PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Management (contd)
5.Thresholds. Have any thresholds been
established? If so, what are they, eg economic,
aesthetic? How much damage can you accept?
Blister mite. Control for Waltham Cross is
required if any blistering (or cane malformations)
occurs on 5% of young spring growth.
6.Action/Control. Take appropriate action when any
threshold is reached. Research tentatively indicates
that most effective management for bud mite may be
the protection and/or introduction of mite predators.
The preferred pesticide treatment for blister mite is
a dormant spray of lime sulphur after pruning and
before budswell. After vines have broken into leaf
control is more difficult.
7.Evaluation. Review IPM program to see how
well it worked. Recommend improvements if
required. Monitor trees after treatment during growing
season. Next year spray lime sulphur before leaf buds
burst if records indicate a need.
Control methods
Mild infestations do not affect yield.
Sanitation. Where only a few shoots or leaves
are affected, these may be pruned out when they
appear during the growing season.
Biological control.
Natural controls include predatory mites,
thrips, hover fly larvae and lacewings.
Predatory mite (Galendromus occidentalis)
feeds on bud mites inside buds in early spring.
Introduction and protection of predatory mites
from harmful chemicals may be the best
treatment option for bud mite in the future.
For purchase. A general mite predator (Euseius
victoriensis) is available for control of eriophyid
mites (rust mites, bud mites) and broad mites in
vines and citrus.
List of suppliers www.goodbugs.org.au
Resistant varieties. Muscats are generally
regarded as being particularly susceptible.
Blister mite form. More susceptible
varieties include European varieties (Vitis
vinifera), Gordo Blanco, Black Hamburg, Black
Muscat, White Shiraz and Rutherglen Tokay. It
also occurs on Zante currant. More resistant
varieties include American varieties (Vitis
labrusca), Isabella and Golden Muscat and the
European variety, Sultana. Currants and sultanas
(rarely attacked) are relatively resistant.
Bud mite form appears to be present on most
varieties but seems to do no harm except on
Ohanez and Waltham Cross.
Pest-tested planting materials.
Do not introduce mites on cuttings.
Only plant mite-free cuttings.
Miticides.
Viticulture Spray Guides are available.
Blister mites. See Table 43 below.
Bud mites.
– Bud mites are protected inside the buds and not
accessible to sprays except for a very short time
when they begin to move into newly developing
buds at the base of new leaves. This is when the
first new leaves of new shoots are unfolding.
– Preliminary work suggests that bud mites might
only be vulnerable to sprays when 2-3 leaves
are separated, just before most mites have moved
into the newly-developing buds in the leaf axils
when they become inaccessible. The length of the
spray window is not yet clear. Where mites are a
problem spray at budswell the following season.
Control may be required during summer. Omit
sprays harmful to predators.
– Recent research in Victoria has shown that lime
sulphur applied with a knapsack sprayer at woolly
bud stage had no impact on bud mite numbers, nor
did wettable sulphur at budburst or greening.
Table 43. Grapeleaf blister mite – Some miticides.
What to use?
DORMANT SPRAYS
Group M2 (fungicides), eg Lime sulphur (sulphur
polysulphides). Just before bud burst.
Spray oils, eg Winter Dormant Oil, Winter Spray Oil,
Stifle Dormant Spray Oil (petroleum oil)
Apply mid-winter after pruning to ensure vines
are fully dormant.
GROWING SEASON SPRAYS
Group M2 (fungicides), eg wettable sulphur
formulations (during budburst/growing session)
Group 1A (insecticide), eg carbaryl (stimulates egg
production in spruce spider mites but is
generally very effective against eriophyid
mites)
Group UN (insecticide), eg Kelthane (dicofol)
FUNGICIDE SPRAYS
Group M3 (fungicides), eg thiram, ziram, zineb - note
they are not registered for grapeleaf
blister mite
When and how to apply?
Mites ‘overwinter’ under bud scales.
Where severe mite injury has occurred the previous
season, lime sulphur may be applied after pruning and
just before budswell during the dormant season (as close
to budswell as possible). This will give complete control
during the following growing season. Thorough spraying
is essential.
Lime sulphur can stain trellises etc. Do not use after new
leaves have appeared.
Do not apply sulphur if temperature is >30 o C (on some
crops not if >24 o C), or within 1 month of an oil spray.
Control is more difficult to achieve during the growing
season. These sprays will not eliminate existing damage
but will help to prevent further damage.
Check label for precise timing, eg when shoots are about
7 cm long.
During summer build up of mites is checked by sulphur
sprays for powdery mildew.
Do not use any sulphur if > 30 o C (also see above).
These protectant fungicides used to control certain
fungal diseases during late spring and autumn have given
some protection against blister mites.
208 Insects and allied pests – Mites (Arachnida, Acarina)