Passionvine Hopper

 

As summer approaches increased levels of Passionvine Hopper (Scolypopa australis) build in kiwifruit orchards. The incidence of sooty mould on fruit also increases at this time. Commonly known as PVH, this phloem feeding insect secretes a sugary substance called honey dew, which sooty mould then grows on.

Sooty mould is largely a cosmetic problem but a major cost burden to the kiwifruit industry. A 2019 Kiwifruit Journal article by Wilson & Tozer stated that sooty mould affected approximately 2.49% of the national crop, equating to $44 million that season.

PVH is a single generation insect. Nymphs appear from early November and adults from late December. Both nymphs and adults feed on plant phloem, leading to vine stunting and damage when large populations are present. Being full of sugars, phloem contains the principle food source for PVH. Sugars and unutilised water are excreted under pressure by the PVH to form honeydew.

Honeydew is an issue, being the food media that supports sooty mould fungi growth. There is a strong correlation between the population of PVH nymphs and adults and the incidence of sooty mould on fruit.

PVH egg laying starts from February, peaks in March and can continue well into May. Each female can lay hundreds of eggs, usually in rows predominantly in dead or dying plant stems. Egg rafts can be visible on the stems of the kiwifruit stalks.

The key to controlling PVH and subsequently sooty mould is to control the nymphs early thus minimising the honeydew expression. Growers should focus on removing host plants around the orchard in the winter. However, the odd host plant can be of some benefit as an early season indicator of pest populations.

Buffer zones outside the orchard boundary should be created through spraying. Some contractors have invested in spray cannons to target gullies potentially hosting PVH. Calypso is the recommended product for this spraying and should be applied before December to minimise insect dispersal.

During summer growers are limited to using pyrethrum products such as Pylon (conventional) and Pyganic (organic). The addition of Wetcit or Oroboost (organic) surfactants will increase the persistency of pyrethrum. These should be added at 200ml per 100L of water.

The bio-fungicide product TripleX provides another option for honey dew control, with both antagonistic and competitive properties towards sooty mould. TripleX is also a preventative and should be used in combination with pyrethrum as part of a management plan.

To maximise the benefit of TripleX, regular monitoring is recommended for assessment of PVH infiltration and requirement for further preventative insecticide applications. Once PVH is observed, fortnightly applications of TripleX are recommended until insect pressure reduces. Hywet should be added to improve the performance of Triple X. For improved rain fastness Hywet SprayTite is recommended.

 

For more information please contact your local Farmlands Technical Advisor.

Article supplied by Dwayne Farrington, Technical Leader - Kiwifruit & Subtropical Crops, Farmlands Co-operative.
Source: Wilson.V and Tozer. P; NZ Kiwifruit Journal Aug/Sept 2019