A residue-free spray has been developed by Hawkes Bay-based Post-Harvest Solutions to safeguard crops against bad weather and protect from rot and disease.

The product, which can be used right up to harvest, could be available commercially once the registration is approved.

The Foundation for Research, Science and Technology provided funding for the development of the spray, which is a new formulation of an existing sanitation treatment.

Post-Harvest Solutions managing director and water engineer Paul Midgley joined with New Zealand-based research and product development company Elliott Technologies to develop the protective, pre-harvest spray.

He said the altered formula quickly converts back to its natural state, leaving no residues or carryover on the crop.

The team will target the rapidly growing grape production in New Zealand, where losses from sour rot and Botrytis can be catastrophic if the weather turns in the few weeks before harvest.

Midgely said: “It is difficult to control Botrytis once the berries start to size and the bunches close. When the product is sprayed before bunch closure it destroys existing disease spores on foliage and decaying flower parts inside the bunch, protecting all the grapes and not just those on the outside where sprays would normally settle.”

Testing was carried out in vineyards treated with the residue-free formulation and on grapes incubated in laboratory conditions that encouraged Botrytis rot by intensifying conditions that may occur in the field. The new product proved effective when sprayed in the field before harvest.