The damaging beet western yellow virus spread into cropping regions up to Bendigo over the last few months, putting a serious dampener on the region's canola season.

The infected aphids brought the virus west from South Australia through the Wimmera earlier this year, and now cropping farmers to the north and west of Bendigo have reported large numbers of aphids on their properties.

Andrew Maher, who uses canola as a rotation crop on his Serpentine property, said the hot, wet autumn might have provided ideal conditions for aphids to flourish.

"You see aphids most seasons, and they might only damage one per cent so the yield can usually compensate for them," he said.

"The issue with this year is that the aphids are in such big numbers.

"We're just hoping it doesn't affect our crops."

The beet western yellow virus is carried on green peach aphids causes major yield and quality loss in canola, with symptoms becoming evident two to five weeks after infection.

Birchip Cropping Group research agronomist Simon Craig said the virus was just one of many aspects potentially threatening this year's harvest.

"The virus is pretty widespread in our region," he said.

"It also affects those with lentils and chick peas.

"Moisture and nitrogen levels are the biggest risks."

The virus caused widespread damage in South Australia, but the Department of Environment and Primary Industries hopes to limit the damage during the upcoming spring.

DEPI pathologist Frank Henry said spraying with registered insecticides to control the aphids was still not warranted in most areas.

"Although unlikely in most regions, if aphids are actively flying at present, chemical control should be considered," he said.

"Growers should remain vigilant, monitor for colonising (winged) aphids, and be prepared to apply insecticides in late winter or early spring to limit virus spread into canola and pulse crops."

The issue was a hot topic during a Grains Research and Development Corporation conference in Horsham on Tuesday.

Mr Henry said canola crops were most susceptible to yield losses at the rosette stage.

"Generally, the yield consequences of beet western yellow virus decrease with infection at later stages of crop development," he said.

"However, canola crops remain susceptible to yield losses from beet western yellow virus infection until approximately the mid-podding stage."