POTATO GROWERS now have another option in the fight against two key soil-borne diseases, according to Syngenta.

This follows the granting of full label approval (Dec 7) for Amistar (azoxystrobin) against both Black Dot and Rhizoctonia (Black Scurf).

Amistar is the first available treatment for soil-borne Rhizoctonia, the company claimed.

Before the changes Amistar could only be used against Black Dot under Specific Off Label Approval (SOLA).

“Skin quality issues alone cost UK potato growers an estimated £7 million a year. Black Dot and Rhizoctonia reduce marketable yield and seriously affect storability,” said the firm‘s Garth Bretherton.

“The approval of Amistar to counter soil-borne Black Dot and Rhizoctonia now offers growers the opportunity to reduce the costly incidence of disease and present the highest quality produce.”

Rhizoctonia stem canker was found to affect 72% of crops in a recent DEFRA survey, while Black Scurf and Black Dot affected 59% and 56% of crops respectively, he said.

“Reducing the initial level of soil-borne Rhizoctonia infection minimises early pruning effects and can help to achieve even crop emergence that makes all subsequent management easier,”

Growers can apply Amistar either at a rate of 6 l/ha across the field and then immediately incorporate to a depth of 15-20cm prior to planting, or use a direct in-furrow application of 3 l/ha, Mr Bretherton recommended.