Grower boost with low blackleg rates

Low levels of blackleg infection in canola crops


Cropping
Canola crops are generally in ruddy health in southern Australia this year.

Canola crops are generally in ruddy health in southern Australia this year.

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Levels of the fungal disease blackleg are at their lowest levels for at least five years in key canola producing regions.

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AUSTRALIAN canola producers are enjoying a season remarkably free of the damaging fungal disease blackleg.

In spite of the wet conditions currently seen in key canola producing areas of South Australia and Victoria blackleg infections are very low.

“It’s the lowest level of blackleg I’ve seen in the canola in quite a few years,” said Craig Drum, an agronomist based at Tatyoon in Victoria’s Western District.

He felt a dry June had been critical in halting the spread of the disease.

“It is wet enough here now, but we had very little rainfall in June and that has probably played a role in stopping the spread of blackleg, there wasn’t that continuous leaf wetness.”

“Seed treatments were probably limiting the disease spread in the late autumn when conditions were wet, then we had the dry June so we aren’t seeing much blackleg around at all and the canola generally looks very healthy.”

Kurt Lindbeck, broadleaf pathologist with the NSW Department of Primary Industries (DPI) in Wagga Wagga said the situation was the same in the Riverina.

“Infection rates are at very low levels compared to the past five years, we’ve seen crops get to the six leaf stage with virtually no signs of infection,” Dr Lindbeck said.

He said the Wagga Wagga area was relatively dry, slowing down the spread of the disease.

“I’d attribute the low levels of the disease to the season, we haven’t had the consistently wet conditions needed to trigger a big blackleg event.”

“When you have consistent moisture over a period of several day you see the stubble taking up moisture and it allows the residual blackleg on the stubble to reproduce and spread the infection to the crop.”

Blackleg can be spread in a number of ways, surviving on canola stubble over summer before either sending airborne spores to new crops, releasing spores from the stubble direct onto plants, resulting in the class stem canker presentation of the disease, or spread through the soil to plant roots.

Dr Lindbeck said canola industry authorities had been concerned about the spread of the disease leading into planting this year.

“We were quite worried given the disease load last year and the fact canola plantings were up and there were some concerns regarding the performance against blackleg of some popular varieties leading in.

“The seasonal conditions have meant it has not been an issue,” he said.

The story Grower boost with low blackleg rates first appeared on Farm Online.

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