HONEYSUCKLE WITCHES` BROOM APHID

PEST DIAGNOSTIC CLINIC
Laboratory Services Division, University of Guelph
95 Stone Rd. West, Guelph, Ontario N1H 8J7
Phone: (519) 767-6299
E-mail: [email protected]
Web: www.guelphlabservices.com
HONEYSUCKLE WITCHES' BROOM APHID
During the past several years, an aphid has caused injury to honeysuckle, Lonicera spp., in
Ontario. This aphid, Hyadaphis tataricae, is of Asian origin, and was likely imported into
Canada on infested Lonicera from Europe.
Honeysuckle aphids are small (less than 2 mm), pale green to cream coloured, and covered
with a powdery, waxy material. They feed in colonies of up to several hundred individuals on
the tips of Lonicera branches. As a response to honeysuckle aphid feeding, growth of the new
shoots is slowed considerably. In addition, numerous buds are produced in the axils of leaves
and branches, which develop into shoots causing a broom-like effect on the tips of the branches
called witches' brooming. Leaves in these witches' brooms are curled and dwarfed, and as the
season progresses, they droop and eventually die. The witches' brooms caused by the aphids
are obvious and unsightly, and are easily seen from a distance, especially in winter and early
spring when most of the leaves have fallen.
The entire life cycle of this aphid is completed on honeysuckle, which is the only known host.
The aphids overwinter as eggs on infested branch tips, which hatch in early spring as the
honeysuckle buds are swelling and beginning to grow. Young aphids feed on the mid-rib of the
leaves, causing the infested leaf to fold upwards, enclosing the aphids in a pouch where they
continue to feed. Initially the aphids are wingless; however, winged individuals may be found by
the 3rd generation. Winged aphids disperse continuously throughout the remainder of the
summer. The honeysuckle aphid reproduces throughout the summer by bearing live young.
Egg laying female aphids begin to develop in late August and lay eggs from September to the
end of the growing season, on honeysuckle branches.
Honeysuckle has long been regarded a low maintenance plant, requiring very little in the way of
pest control. However, these aphids can cause severe injury to the shrubs beginning with
stunting and growth deformation in the early stages of infestation, and ending with the eventual
death of the plant should the infestation go unchecked. Approximately 3 years are required
from the onset of infestation for the shrub to be entirely infested.
CONTROL
1.
Lonicera spp. and varieties differ widely in their tolerance to these aphids. If you are
contemplating using Lonicera as a landscape species, do not choose varieties that are
susceptible to the aphid. If susceptible varieties are severely damaged in the landscape,
consider replacing them with those that are resistant. Often botanical gardens and
arboreta will have collections of these shrubs for viewing their various horticultural
characteristics.
The following list is adapted from published literature and from observations at the University of
Guelph Arboretum:
Resistant
Lonicera caerulea
* L. caerulea edulis
Tolerant
L. ledebourii
L. maackii
Susceptible
L. x amoena
L. x bella "Dropmore"
PDCF-111 (Revised 2012-06-25)
Resistant
L. caerulea dependens
L. caerulea viridifolia
L. tatarica "Morden Orange"
* L. heteroloba
* L. altmannii
Tolerant
L. maximowiczii
L. minutiflora
L. x meundeniensis xanthocarpa
L. orientalis
L. syringantha
L. discolor
L. morrowii
L. syringantha "Grandiflora"
L. tatarica "Arnold Red"
"Rubra"
"Beavermor"
L. x salicifolia
L. tatarinovii
L. xylosteum
* L. standishii
L. ruprechtiana
* L. chrysantha
Susceptible
L. korolkowii "Zabelii"
L. microphylla
L. myrtilloides
L. x notha
L. tatarica "Grandiflora"
"Rosea"
"Bytown"
"Hack's Red"
"Red Giant"
* Exceptional species in appearance, which are recommended as substitutes for susceptible
Lonicera.
2.
In order to remove the eggs, which are overwintering on the shrubs, prune out the
infested branches well below the witches' broom present on the terminal from the
previous year. This must be done before the buds begin to break.
3.
In order to kill aphid eggs remaining on the plant after pruning, a dormant oil application
should be made before the buds break in early spring.
4.
After bud break, to protect young foliage from winged aphids, which can migrate to noninfested bushes, it may be wise to use chemical products. Please contact a local garden
centre for product advice. You may also wish to visit the Ontario Ministry of Agriculture
Food and Rural Affairs “Online Gardener’s Handbook”
http://www.omafra.gov.on.ca/english/crops/gardbk/ghlinks.htm.
** Special thanks to Henry Kock for his observations at the University of Guelph Arboretum.
R.T. Wukasch
PDCF-111 (Revised 2012-06-25)