A leading UK potato researcher has warned that Black Dot is the most important disease in devaluing potato crops, but new trials show Amistar can reduce the problem.
David Firman of Cambridge University Farm said that although Silver Scurf has been the predominant scourge in the past, its impact is far less evident in modern temperature controlled stores. Also, the use of increased irrigation to grow the majority of crops has reduced its severity.
Amistar can reduce the cases of Black Dot. It was available for the first time last year under a Specific Off Label Approval. It may have little impact on total yield, but can have a dramatic effect on the marketable yield of premium crop and the storability of potatoes, according to Dr Firman.
He said: “In every experiment over the past three years we have seen a reduction in the severity of either Black Dot or Rhizoctonia. You will never entirely eliminate the problem with soil-borne diseases, but treatment can bring about a significant reduction down to commercially acceptable levels.”
Dr Firman stressed that Black Dot was prevalent last season. He warned that over irrigation could increase the severity of the disease, so take care with scheduling and monitoring soil water levels. He said: “Lifting as soon as possible after desiccation, once skin set has been achieved, will certainly help.”
Dr Firman also advised growers to take care when applying Amistar to take care. “Amistar should be applied to the soil and not onto the tuber, particularly in conjunction with a fungicidal treatment.”