Disease-beating summer vegies
Summer vegies don’t have to fall victim to disease, as there are plenty of tough varieties out there that can fight back, says JENNIFER STACKHOUSE
Summer crops are going into the garden right now as robust young seedlings, but some will succumb to disease as the heat and humidity of the Australian summer kicks in. The usual suspects among vegies are powdery mildew, downy mildew, wilt and various forms of blight. But you don’t need to throw in the trowel. Good breeding and good gardening will get you and your vegetables through the growing season.
With very few fungicides available to treat garden ailments, especially diseases of edible plants, vegetable growers are turning to good breeding to save the day and their crops, so look for varieties this season that promise disease resistance. These have been selected from breeding programs around the world, as they have shown that they can tolerate exposure to disease-inducing conditions for longer than other plants. So, while they may not escape altogether, these varieties will last long enough to produce a good crop.
Selecting disease-resistant varieties is particularly important where disease has been a problem in previous years. As well as choosing the best variety, also practise crop rotation (see page 48) and good garden hygiene to keep disease at bay.
Some vegetables are less troubled by disease. Those that are generally disease free and grow over the warmer months include corn, celery, pumpkin and sweet potato. When choosing vegies that grow in the cooler months, select peas, kale, garlic, spinach or broad beans, as these crops are also usually disease free.
Most diseases spread by spores that are dispersed by wind onto foliage and fruit, or they can come from the soil. A quick way to limit the spread of disease is to remove affected leaves, stems or fruit early. Place them in a bag and put the bag in the rubbish bin (not the compost). It’s good to do this as part of your daily garden inspection. Also, reduce overhead watering (water the base of your plants, not their foliage), add a layer of mulch to reduce splash from the soil, remove the lower foliage from plants such as tomatoes, regularly weed the garden, and make sure plants are well spaced so there’s good air circulation.
Insects also spread disease as they move from an infected plant to a healthy one. Aphids and other sap-sucking insects are often guilty of spreading viral diseases among plants. So keep plants free of pests to reduce the spread of disease. Ways to do this include squashing aphids, hosing them off new growth or using an organic pesticide (follow the label instructions to minimise harm to beneficial insects).