New facility unveiled August 15 at open house at “Proeftuin Randwijk”
The goal of the retractable roof and walls is to prove that a shift to physical and biological controls can cause a 70%-90% reduction in chemicals used to protect against diseases like botrytis rot, apple scab, neonectria ditissima and the two major pests (common green capsids and rosy apple aphid). Natural predators, pheromones and selective traps will also be incorporated into the retractable roof.
The roof is mainly used to prevent most of the fungal diseases (all except mildew) by keeping the crop dry (excluding rain, shortening morning dew periods); the effect of the Rafter system on pests is very diverse from reduction to somewhat enhancing, but for the two major pests mentioned the roof+walls can be used to prevent them from being harmfull.
For pests we have an integrated strategy based on stimulation and introduction of natural predators, use of pheromones, selective mass capture by traps and the cravo system. Our hypotheses is that we only have to spray chemical agents against mildew (no spraying against pests, herbs and the rest of the fungal deseases). But this is of course an hypothesis.
Lead researcher Rien Van der Maas explains, “We know from foreign research on apples that woolly apple aphid numbers and prevalence of mildew increase when apples are grown under permanent covers. The roofs of such covers must therefore be open most of the time. The open production system ensures that biological control agents, such as parasitic wasps, can continue to do what they do best. Use of the convertible cover also maximizes environmental pollinators’ capacities.
Rainwater from the roof will be collected and transported to a storage tank. The stored water will be used to irrigate the trees through two different 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 allowing rainworms and earwigs to thrive.
This research on apples is part of a larger project where new cultivation systems are being researched that would ensure crops of strawberries, lilies, apples or arable crops are not as dependent on crop protection agents while making sure that growers can maintain their market positions.