Routine tests indicate streptomycin resistance in Psa-V on two Te Puke orchards
Results from KVH’s regular testing programme have showed Psa-V resistance from samples in two Te Puke orchards.
These finds were detected in the most recent round of an ongoing copper and streptomycin resistance monitoring programme that has been in place since 2011. The programme’s aim is to ensure resistance is detected early. These results are not completely unexpected.
The streptomycin resistant Psa-V is still susceptible to copper, meaning growers can still effectively control Psa-V.
Resistance to streptomycin can occur naturally, even on orchards where streptomycin has not been used. KVH and Zespri are working with relevant authorities to understand the implications of this result and other orchards in New Zealand could also have streptomycin resistance. There is no evidence to suggest the resistance has occurred due to inappropriate use of streptomycin.
Streptomycin use and resistance has previously been identified in other horticultural industries in NZ and successful management strategies have been developed to deal with this.
Streptomycin use not permitted at present
Industry use of streptomycin (registered and sold in NZ as KeyStrepto™) is not permitted at this time of year under Zespri’s Crop Protection Standard. KVH and Zespri are reviewing the kiwifruit industry use conditions of Streptomycin for the 2016 season and will notify the industry once this is confirmed in June.
Through the R&D and product testing programme Zespri and KVH are continuing to test and identify alternative and sustainable control approaches for Psa-V. Zespri has been developing options to reduce industry reliance on antibacterial products.
What is being done?
Both orchards have been working with KVH to ensure best practice resistance management is in place. This includes the application of copper spray, movement restrictions on plant material and a strong focus on orchard hygiene. Intensive sampling and testing of the two orchards and the surrounding orchards is underway. Further testing is also being carried out to establish the nature of resistance.
What can growers do?
KVH continues to recommend growers adhere to their orchard management plans, including a robust protective spray programme, orchard hygiene and the removal of infection from orchards as per KVH’s best practice advice through autumn. It is also very important to use protective spray products at label rates.
- Continue to maintain a year-round comprehensive Psa-V management programme.
- Maintain a protective spray programme throughout autumn. Ensure cover is in place prior to high risk weather.
- Always use label rates.
- Immediately after harvest, apply Actigard™ and copper – refer to the KVH Seasonal Management Guide www.kvh.org.nz/seasonal_advice
- Ensure spray calibration is optimal to enhance coverage.
- Remove and dispose of diseased material from the orchard to reduce build-up of inoculum. This also maximises the benefit of applied sprays.
- Sanitise tools between vines.
- Ensure strict orchard hygiene measures are in place during harvest to avoid the transfer of plant material within and between orchards. This includes:
- Checking tractors, bin trailers and picking bags are clear of plant material and sanitised as required.
- Ensuring all harvest bins are sanitised and clear of plant material.
- Making sure clothing, and in particular headwear and footwear, are clear of plant material on entry to and exit from the property.
- Ensure budwood and nursery stock comes from an approved source and is compliant with KVH movement controls.
Refer to the KVH Seasonal Management Guide at www.kvh.org.nz/seasonal_advice.
Kiwifruit growers who believe spraying is providing no control, and suspect resistance, should contact KVH on 0800 665 825 or email [email protected]. KVH will then assess the situation and carry out additional testing for resistance as required.