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Preventive and curative spider mite control in strawberry and raspberry crops

30/08/2021 - Spider mites are a very commonly occurring pest in raspberries and strawberries. As such, Biobest advises growers to be well prepared with preventive introductions of predatory mites, among other things.

The predatory mite Amblyseius californicus is supplied in the form of loose material (Californicus-System) or in sachets (Californicus-Breeding-System). Growers can introduce both from the beginning to the end of the season.

According to Biobest Advisor, Gaby van Kemenade, Californicus-Breeding-System benefits from the fact the sachets contain food, supporting the gradual development of the predatory mites and their release into the crop in phases. “This means they protect the crop for a minimum of 6 weeks,” she says. “It is best to hang the sachets every 2 metres throughout the crop using the handy hooks.”

Preventive

Both Californicus-System and Californicus-Breeding-System can provide good preventive barriers against spider mites. “This predatory mite can even survive on pollen in the absence of prey,” says Gaby. “So, there is always an army of pest controllers standing at the ready. Should the number of insect pests unexpectedly ‘explode’, we advise supplementing the pest control with Phytoseiulus-System.”

Supplemental pest control

Phytoseiulus will effectively handle the pest hot spots. This predatory mite eats only spider mites and has a striking red colour. If sufficient pests are present, it can build up a large population and very quickly suppress the spider mites. We recommend a dose rate of 15 to 20 predatory mites per running metre. If needed, growers can introduce extra Phytoseiulus-System later on.”

Introduce mites as soon as possible

“When the predatory mites arrive, we advise growers to distribute them throughout the crop as soon as possible. This guarantees maximum efficiency. If this is not possible, we advise storing them temporarily at the temperature stated on the packaging.”

She goes on to explain that storage of the bottles is also important. “They are best stored in a horizontal position,” says Gaby. “Before distributing in the crop, it is good idea to gently roll the bottle horizontally for approximately 1 minute, to ensure a homogeneous distribution of the predatory mites.

“For the mites supplied in loose material, we recommend distributing them as uniformly as possible in the crop. If there are places where many spider mites have been found, hot spots, the grower can sprinkle extra predatory mites in those areas,” she says.

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