Molybdenum foliar sprays and other nutrient strategies to improve fruit set and reduce berry asynchrony (‘hen and chickens’) in Australia

This project addressed industry concerns about unpredictable, poor fruit set and bunch yield losses in grapevines associated with the deficiency of the micronutrient molybdenum (Mo) and other factors. This project involved a nutrient survey of commercial vineyards, field experiments and workshops with the aim of developing strategies to manage Mo in vineyards. Improved industry information, based on these findings, included the development of a corrective foliar spray strategy of Mo applied pre-flowering to overcome Mo deficiency during reproduction in grapevines. Responses of different rootstocks, use of plant tests to indicate Mo deficiency, effects after 3 to 5 years of Mo spray regimes, and assessment of potential accumulation of Mo in soils and potential leaching from vineyards were evaluated. Finally, information was communicated to industry with workshops in 4 states and a fact sheet on Mo will be circulated to the CRC for Viticulture, On-line Viti-Notes series.