New Zealand's Kiwifruit Vine Health (KVH) has warned that if copper spray treatments for vine disease Psa are misused, the bacteria will likely develop resistance, media agency Radio New Zealand reported.

KVH chief executive Barry O'Neill told the radio station there were reports pseudomonas bacteria overseas that were resistant to antibiotics and copper sprays, including streptomycin-resistant Psa strains in Japan.

"We are advising growers to follow label rates and not to go lower than label rates with coppper products so there is less likely changes of resistance developing," O'Neill was quoted as saying.

In a KVH bulletin, the organization said it was working with kiwifruit company Zespri to find what additional steps needed to be taken to avoid resistance developing, and determine a course of action if resistance is identified.

"To date, resistance in New Zealand of Psa-V to coppers and antibiotics hasn’t been identified in the testing programme, but with the increasing use of products and concerns that coppers are being applied below label rates, it is likely to be only a matter of time before resistant bacteria are identified in New Zealand," the bulletin said.

"Avoiding resistance developing is of significant importance for the kiwifruit industry. It involves a combination of alternating effective products and using products in combination, along with ensuring label rates are followed."

www.freshfruitportal.com