mealybug control with insecticides

N E W Z E A L A N D W I N E G R O W E R S FA C T S H E E T
MEALYBUG CONTROL
WITH INSECTICIDES
KEY NOTES
• Mealybugs transmit Grapevine Leafroll-associated Virus Type 3
(GLRaV-3).
• Specific insecticides are the most effective way to control this pest.
• Mealybugs live in hard-to-spray areas of vines so good insecticide
coverage is crucial.
Citrophilus mealybugs on the underside of a grape leaf.
• Apply insecticides early in season when mealybug populations
are low and before the full vine canopy has developed.
• Follow label rates of insecticide and do not apply less than the
recommended amount per hectare.
MEALYBUG MANAGEMENT
Mealybugs overwinter under loose bark or in cracks and crevices
of trunks and cordons, and on the roots of grapevines. In spring,
newly hatched crawlers move onto young shoots where they settle
on the underside of leaves before moving into bunches. All these
areas can be difficult to spray.
An extremely high level of mealybug control is needed where
Grapevine Leafroll-associated Virus Type 3 (GLRaV) occurs.
Insecticides should be applied early in the season for optimum pest
control and better spray coverage.
Water-sensitive paper showing a pattern of good
spray coverage.
Budburst is the best time to achieve high spray coverage by
thoroughly wetting the whole vine wood surface, especially trunks
and cordons and around the buds. At this time, pest numbers are
low, which provides greater opportunity for control.
Later in spring, when the canopy has partially developed, you have
another opportunity to achieve good spray coverage of all vine parts
and kill a high proportion of the mealybug population. By summer,
when the canopy is well developed and dense, it is very difficult to
achieve thorough spray coverage, especially to the underside of
leaves (where most mealybugs live) and inside bunches.
Good spray coverage is crucial for effective control of this pest.
The performance of sprayers can vary widely: even having a
properly calibrated machine does not automatically mean that the
insecticide will be sprayed where it needs to go. Water-sensitive
papers (placed in strategic positions) are an excellent tool to show
how well the machine applies spray to different parts of the vine.
The sprayer set up will need adjusting during the season as the
canopy develops and perhaps between different grape varieties
and training systems.
OCTOBER 2009 | NZVE104 | VIRUS ELIMINATION PROJECT
NOTE: It’s also worth using a selective herbicide to remove
alternative mealybug host plants, such as broadleaf weeds, from
the inter-row area.
N E W Z E A L A N D W I N E G R O W E R S FA C T S H E E T
INSECTICIDE RECOMMENDATIONS
Start the season with a Tokuthion and oil application at budburst.
Ensure that the bark is thoroughly wetted. Use a hand lance
to maximise deposits on the cordon and trunks. For machine
applications, the use of high spray volumes with recapture and
reuse of overspray that misses the target is a practical way to
ensure good coverage and minimise the contamination of the
environment with the spray chemical.
Water-sensitive paper showing poor spray coverage.
Follow this spray with two applications of buprofezin (trade
names Applaud, Buprimax, Mortar, Ovation, and Pilan), the
first midway between budburst and flowering, and the second
immediately before flowering at the cut-off date for the use of this
insecticide. Buprofezin disrupts development during the moulting
of immature
mealybugs, so it will be most effective once all the
eggs from overwintering females have hatched. If you decide on a
single application, then leave it as late as possible before the start
of flowering.
Broad-spectrum insecticides (organophosphates and carbamates)
are an alternative to buprofezin after budburst, but they are not
recommended under the Sustainable Winegrowing New Zealand
programme. If you are considering their use, contact the SWNZ
national co-ordinator for approval.
OTHER SOURCES ON THE WEB
Follow the instructions on the product label and do not use
a product rate less than the minimum recommended by the
manufacturer. Ensure you have thorough spray coverage using
water sensitive papers as a guide to the appropriate water rate for
your particular situation. Once you have decided on the water rate
you are going to use you must adjust the insecticide concentration
to maintain the correct amount of insecticide per hectare – this is
important. Do not compromise mealybug control by applying too
little insecticide in too little water. For example, if the label says to
use 100 g of product in 1000 L/ha of water (i.e., 10 g/100 L) and you
want to apply 500 L/ha, then the insecticide concentration needs to
be doubled (i.e., 20 g/100 L).
• New Zealand Winegrowers
www.nzwine.com/reports/
ACKNOWLEDGMENT
• Marlborough Wine Research Centre
www.wineresearch.org.nz
This fact sheet was written with the assistance of
Plant & Food Research.
• Plant & Food Research
www.plantandfood.co.nz
• Foundation Plant Services (UCD)
http://fpms.ucdavis.edu/
• The Australian & New Zealand Grapegrower
& Winemaker www.winebiz.com.au
DISCLAIMER While care has been used in compiling this fact sheet neither
New Zealand Winegrowers nor Plant & Food Research give any prediction,
warranty or assurance in relation to the accuracy of or fitness for any particular
purpose, use or application of any information contained in this document.
To the full extent permitted by law neither New Zealand Winegrowers nor
Plant & Food Research, nor any of their employees, shall be liable for any cost
(including legal costs), claim, liability, loss, damage, injury or the like, which may
be suffered or incurred as a direct or indirect result of the reliance by any person
on any information contained in this document.
© New Zealand Winegrowers 2009. All Rights Reserved.
Contact:
New Zealand Winegrowers
www.nzwine.com Telephone 09 303 3527
OCTOBER 2009 | NZVE104 | VIRUS ELIMINATION PROJECT
Co-funded by: