Dual Action Spray Tackles Alternaria, Blight

Published online: Dec 03, 2013 Fungicide Luke Casswell
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A fungicide spray to tackle both alternaria and potato blight is being launched, claiming a disease control breakthrough for potato growers.

The new product from Syngenta, Amphore Plus, will allow growers to control the two problematic diseases, including all strains of alternaria, and could become the center of many blight spray programs.

Syngenta field technical manager Stephen Williams told delegates at the British Potato 2013 conference that the prevention of these diseases is critical and the timing of Amphore Plus allows growers to stay ahead of the disease.

Areas where alternaria is becoming more of an issue will benefit from the new product, which combines one of the most widely used blight actives-mandipropamid-with a new active ingredient for potatoes, difenoconazole.

Up until now, most products only targeted either blight or alternaria, according to Williams.

The soluble concentrate of 0.6l/ha delivers the same amount of active ingredient as the widely used blight spray Revus with 150 grams of mandipropamid, along with an additional 150 grams of difenoconazole.

"It is highly active against alternaria but it is a difficult pathogen to control, so dosage is everything. We believe with that extra active, we can get on top of the disease," Williams said.

Calculating the cost of alternaria attack, Williams warned that potato crops hit by infection suffer rapid green loss and early senescence, which could reduce yield by up to 30 percent.

A risk assessment will be critical for growers who want to stay on top of the two diseases, Williams said. He stressed the importance of preventing the disease rather than curing it.

Differences in varietal susceptibility will also have to be taken into consideration, with the new product becoming especially important on varieties such as Markies and Ramos where alternaria can be a big problem.

Independent potato specialist John Sarup says the problem of alternaria will certainly be helped by this new product at a time when growers are trying to cut costs.

"With farm incomes coming under increasing pressure, growers are tightening on their fertilizer inputs, which can lead to stressed crops," said Sarup. "On vigorous growing varieties such as Markies, if the nitrogen is cut too much it leaves it open to the threat of alternaria."

Three applications will cover growers through the highest risk period. However, growers have some flexibility in their individual spray programs.

"You can alternate or block them together. We have no real preference," said Williams.

Source: Farmers Weekly