Fruit and vegetable diseases

Page last updated: Friday, 2 February 2018 - 12:07pm

Please note: This content may be out of date and is currently under review.

Leaf spot diseases

There are many types of leaf spot diseases that can affect beetroot, broad beans, carrots celery, peas, potatoes (early blight) silverbeet, and tomatoes (target spot). Sometimes the leaf spots cause only slight damage, but if necessary, control with mancozeb or copper hydroxide.

Close up of plant damage caused by leaf spot disease.


Damping-off fungal diseases such as pythium may kill small seedlings of most vegetables. Seedlings die before they emerge or soon after emergence, which results in plant collapse. Damage may occur all year, mainly in wet conditions. Do not over-water and ensure that plants are not too crowded.

Downy mildew

In spring, with mild, humid weather, downy mildew fungus disease can cause greyish-white patches on the leaves of onions, which can droop from the tips. Cauliflowers, peas and lettuce may show white, downy growth on the underside of the leaves. With rhubarb, patches develop which tear to produce holes in the leaves. The fungus that causes downy mildew in a particular crop is specific to that crop. Control with mancozeb or copper hydroxide.

Downy mildew on grape vine leaf

Powdery mildew

Powdery mildew is a fungal disease. In warm, moist conditions, white patches occur on the surfaces of older leaves and leaves turn brown and shrivel. The disease is common with the cucurbit family such as cucumbers, melons, pumpkins and zucchini. It may also occur in peas and strawberries. Sulphur sprays will help to control the disease, but do not spray on hot days. Fungicides containing bicarbonate of soda also help control mildew but should be applied as soon as the disease is noticed.

Powdery mildew on grape vine leaves

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080