Potato growers are being warned that this season promises to be high risk for blemish disease black dot.
The disease is more likely to take hold when the crop is left in the ground in wet weather.
Dr Jeff Peters of the CSL Plant Health Group said: “Black dot levels after harvest and throughout storage tend to be lower when a crop is harvested early. So the longer the crop is in the ground and the wetter the season is, then the higher the risk is from black dot.”
He explained that for a main crop pre-pack variety such as Maris Piper, which is susceptible to black dot, there is a higher risk of economic loss from black dot when crops are grown for more than 130 days’ duration from 50 per cent emergence to harvest.
Susceptible second earlies such as Estima hit the danger zone after 120 days’ duration.
Peters said: “Using a product like Amistar (azoxystrobin) on the crop won’t get rid of black dot, but it will shift the duration curve along by 10 days or so and delay the epidemic.”
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