![Steve Marcroft is urging farmers to monitor stored seed to see if there is blackleg infection. Photo by Gregor Heard. Steve Marcroft is urging farmers to monitor stored seed to see if there is blackleg infection. Photo by Gregor Heard.](/images/transform/v1/crop/frm/5Q2j7ezUfQBfUJsaqK3gfB/ca82d185-0d0d-4023-b146-ed4be8646986.JPG/r1680_307_6000_4000_w1200_h678_fmax.jpg)
Canola producers looking at using retained seed for this year's sowing have been warned by a leading plant pathologist to keep an eye out for symptoms of blackleg.
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In particular Steve Marcroft, Marcroft Grains Pathology, urged growers to check for a whitening of the seed shell, which is symptomatic of pod damage caused by blackleg.
Speaking at the Grains Research and Development Corporation (GRDC) update in Bendigo recently Dr Marcroft said infection would not necessarily preclude the seed from being used for sowing but said it would need to be treated with an appropriate seed treatment.
Left untreated the disease damage is not expected to spread through the seed stock during storage, but it may reduce emergence rates of infected seed or result in early infection of canola seedlings after sowing.
He said the affected grain could still be used for animal feed.
Farmers can help minimise their risk by storing grain carefully.
"Low humidity and temperature is essential for maintaining grain condition in silos and will help minimise any disease development," Dr Marcroft said.
He said regular aeration is required with temperature and moisture monitors to store grain under optimal conditions.
However, he said the best case was to use sound seed.
When looking for seed to use for planting he said farmers were best to discard discoloured seed.
Pod infections of blackleg occur due to post-flowering rainfall events, with rainfall combined with physical pod damage from events such as hail or frost will increase pod susceptibility.
Dr Marcroft said varietal choice was also critical.
"Cultivars that are early flowering and do not have effective major gene resistance may be more susceptible to blackleg pod infection."
"Look for something with good genetics and then you can be happier knowing you won't have to throw the kitchen sink at it in-crop to keep it clean."
Dr Marcroft said farmers needed to be aware of revised blackleg ratings when retaining seed, with the possibility varieties could be less resistant than stated in GRDC blackleg management guides.
He said blackleg severity had varied last year, according to seasonal conditions and along district lines, with some areas where the disease had overcome resistance genes faring worse.