Journal of the Department of Agriculture, Journal of the Department of Agriculture, Western Australia, Series 4 Western Australia, Series 4
Volume 41
Number 1 Journal of Agriculture, 1999/2000 Article 17
2000
Weevil management in orchards and vineyards looks promising Weevil management in orchards and vineyards looks promising
Stewart Learmonth
[email protected]
Follow this and additional works at: https://library.dpird.wa.gov.au/journal_agriculture4 Part of the Entomology Commons, and the Viticulture and Oenology Commons
Recommended Citation Recommended Citation
Learmonth, Stewart (2000) "Weevil management in orchards and vineyards looks promising," Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 41: No. 1, Article 17.
Available at: https://library.dpird.wa.gov.au/journal_agriculture4/vol41/iss1/17
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WEEVIL MANAGEMENT IN ORCHARDS AND VINEYARDS LOOKS PROMISING
rcti and m o n i t o r i n g undertaken b y Agriculture Western Australia is s h o w i n g that the
*ement of weevils in Western Australia's orchard crops and vineyards is improving. A n u m b e r of alternative m a n a g e m e n t strategies are being implemented, and future research will assess t h e effectiveness of n o n - c h e m i c a l approaches t o weevil management. Stewart Learmonth reports.
Weevil damage
A p p l e weevil, garden weevil and Fuller's rose weevil have affected t h e quality a n d health of t h e State's orchard crops and vineyards since b e i n g accidentally i n t r o d u c e d t o W e s t e r n Australia.
B o t h adults and larvae damage fruit trees and grapevines. A d u l t s of all weevils can defoliate c r o p s . Apple weevil adults can also ringbark stems of y o u n g trees - killing the g r o w i n g tip.
I n addition, they can ringbark fruit pedicels, w h i c h results in cosmetic damage, reduced fruit size and fruit fall.
Weevils also chew fruit. G a r d e n weevil adults voraciously attack a n y y o u n g part of a fruit tree o r vine, w h i c h can kill g r o w i n g tips, grape b u n c h e s , y o u n g apples and nectarines, as well as scar fruit.
Fuller's rose weevil adults can cause havoc t o irrigation systems b y laying egg masses in mini-sprinklers and d r i p p e r s .
Weevil larvae are soil-borne and feed o n the r o o t s of ground-floor plants found in orchards and vineyards. T h e y also feed on the r o o t s of fruit trees and grapevines, which can result in the death of y o u n g plants or the loss of vigour in m a t u r e plants.
A range of weevils occur in orchards and vineyards - from left - apple weevil, garden weevil, whitefringed weevil (minor pest), Fuller's rose weevil (minor pest in vineyards), vegetable weevil (non-pest).
(Above top) Weevil larvae - from left - apple
weevil/garden weevil, whitefringed weevil (minor pest), Fuller's rose weevil (minor pest in vineyards), vegetable weevil (non-pest), cockchafer (non-pest). (Above bottom)
Garden weevils can scar fruit on vines and fruit trees, as can be seen here in grapes (far left), nectarines (middle) and apples (near left).
The laying of egg masses in mini- sprinklers and drippers by Fuller's rose weevils (seen here at the top of the sprinkler) can affect the spray pattern.
(Above left)
Butt-drenching works as an effective chemical option for weevil control. This auto butt-drenching machine was specially built. (Above right)
Progress o n weevil m a n a g e m e n t
Chemical control
Synthetic p y r e t h r o i d insecticides are registered for weevil c o n t r o l b y b u t t - d r e n c h i n g , w h i c h means a p p l y i n g a coarse jet of insecticide solution i n t o t h e c r o t c h and b u t t of trees o r vines. F o r grapevines and avocados, there is also foliar s p r a y i n g , a n d for o r c h a r d s w h e r e Fuller's rose weevil is a pest, t h e r e is foliar spraying w i t h a z i n p h o s methyl and carbaryl.
B u t t - d r e n c h i n g is l a b o u r - i n t e n s i v e a n d requires m o n i t o r i n g t o get t h e timing right.
A g r i c u l t u r e W e s t e r n A u s t r a l i a has b e e n c o n d u c t i n g r e s e a r c h t o find a l t e r n a t i v e , effective a n d less labour-intensive m e t h o d s . Ground-floor food sources
A n a l t e r n a t i v e m a n a g e m e n t s t r a t e g y t o c h e m i c a l c o n t r o l has b e e n t o eliminate alternative food sources for weevil larvae.
O b s e r v a t i o n and s u p p o r t i n g research defined s o m e of t h e g r o u n d - f l o o r plants that w e r e favourable, and r e c o m m e n d e d that weeds such as s o r r e l , c a p e w e e d , d a n d e l i o n , s o u r s o b , plantago and d o c k be r e m o v e d (see Figure 1).
P o t trials indicated that clovers w e r e p o o r food plants for weevil larvae and m a y in fact help r e d u c e weevil n u m b e r s . H o w e v e r , m o r e research o n undesirable food plants will be required before r e c o m m e n d a t i o n s can be m a d e o n the m o s t effective g r o u n d covers for weevil m a n a g e m e n t .
Figure 1 - The survival and growth of garden weevil larvae after being placed for nine weeks in pots sown to sorrel, canola, oats, carrot and
subterranean clover: (a) per cent survival, (b) average dry weight in milligrams and (c) average head capsule width in millimetres.
Sticky bands
I n S o u t h Africa, t h e h o m e of t h e garden weevil, sticky bands on t h e b u t t s of trees and vines are used t o prevent weevils from accessing crop canopies. A tablegrape g r o w e r in Western Australia has a d o p t e d this m e t h o d successfully.
W h i l e labour-intensive, sticky b a n d s avoid t h e n e e d t o use b r o a d - s p e c t r u m insecticides.
Unfortunately, t h e b a n d s have n o t been so effective in controlling the o t h e r major fruit tree pest, apple weevil. F o r this pest, the sticky b a n d s have b e e n f o u n d t o delay, b u t n o t prevent weevils from accessing canopies.
Birds
Research at Agriculture Western Australia's Stoneville Research Station o n garden weevil in an apple orchard s h o w e d that birds could reduce pest n u m b e r s and damage t o fruit (see F i g u r e 2). A n u m b e r of grape g r o w e r s in the
TURKEYS
20-Nov 4-Dec 18-Dec 30-Dec 31-Jan 6-Mar 14-Apr 20-May 19-Jun
! Exclusion DOpen
r^—i
20-Nov 4-Dec 18-Dec 30-Dec 31-Jan 6-Mar 14-Apr 20-May 19-Jun
Q Exclusion D Open CHICKENS
20-Nov 4-Dec 18-Dec 30-Dec 31-Jan 6-Mar 14-Apr 20-May 19-Jun
B Exclusion DOpen
Figure 2 - The abundance of garden weevil adults in trunk-monitoring bands on trees either excluded from birds by cages or uncaged (open) in an orchard stocked with turkeys, chickens or guinea fowl in separate partitions; at Stoneville Research Station, Perth Hills, 1996-97 season.
M a n j i m u p area have fox-proofed their vineyards, and stocked them with birds such as guinea fowl, bantams, chickens and turkeys.
M o b i l e cages and cages with self-opening d o o r s are just some of the innovations being developed to make the use of birds easier.
Sprinkler types
T h e blocking of mini-sprinklers b y egg-laying Fuller's rose weevil was examined in a trial w h i c h c o m p a r e d m o s t c o m m o n t y p e s of sprinklers. It was found that only sprinklers w i t h certain features w e r e susceptible and should not be used in infested orchards.
Sticky bands (seen here at the base of the tree) effectively prevent garden weevils from accessing canopies. (Left)
Prospects for weevil management
New initiatives in a recently completed national project, supported by the Horticultural Research and Development Corporation ( H R D C ) , provide hope for reduced reliance on insecticides.
The main approaches to be pursued in the new HRDC-supported project involve the use of a new strain of insect-parasitic nematodes. This new strain, referred to as JB1/X1, has been shown to be very effective in laboratory pot trials (see Figure 3). Further, in demonstration trials in weevil-infested horticultural crops in Manjimup in the 1999-2000 season, infection of weevil larvae was observed. Future trials will involve better methods of nematode application, in combination with manipulating the plant composition of the ground cover.
Other activities to improve weevil management will involve alternative approaches to insecticide use. This will include examining the application methods of insectigation, and dripline drenching by orchard sprayers.
Biology studies on apple weevil show they do not lay eggs until some considerable time after
Figure 3 - Mortality of garden weevil larvae exposed to three strains of entomopathogenic nematodes at a range of doses (IJs/ml) in a laboratory bioassay by R. Bedding, CSIRO, Canberra, ACT.
emergence. Therefore, a second application of insecticide in late summer, to control apple weevil adults before they lay eggs, will be examined to determine if longer-term pest suppression can be achieved.
Much effort has also been undertaken in the area of baits to kill weevil adults at the time of emergence. N o effective bait has been identified as yet, but work in the United States on a similar weevil has had some success using baits, and will be used to further this aspect of weevil management in Western Australia.
