Netherlands: Further research into efficiency of spraying against thrips

Efficient spraying to combat pests, and in particular thrips, is difficult in many ornamental crops. The thrips are located in the bud, at the bottom of the leaf or in the axil. During cultivation, thrips are moving through the crop. This is called vertical migration.

Thrips are in the youngest leaves at the beginning of the cultivation. So they are well protected. When the bud is developed, the majority of the thrips are no longer visible. When the buds appear, the thrips are suddenly back. This was demonstrated by the amount of thrips counted in the flowers that were cut into pieces.

Spray before bud formation
It is important to know that spraying (with an average penetration into the crop of a few decimeters) is not efficient at the time of bud formation. A few days before is much more efficient. ChrIP (evaluates research proposals and advises) and the National Commission Chrysanthemum LTO Glaskracht Netherlands have made budget available to Robur from De Lier to develop a slim nozzle that touches the underside of the leaves. At the bottom of the leaves are the thrips which you normally don't touch. A number of companies use this nozzle now, with positive results.

Source: LTO Nederland