THE FREEZING temperatures of the past week may have cut locust activity right back, but co-ordinators of the PestFacts program have found other insect pressures are now taking their toll.
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Slugs, weevils, lucerne flea and red legged earth mite are among the pest species doing damage to grain crops across the state, according to PestFacts co-ordinator Stuart McColl.
Black keeled slugs have been responsible for damage in emerging canola crops and pastures in parts of the Western District.
Mr McColl said significant numbers of black keeled slugs (Milax gagates) have been found in several paddocks around Willaura and Lake Bolac. A high number of slugs have also been found across numerous paddocks near Inverleigh and Mortlake, where several canola paddocks have required baiting to protect emerging seedlings from attack.
Vegetable weevils have been prevalent in attacking canola, both in the Riverina and in the Western District, with Mr McColl reporting outbreaks at both Young and Henty in NSW and lupin crops near Lake Bolac in Victoria.
The weevils become active in autumn and then may move into the edges of paddocks soon after crop emergence and are commonly found damaging germinating canola.
Mr McColl said a border spray at crop emergence can help control vegetable weevils before they move into paddocks.
“Controlling capeweed and marshmallow weeds early in the season may also assist in reducing crop damage,” Mr McColl says.
“Rotating crops with non-host plants, implementing a long period of ‘weed-free’ fallow prior to sowing and planting susceptible crops away from previously affected areas may all reduce the risk of invasion by weevils.”
Vegetable weevils are dull brown-grey coloured beetles and have two short white angled ‘v-shaped’ markings near the middle of their back. They are approximately 8 mm long and have a very pronounced snout.
Meanwhile, more traditional pests such as earth mites and lucerne fleas are also becoming an issue.
Mr McColl’s South Australian colleague Kym Perry said there were four main mite species that commonly damage crops: redlegged earth mites (RLEM), blue oat mites (BOM), Balaustium mites and Bryobia or clover mites.
“Redlegged earth mites and blue oat mites attack all winter crops and pastures, however, canola, lupins, cereals and legume seedlings are most susceptible,” he said.
PestFacts has already received reports of Bryobia mites damaging canola crops in parts of South Australia.
