Alternative Fungicide Aids Organic Table Grape Production
Storage rot is a problem caused by fungi that attack fruit held in cold storage. Growers and packers manage the disease by applying pesticides in the field and with sulfur gas, respectively. However, growers producing organically grown table grapes are restricted from using standard fungicides. As a result, organic table grape growers have to harvest, store and ship their grapes within a week to reduce decay. An organically approved, pre-harvest disinfestation that decreases post-harvest losses would be beneficial for organic table grape production. Stephen Vasquez and UC Davis colleagues tested the disinfectant peracetic acid (PAA) to manage storage rot. PAA, which breaks down into acetic acid and hydrogen peroxide, is currently registered as a dip or spray on raw unprocessed fruit with no restrictions on immediate consumption at low doses. Steve tested higher PAA rates applied 1-day pre-harvest and evaluated fruit weekly. Storage rot was reduced to 4% compared to untreated fruit that had 10% rot after one month.
The increased duration of storage time will allow organic table grape producers to better manage their harvest, storage and shipping schedules, allowing for a longer season and higher quality fruit.