From floods to bugs and everything in between

Most table grape producers, alongside other industries, have been impacted by La Niña conditions bringing with it a wet season and associated risks.

Some producers suffered varying degrees of downy and powdery mildew, along with botrytis. Early in November, the team responded to reports of bruising on bunch stems. We collected samples for analyses and diagnostic results indicated that the bruising may have been associated with Pseudomonas syringae. Pseudomonas is a bacteria that causes necrotic lesions in various parts of plants, including rots in grapevine inflorescences, bunches or berries. No fungal pathogens were isolated. Recent flooding in the Greater Sunraysia region impacted many, including table grape producers in flood plain areas. We worked with affected producers, Rural Financial Counselling Services (Vic NSW), and Agriculture Victoria, specifically to seek clarification on grant application criteria, leading to a revision and extension of the criteria – a positive result for flood-impacted producers. We will continue to assess the health of inundated vines to discern the long-term effects on production.

The team continued to assess the dormancy breaker and mealybug demonstration trials.

Preliminary results from the dormancy breaker demonstration trial showed that one of the 13 treatments provided a similar response to Dormex®, in timing of bud burst and uniformity at flowering, however most treatments did not provide any clear advantage over the untreated or water-only treatments.

It is hoped the trial will continue for at least two more seasons, to ensure that new treatments have no adverse effects (e.g., impacts on fruitfulness) and to refine the rates and timing.

The mealybug demonstration trial site was treated post-harvest in 2022 with a selection of chemistry, with and without a wetter. We have been monitoring the mealybug population, to determine whether post-harvest treatments reduce mealybug populations.

Running in parallel to all these activities, the team continued its work on restricted spring growth (RSG). We are currently exploring the possible link between carbohydrate levels in roots and leaves and RSG symptoms.

The team has collected the first of four sets of root and leaf samples scheduled for carbohydrate testing throughout the year. The prepared samples were sent to South Africa for analysis (total carbohydrates, starch and sugar). When all four scheduled samples have been analysed – October 2023 – we will share the results. Meanwhile we are consulting with plant physiologists to interpret results.

The team is looking forward to bringing you some grower events this year and sharing some more research, development and extensions news, updates on innovation in industry and more.v

Alison,