Most pests in cannabis cultivation can be controlled with natural enemies, such as certain beetles and wasps, but top rot and powdery mildew just cannot be controlled that way, as was researched by the National Institute for Public Health and the Environment in the Netherlands in preparation for the start of the experiment with cannabis cultivation for recreational use in the closed coffeeshop chain. Growers can register from 1 July. (In the Netherlands, coffeeshops are establishments where the sale of cannabis for personal consumption by the public is tolerated by the local authorities.)
Ten products have been identified for diseases and pests for which no or only limited natural enemies are available, based on the expertise in the Netherlands and user experiences in Canada. Eight of these products fit within organic cultivation. Test exemptions for the use of plant protection products during the experiment must be issued by the Ctgb (Dutch Board for Authorization of Plant Protection Products and Biocides).
When used according to the instructions of the plant protection products, it is possible that residue from these products remain on the cannabis. The exposure to the investigated plant protection products through recreational use of cannabis is not harmful to health. For four out of ten selected products the maximum residue that may remain on cannabis has been determined. This does not need to be determined for six out of ten selected products because these substances are not dangerous.