Early detection and treatment

of pests means a healthier

growing environment.

In your garden

Pest management can be one of the greatest challenges to

the home gardener. Yard pests include weeds, insects,

diseases, and some species of wildlife. Weeds are plants

that are growing out of place. Insect pests include an enormous

number of species from tiny thrips, that are nearly invisible to

the naked eye, to the large larvae of the tomato hornworm.

Diseases are caused by fungi, bacteria, viruses, and other

organisms, some of which are only now being classified. Poor

plant nutrition and misuse of pesticides also can cause injury to

plants. Slugs, mites, and many species of wildlife such as rabbits,

deer, and crows can be extremely destructive.

Identify the problem

Careful identification of the problem is essential before control

practices can be used. Some insect damage may appear to be

a disease, especially if no visible insects are present. Nutrient

problems may also mimic diseases. Herbicide damage resulting

from misapplication of chemicals also can be mistaken for other

problems.

What to look for

Insects and mites All insects have six legs, but other than that

they are extremely variable. They include such organisms as

beetles, flies, bees, ants, moths, and butterflies. Mites and spiders

have eight legs– they are not insects. But for the purposes of this

article, they will be considered as insects.

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Pest Management BARD

Insects damage plants in several ways. The most visible damage is

chewed plant leaves and flowers. Many pests are visible and can be

readily identified, including the Japanese beetle, Colorado potato

beetle, and numerous species of caterpillars such as tent caterpillars

and tomato hornworms. Other chewing insects, however, such as

cutworms (which are caterpillars) come out at night to eat, and burrow

into the soil during the day. These are much harder to identify but

should be considered if young plants seem to disappear overnight

or are found cut off at ground level. Sucking insects are extremely

common and can be very damaging. These insects insert their mouth

parts into the plant tissues and suck out the plant juices. They also

may carry diseases that they spread from plant to plant as they move

about the yard. You may suspect that these insects are present if you

notice misshapen plant leaves or flower petals. Often the younger leaves

will appear curled or puckered. Flowers developing from the buds may

only partially develop. Look on the underside of the leaves as that is

where many species tend to gather. Common sucking insects include l

eafhoppers, aphids, mealy bugs, thrips and mites. Other insects cause

damage by boring into stems, fruits, and leaves. They may disrupt the

plant’s ability to transport water. They also create opportunities for

disease organisms to attack the plants. You may suspect the presence

of boring insects if you see small accumulations of sawdust like material

on plant stems or fruits. Common examples of boring insects include

squash vine borers and corn borers.

Diseases

Plant disease identification is extremely difficult. In some cases,

only laboratory analysis can conclusively identify diseases. Disease

organisms injure plants in several ways. Some attack leaf surfaces

and limit the plant’s ability to carry on photosynthesis. Other organisms

produce substances that clog plant tissues that transport water and

nutrients. Other disease organisms produce toxins that kill the plant or

replace plant tissue with their own. Symptoms associated with plant

diseases may include the presence of mushroom-like growths on trunks

of trees; leaves with a grayish mildewy appearance; spots on leaves,

flowers, and fruits; sudden wilting or death of a plant or branch; sap

exuding from branches or trunks of trees; and stunted growth.

Misapplication of pesticides and nutrients, air pollutants, and other

environmental conditions such as flooding and freezing can also mimic

some disease problems. Yellowing or reddening of leaves and stunted

growth may indicate a nutritional problem.At first glance, blossom end

rot of tomato, in which the bottom of the tomato turns black, might

appear to be a disease caused by some pathogen. It is actually caused

by the plant’s inability to take up calcium quickly enough during periods

of rapid growth. Prevent this problem with adequate moisture–adding

more calcium is of no benefit! Leaf curling or misshapen growth may be

a result of herbicide application.

Pest management practices

Preventing pests should be your first goal. But it’s unlikely you will be

able to avoid all pest problems, since some plant seeds and disease

organisms lay dormant in the soil for years. Diseases need three elements

to become established: the disease organism, a susceptible species,

and the proper environmental conditions. Some disease organisms can

live in the soil for years; other organisms are carried in infected plant

material that falls to the ground. Some disease organisms are carried

by insects. Good sanitation will help limit some problems. Planting

resistant varieties of plants prevents many diseases. Rotating annual

crops in a garden also prevents some diseases. You will likely have the

most opportunity to alter the environment in favor of the plant and not

the disease. Healthy, vigorous garden plants have a higher resistance

to pests. Plants that have adequate, but not excessive, nutrients are

better able to resist attacks from both diseases and insects. Excessive

rates of nitrogen often result in extremely succulent vegetative growth

and can make plants more susceptible to insect and disease problems,

as well as decrease their winter hardiness. Proper watering and spacing

of plants limits the spread of some diseases. Some disease species

require free standing water in which to spread, while other species just

need high humidity. Proper spacing provides good aeration around plants.

Trickle irrigation where water is applied to the soil and not the plant

leaves may be helpful. Barriers may be effective to exclude some pests.

Mulching is effective against weeds. Fences can limit damage from

rabbits. Row covers may prevent insect damage on young vegetable

plants. Netting can be applied to small fruit trees and berries to limit

damage from birds.

Integrated Pest Management (IPM)

It is difficult, if not impossible, to prevent all pest problems every year.

If your best prevention efforts have not been entirely successful, you

may need to use some control methods. Integrated Pest Management

(IPM) relies on several techniques to keep pests at acceptable population

levels without excessive use of chemical controls. The basic principles

of IPM include monitoring (scouting), determining tolerable injury levels

(thresholds), and applying appropriate strategies and tactics. Unlike

other methods of pest control where pesticides are applied on a rigid

schedule, IPM applies only those controls that are needed, when

they are needed, to control pests that will cause more than a tolerable

level of damage to the plant. Monitoring is essential for a successful

IPM program. Check your plants regularly. Look for signs of damage

from insects and diseases as well as indications of adequate fertility

and moisture. Early identification of potential problems is essential.

There are thousands of insects in the garden, many of which are

harmless or even beneficial. Proper identification is needed before

control strategies can be adopted. It is important to recognize the

different stages of insect development for several reasons.

The caterpillar eating your plants may be the larvae of the butterfly

you were trying to attract. The small larvae with six spots on its

back is probably the young of the ladybug, a very beneficial insect.

Some control practices are most effective on young insects. Different

stages may also be more damaging than others. This is where the

concept of thresholds comes in. The economic threshold is the point

where the damage caused by the pest exceeds the cost of control.

In a home garden, this can be difficult to determine. What you are

growing and how you intend to use it will determine how much damage

you are willing to tolerate. Remember that larger plants, especially those

close to harvest, can tolerate more damage than a tiny seedling. A few

flea beetles on a radish seedling may warrant control whereas numerous

Japanese beetles eating the leaves of beans close to harvest may not.

If the threshold level for control has been exceeded, you may need to

employ control strategies. Strategies can be discussed with the

Cooperative Extension Service, garden centers, or nurseries.

Control strategies

Mechanical/physical controls

Insects–

Many insects can be removed by hand. This method is preferable if a

few, large insects are causing the problem. Simply remove the insect

from the plant and drop it into a container of soapy water or vegetable

oil. Caution: some insects have spines or excrete oily substances

that can cause injury to humans. Use caution when handling unfamiliar

insects. Wear gloves or remove insects with tweezers. Many insects can

be removed from plants by spraying water from a hose or sprayer. Small

vacuums can be used to suck up insects. Traps can be used effectively

for some insects. These come in a variety of styles depending on the

insect to be caught. Many traps rely on the use of pheromones–naturally

occurring chemicals produced by the insects and used to attract the

opposite sex during mating. They are extremely specific for each species

and, therefore, will not harm beneficial species. One caution with traps is

that they may actually draw more insects into your yard. You should

not place them directly in the garden. Other traps are more generic

and will attract numerous species. These include such things as yellow

and blue sticky cards. Different insects are attracted to different colors.

Sticky cards can also be used effectively to monitor insect pests.

Weeds–

Hoeing, pulling, and mulching are the most effective physical control

methods for weeds. Weeding is most important while plants are small.

Well established plants can often tolerate competition from weeds.

Diseases–

Removal of diseased material limits the spread of some diseases. Clean

up litter dropped from diseased plants. Prune diseased branches on

trees and shrubs. When pruning diseased trees and shrubs, disinfect

your pruners between cuts with a solution of chlorine bleach to avoid

spreading the disease from plant to plant. Control insects known to

spread plant diseases.

Other pests–

Fences, netting, and tree trunk guards can be extremely successful

in limiting damage from small mammals and birds. Numerous traps

are also available to catch or kill some animals. (Caution: In many states

it is illegal to move wildlife, including squirrels. Traps may also catch

animals other than the ones targeted. Check local regulations before

trapping.)

Diatomaceous earth, a powder-like dust made of tiny marine

organisms called diatoms, can be used to reduce damage from

soft-bodied insects and slugs. Spread this material on the soil–

it is sharp and cuts or irritates these soft organisms. It is harmless

to other organisms. Shallow dishes of beer can be used to trap slugs.

Biological controls

Biological controls are nature’s way of regulating populations. Biological

controls rely on predators and parasites to keep organisms under control.

Many of our present pest problems result from the loss of predator

species. Other biological controls include birds and bats that eat insects.

A single bat can eat up to 600 mosquitoes an hour. Many bird species eat

insect pests on trees and in the garden. Bacillus thuringiensis (Bt) is a

bacteria that specifically attacks larvae of some insect pests including

white grubs in the lawn and Japanese beetles. This bacteria is harmless

to desirable species.

Chemical controls

When using chemical controls, be very careful with pesticides. Most

common pesticides are broad spectrum in that they kill a wide variety

of organisms. Spray applications of insecticides are likely to kill

numerous beneficial insects as well as the pests. Herbicides applied

to weed species may drift in the wind or vaporize in the heat of the day

and injure non-targeted plants. Runoff of pesticides can pollute water.

Many pesticides are toxic to humans as well as pets and small animals

that may enter your yard. Some common, non-toxic household

substances are as effective as many more toxic compounds. A few

drops of dishwashing detergent mixed with water and sprayed on plants

is extremely effective in controlling many soft-bodied insects such as

aphids and whiteflies. Crushed garlic mixed with water may control

certain insects. A baking soda solution has been shown to help control

some fungal diseases on roses.

When using pesticides, follow label directions carefully. Altering the

rate of application or increasing the frequency of application can injure

desirable plant and animal species. Spot applications of the pesticide to

the targeted pest can reduce the amount used and help reduce the

risk of injury to non-targeted species. Do not apply on windy days.

Read the label for information on other environmental conditions such

as temperature and rain that may influence the pesticide’s effectiveness.

Be aware that many so-called “organic” pesticides may be just astoxic as

the synthetic or chemical products.

Apply only the nutrients

plants can use.

In your garden

Twenty nutrients have been identified that are required by plants.

Of these, nitrogen, phosphorus, and potassium are required in

relatively large amounts. Nitrogen is associated with lush vegetative

growth, adequate phosphorus is required for flowering and fruiting,

and potassium is necessary for durability and disease resistance.

Calcium, sulfur, and magnesium are also required in comparatively

large quantities. These six nutrients are referred to as macronutrients.

The other nutrients, referred to as micronutrients, are required in

very small amounts. These include such elements as copper, zinc,

iron, and boron. While both macro and micronutrients are required

for good plant growth, over-application can be as detrimental as a

deficiency. Over-application of plant nutrients not only may impair plant

growth, but may contaminate groundwater by leaching through the soil

or pollute surface waters by washing away.

Soil testing

Testing your soil for nutrients and pH is important to provide your

plants with the proper balance of nutrients while avoiding over-

application. If you are establishing a new garden , a soil test is

strongly recommended. The cost of soil testing is minor in comparison

to the cost of plant materials and labor. Correcting a problem before

planting is much simpler and cheaper than afterwards. Once your garden

is established, continue to take periodic soil samples. While many people

routinely lime their gardens , this can result in raising the pH too high.

However, since many fertilizers tend to lower the pH, the pH may drop

below desirable levels after several years, depending on fertilization and

other soil factors. Home tests for pH, nitrogen, phosphorus, and potassium

are available from garden centers. While these may give you a general

idea of the nutrients in your soil, they are not as reliable as tests performed

by the Cooperative Extension Service at land grant universities. University

and other commercial testing services will provide more detail and you can

request special tests for micronutrients if you suspect a problem. In addition

to the analysis of nutrients in your soil, they often provide recommendations

for the application of nutrients or on adjusting the pH. The test for soil pH

is very simple– pH is a measure of how acidic or alkaline your soil is.

A pH of 7 is considered neutral. Below 7 is acidic and above 7 is alkaline.

Since pH greatly influences plant nutrients, adjusting the pH will often

correct a nutrient problem. At a high pH, several of the micronutrients

become less available for plant uptake. Iron deficiency is a common

problem even at a neutral pH on such plants as rhododendrons and

blueberries. At very low pH, other micronutrients may be too available,

resulting in a plant toxicity. Phosphorus and potassium are tested

regularly by commercial testing labs. While there are soil tests for

nitrogen, these may be less reliable. Nitrogen is present in the soil in

several forms and the forms can change rapidly. Therefore, a precise

analysis of nitrogen is more difficult to obtain. Most university soil test

labs do not routinely test for nitrogen. Home testing kits often contain a

test for nitrogen which may give you a general idea of the presence of

nitrogen, but again, due to the various transformations of nitrogen, the

reading may not be reliable. Organic matter is often part of a soil

test. Soil organic matter is highly desirable. Organic matter has a large

influence on soil structure. Good soil structure improves aeration and

water movement and retention. This encourages increased microbial

activity and root growth, both of which influence the availability of

nutrients for plant growth. Soil organic matter also affects the availability

of plant nutrients and how pesticides react in the soil. Soils high

in organic matter tend to have a greater supply of plant nutrients

compared to many soils low in organic matter. Organic matter tends

to bind up some soil pesticides, reducing their effectiveness. Tests for

micronutrients are usually not performed unless there is reason

to suspect a problem. Certain plants have greater requirements for

specific micronutrients and may show deficiency symptoms. Iron

deficiency is common on blueberries, unless the soil is quite acidic. On

these plants, the younger leaves will usually show signs of the deficiency

first. The areas between the veins will be yellowish while the veins remain

green. Other plants growing in the same soil will show no signs of a

deficiency. In this case, altering the pH will often correct the problem.

Taking a soil test

1. If you intend to send your sample to the land grant university in your

state, contact the local Cooperative Extension Service for information

and sample bags. If you intend to send your sample to a private testing

lab, contact them for specific details about submitting a sample.

2. Follow the directions carefully for submitting the sample. The

following are general guidelines for taking a soil sample.

a. Sample when the soil is moist but not wet.

b. For each acre of land to be tested, 10 to 15 sub-samples are

recommended. Areas that appear different or that have been used

differently should be sampled separately. For example, a separate

sample should be submitted for an area that has been in a garden

and one that has been lawn.

c. Obtain a clean pail or similar container.

d. Clear away the surface litter or grass.

e. With a spade or soil auger, dig a small amount of soil to a depth

of 6 inches.

f. Place the soil in the clean pail.

g. Repeat steps d through f until the required number of samples

have been collected.

h. Mix the samples together thoroughly.

i. From the mixture, take the sample that will be sent for analysis.

j. Send immediately. Do not dry before sending.

3. If you are using a home soil testing kit, follow the above steps for

taking your sample. Follow the directions in the test kit carefully.

Fertilizers and soil amendments

Once you have the results of the soil test, you can add nutrients or soil

amendments such as lime, as needed. If you need to raise the pH, use

lime. Lime is most effective when it is mixed into the soil, therefore it is

best to apply before planting. For large areas, rototilling is most effective.

For small areas or around plants, working the lime into the soil with a

spade or cultivator is preferable. When working around plants, be

careful not to dig too deeply or so roughly that you damage plant roots.

Depending on the form of lime and the soil conditions, the change in pH

may be gradual. It may take several months before a significant change

is noted. Soils high in organic matter and clay tend to take larger amounts

of lime to change the pH than do sandy soils. If you need to lower the pH

significantly, , you can use aluminum sulfate. Other commercially available

fertilizers will also help lower the pH. In all cases, follow the soil test or

manufacturer’s recommended rates of application. Again, mixing well into

the soil is recommended. There are numerous choices for providing

nitrogen, phosphorus, and potassium. If your soil is of adequate fertility,

applying compost may be the best method of applying additional nutrients.

While compost is relatively low in nutrients compared to commercial

fertilizers, it is especially beneficial in improving the condition of the soil.

By keeping the soil loose, compost allows plant roots to grow well throughout

the soil, allowing them to extract nutrients from a larger area. A loose soil

enriched with compost is also an excellent habitat for earthworms and

other beneficial soil microorganisms that are essential for releasing

nutrients for plant use. The nutrients from compost are also released slowly

so there is no concern for “burning” the plant with an over-application.

Manure is also an excellent source of plant nutrients and organic matter.

Manure should be composted before applying. Fresh manure may be too

strong and can injure plants. Be careful when composting manure. If left

in the open, exposed to rain, nutrients may leach out of the manure

and the runoff can contaminate waterways. Make sure the manure is

stored in a location away from wells and any waterways, and that any

runoff is confined or slowly released into a vegetated area. Improperly

applied manure also can be a source of pollution. For best results, work

composted manure into the soil. If preparing a bed before planting,

compost and manure may be worked into the soil to a depth of 8 to 12

inches. If adding to existing plants, work carefully around plants.

Green manures are another source of organic matter and plant nutrients.

Green manures are crops that are grown and then tilled into the soil.

As they break down, nitrogen and other plant nutrients become available.

Green manures may also provide additional benefits of reducing soil

erosion. Green manures such as rye and oats are often planted in the

fall after the crops have been harvested. In the spring, these are tilled

under before planting. With all organic sources of nitrogen, whether

compost or manure, the nitrogen must be changed to an inorganic

form before the plants can use it. Therefore, it is important to have

well-drained, aerated soils that provide the favorable habitat for the soil

microorganisms responsible for these conversions. There are numerous

sources of commercial fertilizers that supply nitrogen, phosphorus,

and potassium. The first number on the fertilizer analysis is the percentage

of nitrogen, the second number is phosphorus, and the third number is

the potassium content. A fertilizer like 10-20-10 has twice as much of each

of the nutrients as a 5-10-5. How much of each nutrient you need depends

on your soil test results and the plants you are fertilizing. As was mentioned

before, nitrogen stimulates vegetative growth while phosphorus stimulates

flowering. Too much nitrogen can inhibit flowering and fruit production.

For many vegetables, a fertilizer higher in phosphorus than nitrogen is

preferred such as a 5-10-5.

Fertilizer application

Commercial fertilizers are normally applied as a dry granular material, or

mixed with water and watered onto the garden. If using granular materials,

avoid spilling on sidewalks and driveways. These materials are water

soluble and can cause pollution problems if rinsed into storm sewers.

Granular fertilizers are a type of salt, and if applied too heavily on

plants, they can burn the plants. If using a liquid fertilizer, apply directly

to or around the base of the plant. For the most efficient use and to

decrease the potential for pollution, fertilizer should be applied when

the plants have the greatest need for the nutrients. Plants that are not

actively growing do not have a high requirement for nutrients. Therefore,

applications of nutrients to dormant plants, or plants growing slowly due

to cool temperatures, are more likely to be wasted. Generally, nitrogen

fertilizers should not be applied to most plants in the fall in regions of the

country that experience cold winters. Since nitrogen encourages vegetative

growth, if it is applied in the fall it may reduce the plant’s ability to harden

for winter. In some gardens, fertilizer use can be reduced by applying it

around the individual plants rather than broadcasting across the entire

garden. In the case of phosphorus, much of the fertilizer phosphorus

becomes unavailable to the plants once spread on the soil. For better

plant uptake, apply the fertilizer in a band near the plant. Do not apply

directly to the plant or in contact with the roots.

___________________________________________________________

This is from a Backyard Conservation Tip Sheet published by the

Natural Resources Conservation Service.