Consultant's Corner: Sclerotinia - The commercial view
Growers will benefit from ongoing research to fine-tune best practice fungicide management for sclerotinia stem rot.
Research into the disease over the last 5 years has given farmers and researchers a deeper understanding of the disease and the influence the season can have on its progression.
Trials led by the Department of Agriculture and Food (DAFWA) and funded by the Grains Research and Development Corporation (GRDC) have shed more light on the optimum time to apply foliar fungicides.
In summary this work has highlighted:
- The importance of a two-spray strategy if the infection window for the disease is protracted
- The need for growers to be flexible with the timing of fungicidal applications. If conditions are dry then disease onset can be delayed significantly which can reduce the number of sprays required or eliminate the need for fungicidal sprays completely
- The importance of growers having fungicide on-hand, as the optimum spraying window – in most seasons when the crop is at the 15 to 30 per cent flowering stage - can be very short
- That the disease can be significant and result in large yield losses. Doing nothing can be a very expensive decision.
In 2012 I also conducted trial work - funded by the GRDC Geraldton Regional Cropping Solutions Network (RCSN) – to better understand this damaging disease in the northern grainbelt.
The one-year project was conducted in conjunction with DAFWA and other local agronomists.
We found that sclerotinia was most damaging in high-biomass crops, which was determined by soil moisture (linked to soil type and landscape position), adequate seasonal rainfall and the crop emergence date.
Even though 2012 was a very dry season in the northern grainbelt (sclerotinia is generally more damaging in wetter seasons like 2013), there were still crops in this region that lodged in places due to damaging levels of the disease.
The RCSN project found that canola susceptibility to sclerotinia increased on:
- Loam and clay soils that held moisture longer, compared with sandy soils
- Shorter-season varieties that flowered earlier when the disease was sporulating
- Paddocks where there had been reasonable disease levels in previous years
- Crops that were early sown – leading to high crop biomass early in the season.
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827