Rizolex still registered for use on potatoes

The seed potato fungicide treatment Rizolex has been given an extension of its registration from CRD so that it can be continued to be used by potato growers at planting. Available as a 10% w/w dry powder formulation designed for good adherence onto seed tubers, this established fungicide is recommended in seed potatoes for the control of black scurf and stem canker, caused by the pathogen Rhizoctonia solani and can be applied using automatic planters.

Dr. David Stormonth, Technical Manager for Interfarm, explains that the current approval for Rizolex 10D has been extended by CRD, so that growers are not hindered whilst the product’s re-registration process continues. "We had thought that there may be an interruption in registration for the active ingredient, toclofos–methyl, but it appears that the registration authorities in the UK have seen the need for Rizolex in potato growing this season. Trials in support of its re-registration show its strong performance against Rhizoctonia."

Seed potatoes are treated before planting. Rizolex is a 10% powder formulation designed to be applied directly to the tubers. It is important that the fungicide is distributed evenly over all tubers. For Rizolex this is easily done on an automatic potato planter during hopper loading. The hopper is half filled with seed and the recommended quantity of the dry formulation, sufficient to treat one hopper load, is spread over the tubers. The hopper is then filled with tubers and agitation in the planter will spread the fungicide uniformly over the seed tubers.

The recommended dose rate of Rizolex 10D is 2.5 kg per tonne of seed for maincrop and second earlies and 1.25 kg per tonne for first earlies seed tubers.

David explains that Rhizoctonia is a serious disease of potatoes, with the fungus damaging both yield and quality of seed potatoes. "Rhizoctonia is both seed-borne and soil-borne, with symptoms on the surface of the tuber seen as black scurf. On seed potatoes it attacks sprouts and in some cases can prevent plants from emerging. Rizolex is a well developed, tried and tested fungicide that is recognised to be as good as any other fungicide for the control of Rhizoctonia, helping UK potato farmers to produce high quality produce," he says.