Managing Mites in Ontario apple orchards
Growers following a resistance management program for mites should use early season oil sprays to reduce mite populations in the spring. Avoid using insecticides such as pyrethroids that are harmful to beneficial mites or disruptive to phytophagous mites in orchards. Research has also suggested that the application of more than 4 sprays of Assail per year may also be disruptive to mite populations. Miticides should only be applied when thresholds have been reached: (see Pub 360: Fruit Production Recommendations for Ontario). Early season oil sprays are recommended to suppress overwintering European red mite and improve the potential for natural enemies to keep pest numbers below damaging levels. Ideally, no more than one miticide should be used each year. If a miticide is needed two years in a row, it is important to use a product from a different chemical family. While many of the new products work exceptionally well, and have been touted as being less prone to the development of resistance-don't take a chance on applying them two years in a row. The economic repercussions of the development of miticide resistance are much greater than the benefits any miticide. Pree et al. (2005) determined that populations of ERM that were highly resistant to Apollo (>2000-fold), also exhibited low level resistance (4.2-fold) to a new miticide Zeal (etoxazole) which is not even registered here in Canada. This research stresses the importance of using miticides responsibly today, to optimize the efficacy of new miticides that will be registered in the future.
Tips on using miticides effectively
The miticide programs listed below suggest potential timings for the application of new miticides that are registered in apple. Only one miticide should be applied per season, in orchards where populations are above thresholds.
Do not apply any miticide more than once per season. Envidor also controls apple rust mite. All of the above products will also provide subsequent control of two spotted spider mites (except superior oil), but be sure to check label for the appropriate rate. Envidor has slow activity and results may not be apparent for up to 1 week.
Both of the new miticides (Acramite® and Envidor®) should be applied at the low end of economic thresholds.
Do not apply any miticide more than once per season. Note: Acramite is more efficacious on TSSM than on ERM, and Pyramite is more efficacious on ERM than on TSSM: Be aware of differences in label rates for different mites.
ReferenceD.J. Pree, K.J. Whitty and L. Van driel. 2005. Baseline susceptibility and cross resistances of some new acaricides in the European red mite, Panonychus ulmi. Experimental and Applied Acarology.37: 165-171.
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