Three species of armored scale (Hemiptera: Diaspididae) are found on kiwifruit (Actinidia spp.) in New Zealand orchards: latania scale, Hemiberlesia lataniae (Signoret); greedy scale, Hemiberlesia rapax (Comstock); and oleander scale, Aspidiotus nerii (Bouché). Each of them is a quarantine pest in some of the markets to which New Zealand kiwifruit are exported. Adult females of the three species can be distinguished morphologically; however, the task is laborious when large numbers must be identified. Furthermore, it is not possible to distinguish among the immature stages. A DNA-based diagnostic using a multiplex polymerase chain reaction (PCR) method based on differences in the cytochrome oxidase I and II genes was developed to distinguish the three species. The test relies on the rapid isolation of amplifiable DNA by using a protease (prepGEM), followed by multiplex PCR using primers that distinguish the species at three or more nucleotide positions within cytochrome oxidase I and II, resulting in PCR products of characteristic size for each species. The test was validated in a double-blind experiment and then used to determine the relative distribution and abundance of the three species on leaves and fruit of 'Hayward' and 'Hortl6A' kiwifruit across the dominant growing regions throughout New Zealand during the 2007 season. In total, 3,418 scale insects were identified to species level: 1,904 (56%) were latania scale; 1,473 (43%) were greedy scale; and 41 (1%) were oleander scale. Since the last survey in 1988, latania scale has displaced greedy scale as the dominant species of armored scale on Hayward kiwifruit in the North Island and was found for the first time in the South Island. Only a single latania scale was found on Hortl6A fruit, consistent with previous reports of reduced rates of settlement on the fruit of this cultivar by latania scale compared with greedy scale.

Spirotetramat (Movento† ) is a phloem-and xylem-mobile insecticide developed and registered for use pre-flowering to control armoured scale insects on kiwifruit vines in New Zealand. In a field study in 2010Á11, the effectiveness of a postharvest application was investigated. A single spray of spirotetramat plus adjuvant(s) reduced the percentage of scale-infested fruit from 49% on control vines to less than 7.5% on spirotetramat-sprayed vines 12 months later. No residues were detected in the fruit. Applying spirotetramat with a penetrating adjuvant (Engulf † ) provided the best result, with only 1.5% of the fruit infested. Despite the high pest pressure, counts of scale insect crawlers on sticky bands remained very low for 18 months after treatment. Uptake of spirotetramat into the mature kiwifruit leaves occurred in less than 24 h and was not affected by leaf age. Translocation out of the leaf was slow and decreased with leaf age, indicating that a postharvest spray should not be applied to canopies exhibiting advanced senescence. These results show that a single postharvest application of spirotetramat plus adjuvant(s) can provide excellent season-long control of armoured scale insects on kiwifruit while minimizing the risk to crop pollinators and the potential for residues in fruit.

In New Zealand, the causal agent of kiwifruit canker, Pseudomonas syringae pv. actinidiae (Psa), can survive in overwintered kiwifruit plant debris on the orchard floor at least until spring. This study used trap plates and trap plants to determine the importance of fallen leaves and winter prunings on the orchard floor as inoculum sources. Trap plates were positioned 15, 50 and 100 cm above the debris. Psa was detected only when the plates were exposed during rain events and was found to be splashed upwards in small amounts from the debris during rain. Leaf lesions developed only on the trap plants exposed during the first week of the 20-week trial. In this trial, there is some evidence that plant debris is not a significant inoculum source and would not have posed a major risk for re-infection of any surrounding kiwifruit vines at the time of budburst in spring.

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker of kiwifruit, which is an ongoing threat to New Zealand kiwifruit production. Disease control depends on orchard practices such as removal of visibly diseased material, pruning during low-risk periods, and the application of foliar bactericides. Although the use of copper compounds on Actinidia species (kiwifruit) can cause phytotoxicity, copper-based formulations remain a key component of Psa control in New Zealand. The effect of single copper applications on Psa infection of ‘Hort16A’ trap plants was studied over the Spring of 2014 (Sept—Nov). Psa leaf spots were observed at the beginning of October, appearing first on the untreated plants. Although the copper sprays did not achieve complete protection, particularly as the inoculum built up during November, the copper-sprayed plants always had less disease than the untreated plants.

Hayward and Hort16A kiwifruit are susceptible to attack by the brownheaded leafroller (BHLR) Ctenopseustis obliquana but the incidence and severity of damage to Hayward can be twice that of Hort16A Three bioassay techniques were tested for their ability to detect differences in the relative susceptibility of the two kiwifruit cultivars to BHLR larvae No differences were detected when larvae were reared on artificial diets containing Hayward or Hort16A plant material Significantly more larvae survived when reared on Hayward versus Hort16A leaf discs Caging larvae onto leaves and fruit resulted in significantly more damage to Hayward compared with Hort16A Measuring larval survival after 21 days on leaf discs or the incidence and severity of damage caused by larvae caged on leaves or fruit are both potential techniques for screening Actinidia plant material for resistance to leafrollers