Some moulds, such as toxic black mould occasionally found in homes, can hurt humans. Others can be beneficial like penicillin. If you see white powdery looking mould on the plants around your home, you should know it isn't a direct threat to you or your family, although it can be indirectly harmful.
The white mould is called powdery mildew and is easily recognisable. It begins as a few white spots on the upper side of a plant's leaves. Over time, the spots spread until they cover the plant's leaves, making them look as though they've been liberally sprinkled with flour. It can spread to stems, flowers and fruit. Powdery mildew can infest a variety of plants, from grass and flowers in your landscaped lawn to vegetable plants in your garden. It also infests farm crops like cereal grains, fruits and vegetables.
Powdery mildew is unsightly. Severe infestations damage plants. It can't infect humans and won't hurt you if you touch it. While it is not directly harmful to humans, it does harm to potential food sources. By causing flowers to die or never bloom at all, powdery mildew prevents plants from growing fruit. If an infected plant does manage to produce fruit, it is likely to be smaller than normal with a dull, inferior taste. Getting rid of powdery mildew protects people's food supply.
At home, get rid of powdery mildew as soon as you see the first signs of white mould, to prevent it from harming your plants. Combine 1 part milk and 9 parts water in a spray bottle and liberally coat infected portions of plant with the mixture. Reapply it every week or so until the infection is gone. On farms, fungicides can get rid of powdery mildew before it has a chance to damage a crop. Fungicides like sulphur and triforine are effect against it.
You can prevent powdery mildew from attacking your plants through cultural controls. Space plants far enough apart so air easily circulates around their leaves. Water them near their bases at the ground level, rather than from above. Place plants in areas where they will receive some direct sunlight every day. These measures create a hostile environment to the white mould. To prevent powdery mildew from harming humans' food supplies, farmers use less-susceptible varieties of plants, making infections less likely to occur and easier to control.
- "The Complete Guide to Growing Windowsill Plants"; Donna Marie Murphy, Angela Williams Duea; 2010
- Colorado State University Extension; Powdery Mildew; B. Edmunds and L.P. Pottorff; May 2009
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