Supplementary feeding with Nutrimite™ helps control spider mite in cucumbers

25/08/2021 - Cucumbers, like all crops, experience variable pest pressures. Particularly during dry periods, pest numbers can suddenly increase dramatically. To be prepared, Biobest advisor Arno Hellemons advises growers maintain a 'standing army' of biological control agents in the crop at all times.

“For many cucumber growers, supplementary feeding is a good way to quickly building up robust populations of biologicals,” says Arno. “The use of Nutrimite™ has increased significantly in recent years. In the absence of pests, this feed supplement is sufficient for predatory mites to build up numbers in the crop, ready to intervene immediately when spider mite, thrips or whitefly enter the greenhouse."

Basic strategy

Biobest recommends growers blow Nutrimite™ into the crop immediately after introducing Swirskii-System and Montdorensis-System. Both predatory mites are effective against thrips and whitefly and exert some control of spider mites.

“This preventive army can then be strengthened with the addition of our Californicus-Breeding-System,” says Arno. “These sachets, which should be hung every 4-5 metres throughout the greenhouse, contain efficient spider mite predators that are gradually released into the crop.”

Extra introduction

For some cucumber crops this basic control strategy can be sufficient. However, for others Arno recommends further additions of Phytoseiulus-System and Feltiella-System.

"Phytoseiulus persimilis is a voracious predatory mite that develops at lightning speed,” he says. “It eats all stages of spider mite and can clear the cucumber crop of hot spots in a matter of days.”

“We also have good experiences with the gall midge Feltiella acarisuga. With this predator you simply remove the lid from the pot and place it in the crop. The highly mobile gall midges fly out and actively search for spider mites in the crop. The females deposit their eggs in the pest hot spots and the resulting larvae suck out the contents from their prey as soon as they hatch. The ultimate spider mite predator!”

Be prepared

Arno concludes that spider mites can reappear at any time. "Always be prepared,” he says. “Have a standing army ready and ensure you maintain a hygenic and tidy environment - the fewer weeds and crop residues the better - as less attractive to insect pests."

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