Pests and Diseases

At our meeting in June, Larry Pletcher, organic farmer and owner of The Vegetable Ranch, talked about controlling pests in the organic vegetable garden.

Pests and Diseases PDF

Spotted Cucumber Beetle

Larry likes to take a more laid back approach to fighting pests in the garden. His first question is, “Is the cure more expensive than the cost of losing a few plants?” As a production farmer, this is something he has to consider when faced with an infestation or disease. He has to balance the cost of purchasing organic pesticides and sprays against his estimated harvest/income. As gardeners, we are not concerned with selling our produce so we have a lot more leeway. If the damage is basically cosmetic and the plants are continuing to grow and thrive, then he recommends doing nothing. That’s right…NOTHING! How easy is that?

We talk about this time and time again and Larry talked about it some more. The most important thing about organic gardening is to make sure that you have healthy soil. Good soil supports strong and healthy plants. Healthy plants are better able to fight off diseases and infestations.

Even so, there is a lot you can do to help your plants thrive. Here are a few hints…

• Row Covers: Putting floating row covers like Reemay or Agribon over your crops when you first plant early in the season really helps them get a head start. You can create hoops with wire or PVC bent over stakes. The fabric prevents flying insects from landing on your tender seedlings. It also raises the temperature inside the tunnels a couple of degrees which encourages growth of veggies that like warmer weather. The fabric is also porous so it lets the rain water your plants and it helps retain the moisture. Plus, it’s reuseable from season to season. The only drawback is that you can sometimes TRAP pests inside your fabric! Check the plants periodically to see how they are doing. If you have pests, treat accordingly and replace the fabric. Once the plants are well established and flowering, you can  remove the fabric. Bring it out again in the fall to protect against frost.

• Use Cutworm Collars: Take the time to put cutworm collars on your transplanted seedlings. You can make collars using toilet paper rolls, plastic cups, yogurt cups, etc.. There is nothing more heartbreaking than seeing your seedlings mowed down by cutworms, especially if you have tenderly raised them yourself!

• Rotate your crops, especially potatoes!: Larry has the luxury of rotating crops miles from the last place they were planted. This is especially helpful with potatoes. As backyard gardeners, we can’t relocate our gardens, but we can plant our crops in different places each year. This helps not only the soil, but might confuse the pests as well! We wrote about planning crop rotation in May.

• Mulch your garden: This prevents plant diseases splashing up from the soil. Especially important around tomatoes. Use straw or grass clippings.

• Check your plants daily: Check your plants daily and hand pick insects and remove/squish their eggs. This is fairly easy to do with a small garden and doesn’t take too much time.  To kill the insects, throw them into a bucket of soapy water.

• Keep your garden clean: Clean up plants at the end of the season.

If it turns out that you have a major infestation, here are a few good products that are safe to use on organic gardens…

• Ladybugs: Ladybugs are especially good at controlling aphids. Release the ladybugs into the garden in the early evening. As long as there are aphids around, they should stick around long enough to eat them. An alternative idea is to cover your plants with row cover and release the ladybugs inside. This will also trap your aphids, but the ladybugs will most likely eat them.

• Use only products that have a OMRI label on them: OMRI stands for Organic Materials Review Institute which is a non-profit organization that conducts independent reviews of products intended for use in certified organic production, handling, and processing.

Some of Larry’s favorites products…
Bt is good for cutworms
Entrust is especially good for potato bugs. Entrust is extremely expensive but a tiny bit goes a long way. Consider purchasing some with a group of friends.
Surround: Is a clay based spray. Good for protection against plant diseases and pests.
Pyrethrum: Which is an pesticide derived from chrysanthemums. It is especially good for cucumber beetles.
Sluggo: Great for slugs.

In the end, nothing is better that paying attention to your plants on a daily basis. You can catch infestations and diseases early enough so that you can take action as needed to preserve your plants and the harvest.

For additional information, the UNH Cooperative Extension is a good place to start.

A book that was recommended was What’s Wrong With My Plant? (And How Do I Fix It?): A Visual Guide to Easy Diagnosis and Organic Remedies by Deardorf and Wadsworth.

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