Control of the two-spotted spider mite (Tetranychus urticae Koch) in glasshouse roses.
Populations of the two-spotted spider mite, Tetranychus urticae, can increase rapidly in glasshouse production, especially during summer. Both chemical and biological control must start at low densities for effective control. The combined efficacy of Phytoseiulus persimilis and the predatory midge, Feltiella acarisuga to control T. urticae on roses was evaluated in 2002. A second year rose crop (Rosa hybrida cv. First Red) was used for this experiment. Two glasshouse compartments of 200 m2 each were used, one was assigned for integrated control and the other for chemical control. The mite populations were monitored by bi-weekly analysis of 12 randomly selected harvestable flower stems, extracted on the Berlese funnel. Sticky plates (3 yellow and 3 blue/200 m2) were used for monitoring the Feltiella adults. End of January a population of +/- 2 spider mites/flower was present in both compartments. In the integrated control, the first Phytoseiulus were released on February the 7th, while the first release of Feltiella was on February the 20th. From week 7 till 13 the population of T. urticae increased exponentially to 90 spider mites/flower stem, while Phytoseiulus population was below one/flower stem. A treatment of fenbutatinoxide + hexythiazox (Torque + Nissuron) was necessary to reduce the spider mite population. A maximum number of predatory mite (4/flower stem) and predatory midge (106 adults/sticky plate) was found only 4 weeks later. A second increase of spider mite population occurred in week 27. Although 2 weeks later 3 predatory mites/flower stem were present, additional chemical treatment was necessary to control. A third and last increase of spider mite occurred in week 39. This last raise could be controlled effectively by Phytoseiulus and Feltiella. Chemical control in the second compartment was effective all-year-round with the exception of week 23 when a major increase up to 60 spider mites/flower stem was found. The applied biocontrol agents could not efficiently control spider mite in glasshouse rose. However, combined with selective insecticides they offer possibilities for IPM in glasshouse roses.
Blindeman
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Research Centre for Omamental Plants, Schaessestraat, 18, 9070 Destelbergen. liesbet.blindeman@pcsierteelt.be
Van Labeke
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MC
D000053:Acari; D000818:Animals; D007306:Insecticides; D008925:Mites / Q000472:pathogenicity*; D010572:Pest Control, Biological / Q000379:methods*; D011235:Predatory Behavior; D027826:Rosa / Q000254:growth & development / Q000469:parasitology*; D013997:Time Factors
D007306:Insecticides