Features
What Do Organic Growers Do About Mildew?
There are two types of mildew, Downy Mildew and Powdery Mildew.
Downy Mildew
Downy Mildew, is prevalent when conditions are cold and wet. The upper surfaces of leaves turn yellow with a white mould beneath. It thrives in badly drained soils. Sowing plants too close together will also encourage it. In greenhouses, it's presence may indicate inadequate ventilation. In the flower garden, sweet peas and antirrhinum are particularly susceptible. Fruit bushes, especially gooseberries can also be affected.
If caught in time, removing the infected leaves may be sufficient to control it. Mildew, can be brought in on plants so if not raising your own, buy only from reputable growers.
It can be controlled with a mixture of washing soda and soft soap. Dissolve one hundred grammes of washing soda in four litres of water, add in fifty grammes of soft soap and spray on the infected plants.
Powdery Mildew
Powdery mildew occurs in dry weather. White moulds appear on the leaves and stems of plants. It is as much of a problem in the vegetable plot as it can be in flower beds where delphiniums, chrysanthemums and michaelmas daisies can be affected, especially if the bed is dry and overcrowded.
Again,removing the infected leaves will help to control the disease. Mulching and regular watering will help to prevent it Some organic gardeners use a garlic or onion spray to prevent the disease. Soak 10 gms of crushed garlic or 15 gms of onions in a litre of water. Leave for a few hours before applying.
Spacing
Organic gardeners like to give their plants a head start against the weeds, so most of their seeds are germinated in pots or modular trays. But mildew will be encouraged if the plants are left too long in their containers and allowed to grow into each other. If using modular trays, then the larger the sections in your tray the better.
If plants are affected, then plant them out immediately, as giving plants their own space sometimes enables them to 'grow out' of the disease or at least, prevents it spreading.
Mildew can be particularly bad in autumn, so if planting late or winter crops it's a good idea to give them a wider spacing than you might in the spring.
Resistant varieties
It may be worth considering a variety resistant to mildew. Frequently a problem with lettuce, many organic gardeners opt for Avondefiance and Avoncrisp. The National Institute of Agricultural Botany in Cambridge, publishes lists of vegetable varieties suitable for organic gardeners. A lettuce variety, Debby, comes highly recommended as resistant to downy mildew.
Dock roots
Experiments with the roots of the common dock weed as a control for mildew have been carried out in Switzerland. Mature dock roots were pureed and mixed with water at the rate of 15gms per litre. Left to soak for an hour they were then sprayed on cucumbers and apples.
Results suggest that the solution is as effective against powdery mildew as many modern fungicides. So now you know what to do with your docks- if you are strong enough to pull them out of the ground.
