KVH follow-up of unusual symptoms including “sudden collapse of vines” during flowering or leading up to harvest, often identifies symptoms which have gone unnoticed for some time.

Leader dieback; swellings at, above or below the graft; swelling at the trunk crown (base); or cracking, cankering, or swelling of leaders and trunks is often not noticed, as the focus in any production year is generally on the canopy, buds, flowers, and fruit rather than the architecture of vines.

A perfect job for autumn and early winter is to complete a monitoring round to assess and act on vine symptoms that have crept in under the radar across the years and which are indicative of kiwifruit vine disorders.

Mapping of symptomatic vines allows insight into areas where gaps are emerging, or canopies are becoming sparse due to a decline in vine health.

Replacement strategies, such as replanting alongside affected plants or stringing of replacement canes from vines in adjacent rows will allow for the cut-out of infected vines without a significant drop in production.

The earlier infected vines are removed the better, as spores from the fungal invaders can be harboured in fruiting bodies within the infected area and spread via soil, water, and air movements. Infections in leaders and canes can also be spread by unclean tools and infections in rootstock can travel across graft unions and impact on newly grafted cultivars.

Research projects initiated through the Zespri Biosecurity Innovation portfolio have identified several fungal organisms associated with the various kiwifruit trunk disease symptoms and shown that disease complexes rather than single species are generally involved.

Regular monitoring of sites is valuable as new growing situations can change the status of fungal diseases. Different cultivars and rootstock may be more susceptible, marginal growing areas, environmental factors, stressed and aging vines, different management practices (e.g. girdling) and build-up of site inoculum are all factors that can lead to a change in vine impacts. Annual review helps ensure orchards remain resilient and successful into the future.

More information on vine decline and trunk diseases is available here and an image library of trunk symptoms to watch out for is available here.

If you have unusual symptoms that need follow-up, contact info@kvh.org.nz