The programs that follow are general
guidelines that have been used with success in ornamental nurseries in Canada.
An IPM program must be custom designed for each different crop and greenhouse
or nursery situation. This should be done initially before purchasing the
biocontrol products and then in consultation with the biocontrol producer,
supplier or IPM advisor. Regular monitoring using sticky traps or other
monitoring devices is necessary in any IPM program to provide accurate updates
on both pests and native biocontrol. Integrated pest management using
biological control requires a knowledge of
pest life cycles and threshold levels and modification of spray programs
to avoid harm to the biocontrol agent. The rewards of using biological control
in IPM programs are better pest control, healthier plants, lower costs, lower
pesticide inventories, reduced health and environmental hazards and happier
employees.
Fungus Gnats (Bradysia sp.)
Root damage by fungus gnats can
spread disease to healthy roots and if common can cause losses of 20-40% of
plants in early propagation stages. In greenhouses, excellent preventive
control of fungus gnats can be obtained with early applications of the
predatory mite Hypoaspis miles. This predator also feeds on spring tails,
thrips, root mealybug mites and other small soil organisms. If fungus gnats are
established on the crop and appearing in high numbers, beneficial nematodes or
the new fungus gnat strain of Bacillus
thuringiensis (BtI) may be applied for control of the larval stages.
Improve drainage and avoid over watering to limit algal growth and sites for
fungus gnat and shore fly breeding. Bleach solutions can be used to help
control algae.
Monitoring tips
Monitor plants for adult fungus
gnats weekly using 1 yellow sticky trap per every 500 square meters. If adult
fungus gnat counts are above 20/trap/week, treat area with parasitic nematodes
or fungus gnat Bt formulations using the recommended rates. Repeat these
treatments weekly until the adult fungus gnat numbers are below 20/plant. This
treatment will not harm other biocontrol agents.
Treatment
Hypoaspis is most effective when applied before
fungus gnat population become established or while numbers are still low. One application of Hypoaspis per crop cycle is usually sufficient, if used early in
the season.
1. Soil Culture – Apply 1 L(15,000)/100 m2
(1000 ft2) to the soil at the time of planting. Be sure to treat
wet, exposed areas of soil, where fungus gnats are likely to breed. Mites can
also be applied to propagation media before striking cuttings.
2. Pot Culture
– Apply 1 L(15,000)/ 100 m2 (1000 ft2) of bench
area. Treat the floor of the greenhouse
if it provides conditions for fungus gnats to breed and occasionally treat the
perimeter of the greenhouse.
It is not necessary to apply mites to every pot if
applications are done early to allow them two weeks or more to spread (e.g.
apply Hypoaspis to every second row of pots).
For Best Results
Do not mix predators into the growth media before
potting because many will be killed when mixing.
Apply Hypoaspis shortly after planting and before
fungus gnat levels reach more than 20 adults/trap/week.
To control high numbers of fungus gnats, use of
Hypoaspis can be integrated with insect parasitic nematodes (e.g., Steinernema spp.) and Bacillus thurinigiensis ioensis (BTI)
(Vectobac®), both of which control the larval stage of fungus gnats.
Using Pesticides
See compatibility chart for expected effects of
pesticides on Hypoaspis. In general, do not apply Hypoaspis to soil that has
been treated with lime or residual pesticides (particularly soil treated with
diazinon).
Foliar sprays are usually less harmful than soil
drenches, depending upon how much pesticide reaches the soil surface. Fungicide
drenches containing benzimidazoles are known to reduce reproduction of
Hypoaspis. Microbial pesticides, such as Vectobac® (BTI) will not
harm Hypoaspis.
Spider Mite
Control of mites has been achieved on many species of woody ornamental
shrubs in British Columbia using the predatory mite Amblyseius fallacis. Fallacis is used to control
two-spotted spider mites and other mites on greenhouse peppers, field
strawberries, raspberries, currants and mint. In British Columbia, Washington
and Oregon, IPM programs for field berry crops are based on using Fallacis as
the primary control for spider mites.
Fallacis is also used on container and field-grown
nursery stock. Research in Oregon indicated that Fallacis can control spruce
and outher spider mites (O. ilicis, O.
ununguis, and T. urticae) on
woody ornamentals (Thuja, Skimmia,
Weigela, Potentilla, Euonymus, and
Buddleia). Fallacis feeds on apple rust mite (Aculus schlectendali), cyclamen mite (Steneotarsonemus pallidus) and tomato russet mite (Aculops lycopersici), however, whether
or not it controls these species is not known.
Fallacis is more resistant to pesticides than most
biological controls and a strain highly resistant to pesticides is available
commercially. Unlike other predatory mites, such as the Persimilis predatory mite,
Fallacis can remain in areas with low levels of spider mites; they survive in
the absence of mite prey by feeding on other small arthropods and pollen.
Fallacis feeds and reproduces over a wide range of
temperatures [9-32°C (48-85°F)]. They
do best where there is a dense plant canopy and when relative humidity is over
50%.
Fallacis can reproduce at lower temperatures than
other predatory mites (Phytoseiulus
persimilis, Neoseiulus californicus) and displaces them in the cooler
growing areas in Canada and northern USA.
Where there are species of plants
that are very attractive to mites the new predatory beetle, Stethorus
punctillum and the predatory midge,
Feltiella acarisuga may be released. Release 100 adult beetles
or 100 midges into each infested plant site. Make weekly introductions for 3
weeks. These biological controls can fly and feed on all stages of spider mite
and will reproduce and remain in the area for more than one season. Feltiella
will only establish if humidities are 65% or higher.
Monitoring tips
Use a headband magnifier or 10-15X hand lens. The
predators are usually easy to tell from their prey, which are slow-moving.
Adult mites often hide under leaf hairs and along the edge of leaf veins. They are most easily seen on parts of the
leaf where spider mite numbers are low or around the edges of the main spider
mite infestation. Eggs are usually
found singly or in pairs in crevices along, or partly under, the leaf midrib or
where prey is abundant.
Life Cycle of A. fallacis Predatory Mite
Development from egg to adult takes from 7-9 days at
21oC (70oF) to 3 days at 32oC (85oF). At 26oC (78oF) a
fourfold increase in numbers can occur within 4 days; in the field, under
optimum conditions, populations can increase from 10 predators/100 leaves to
200-500 predators/100 leaves, in just 2 weeks.
Adult females lay 1-5 eggs per day, for a total of
26-60 eggs over their 14-62 day life time. The eggs hatch in 2-3 days. Eggs are
oval and twice the size of two-spotted mite eggs.
Newly hatched predators do not eat, but later stages
and adults feed on all stages of prey. Female Fallacis eat 2-16 spider mites
per day.
Adult females enter diapause in response to the short
days (daylight of 14 hours or less in Canada) in fall. They stop reproducing
and move into sheltered areas, such as under bark or ground cover.
Product Information
Fallacis is available commercially either on bean
leaves or in a granular carrier (usually vermiculite or corn grits). Both
formulations should be applied as soon as possible. Fallacis packages can be
held at 10-15oC (50-60oF), out of direct sunlight, for
1-2 days--but quality and egg laying will be lower.
Two new more mobile mite predators,
the beetle Stethorus punctillum and
midge, Feltiella acarisuga are also
now available and are being used with Fallacis with good results as both have
flying adult stages.
Treatment:
1.Apply Amblyseius fallacis onto all
spider mite sensitive ornamental plants during propagation or when setting them
out in cold frames or the field. Use a general rate of 3 predators per square
meter of infested plant area repeated weekly for 3 weeks if spider mites are
present.
2.Monitor these plants weekly to
check spider mite levels. If mites are
building up or causing webbing apply fenbutatin-oxide (VendexÔ, TorqueÔ) through a high volume sprayer.
This will not harm predators.
Aphids (many species)
There has been excellent success
treating aphid infestations in nurseries with biological control agents. In
fact, if biological control agents are introduced in open screen houses and
field settings, it is usually unnecessary to apply pesticides for most species
of aphids. Unfortunately, protected or gall forming aphids are not controlled
by biological control agents that are presently available from commercial
suppliers.
Treatment:
1. At the first sign of aphids,
apply the Aphidoletes aphid predatory
midge at the rate of 2 predators per square meter of infested area, repeated
weekly for 3 weeks. These biocontrols can fly and feed on all stages of most
species of aphids and will reproduce and often over-winter and remain in the
area providing control for more than one season.
2. At the first sign of aphids,
apply the aphid parasite, Aphidius at
a rate of 1 parasite for every 2 square meters of infested area, repeated
weekly for 3 weeks. Three weeks
following the release look for signs of parasites in the form of
parasitized aphid mummies attached to the leaves.
3. Monitor plants weekly, if aphid hot
spots continue to develop and there is plant damage, spot spray with pirimocarb
(PirlessÔ) or Insecticidal Soap. This will
cause minimal harm to the biologicals. Avoid the use of other pesticides unless
determined to be safe for biological control agents.
Caterpillars (Lepidopteran larvae)
Caterpillar damage may be controlled
by releasing the commercially available moth egg parasite Trichogramma spp. or
spraying the spores and insecticidal crystals of strains of Bacillus thuringiensis (Bt). A new larval
parasite, Cotesia marginiventris, is
also available for experimental use. Cotesia
attacks a wide range of hosts and is a natural enemy of 21 different
Lepidopteran species.
Treatment:
1. Monitor planted area for adult
moths using pheromone traps or ultra violet light traps.
2. Release Trichogramma egg parasites as soon as adult pest moths are detected
at rates of 50,000-100,000/acre or as advised by the supplier.
3. Bt is usually applied as a high volume spray at first sign of larval
damage. Follow the formulators recommendations for rates.
Vine Weevil (Otlorhynchus sulcatus)
The vine weevil can cause serious
harm to nursery plant roots and the adult also feeds on leaves. Unfortunately these root weevils are all
female do not require mating and can lay up to 1000 eggs each! Adults are also flightless, are most active
at night and they can walk s far as 1000 meters per day. Adults lay eggs in the root ball and both
larvae and adults continue feeding at temperatures as low as 2ºC. As many as 400 weevils have been found in a
single 2 gal. container root ball.
A nematode is available as a
bilogical control agent of this pest but nematodes are most effective when
applied into potted plants under warmer growing conditions in greenhouses or
when soil temperatures are greater than 12ºC. Nematodes are mixed with water
and applied as a drench. Nematodes in
the Heterorhabditis group have been found more effective than other types
against vine weevil.
Treatment:
1. Monitor plants weekly for damaged
leaves and check the root ball of wilting plants for weevil larvae causing root
damage.
2. Apply nematodes to the root zone
following label recommendations. Apply 2-3 treatments at weekly intervals.
Spring and fall applications are best as most adult weevils are in the soil at
this time. Treated plants should be watered before treatment and kept moist as
the nematodes can only move through moist substrates. Do not overwater treated
plants as this will wash away nematode larvae. Nematode biocontrols are
resistant to Orthene and it may be applied as a combined drench where
necessary.
Biocontrol of Lygus Bug?
At the moment there is no
commercially available biocontrol for Lygus Bug for nurseries and the only
control method is excluding by screening vent openings or use of pesticides.
Entomologists in Canada are investigating the use of an native egg parasite Anaphes iole for biological control of
Lygus. Cornell University is experimenting with the fungus, Beauvaria bassiana,
a microbial biocontrol that is now available in the USA. Work is also being
done at Simon Fraser University on Lygus attraction or mating disruption
pheromones and this may have direct application to nursery IPM. Presently Lygus appear quite sensitive to most
pesticides and half rates of thiodan
have provided control of the mobile stages while allowing some survival of
other beneficial parasites and predators in field berry crops in British
Columbia.
IPM SUMMARY FOR NURSERY PESTS
Fungus Yellow Sticky Traps use
1 trap/500m2 for monitoring adults
Hypoaspis
miles if fly trap
counts are below 20/trap/week
Steinernema apply at least 2X at 2
week intervals
feltiae if fly
trap counts are above 20/trap/week rate-
50,000,000/250 m2 or as recommended
Bacillus apply weekly
thuringiensis if fly trap counts are
above 20/trap/week
ioensis rate-
4-8 litres/1000 litres of water, or as directed
Spider Amblyseius preventative
and low curative
Mite fallacis
3
predators/m2 repeated weekly
for
three weeks once mites are detected
Stethorus preventative and
low curative
punctillum 100/hot
spot/weekly for 3 weeks
Feltiella preventative
and low curative (requires Rh+70)
acarisuga 100/hot
spot/weekly for 3 weeks
fenbutatin 500g-1Kg Vendex
50W/1000 litres water
oxide
(Vendex 50W™)
(many species) aphidimiza repeated
weekly for 3 weeks
Aphidius preventative
and curative
spp. 1
parasite/2m2 of infested area
repeated
weekly for 3 weeks.
pirimicarb 500g Pirliss 50
DF/1000 litres water or as directed
(Pirliss™
50DF) moderately
harmful to biologicals so apply at low
rate
to tops of plants only or use only in hot spots.
insecticidal
soap 1 part soap/100
parts water or use low rate
(Safer's
Soap™) moderately
harmful to biologicals so apply
to
tops of plants only or in hot spots.
Caterpillers pheromone traps use
1trap/5000m2 for monitoring adults
ultraviolet light or
as advised by supplier
Trichogramma egg
parasites should be released as soon as
brassiere pest adult moths
are detected, release
50,000-100,000
parasites/acre weekly
for
3 weeks or as advised by supplier.
Bacillus apply as a
high volume spray at first sign of
thuringiensis larval
damage at recommended rates
var.
kurstaki (eg.)
1.2Kg. Dipel/1000 liters water
(Dipel™)
Vine Weevil Heterorhabditis soil
temperature must be 12°C or greater
megidis most effective
in pot or container culture
(Nemasys™) apply as a soil drench
as directed
(eg.)
50,000,000/250 m2