Six-spotted mite - pest of grapevines and avocados

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Six-spotted mite can defoliate grapevines and avocado trees in the lower South West of Western Australia.

Natural enemies tend to keep numbers in check, but occasionally chemical intervention may be required.

Origin

Six-spotted mite, Eotetranychus sexmaculatus (Riley), is native to the Americas and was first recorded in Western Australia in 1986 on avocado seedlings from eastern Australia.

In the same year and presumably from the same source, the mite was recorded for the first time on avocados in New South Wales, Queensland and South Australia. It also occurs in New Zealand.

Damage

The mite feeds primarily on the lower surface of leaves, concentrating its activity adjacent to leaf veins. During feeding, the mites penetrate leaves with their stylets and suck out the cell contents. This results in discolouration and death of leaf tissue.

Yellowing adjacent to leaf veins on underside of white grape variety by feeding of six-spotted mite

Feeding by six-spotted mite on white grape variety

Yellowing adjacent to leaf veins on upper side of white grape variety by feeding of six-spotted mite

Leaf feeding by six-spotted mite on white grape variety

Reddening of area adjacent to leaf veins on underside of red grape variety from feeding by six-spotted mite

Leaf feeding by six-spotted mite on red grape variety, underside of leaf

Reddening adjacent to leaf veins on upper side of red grape variety from feeding by six-spotted mite

Leaf feeding by six-spotted mite on red grape variety

Signs of feeding on white and red grape varieties are yellow or red shadows respectively, on either side of the veins and visible from both sides of leaves.

Purple discolouration adjacent to veins on underside of an avocado leaf by feeding of six-spotted mite

Feeding by six-spotted mite on underside of avocado leaf

Purple discolouration adjacent to veins on the upper side of an avocado leaf by feeding of six-spotted mite

Feeding by six-spotted mite on avocado leaf

On avocado, six-spotted mite feeding appears as purple discolouration next to leaf veins.

In citrus, primarily grapefruit but also oranges, feeding on the leaf stems and occasionally the fruit stems will cause the fruit to yellow and fall. Six-spotted mite on citrus has not been recorded in Western Australia.

Kiwifruit is also a host for six-spotted mite, but this has not been observed in Western Australia.

Near panel of grapevines defoliated by six-spotted mite with next panel protected with a miticide

Defoliation of grapevines by six-spotted mite next to protected vines

Heavy infestations result in severe defoliation. This results in delayed ripening or failure of grapes to ripen and reduced quality and yield of fruit.

Defoliation of avocado tree by six-spotted mite

Defoliation of avocado tree by six-spotted mite

Avocados are particularly susceptible to the mite and low numbers can defoliate trees, exposing fruit to sunburn.

Awareness of whether the mite is present is the first step in minimising its potential for damage.

Contact information

Stewart Learmonth
+61 (0)8 9777 0167
Page last updated: Wednesday, 1 June 2016 - 2:37pm