Managing Insects and Diseases in Organic Crops

There are many ways to manage pests on organic farms. The overall strategy should always be to try to manage your cropping system to avoid the insects, diseases, weeds, etc. Easier said than done but here are some strategies. Each pest will have their own weakness.

You will however have competing interests and need to decide which is more important. For example adjusting the planting time to be later may exclude some insects or weeds but may result in slightly lower yields - assuming there were no pests. You also have to have the capacity to do all of the important things that need doing in a timely manner.

Pest Management Strategies

Crop rotation should be your number one strategy. Growing a high frequency of the same crop or same crop family will lead to more problems. Rotating from cabbage to another crucifer species such as broccoli does not help. Rotating grass type plants and broadleaves is ideal but not always practical. Growing a wide diversity of crops will give you more options for crop rotation. Use cover crops whenever possible.

Resistant varieties work well for many pests, especially diseases. Varieties can lose their resistance over time so keep watching for newer varieties with improved resistance. Know your problem diseases and which resistance traits that you need in a good variety.

Crop health is very important. Anything you can do to keep the crop healthier will help the plant to resist and tolerate pests.

• optimum nutrition - not excessive and not deficient
• good soil conditions - good structure, no compaction, active soil OM
• no moisture stress - neither too much or too little
• maintain correct plant population
• use clean seed and healthy transplants

Beneficial organisms are very important partners. These can be beneficial soil organisms (critters and fungi), beneficial insects that prey on other insects or weeds, beneficial fungi that suppress plant diseases or fungi that become a disease to insect pests and weeds. Many of our cropping practices have an impact on these. Some beneficials can be added to the field/crop but these will not be useful if your field conditions are not conducive to them surviving and remaining in and around the crop environment. Encourage beneficial plants in boundary areas to host predator insects and pollinators.

Sanitation is critical to prevent the spread for one field to another and from one season to another. Clean bins and storages after use. Clean equipment from one field to another. Maintain field margins to prevent spread of diseases and weeds. Don't spread your problems around.

Mechanical equipment, vacuums, flaming, row covers, hand picking can all work but may have high cost. Some strategies work well but must be suited to the crop situation and scale of production.

Biopesticides (that are organically approved) is another set of tools that are becoming more readily available for the organic farmer pesticides but I will write more about these in a future issue. Don't depend on biopesticides as the main means of control, they are tools to complement the other strategies listed above when needed.

Pest management starts with knowing your crop and pests and when there is a problem. What is the threshold for action? What were your problems this year? What worked? What didn't. Eliminating the pest is not a realistic goal but reducing it to tolerable levels is. Knowing how to prevent the problem is key. The biopesticides and mechanical options are last resorts when there is a problem. No one single strategy will be a success. A successful pest management program uses "many little hammers".

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