Management of Post-Harvest Fruit Still Hanging A Message from Lynn Wunderlich, Farm Advisor UCCE-Central Sierra
Unsold fruit hanging on the vine can be unsightly for many growers but does paying to drop unsold fruit make sense? My colleague Rhonda Smith (UCCE Sonoma, retired) with our UC plant pathologist Akif Eskalen wrote an excellent article addressing this question which may be of interest to you: https://cesonoma.ucanr.edu/viticulture717/Should_You_Drop_Unsold_Fruit/
Bottom line: you can leave unsold fruit hanging on the vine until pruning when it will be dropped as long as you can incorporate it into the soil for decomposition. Disease depends on many factors-including weather, susceptible tissue present, and inoculum (remember the disease triangle?). Incorporating clusters with prunings will ensure that they decompose before spring bud break.
Rhonda told me that for many of her growers, the hardest thing was to see the unsightly fruit hanging until pruning time in late winter, early spring…once the pruning was done and the fruit dropped with the prunings, everyone was relieved and ready to start a new season.
Footnote: After I sent the above message (to growers who signed up to receive my email updates) regarding leaving unsold fruit hanging until pruning, I received a message from someone who had an issue with bears after leaving olives hanging during the winter. It certainly makes sense to me that wildlife, especially during this time of drought, would be attracted to any food sources left out there. So, please, be bear-aware and consider your local environment! And, thanks for any and all feedback on this topic.