Best practice management of potential copper tolerance

25 June 2015

Results from KVH’s latest round of resistance testing show the importance of applying copper at the correct label rates for effective Psa control. In lab tests, Psa-V samples from 5 of 56 KPINS tested in the wider Bay of Plenty Region showed some growth when a 15% concentration of copper was applied. It is concerning to see possible signs of tolerance to one of our key tools for fighting Psa-V.

What is being done?
KVH is carrying out further work to establish the nature of the tolerance, including re-sampling and further sampling from the five orchards. KVH is working with scientists to quantify the level and develop a recommended programme to monitor and manage the issue going forward.

KVH will work with orchard owners where tolerance or resistance has been identified to ensure best practice management is in place. This includes removal of infected material, the application of sprays at label rates, alternating spray products, movement restrictions on plant material and a strong focus on orchard hygiene.

Through the R&D and product testing programme Zespri and KVH are continuing to look for alternative and sustainable control approaches for Psa-V.

What can growers do?
KVH recommends growers remain proactive and maintain a year-round comprehensive Psa-V management programme. This includes monitoring, removing signs of Psa-V, applying protective sprays at label rates, and alternating protectant spray products where possible. It is also very important to maintain orchard hygiene to reduce the potential for resistant Psa to enter your orchard, or spread within if present.