Integrated control of apple pests in New Zealand 16. Progress with integrated control of European red mite

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Abstract
Studies were made in an orchard near Nelson from 1974-1978 on integrated control of Panonychus ulmi (Koch) using the organophosphate-resistant predator Typhlodromus pyri Scheuten. Correct timing of selective acaricides druing the Oct.-Jan. period is essential and can be achieved by close observation of P. ulmi development. When the majority of winter eggs have hatched (late Oct. to early Nov.) or the majority of the summer eggs laid by the 1st generation (very late Nov. to early or mid Dec.), there is a short period when a maximum of immature mites occurs. This is before many adult females have matured, and is the most effective time for application of an acaricide such as cyhexatin. The development of P. ulmi, particularly the incubation period of the summer eggs, is controlled by temperature, and in seasons when mean temperatures are well below average in Nov. and Dec. the delayed mite development makes accurate timing of the Dec. spray more difficult. Other factors which also affect mite development are the use of dormant oil, cultivar and orchard aspect and shelter. On the block of trees where no acaricides were used since 1968, although regular applications of azinphos-methyl were made, T. pyri maintained P. ulmi at acceptable levels over the 5 yr from 1973-1978, a maximum of P. ulmi occurring each season in Jan. with the 3rd generation. In 3 seasons the peak was well below the threshold for commercial spraying; in 2 seasons this threshold was exceeded, but despite the absence of acaricides P. ulmi numbers fell. An experiment demonstrated the utility of mineral oil and cyhexatin as selective acaricides in integrated programs. Cycloprate, tricyclotin and fenbutatin oxide were effective and selective as cyhexatin, a single application in early Dec. giving good survival of T. pyri and season-long control of P. ulmi. In another experiment propargite was as effective and selective as cyhexatin; amitraz was more toxic to T. pyri and less persistent against P. ulmi, and resulted in a poor P. ulmi:T. pyri ratio; and chlorpyrifos, though not more toxic than cyhexatin to T. pyri, was less effective against P. ulmi. Mancozeb and dinocap plus mancozeb, used in a summer-long program of 12 treatments were more toxic to T. pyri than were binapacryl or dinocap alone.