New advice for chickpea growers on managing ascochyta blight is flying in the face of conventional wisdom.
A study conducted by the University of Saskatchewan’s Crop Development Centre has concluded it is critical to control the disease in the pre-flowering stage of development.
“The standard recommendation in the early days was to basically start scouting when the plants started flowering,” said Sabine Banniza, assistant professor at the centre.
However, results of a three-year study conducted in various Saskatchewan locations indicate that pre-flower application of fungicides can lead to 20-30 percent less disease than early-flower treatment if farmers are facing moderate to high infestation levels.
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Waiting for plants to reach the flowering stage could be a costly tactical error.
“At that point the disease can spread very quickly,” Banniza said. “Once you are behind it, it becomes impossible to control. Therefore, pre-flower application is very important.”
Ascochyta has become a blight on the prairie chickpea industry, contributing to the demise of a crop that peaked at 1.1 million acres in 2001.
Agriculture Canada expects this year’s plantings to be 133,000 acres, up 15 percent from 2004.
The dramatic contraction in acreage can be blamed in part on the devastating seedborne fungus that has been known to cause yield losses in excess of 90 percent in Saskatchewan.
Before 2003, Bravo was the only registered fungicide that could be used to control ascochyta blight in chickpeas. Quadris and Headline became available for use in 2003, followed by Lance in 2004.
The new generation of fungicides is known as the strobilurin group.
“When they came on the market there was a lot of buzz around them,” said Banniza.
“But people were also asking us how they should be applied. Our project looked at the order of application itself and whether or not it matters and at what stage of plant growth the spraying should occur.”
Due to the high cost of strobilurins and a label limitation that restricts farmers to two applications per crop per year, producers wanted to know the most effective time to attack the disease.
The new advice should be particularly useful in a year like 2005, where farmers are heading into what looks to be a wet season with poor quality seed.
“There is probably quite a bit of ascochyta blight in the seed and with the rain now, that can get the disease started really early,” Banniza said.
Her primary recommendation to growers is to scout their fields early and often. As soon as the seedlings emerge, they should be looking for signs of the disease.
One tool to help growers spot and assess the severity of infestation is a guideline document available on-line from Saskatchewan Agriculture.
Go to www.producer.com and type chickpea advice in the go box.
“As soon as you see (symptoms), spray right away if wet weather is forecast,” Banniza said.
