June 2012
Three steps to pest management
This year's warm winter and early spring have created some unusual pest management problems for growers. In some cases, insect pests and diseases have become active earlier and are more abundant than usual. They may be damaging crops not typically affected. There may even be some pest species that are not normally found on your farm. Whatever pest pressure you may be seeing this year, you can attack the problem in three steps: Identify the pest; choose appropriate
pest control products if necessary; and implement management practices to reduce pest pressure in the future.
Step 1: Identify problems
Begin by scouting regularly; at least once a week, walk your fields and inspect all your crops for pest damage. Don't just look from a distance -- get up close and check on the overall health of the plants. Turn over leaves to scout for eggs, aphids, and other potential problems. With root crops, pull up a few plants to be sure they are developing normally. Any time you find a problem, you need to quickly identify its source and determine whether it's a real threat to your crop.
Identifying pests may be simple in some cases -- if your lettuce is getting munched and you find caterpillars on it, you've probably found the culprit. Other times, it's not clear what is causing the damage. It may be an insect that flew away when you touched the plant, too small to see without a hand lens, or one that feeds at night. Sometimes the problem may be environmental, caused by heat, cold, water stress, or nutrient deficiency. In any case, it's important to put a name to the problem before you go further.
Your state Extension service is the best place to seek help with identification. First, do an internet search for your state + commercial vegetable production. Many states have excellent vegetable guides that name the usual sources of problems in your area. If you don't find the answer there, you might try one of these:
Cornell Cooperative Extension Guides to organic production of beans, carrots, cole crops, cucumbers and squash, lettuce, peas, potatoes, spinach. Each guide lists common insect pests and diseases.
The
University of California Davis IPM program has a website that lists pests by crop.
Another great resource for photos of insects throughout their life cycles is the
Insect Images section of the Bugwood Project at the University of Georgia.
If you don't find the answer with your own research, call your state Extension office to seek help. You can find your
local Extension office here.
Step 2: Choose the most effective controls
With the problem identified, your next step is to choose appropriate controls. The presence of an insect pest doesn't always require action; natural enemies may take care of the problem for you if it's not severe. Low-cost home remedies may be effective, such as milk for
powdery mildew control.
However, if you do need to spray a commercial product, choose the least-toxic method such as horticultural oils and insecticidal soaps. Other options include botanical controls such as pyrethrin
(Pyganic) and biological controls such as Spinosad
(Entrust) and Bt
(Dipel). To find the right product for the problem, consult Johnny's Comparison Charts of
Insecticides,
Fungicides, and
Repellents. Those approved for use on organic farms have the OMRI logo beside the name.
Bear in mind that pests can develop resistance to pest control products very quickly. To avoid that risk, rotate among products with a different Mode of Action. For example, at the Johnny's research farm, we treat tomatoes for Early Blight and Late Blight by alternating the fungicides
Champ WG and
Actinovate. For more information on preventing resistance, read this article from the
National Science Foundation's Center for Integrated Pest Management.
Step 3: Prevent problems in the future
Once you have the current pest problem under control, think strategically about how to avoid a repeat occurrence. Many factors contribute to pest outbreaks and crop damage, so assess whether you could do a better job in these areas:
- Crop rotation. Don't plant the same family of crops in the same field several years in a row.
- Variety selection. Look for resistance in the varieties you choose when you know you have a specific disease problem on your farm. Insects that vector specific diseases become less of a problem when you're growing resistant varieties.
- Weed control. Many pests can be eliminated from the crop field simply by destroying their cover and overwintering habitat in weedy adjacent areas.
- Water and nutrient management. Healthy plants, growing vigorously, are less susceptible to pest damage.
- Cleaning up fields. Destroy crop residue as soon as possible after the final harvest. You will destroy insect pests and remove potential overwintering sites for them.
- Attracting beneficials. Natural enemies can be powerful allies, so do all you can to provide nectar and pollen to keep them in your fields. Consider planting strips of flowering plants to attract and keep beneficials.
For more ideas about prevention and organic controls, see
Organic Insect Control for Commercial Vegetable Production from Mississippi State University.
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