Speaking at the Southern Growers Show, Fargro Plants integrated pest management specialist Neil Helyer said: "You should pick pesticides with a different code number, and therefore a different mode of action, so that we are not going to get a resistance with some products.
"There are different trade names and active ingredients but for the insects they are doing the same. You should try and see a specialist and work out a special spraying programme if you are going to stick to spraying," he told growers.
He added that the Horticultural Development Company and the Chemicals Regulation Directorate are working with manufacturers to address problems with different re-entry periods and handling interval guidance issued by companies using the same products, but under different trade names.
In a bid to avoid these re-entry periods, he recommended the use of bio-pesticides. "We will be seeing a lot more of these sorts of products coming through in the next few years," said Helyer.
He pointed growers toward products such as Serenade which can be used to treat downy and powdery mildew, and a new product called Metarhizium which should be hitting the market next year.