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Let’s talk mites

bumpy leaf

By Scott Mathew, Syngenta Solutions Development Manager

There are a number of key pests and diseases we need to consider at this stage of the season. Too often we wait until we see the damage from these pests and diseases before taking action. This is often too late to achieve acceptable control and often more expensive that tackling the problem early.

Many grape growers are generally unlikely to experience mite problems, but problems can arise from time-to-time. Mite problems can be made worse by the use of some commonly used insecticides and fungicides that can harm predatory mites and other natural enemies of pest mites.

Bud mite (and blister mite) are two strains of a mites which only occur on grapevines. They are almost identical except for the damage they cause by their feeding activities–bud mites feed on and damage young buds before budburst, and blister mites cause galling on leaves. A spray of sulphur (e.g. THIOVIT JET® at 600 g/100 L) within 1 to 2 weeks after 100% budburst should provide effective control of bud mite. THIOVIT JET should be timed immediately after 100% budburst when thorough coverage can be achieved. That is the earliest time that bud mites, which have over-wintered inside the grape buds, are vulnerable to treatment.

If rust mite activity was observed in the previous season, such as significant leaf bronzing in the late summer/autumn, control measures for rust mite may be required prior to budburst in the upcoming season. Research indicates that, in order to control rust mite, growers have only a small window to target this pest. Rust mites are most vulnerable during migration from their sheltered, over-wintering sites and before leaf expansion provides them with shelter from sprays and before they can lay their eggs. To get the most out of your spray, THIOVIT JET must be applied in a way that thoroughly wets the bark of the vine crown and canes.

Sulphur sprays offer excellent control of many mites. THIOVIT JET generally works by inducing respiratory problems in the mite, suffocating them. This makes it essential to achieve excellent coverage in order to limit the number of areas on the treated grapevine where mites can move in order to protect themselves from the sulphur residue.

Always remember to seek professional advice for your specific situation.