chemical fungicides are by far the most effective tool for eradicating and preventing PM infections, but be sure to read the labels carefully since there are many that aren’t safe for use on food crops. Safe handling of
when the relative humidity is high and soil moisture is low
chemicals is always of extreme importance, so make sure you use the suggested safety precautions when going this route. For the organic gardeners out there, potassium bicarbonate and liquid elemental sulfur products offer a safer, more natural way of dealing with a PM outbreak. Organic methods are not as strong and reliable as chemical fungicides, but they are much safer to use. Postpone any planned fertilizing until the PM infection is completely dealt with. PM promoting fungi like to attack younger, more susceptible growth. GARDENCULTUREMAGAZINE.COM
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