This week KVH met with Gisborne growers to see first-hand the level of Psa-V progression on positive orchards within the region.
Gisborne did not suffer severe winter or spring frosts this year. However, spring growing conditions have been difficult with significantly higher than normal rainfall for both August (155% higher than 2013) and September (185% higher than 2013). Cooler temperatures and long periods of wet weather, particularly toward the end of September, have led to higher levels of cane die-back and leaf spot symptoms on already infected orchards.
The level of symptoms seen on Gold variety orchards was generally low. Males and vines in tougher growing conditions, such as those suffering from water-logging, had more die-back and leaf-spot. However, monitoring and cut-out rounds are continuing to minimise infection levels within the orchards. Removed material continues to be bagged and buried, or burnt.
Growers with vulnerable Gold varieties have clear plans for the removal of these blocks. With pollination now complete, the removal of the higher-risk male varieties from Hort16A blocks in their final production year is recognised as a means of reducing Psa-V risk for these orchards. Early removal also provides the opportunity for the earlier establishment of males suitable for Gold3.
Gold3 is performing well. Growers commented that signs of Psa-V are limited to a few canes with dieback, and on individual blocks some minor infection has been seen in a few M91 males. Again, male pruning provides an opportunity to remove this infection and to restructure vines to support good penetration of protective sprays for the balance of the season.
Some leaf spotting and sepal staining has appeared in the last three weeks in Hayward varieties on cold, wet sites and the impact of this is still to be seen.
The progression of bounty rootstock is being observed with interest. To date, some failed plants have been attributed to Psa-V infection. Overall however, this rootstock is showing promise in blocks with more difficult soil conditions where this new rootstock is being established.
Overall, as weather conditions start to improve, the rate of symptom progression is expected to slow across the region. However, robust protective spray programmes are still recommended to put vines in the best position as Hayward varieties move through to the higher-risk flowering period.
The Gisborne region now has 19 Psa-V positive KPINS. This represents 29% of orchards and 44% of kiwifruit hectares. Of these KPINS seven new finds were reported since 1 August 2014.