SOUTH Australian strawberry grower, Jim Rozaklis, remembers the days of spending 500 plus hours a year on a tractor spraying broadspectrum pesticides before adopting beneficial insects and more specific chemical applications.
Of course, he doesn’t miss those days.
There are now less products to handle and store, and he can concentrate on other things, including nutrition.
Witholding periods are no longer a concern, allowing strawberries to be picked immediately for local and interstate markets.
The Rozaklis family run Green Valley Strawberries in Hay Valley, near Nairne in the pristine Adelaide Hills.
What started out as less than one hectare of strawberries in 1985 has since become more than 12 hectares, while they also run some livestock on their 40ha property.
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Green Valley Strawberries are sold through supermarket chains in Adelaide, Melbourne and further to NSW, Qld and across to WA, as well as to local independent green grocers.
They also operate their own, on-property Green Valley Cafe, which sells freshly picked strawberries, homemade jams, the finest coffee, in-house cakes and desserts.
About a dozen different varieties have been grown over the past 20 years, with Albion the main variety grown today.
Mr Rozaklis said as a grower, wholesaler and re-seller, constant feedback has helped guide their variety selection to further suit customers.
Following soil preparation of their rich loam soils, bed forming, composting, laying plastic and pre-plant nutrition, the strawberry runners are planted over May-June and lie dormant before emerging 60-80 days later.
The growing cycle spans over 240 days and they get three to four crops over spring, summer and autumn. The first crop is normally harvested in early October.
The strawberry plants produce 1-2kg each or six to eight punnets over the season.
The plants are fertigated weekly through the drip irrigation system and monitored when necessary to control diseases such as powdery mildew and botrytis.
Mr Rozaklis said in September they start monitoring for chewing pests, including two-spotted mite, western flower thrips, heliothis, light brown apple moth and cabbage white butterfly larvae.
To help control them, he said they have used “beneficial bugs’’ sourced from all over Australia for about eight years.
“It became a case of ‘why not use natural predators’, the costs are similar, it’s more effective than conventional spraying, you are not handling the volume of chemicals and you save about an extra 500 hrs on the tractor,” Mr Rozaklis said.
“I now look in the chemical shed and there might be a couple containers of fungicide and miticide.
“Our insecticides have gone from 100 per cent broadspectrum chemistry to specific target chemistry.
“We now use Belt (for heliothis and cluster caterpillar).”
Mr Rozaklis previously used biological insecticides including DiPel, containing the active ingredient Bacillus thuringiensis (Bt), however Belt, from Bayer, is soft on most beneficial bugs and pollinators when used as directed and has been more effective and longer acting.
Recently registered for use in strawberries, the fast activity, long lasting residual effect and suitability in integrated pest management (IPM) programs provided by Belt offers benefits to growers.
Mr Rozaklis said they apply Belt at 100 mL/ha, using an air blast sprayer featuring cone jets over each crop row, when pests are active throughout the growing season.
“We can be spraying on egg hatching or on the first sight of insects,” he said.
“We have seen excellent control immediately, just by walking through the patches and not seeing the ‘helicopter’ pests – and there is no impact or setback on the ‘beneficials’.”
Bayer Commercial sales representative, Darren Alexander, said it was important for growers to also rotate insecticide treatments for maximum control of chewing pests and to reduce the chance of developing resistance.
- Copy supplied by Bayer.