SPRING BEAN growers should beware of increased downy mildew threat to crops where conditions are conducive to the disease, the Processors and Growers Research Organisation (PGRO) has warned.

Warmer, muggy weather, interspersed with rain showers will increase the risk of primary infection spreading to new foliage and growers with untreated crops must be vigilant for signs of the disease, it said.

While spring bean crops are generally looking good this season, downy mildew symptoms are prevalent, said The Arable Group’s agronomist, Peter Riley.

Treatment is particularly necessary on farms where beans have been grown before, or where more susceptible varieties are being grown, he said.

“Chlorothalonil is the core of the early fungicide application, topped up with Folio Gold [chlorothalonil + metalaxyl-M] for added Downy mildew activity,” he suggested.

Bean growers should also be aware of Bean Seed Beetle activity increasing with any warmer weather, said Syngenta’s technical manager, Simon Laidler.

“Bruchid beetles feed on pollen for around two weeks, before laying eggs on newly forming pods. Growers need to disrupt the egg laying process to protect the lowest pods on the plant.”

Insecticides should be applied when plants have six flowering trusses, with a follow up treatment 7-10 days later to minimise seed damage, he recommended.