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Reduced plant disease boosts greenhouse crops
Above: Dr Kaye Ferguson assesses foliar disease in cucumbers in a commercial greenhouse at Virginia, South AustraliaA sustainable approach to disease management is delivering better results for South Australian greenhouse cucumber and capsicum crops growers. .
Senior research officer in SARDI's Plant and Soil Health Division Dr Kaye Ferguson says the four-year research project found that diseases such as powdery mildew and Botrytis grey mould begin on different parts of the plant and at different times of the year.
“Powdery mildew is the white mould that appears first on the oldest cucumber leaves while Botrytis grey mould is a fuzzy grey fungal growth found on the flowers, stems and developing fruit.”
These two foliar diseases cause yield loss and requires significant investments of growers’ time and money to manage.
The research was undertaken at the request of the industry to help growers develop a more sustainable approach to disease management. With funding provided by the vegetable industry and the Commonwealth Government through Horticulture Australia Limited, the investigations provided strategies to manage diseases in greenhouses, moving away from a reliance on fungicides.
Data from 2007 identified about 650 greenhouse growers with 500ha of greenhouses in SA. Dr Ferguson's research will particularly benefit those greenhouse growers growing various types of cucumbers.
Dr Ferguson monitored cucumber crops in commercial greenhouses fortnightly to check for disease and to measure the temperature and humidity in the structures.
“The conditions that are best for growing cucumbers are really favourable to fungal diseases,” Dr Ferguson said.
“Those diseases like it a little bit warm and humid, like the greenhouses.”
“For management of diseases, you've got to start early - as soon as you first see the disease,” she says.
Growers now have at their disposal knowledge and tools to greatly improve their management of these diseases. They’ve gained a better handle on correctly identifying and monitoring disease – knowing when and where to look for the first signs of the diseases, as the critical first steps in choosing suitable management strategies.
Research has increased understanding of how diseases can affect yield, when intervention is required and options worth trying.
“Growers need to consider a range of disease management strategies including beneficial bacteria and fungi, plant health products, fungicides, crop varieties that are resistant to disease, and changing the greenhouse climate to make the conditions less conducive to diseases,” Dr Ferguson said.
Like commercial vegetable growers, home gardeners are encouraged look at using more than just fungicides to control moulds in their home garden plots. Check regularly for diseases. Prune off infected leaves and flowers when they first appear and dispose of them in the green bin or compost to reduce the amount of disease. Experiment with some of the softer products available such as potassium bicarbonate products or oils.
