PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Pest cycle
There is a gradual metamorphosis (egg,
nymph, adult) with many generations each year.
Blister mites in spring move from bud scales
to undersurfaces of emerging leaves. Males and
females multiply in the protection of the felty
areas during spring, summer and autumn. In late
autumn mites move back to buds for protection.
Damage begins at budswell in spring with the
first generation produced by the ‘overwintering’
female mites. Usually the first 3-5 leaves on the
cane are blistered and then the auxiliary leaves
are damaged by the next generation. All
remaining leaves on the developing canes will be
affected.
Bud mites. Similar life cycle except that mites
spend most of their life in buds.
‘Overwintering’
As non-feeding adults under outer bud scales in
dormant buds, also in cracks on canes and under
rough bark at bases of canes.
Spread
By mites crawling over a plant or crop (they
have limited ability to crawl).
By wind or on insects, birds, etc.
Infested canes, cuttings, nursery stock.
Conditions favoring
Warm moist weather, wet springs.
Management (IPM)
Are you a commercial grower or home gardener?
1.Obtain/prepare a plan that fits your situation..
Where mite damage is suspected, sampling and
identifying the mites is necessary to the
implementation of a successful control program.
2.Crop, region. Most states and viticulture
organizations have management plans for pests and
diseases of grapevines.
3.Identification. Mites can be found in dormant
buds but they can be difficult to find and
differentiate one from the other. Using a diagnostic
service if necessary (page xiv) confirm that the
problem is eriophyid mites. Misdiagnosis often leads
to inappropriate chemical applications which can have
a negative effect on mite predators.
4.Monitor mites and damage in areas of the vineyard
where mites have been a problem in previous seasons
and record results (page 39). Accurate monitoring
methods have been developed which involve washing
leaves and collecting mites and predators in a series of
fine mesh sieves.
Blister mite. Monitor at regular intervals before
making a decision to apply an insecticide, eg
examine 5 terminals of 6 widely spaced locations
throughout the grape crop.
Bud mites are found in greater numbers in the
basal 2-3 buds. Bud mite presence can be
determined in winter by examining dormant winter
buds for mite or ‘bubbling’ of the tissue inside the
outer bud scales using a dissecting microscope
(x30). Given that bud mites tend to infest basal buds
sampling should focus on these buds. Soon after
budburst at the leaf rosette stage bud mites may be
found in leaf axils and internodes of growing
shoots. Small newly-developing buds can contain
mites almost as soon as they begin to develop when
2-3 leaves are separated.
Fig. 127. Grapeleaf blister
mite (Colomerus vitis).
PhotoNSW Dept of Industry and
Investment (E.H.Zeck).
Enlarged about x70
1. Mites on undersurface of leaf;
note erinose development
Actual size
2. Undersurfaces of leaves
showing hairy development of
erinose condition caused by
the mites feeding; early
erinose is yellowish, old
erinose is reddish
3. Upper surface of leaf showing
blister-like formations caused
by the mites feeding below
Insects and allied pests - Mites (Arachnida, Acarina) 207