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Flaring mites

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There have been reports of mites in the Liverpool Plains region particularly as corn has matured and dried off. Green crops of cotton, soybean, canola, lucerne, sorghum, mungbeans, navy beans and adzuki beans are at risk of invasion by these mites.

The mite in question is the Two spotted mite, Tetranychus urticae, which is the same species as the red spider mite. The two spotted mite is the summer form (pale green with two dark spots) and the red or orange form is the end of season, overwintering form.

Any early season, injudicious use of hard chemistry is likely to lead to flaring of mite populations due to the disruption to complexes of beneficial insects and therefore natural control.

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Specifically in beans (mung, adzuki, soy) as well as sorghum, control of Helicoverpa can be achieved in the pre-flowering stages with the virus biopesticides – Gemstar and Vivus Max. These will target only Helicoverpa (the virus works effectively on caterpillars less than 7mm in length and therefore early detection is essential). Other relatively soft-options for use in the flowering stage of bean crops include Indoxacarb (Steward) for Helicoverpa, Soy loopers and mirids. These products will preserve beneficial activity and save costs in the long run.

Hopefully, if IPM guidelines are followed in the early part of the season mite control will not be necessary until later on (if at all). Options for controlling mites are limited to Dimethoate, which resistance problems are known to occur with.

Importantly, it is not necessary to spray for pod-sucking pests in beans until the pod-sucking stage. Doing so will only flare mites and increase opportunities for the development of resistance in target pests.

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