This is a great program of using natures own eco balance for your own needs. It reduces
your pesticide use while increasing the overall health of the plant by not adding poisons.
Anywhere that you can utilize biologicals I would encourage you because we all have to eat
and sleep in this world and integrated pest management makes it that much easier.
The Problem
Red spider mite feeds on leaf cells causing yellowish, speckled marks. Depending on the degree of infestation, damage can range from small chlorotic patches, to dying leaves. Webbing can be found in extreme cases which leads to rapid spread of the spider mites to surrounding plants. The resulting damage can seriously reduce crop yields.
The Solution
Phytoselulus persimilis is a very efficient and cost effective way of controlling red spider mite levels in outdoor crops. Phytosefulus mites can be targeted where spider mite hot spots exist, and they will also travel considerable distances to actively seek out their prey. Whilst sprays can offer limited control, they often miss spider mites on the underside of leaves. Furthermore, harvest intervals should be carefully observed when spraying prior to fruiting. Phytoselulus can be introduced at any time after the risk of frost has passed.
Problem
Western flower thrips (WFT) and now to a lesser extent
Onion thrips are serious pests on very many plants
causing bleached patches on the undersides of
leaves, and in severe attacks whole plants will be
defoliated. WFT has become resistant to most
pesticides since it was found attacking crops in Europe
in the early 1980's.
Solution
Amblyseius available in a vermiculite formulation with
10,000 or 50,000/litre may be sprinkled onto low
growing bedding or pot crops. Specially formulated
breeding colonies of the predator are available in
sachets for larger pot crops or salad crops. Orius spp
is available in units of 250.
Benefits
CRS sachets provide predators before thrips invasions.
Amblyselus can penetrate buds where thrips can avoid sprays.
Orius supplement control in heavy infestations.
WFT - Biology of the pest
The life cycle takes between 2-7 weeks and the eggs
are laid at a rate of 2-5/day. Adults live for about 6 weeks.
Pupation usually occurs in the soil but it can occur on
any horizontal surface.
The pest over winters in the soil as a pupa and mobile
stages can feed on any greenery left in the glasshouse.
Amblyseius cacumeris
This predator has been developed for use in a wide
range of situations, with the unique controlled release
sachets being ideally suited for use on long season
crops (eg cucumbers, peppers). The colourless mite
looks like a very small Phytoselulus and can be seen
moving very rapidly over leaves. It eats 1 + young thrips
larvae/day.
Orius spp.
There ore two species of Orius available in U.K. for
WFT control. These are produced in bottles containing
250 predators in a buckwheat/vermiculite mixture.
Orius laevigatus is preferable in shorter day lengths,
whilst Orius majuscules being larger is also used in
the summer months. Adults have been known to lay as
many as 150 eggs at rates up to 3/day. The build up of
population is dependent on temperature and prey
levels, the life cycle taking 25 weeks. Being day length
sensitive Orius laevigatus are normally introduced from
mid-March and Orius majuscules from mid-late April.
Control
Thrips are difficult to control with chemicals and
because of their very rapid multiplication rates
Amblysefus should be introduced as soon as the first
thrips are seen.
Control relies on complete cover of the crops with
predatory mites, to catch young thrips larvae as they
hatch.
Orius on longer term crops would be applied at 1-5/
m2 but should not be used until the pest is seen
attacking the crop.
Glasshouse Whitefly and its control
Problem
The glasshouse Whitefly (Trialeurodes vaporariorum)
has been a serious pest of plants in glasshouses
during the whole of this century. Both adults and larvae
excrete copious amounts of sticky honeydew; black
moulds grow on this, smothering plants and making
them unsightly. Massive populations develop in plant
heads, which together with the black mould kills the
plants.
Solution
Encarsia is available on hooked cards (60/card) for
hanging in the crop. They are provided in units of 25
cards. designed for easy application to plants. Use as
an insurance to control Whiteflies as soon as they
infect a crop.
Benefits
Quick and easy to use
Controls resistant strains of Whiteflies
Low cost treatment
Whitefly - Biology of the pest
Whiteflies can survive outdoors on plants even at
temperatures below 0C where infestation can occur
from weeds round the greenhouses. Once in
the greenhouse adult flies lay eggs on young leaves
After hatching ( 1-2 weeks) the young disc like larvae
crawl over the leaf and settle. getting bigger with each
moulting until pupation (1-2 weeks). The whole life
cycle takes 3-7 weeks.
Encarsia formosa
These minute wasps (1.5mm long) attack young
whitefly larvae (scales) by stinging and laying eggs
within them. On pupation the Whitefly pupae turn black.
Each wasp lays 60-100 eggs. and the life cycle takes
2-4 weeks to complete. The parasite will not fly below
20C. Introduction rates vary from 0.5-4
parasites/m2/week.
Control
Successful control depends on two important factors:
1. 'Insurance" introductions are made weekly
2. A temperature of 20C+ is required for a short while
each day to allow the wasp to fly.
Some pesticides are lethal to Encarsia formosa.
Contact your technical manager for guidance.
Practical use of Encarsia on crops
Cucumbers
Whiteflies overwinter on the smaller weeds so good
clean up in the autumn is essential. Introduce
Encarsia throughout the crop from 2 weeks after
planting at 1-4/ m2/week.
Tomatoes
Parasites must be introduced throughout the season
from ane week after receiving plants on the nursery
until the heads are stopped. Care must be taken not to
remove leaves with unemerged black scales. Use at
rate of 0.5 - 1 parasite/ m2/week.
Ornamentals
It is especially important to clean up glasshouses
before introducing new crops. This is sometimes
difficult where stock plants are overwintered. In all
situations introduce Encarsia at 1-3/ m2/week.
Poinsettias must have Encarsia introduced onto the
crop from receiving the plants until 2 weeks before
marketing. Use 1 parasite/3 plants.
Sticky yellow traps are valuable in monitoring for
adult whiteflies.
Note:
Another species of Whitefly, Bemisia tabaci (the cotton
whitefly) is potentially a very serious pest of many
glasshouse crops. At present it is controlled under
plant quarantine regulations.
Aphis gossypii and its control
Problem
Aphis gossypiis a pest of many crops covering leaves
with honeydew which encourages the growth of sooty
moulds and virus transmission. The pest has become
resistant to many pesticides except those which disrupt
other systems of biological control used in the
glasshouse. Therefore control using Aphidius
colemanior Aphidoletes aphidimyza is highly
preferable.
Aphis gossypii - Biology of the pest
Aphis gossypii can appear in the glasshouse at any time from April to
September. They appear as winged adults which then reproduce asexually very rapidly to form
large colonies of phloem feeding aphids.
Aphidius colemani
The parasitic wasp will lay a single egg in the aphid
host by inserting its ovipositor. The Aphidius larva
develops within the aphid and consumes the entire
body contents. The mature larva cuts a slit in the
underside of its host and attaches it to the leaf after
which it spins a cocoon and pupates. At this stage the
aphid resembles a swollen. papery 'mummy'. The
adult Aphidius cuts a round hole in the aphid cuticle
and emerges. The life cycle takes approximately 3
weeks and a single female will attack up to 300 Aphis
gossypii.
Benefits
Easy and covenient to use.
The natural enemies are winged and
therefore extremely mobile.
Overcomes the problem of resistance to
chemicals.
Completely safe to use.
Control
Ongoing trials suggest the following introduction rates.
Preventative - when the risk of invasion by Aphis
gossypii is high, introduce 0.5 per m2 weekly.
Curative - Once Aphis gossypii has been seen
increase rate to 2 per m2 for 3 weeks, concentrating
Aphidius in the worst affected areas.
Warning
Failure to detect early infestation may result in the
removal of badly infested leaves becoming necessary.
Aphidius and Aphidoletes should be applied on the day
of receipt. Bottles should be opened near infected
areas. Aphidoletes can be split into smaller receptacles
containing moist peat and spread around. In badly
affected areas bottles of Aphidius can be hung within
the crop.
Some pesticides are harmful to Aphidius and
Aphidoletes. Consult your Technical Services
Managers for guidance.
Always read the instructions on the product label.
Aphidoletes aphidimyza
The small, nocturnal midge lays eggs beside aphid
colonies and the orange coloured larva hatches to feed
on the aphids. The larva bites aphid knee joints and
injects a paralyzing toxin after which it sucks out the
aphid's body fluids. A larva will kill up to 50 aphids
during its lifetime. The larval stage lasts about 5 days
and the life cycle is complete in 3 weeks. A female will
lay between 100 and 200 eggs.
Warning
Aphidoletes will hibernate when day length falls to less
than 15.5 hours. This can be avoided by the use of low
intensity lights.
Control
At the first sign of Aphis gossypii or other aphids 2 to 5
Aphidoletes should be introduced per m2 for at
least 3 weeks.
NB. Aphidoletes alone will not be suitable for the
control of Aphis gossypii in cucumber crops.
Practical use of Aphidius &
Aphidoletes on crops.
Cucumbers
Introduce Aphidius colemani as a preventative
measure when Aphis gossypii is known to be
appearing in the area or as a curative measure when
first seen in the crop. Effective monitoring is vital so
that outbreaks can be dealt with immediately. It may be
necessary to remove badly affected leaves or to spray
them with soft soap to disperse the aphid colony.
Preventative introductions should be at the rates of
0.25 - 0.50 Aphidius per m2 per week.
At first sighting of Aphis gossypii introduce 0.50
Aphidius per m2 per week, and in hot weather or in
high levels of infestation 1.00 per m2 per week will be
needed.
Ornamentals
Introduce Aphidius colemani as a preventative
measure from the beginning of the season at 0.5/m2
every two weeks. Monitor carefully so that invasions
from outside the glasshouse late in the season may
be dealt with quickly.
Aphidoletes may be introduced preventatively but will
be more effective after aphid colonies are established.
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