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Pests with Cultural Methods
Michelle Infante-Casella, Gloucester County Agricultural Agent, RCE
[Editors note: this article was directed at organic farmers; the advice is excellent for home gardens, too.]
Using cultural controls is a good first step for preventing crop loss from pests and plant stresses. Some cultural controls need long term planning and are usually not a quick method of stopping a disease or insect pest. However, if the preferred option is to use cultural controls, overall farm health can improve over time. Many farms are already using cultural controls like planting resistant or tolerant varieties, improving soil health, and other methods. There are other simple solutions to consider in the area of cultural controls to manage plant pests .
Improving Soil Health: There are many ways to improve the soils on the farm. One of the best ways is to increase organic matter levels. Although adding mulch, leaves, and manure may help to increase your organic matter levels, a more effective method is to grow cover crops with high biomass production. By increasing organic matter in the soil, moisture and nutrient retention levels will improve. Additionally, more organic matter will enhance the bioactivity of the soil and increase beneficial microorganisms.
Proper Planting Dates: Plant seeds or transplants at the correct time of year. Setting out transplants too early or too late can cause unnecessary stress to the young plants. Plants under stress will never out-yield a plant that has not seen stress periods. Additionally, some plants that have undergone undue stress may flower, bolt, or senesce (grow old) before it is time. A stressed plant is a weakened plant and may be more susceptible to disease and insect pests.
Plant Resistant or Tolerant Varieties: Many new varieties being released have some type of pest resistance. Resistance or tolerance to an insect or disease is usually listed next to the variety in seed catalogs or the seed salesman can provide more information. With an increased number of chemical labels being cancelled, it is important to look into alternative controls. Using resistant or tolerant varieties is a good way to control pests in the field. Besides pest tolerance or resistance, it is important to produce locally adapted varieties that do well under regional environmental conditions. Varieties that do not tolerate cold or hot conditions for a certain region should not be grown for commercial production in the region.
Crop Rotation: Planning crop rotations is a long term project and can be a key way of culturally controlling pests. Because different plant families are hosts to different plant diseases and insect pests, some problems can be avoided by planting non-susceptible crops. Many rotations should be prolonged for more than one growing season. Some soil-borne diseases may take up to 5 or more years to suppress through crop rotation.
Increase Crop Diversity: Using methods like intercropping, companion planting, and trap cropping can help to control insect pests in the field. Additionally, intercropping and companion planting may create symbiosis (both plants benefit from each other's presence) among the plants. For instance, planting a legume crop within a corn or grain crop may give off supplemental nitrogen fixed by the legume to the corn or grain crop. Some crops also are offensive to certain pests and may act as a repellent. Also, some plants may be more attractive to some pests and can be sacrificed as trap crops.
Timing and Amount of Irrigation: Many plant diseases thrive under wet conditions. It is important to keep the plant foliage dry to prevent conditions that are suitable for bacterial or fungal growth in the plant. Overhead irrigation early in the day will give enough time for plants to dry under sunny or windy conditions. Allowing the plants to stay wet overnight will increase the chance of disease. Additionally, wet soil conditions favor growth of soil-borne diseases. The use of soil moisture measuring devices, like irrometer tenisometers, is a good way to prevent under watering or over watering and soil saturation. When soil is saturated disease organisms can swim or flow through a field, increasing the chance for infecting plants. Additionally, when soil is saturated, oxygen is depleted and roots can be suffocated. Roots require oxygen as well as water for good growth.
Avoid Working in Wet Fields: Any activity in a wet field can spread fungal spores or bacteria throughout a field. Tractors that brush plants down a row or workers moving from plant to plant will easily spread disease organisms that are in the water on plants. It is best to wait until the field dries before working in the field.
Handle Plants Carefully: Any bruised, cut, or broken part of a plant is an entrance spot for disease organisms. It is important to reduce the amount of plant damage at all times. This is especially true when setting out new transplants. These young and often tender plants bruise and break easily. When pulling plants out of a tray do not squeeze the stem too tightly or it can bruise. The bruised area will most likely be near the soil line and can easily be infected by soil-borne diseases. The stem can also be so bruised that the movement of water and nutrients is hindered from the roots to the rest of the plant. Also, be careful during harvesting or pruning. Use knives or pruning shears if necessary, rather than pulling fruit off of a plant to avoid breaking the branches. When walking in the field, try not to step on vines or branches. Use breaks in the rows to create paths to carry out harvested produce.
Do Not Introduce Pests: Before planting look over the transplants to check for insects or diseases. Make sure the seed you buy is certified and treated properly. Cleaning your tillage equipment before traveling into a new field is important. Wash off any soil or plant debris from your tractor or equipment with a sanitizing agent like chlorine. Also, cleaning hand tools like pruning shears, hoes, rakes, or shovels can help reduce the spread of soil-borne disease.
Use Mulch as a Soil Covering: Using plastic or organic mulches to cover the soil will help to control weeds and may reduce the spread of soil diseases. Remember, however, that some plastic mulches will not be good at controlling weeds (i.e. white, clear, yellow, red, blue). By having the soil covered, fungal and bacterial disease organisms may not be splashed up onto the plant. Be cautious about using some organic mulches that may utilize high amounts of nitrogen during decomposition or may help to encourage some unwanted pests, like rodents.
Practice Good Sanitation: Keeping fields free of weeds or infested or infected plants is a way to reduce plant stress and pest spread. Weeds are prolific seed producers and one plant can produce thousands of seeds for next year's weed crop. A plant that is dying from a disease should be removed from the field to reduce the source of innoculum to other plants. When removing these infected plants, make sure they are disposed of far away from the crop field so that wind or water will not transport the spores from the discarded plants.
Encourage Beneficial Organisms or Enemies: Planting buffer strips to create environments for insects like ladybugs, lacewings, and other beneficial insects can help to control insect pests in a natural way. Reducing the amount of unnecessary chemicals can help beneficial microorganisms and earthworms to flourish in soils.
Scout Fields for Problems Before They are Out of Hand: Taking the time to inspect fields for pests and other problems is an important step in preventing widespread problems. When a problem in the field is first spotted it needs to be identified quickly and a control plan needs to be implemented immediately. Contact the local extension office as soon as possible if you need further information. Once the field is decimated, controls are not an option and the field is lost.
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