The following presentations from Tuesday’s R&D grower meeting in Te Puke are now available on the KVH website:
Psa-V continues to spread throughout the Kerikeri region with 32 out of 106 KPINS now testing Psa-V positive. KVH staff recently visited positive orchards in Kerikeri with growers and orchard management staff.
In most cases disease expression has continued to be relatively slow. However, in one location inoculum levels have clearly increased and disease expression in Hort16A has increased significantly. This has led to a number of part blocks being removed. These orchards are carrying out weekly monitoring and removal of infected material, followed by weekly spraying.
Growers are advised to be aggressive with removal to help reduce the rate of spread and to protect young Gold3 grafts. The continued wet weather has clearly been a factor in disease spread, and unless the region sees a long period of warm, dry weather soon, growers can expect expression to continue to accelerate.
KVH recommends growers actively monitor their orchards, remove signs of infection and to contact packhouses or KVH staff for support if required.
In late 2013, Chile suffered one of its most damaging frost events in 80 years—causing almost $1 billion damage to fruit crops and reducing kiwifruit export volumes by over 50%.
Further impacts from this frost event are also expected in the form of Psa-V, with the number of positive orchards expected to increase when national surveys are carried out later this year. It is expected the colder areas near the mountains and further from the coast will be the most severely affected.
Over the past few years, Chile has seen a steady increase in the number of positive orchards as shown in the graph above.
Symptoms at newly-detected orchards are often severe, leading local authorities to believe these infections are not new, but have been undetected in previous monitoring rounds.
The Chilean Kiwifruit Committee states the industry needs a greater permanent awareness to biosecurity, and orchard management complacency is the biggest problem facing the Chilean industry.
Zespri’s Focus Orchard Network (FON) field days are scheduled from 7-21 October and include the following topics:
Click here to find the FON field day coming to your area
During spring, Psa-V symptoms can change quickly as sap rises. Therefore, ongoing monitoring of orchards is essential at this time of year.
Monitoring of male vines, particularly in areas where males were affected by Psa-V in previous years, is recommended to allow growers to make early assessments of likely artificial pollination needs. Pollen suppliers have indicated stocks are lower than in past years.
Following recent orchards visits, KVH has prepared the following observation reports:
Last month, ACVM granted a limited label claim to a second CPPU (forchlorofenuron) product – Caplit™ – for the control of Psa-V in kiwifruit.
Zespri has updated the CPPU User Guide and Crop Protection Standard to reflect this change; and KVH has included Caplit™ in its Recommended Product List.
The use conditions are the same for both Caplit™ and Ambitious® 10SL, so growers are prompted to add Caplit™ to their Seasonal Management Wall Chart alongside Ambitious® 10SL. Please note the rate for Caplit™ is 50-75g/100l.
Due to concerns around fruit deformation observed on Gold varieties off-shore, CPPU products should not be applied to Gold varieties.
CPPU products are not systemic and therefore good coverage is required. Apply approximately 5–7 days prior to an infection event. CPPU should not be applied within seven days of the first flowers opening on an orchard. Extreme care should be taken to mitigate the risk of spray drift.