|
Insect Pests Getting Control
|
|
|
Bulletin #TP2700
|
Horticultural Observations for Healthier Landscapes |
As plant population
increases, the insect population grows with it. The majority of plants used in
throughout drought prone areas are imported from other locations and the pests come with them. Few
are dangerous but most are annoying to us and can damage our plants. Our warm,
dry climate is ideal for a variety of insects and we must learn how to control
them. Forget about eradication; they are here to stay. Understanding and
using proper control measures will make things easier.
It has been my observation during the past that Many Brand named pesticides change
the chemical used in a product without changing the products name. Sometimes this
is due to a chemical improvement, or often the previous chmical was banned.
I have even seen where different sizes of the same brand-named chemical use different
primary pesticide chemical.
For these reasons I have chosen to identify the specific pesticide chemical rather
than the brand name. An example; Round Up (an herbicide) is the brand name for glyphosate. Gluphosate
is bottled by a number of manufacturers. By focussing on the chemical (and not the
band name) I can provide advice that doesn't become inaccurate just because a
manufacturer has changed a formula. To find out what brand named pesticide uses a
recommended chemical - simply put the recommended chemical name into an internet search
and you will be made aware of many brands for that chemical.
Here are some of the most common pests and recommended controls:
☞ Ants
☞ Aphids
☞ Borers
☞ Cicadas
☞ Mealybug
☞ Thrips
Ants are not the actual culprit causing damage to
plants! Their presence indicates that other insects are likely
present and preying on them. Many ants like sugary substances that other insects (aphids) produce, so
you often see a plant with damage at the same time you see the ants.
If you only focus on killing ants, you'll not likely solve the real issue.
Ants will go
after sugary sap and fruit. If their after your fruit it is probably time to
start picking. If it's sap they are after, then find out why the tree is
stressed first.
Treatment is usually needed for aphids.
Controls:
Read the section on controlling aphids.
To control ants outdoors on trees, you can use one of the many "sticky coating" products
that are intended to be applied around the trunk of the subject tree. NOTE:
avoid applying these sticky products right onto the bark; rather
use some duct tape first - make a band around the trunk - press it deeply into the crevices
- then put the bead of sticky product completely around the ring of tape.
The ants can't get past this. Renew annually - as needed.
Otherwise "ant bait" is by far a better solution than ant sprays.
With many types of ants; a spray will only cause them to move their colony and often
create mutiple colonies. Various types of ant baits are available, read the label to
see which type ant you are trying to control.
For protein eating ants -a home made receipe of diatomaceous earth and peanut butter
is very effective. D.E. is the hard shells of sea
creatures and is generally not harmful to humans or other large animals. Put a
dab of this mix in their line of traffic, and they'll bring it to the colony.
If you suspect that you
might have fire ants, however, contact the regional Department of Agriculture
(top)
Aphids
are
probably noticed more than any other plant pest. They feed on plant juices
from stems, leaves and flowers. In large enough numbers, they can cause
extreme damage to plant life. Contrary to popular belief, they are not just
green. Aphids come in a variety of colors like red, brown, purple, gray,
yellow, orange and black. While feeding, they excrete a sap-like liquid called
honeydew that attracts ants and other insects. Some ants "herd" and
"milk" aphids, using the liquid as a food source. They appear in largest
numbers during spring and fall since neither severe heat or cold agrees with
them. Get the upper hand early to prevent any serious damage.
Controls - Organic: Ladybugs, Praying Mantids, commercially packaged Insecticidal Soaps or natural horticultural oils like Neem. A recent addition as an organic pesticide Spinosad ® can be used on vegetable gardens, fruit trees,lawns and ornamentals. Commercially packaged garlic sprays have proven effective in deterring aphids. Strong streams of water from a sprayer or hose can wash them away from your plants, but you will need to be very thorough. They hide under the leaves, and if you don't get them all, they'll be back in numbers.
Chemical: For ornamental plants - -
acephate, permethrin, organophosphates, carbamates, pyrethroids, cyclodienes
are all effective.
Systemic insecticides like Imidicloprid
(a neonicotinoid) can help reduce the number of sprayings required to
control this pest. Because Neonicotinoids are systemic (stay within the plant)
the use of them on a flowering plant can threaten Bee populations.
For Vegetables
Insectidical Soaps, pyrethrins and synthetic pyrethrins are available.
(top)
Borers
generally
attack stressed or injured plants, not healthy ones! They are the larvae of
several species of moths and beetles. So it may be better to show the damage
they cause, than a lot of different beetles.
They tunnel beneath the bark and eat into
the cambium (nutrient bearing tissue). Some bore into the heartwood and
branches. Symptoms include holes in the bark, peeling bark and fine sawdust,
and areas or spots of sap on the trunk or branches. Caution! Cracked bark and
sap are also signs of a stressed plant, so you will need to do some thorough
examination of the tree before making a decision. Sudden death of individual
branches is another tell-tale sign of borer infestation. Left untreated you
will likely lose the tree or shrub, and provide a launching point for the
borers to multiply and attack the rest of your landscape. Watch neighboring
landscapes for these signs and share this technical bulletin if you see them.
Some of their favorite plants to invade are: Cypress, Juniper, Albizzia and Fruit Trees.
Flowering Plum Trees are a favorite - as they are often underwatered. Any fruiting tree that is improperly watered or have
sunscald trunks is suseptable. Borers have even been found in shrubs like Hawthorn, and
Photinia.
Controls : Prevention is the key with this insect! Proper irrigation, fertilization and routine clean-up can do wonders. To kill borers we need to get the pesticide into the tree, not just treat the surface, so a systemic is required. Borers can be very difficult to eliminate once they are established. Perform annual irrigation checks, expand the root zone of your plants by adding drips away from the trunk as it grows, and fertilize regularly and properly. Keep the area around your shrubs and trees clean of debris. In March, paint the trunks and major branch junctions of all fruit trees, willows (except chilopsis; desert willows) and ornamental trees with a white latex - water based tree paint. The paint will protect trees from sunburn and heat stress thereby lessening the chances of borer attack.
Chemical
: On your ornamental trees apply a protective
drench of Imidicloprid (systemic Insect Control) in the fall or early
spring. Read the label for application rate and instructions. Putting the
chemical into the soil allows the plant to uptake it, which then puts it
into the xylem tissue. When the larvae attempt to feed - this pesticide will kill them.
This product gives systemic control of borers in ornamental trees and
shrubs for up to one year. There are weaker formulations available that are labeled
as safe for use on fruiting trees, otherwise do not use this product on trees or shrubs that
bear fruits you intend to eat! As always, follow all pesticide
label instructions exactly!
(top)
Caterpillars are the larvae of moths and butterflies. If you want Butterflies in your garden, you will need to allow a reasonable number of caterpillars to survive, and so chemical control would not be recommended. Caterpillars are leaf-chewing insects and included harmful varieties like the small cabbage looper, cutworm, grape leaf skeletonizer, and the huge tomato hornworm. All can cause serious damage if left unchecked. Use control measures at the first sign of these.
Control - Organic
Bacillus thuringensis
[BT] is a bacteria
that attacks the digestive system of caterpillars. It's available in liquid
concentrates or dust and gives
outstanding results. If you can stand to handle them, handpicking hornworms on
tomato plants is very effective since there are rarely more than one or two on
each plant.
Chemical: For ornamentals use
Synthetic Pyrethrin,
acephate, permethrin, organophosphate, carbamate, pyrethroid, and cyclodiene
Products are all effective.
Controls:
Many of the products that were effective are no longer available.
Please read this article by UC Davis (click here)
Snails and
Sowbugs
(top)
(Leptoglossus phyillopus) are attracted to pomegranates and other
will be after your pomegranates and fruits like almonds, pistachios,
and peaches. They are heavy feeders on these trees and can devastate a crop
quickly if not controlled. They not only disfigure the fruit, but basically ruin the crop.
(top)
These a perennial problem for ornamental plants and edible vegetables. They damage young, tender vegetables and bedding plants. You may not get a chance to
actually see them before they have ruined your crop. Filling a mayonaise lid with
cheap beer is one way to discover if they are present.
Controlling Snails & Slugs
These are easily controlled with a safe natural application of Iron Salts
(ferris sulfate). Slugs and snails feed early in the morning or at night;
it is best to apply the bait at night. Simply scatter the bait on the soil around and near the plants that you want to protect. Use one teaspoon per square yard,
then reapply when it is consumed or every two weeks.
Sowbugs
Sowbugs and pillbugs feed primarily on decaying plant material.
They and are important decomposers of organic matter.
When large enough numbers are present they will chew on plant feeder roots.
They occasionally feed on seedlings, new roots, lower leaves,
and fruits or vegetables touching the soil.
They are very damaging in strawberry beds,
attacking the ripe berries just when you want to pick them.
Controlling Sowbugs
Boric acid and diatomaceous earth both of which work by killing on contact.
An issue here is that often these pests are hidden, or in the soil and
can't be reached by contact.
In order to get after the hidden sowbugs, the chemical Bifenthrin is very effective.
Careful not to get any where aquatic life are affected. Care when discarding.
Bifenthrin is a pyrethroid and is safe for use with vegetables.
Earwigs
Earwigs are among the most readily recognized insect pests
in home gardens. Although earwigs can devastate seedling vegetables
or annual flowers and often seriously damage maturing soft fruit or corn silks.
Conversely they also have a beneficial role in the landscape and have been shown to be important predators of aphids.
Snails - Sowbugs & Earwigs are more active at night.
(top)
Spider
Mites
cause damage by sucking the cell contents from leaves.
A small number of mites isn't usually a problem,
but very high populations can be damaging,
especially to annual plants.
Often, damage first appears as a stippling of light dots on the leaves;
sometimes leaves turn a bronze color.
Some of their favorites plants are cypress, junipers, euriops daisies,
pyracantha, and many plants that are capable of tolerating drought,
and so watered very infrequently. Symptoms include a dusty look
with off-color foliage surrounded by light webbing. You can check
to see if they are present by shaking some of the affected foliage
over a piece of white paper. Otherwise they are very tiny and hard to see.
Mites are most active in hot, dry weather.
Failure to control them will result in foliage drop, and plant stress.
This situation often subsequently leads to the presence of Borers
Controls
Periodic washing of foliage with strong sprays
of water will help keep these pests under control. If the infestation is
severe, applications of a chemical miticide may be required.
Please read this article by UC Davis (click here)
(top)
Cicadas
Controls:
Prune out and destroy young twigs that have been infested
by egg laying within a three week period after eggs are laid. This will prevent
newly emerged nymphs from reaching the ground. Chemical
Mealybug
Controls Organic:
Lady bugs are a predator of the mealybug.
A moderately strong spray of warm water will dislodge most of the mealybugs.
Alternatively, you can try wiping the insects and egg masses off the
plants with a cotton swab or cloth dipped in rubbing alcohol.
Thrips
are very large, noisy insects that are
often more irritating to you than to your plants. BUT. Cicadas damage fruit trees
in two ways. The most obvious damage is done during the egg-laying process.
The slits made by the female in small branches severely weaken them;
often the weakened branches snap off in the wind.
Under a heavy attack a majority of the branch tips may be killed.
Damage is also done by the nymphs that suck sap from roots. Prolonged feeding by nymphs on
a tree's root system may reduce plant growth and fruit production.
Please read this article by PennState Extension (click here)
is another pest common to our houseplants,gardens and
landscapes.
Mealybugs damage plants by sucking sap. Their feeding can result in yellowing leaves,
stunting, dieback or death of the plants.
They secrete a toxic honeydew that supports the growth of black sooty mold
and can cause curling and contortion of plant leaves.
Adult mealybugs are small (about 3 mm long) and pink in body color
but covered with a waxy secretion, so they look cottony.
Chemical
This pest is difficult to kill, however
products containing the systemic insecticide dinotefuran
may reduce mealybug numbers on some landscape plants,
and plant spikes or granules containing the related insecticide
imidacloprid may reduce mealybug crawler numbers on houseplants.
Please read this article by UC Davis (click here)
Thrips are very damaging, almost impossible to see, and equally as difficult to
control. You can see how timy they are.
In order to have a decent chance controlling these tiny guys; understanding
their life cycle is a good thing.
Eggs are laid in leaf tissue and hatch after 5-8 days.
Female thrips can lay 6-10 eggs per day over their life span of 4-5 weeks.
Just one female can lay upwards of 200 eggs in her lifetime.
The nymphs feed on plant tissue for 8-10 days,
then drop to the ground to complete development in protected sites in the soil.
The prepupa and pupa stages are both non-feeding stages while
in their underground development stage. When fully grown adults emerge,
they fly to upper parts of plants to continue feeding and laying
eggs after a day or two.
This is how a new rose bud typically looks when infested by "rose" thrips.
The bud never fully opens, and soon all the buds on all your roses begin
to look like this.
Verify that your plants and flowers are truly infested by thrips
and not some other insect! First; cut off several "apparently infested" rose/flower buds,
and bring the specimens to a table where you can perform this experiment.
1) Lay a blank white sheet of 8.5 x 11 paper on the table.
2) Cut one of the bud specimens in half with small shears.
3) Twizzle (over the paper) the base cut piece with your fingers. Pressing and rolling enough to
pry the insects loos from their hold on the pedal.
4) Look closely for any tiny moving or jumping critters on the paper.
If you see any, and they jump if you touch the paper near them - Your
flower has Thrips.
Control
: In flowers, the thrips feed inside the bud, and because of this - any product
sprayed onto the plant will not be able to attack the hidden thrip (only
those on the foliage). So, the first step to take is to cut off every flower
that has opened (even slightly) on all the similar plants in that area.
Now you can see why it's a good idea to make sure you have a Thrip infestation
and not something else.
The second step is to use a strong spray of water to wash the foliage of the
entire plant(s) in order to knock any thrips onto the soil.
Controls Organic
: Spinosad (an organic pesticide) lasts 1 week or more and moves short distances (unfortunately
not enough to reach inside a flower bud)
into sprayed tissue (has translaminar activity)
to reach thrips feeding in protected plant parts.
Adding horticultural oil to the spray mix can increase
its persistence within plant tissue.
This will take care of any remaining foliar thrips.
Dealing with the pupa that are in the soil is another matter.
Diatomaceous Earth is effective again larvae-like creatures near the soil surface.
(wear a mask when applying - microscopic sharp shells - bad for the lungs)
Cover the soil surface surrounding the infested plants, and lightly
mix into top 1/4 inch.
Controls Chemical
Chemical insecticides that control thrips are:
Acephate (Orthene), bifenthrin, imidacloprid.
Spray onto foliage (top of leaf and under - as possible)
To treat the soil; use bifenthrin as a drench.
Applying enough to wet the soil 1/2 inch deep.
Spray 2 or more times at intervals of 7-10 days
to control thrips as they hatch.
Thrips are a very difficult pest to control.
Please read this article by UC Davis (click here)
Some content courtesy Star Nursery, Inc.
Editing and Updating by Garden Galaxy
©
2023 www.GardenGalaxy.xyz