Powdery mildew is one of the most widely spread plant diseases and it can affect many plants. In the vegie garden, it might affect melons, squash, cucumbers and zucchini as well as strawberries but it also infects ornamental plants such as roses and begonias. It is particularly bad on grape vines as well as trees such as apples and oak trees.
Powdery mildew is very easy to identify. It starts with white or grey powdery circles on the leaves, buds, stems or fruit of the plant and eventually covers the whole area. If you look at the powder with a magnifying glass, you will see that they are actually millions of spores which sit on the surface.
The problem with this disease is that it sucks the nutrients out of the plant, eventually causing the leaves to wilt and eventually die. In vegetables, this might mean that the whole plant will die.
The spores of powdery mildew are spread from one plant to another in the breeze and if the temperature is humid enough, the spores will multiply, infecting the new plant.
Prevention is the best way to deal with powdery mildew. Make sure the plants are growing in full sun because, if they are in shade, the humidity will be perfect for the spores to grow. Also, if you can, apply water to the soil instead of all over the leaves and if there are any diseased leaves, remove them or collect them from the ground and put them into a plastic bag and straight into the bin.
Organic gardeners believe that milk can help to deal with fungal diseases such as powdery mildew. Put 500mL of water in a spray bottle and then add in 50mL of full cream milk (don’t put in any more than that!). Give it a shake then spray it all over the leaves and stems. Repeat this every 7 to 10 days.