Tuesday, October 26, 2010

Pest Management, Control strategies

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, 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
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
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. It is not necessary to kill every insect, weed, or disease organism to have a healthy garden.
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 unfamiliarinsects. 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 ttract 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 garden.
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.


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.


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 plants, 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 plant 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.