Apple production under rainproof covers – benefits and limitations

Abstract: To reduce losses caused by pests and diseases, fruit growers still rely on a high use
of pesticides. However, both consumers and retailers are demanding a large reduction in the
pesticide use, aiming to have zero-residues fruit on the market. Rain-proof covers have been
deployed on fruit crops to reduce diseases such as apple scab (Venturia inaequalis) and fruit
rots that need rain to infect fruit. An experimental orchard for growing apples at the
experimental garden ‘Proeftuin Randwijk’ (WUR, The Netherlands) has been fitted with a
convertible rain cover. When it rains, the cover will close. This will ensure that the trees stay
dry. The convertible cover can also be used for pest exclusion by closing the system when there is high risk, for example of common green capsids. The open system ensures that biological control agents, such as parasitic wasps, can continue to visit the orchard. Use of the convertible cover also maximises environmental pollinators’ capacities. The rain water that lands on the convertible cover is transported via gutters and pipes to a storage tank. This water is used to irrigate the apple trees through two systems: buried drip irrigation pipes for the grass patches and mini sprinklers for the rows of trees. This ensures that the condition and composition of the soil remains consistent. Earthworms – to increase nutrient availability, better drainage, and a more stable soil structure – and earwigs – a biocontrol agent of fruit pests – will then still be able to do their useful work.