Have you got white spots on the leaves of your tomato plant? Then you probably have to deal with a fungus called mildew (Oidium lycopersici). In the beginning, the mildew fungus is always found on the bottom leaves of the plant. It consists of round, white to slightly gray spots, with (if you look very closely) white fungus. If nothing is done, the white spots become larger and they can cover a large part of the leaf surface. As the mildew damage becomes more severe, it also attacks the higher leaves growing toward the crown of the plant. Eventually a large portion of leaves will be covered with the fungus and in the worst case, the plant can die. But of course we won’t let that happen.

In our nursery (in the greenhouse) we have a sulfur-burning vaporizer. Itis switched on for about 8 hours,3 times a week, which produces a very thin layer of sulfur on the leaves. This layer of sulfur ensures that no mildew forms, and if it does form, it spreadsless rapidly. When mildew spores want to germinate, the sulfur burns away the germ tube from the fungus so that the spores die. Mildew spores that have already germinated do not go away because of the sulfur. But if you start vaporizing before mildew gets into the plants, you can prevent it forming.If,like us,you grow tomatoes in a greenhouse, you can make good use of sulfur vaporizers. It doesn’t make sense to use them outside.

In hot and humid weather, there is a great chance that the tomato plants will suffer from mildew. Pay extra attention then. 

If your tomato plants still get mildew, despite all the pampering they are getting, you can combat it organically with ordinary house, garden and kitchen equipment. 

No, we're not going to bake bread!We’re fighting mildew with milk and baking soda.

More than 50 years ago, researchers in Canada discovered that spraying a solution of milk and water on tomato leaves can prevent mildew. There are antifungal substances in milk.

Ingredients:

- Skim milk

- Bicarbonate (for sale at the chemist or in supermarkets)

- Water

Mix 1 teaspoon of bicarbonate in 700ml of water. It will start fizzing.

Once the fizzing dies down, add 300ml milk.

Pour the mixture into a spray bottle and your bio-spray is ready to use.

First remove the most affected leaves. Spray the plant soaking wet twice a week, preferably when it is sunny, until the mildew disappears. Once the mildew is completely gone, it is wise to repeat the spraying once a month. Just with milk is sufficient;now you can leave out the bicarbonate.