Spud black scurf options increase
AFTER a year in which the choice of anti-rhizoctonia potato fungicides was effectively cut to two, the armoury available to growers has been widened with the re-launch of Rizolex (tolclofos-methyl).
Only limited amounts of the product, formerly sold by AgrEvo, were available last season, says Peter Hingley of Hortichem which now has exclusive marketing rights to it.
"Last year was a tough one for stem canker and black scurf and growers have limited options for controlling rhizoctonia," he says. Monceren (pencycuron) and Rovral (iprodione) were approved for seed production.
"Rizolex is slightly cheaper and similar in terms of efficacy and yield." SAC trials also show it can be as effective on silver scurf as imazalil.
SAC pathologist Stewart Wale welcomes the re-launch. "We need as many options as possible because it gives us more chances of avoiding resistance. Over the years we have also found Rizolex has given some reductions in silver scurf on occasions. But I am not prepared to say it is as good as conventional silver scurf products."
Although an organo-phosphorus compound Rizolex is less toxic than OP insecticides, says Mr Hingley.
"It is atypical, with weak acetylcholinesterase activity." *