C. Prevention - Discourage Pests with Cultural Controls
1. Grow healthy plants. Pests seem to be drawn toward crops that are already weakened or damaged. Some crops have extra special requirements, but all plants need:
a. Healthy Soil - Not too heavy or too sandy either. The soil should hold moisture for a reasonable period of time, but also allow for proper drainage. It should provide a variety of nutrients for plant growth. A major component should be loam or compost.
b. Proper Nutrition - Some crops are heavy feeders of certain nutrients. You may need to supplement what is naturally available in your soil. This is especially important during flowering and fruiting. The pH of your soil may inhibit the availability of certain nutrients to your plants.
c. Correct Watering - For most crops, infrequent watering deep into the root area will maintain the consistently moist environment they need for optimum development. Daily shallow sprinkling can actually be dangerous, as it encourages shallow root growth. These plants are more likely to suffer damage from a temporary drought than those whose roots extend deeper into the soil where the moisture remains longer. Investigate soil or root-level watering methods such as drip systems or soaker hoses. This puts the water right where it is needed without wasting a lot or getting foliage wet (which can invite disease problems for many crops).
d. Favorable Climatic Conditions - All plants need a certain amount of sun, shade, wind, rain, warmth or cool, humidity, etc. Too much of anything can be as bad, or worse than not enough. Try to select plants to fit the conditions that are available and plant them in areas that will meet their needs the best. Put sun and warmth loving crops near the heat holding masonry walls, or where they can get full sun. For plants that burn easily, plant them on the east side, in the shade of taller crops or provide shade cloth or lath structure. Erect windbreaks where needed and provide protection from late or early frosts.
2. Plant resistant or tolerant varieties. Use native or adapted plants if possible. They have already evolved ways of dealing with many local problems. Some available varieties have inbred characteristics that make them less attractive to certain pests. Some may simply taste bad to bugs and others may actually make the pest ill if eaten. Other species are developed to be less accessible, having thicker foliage or tighter shucks perhaps.
3. Time your planting to avoid trouble. If your particular pest shows up late in the summer; plant your crop as early as possible. Try a species of vegetable that is bred to ripen a few weeks earlier so you can harvest the crop before the hordes arrive. Conversely, you could try a crop that can tolerate the heat better so that you can plant later to avoid the bugs. Consider transplants; the older, hardier plants can tolerate damage better than tender young sprouts.
4. Interplant (between or around) your crops with companion/repellent plants. Certain plants, planted together, seem to encourage healthy growth in each other. And added benefit is that many of the plants are reputed to keep many common pests away from their companions. Most of these protectors are heavily scented so perhaps they simply act as a living screen that your crop can hide behind (the pests are often drawn to a crop by its fragrance and the herbs hide the crops scent). Some of the more common repellent type plants include Basil, Borage, Catnip, Chives, Dead Neetle, Garlic, Horseradish, Hyssop, Marigolds, Mints, Mole Plant, Nasturtium, Onions, Petunias, Radishes, Rosemary, Rue, Sage, Tansy, Thyme, and Wormwood.
5. Don't have monocultures. Put a few of each variety here, a few there. Make it hard for the pest to find them all. This will also serve to slow or stop the spread of many common diseases.
6. Rotate your crops location from season to season or from year to year. Don't let pest populations build up over time in a certain location. This will not only help keep your soil from being depleted of certain nutrients, but it also helps keep your insect pest population from building up. For example: if a few Corn Rootworms emerge from overwintering in your old corn patch only to find that it is now an onion patch, they will simply starve. You will have effectively broken the reproduction chain in that particular pest.
7. Use mulch and ground covers. They conserve moisture, decrease erosion and reduce competition from weeds. Many types of mulch are available and some are more suited for certain situations than others. You can use clear plastic to pre-warm the soil for an early spring planting or to "pre-sprout" weed seeds in a patch. These unwanted plants are then plowed under or pulled up before your crop is planted. Clear plastic can also be used to "pasteurize" a plot by using the sun to "cook" many of the weed seeds, overwintering pests or micro-organisms that may be lurking in the soil.
Black plastic is useful around winter crops or even some summer crops (like peppers and eggplants) that like their roots extra warm. The plastic can make it a bit difficult to water certain plants, but this can be overcome by leaving space around the stem of the plant for the water to run into. You could also consider using a drip system or place a soaker hose under the mulch. Being totally water-proof, plastic mulch does an excellent job of retarding water evaporation. Some folks object to the slick appearance of the plastic, but this can easily be taken care of by covering it with a thin layer of the decorative mulch of your choice later in the season when the soil is naturally warmer. In contrast, many organic mulches such as hay, leaves, straw, nut hulls etc... are excellent choices when you want our soil to stay cooler than normal. By using these, you may be able to extend your growing season for such crops as lettuce, cabbage, Brussels sprouts, and broccoli. (See "Cleanup").
In addition to helping maintain an even soil temperature and moisture level, mulch also helps control weeds. Not only do these weeds compete with your crops for water and nutrients from the soil, but they also attract and harbor many pests. Commercially available mulches include woven poly barrier cloth and horticultural paper products, but a very satisfactory homemade mulch can be made from layers of newspapers (no comics please!) or computer paper.
8. Use agricultural fleece or netting when appropriate. These come in many varieties and their primary purpose is to act as a barrier to keep pests away from your crops. Tree netting is used to exclude birds that like to dine on your ripening fruit and berries. Be sure to support it far enough away from the fruit so that the feathered diners don't just use the twine as a convenient perch as they reach in and peck away at your crop. The relatively large holes are small enough to keep out most birds but are large enough to admit pollinating insects. Unfortunately this also means that the netting will also admit fruit-destroying insects such as Codling Moths and Green Fruit Beetles.
Agricultural Fleece (Remay, etc...) will effectively exclude most, if not all, insects that threaten your crops. You can place these row covers over your newly seeded or transplanted crop and leave them there until they need to be uncovered to allow access by pollinators. With the edges properly pinned down or covered with soil, the pests simply cannot get to your plants to chew on them or to lay their eggs. These barriers readily admit sunlight, air, and water. And for crops not needing outside pollination, they can be left on from the planting until harvest. On the down side, one major problem to watch for is heat buildup. The fleece tends to hold in heat and may literally "cook" your veggies right in the garden in the late spring, summer, or early fall. Keep an eye out for signs of heat stress and vent the comer on warmer days. This very tendency of heat retention makes fleece a good option for late fall, early spring, or even winter crops as it helps provide a longer growing season and some frost protection. Check with your gardening supply source, some varieties of agricultural fleece are designed to hold in more or less heat than others.
9. Clean up the area. Remove any fallen fruit, dead foliage, etc...
a. The open area will make pests easier to spot and it will be harder for disease to spread.
b. Proper pruning will make for healthier trees and better air flow.
c. Overripe or fallen fruit or veggies are simply an invitation for pests.
d. Chop down or pull up weeds in non-mulched areas. If possible, get your neighbor to do the same. Chances are that any pests living on their property will eventually visit yours also.
e. Rake away old mulch each season and put down fresh. Pests can use it as an overwintering or egg-laying material. Most natural mulches can then be composted and become part of next year's soil, the pests will be destroyed as your compost pile "cooks".