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How to Prevent Garden Pests and Diseases

Keeping Out Pests

When pests strike at your garden, you need to strike back. Use organic repellents to chase away rodents and deer. Sprays made out of hot peppers, coyote or bobcat urine, rotten eggs, bonemeal, or bloodmeal (even castor oil) can make your garden unappetizing to herbivores. Reapply the repellents frequently, especially after rain.

Soap and human hair can also be used to deter deer. Soap can be stuffed in a mesh bag and dangled from branches at the nose height of deer -- about three feet. Replenish the soap supply frequently so it won't dissolve away or lose its smell. Human hair stuffed in mesh bags will make deer wonder if you are hiding in the garden.

Floating row covers can keep flying insects away.
Floating row covers can keep flying insects away.

Grow French or American marigolds to kill any nematodes in the garden soil. Nematodes -- microscopic wormlike pests that can damage tomatoes, potatoes, and other crops -- are killed by chemicals that are released by marigold roots and decaying foliage. You can plant marigolds in and around other nematode-susceptible plants. Or just till marigolds into the soil and let them decay before planting potatoes or tomatoes.

Floating row covers will keep pests off vegetables. When draped over plants, these lightweight fabrics allow sun, rain, and fresh air to penetrate but keep flying insects out. Secure them to the ground with rocks, bricks, or long metal staples. They can:

  • Eliminate maggots (fly larvae) that tunnel into the roots of radishes, turnips, carrots, and onions. They keep egg-laying flies away. If there are no eggs, there are no maggots.

  • Keep potato beetles from eating the foliage off potato leaves and vines. Pin the row cover edges down tightly so the beetles can't crawl under.

  • Protect cucumbers, squash, and pumpkins from cucumber beetles, which carry a wilt disease capable of killing entire vines. Since flowers of these vines need insect pollination for fruit set, the covers must be lifted for several hours at least every other day for honeybees to do their work.

Use barriers of copper strips or diatomaceous earth to keep slugs away. Slugs eat tender plants down to the ground. They come out from under rocks, logs, or mulch when it's rainy or cool and dark. Diatomaceous earth is a gritty substance that pierces the skin of soft-bodied slugs. Sprinkle it on the soil, encircling plants plagued by slugs. Use the horticultural grade, not the kind sold in swimming pool stores. Copper strips, set around the edge of the garden, prevent slug trespass by creating an unpleasant reaction when touched by slimy slugs. Set strips on edge an inch deep and several inches high.

Spray aphids off plants with a strong stream of water from the hose. Aphids, small sap-sucking insects with soft bodies, cling to succulent young stems and buds but are easily dislodged. This works best on roses and mature or woody plants that won't be damaged by the force of the water. Repeat every few days or when you see new aphids.

Using these disease-resistant cultivars should help to keep your garden healthy:

  • Apples: Freedom, Jonafree, Liberty, MacFree

  • Beans: Buttercrisp, Florence, Jade

  • Cucumbers: Fancipack, Homemade Pickles, Park's All-Season Burpless Hybrid, Salad Bush, Sweet Success, Tasty King

  • Peas: Green Arrow, Maestro, Sugar Pop, Super Sugar Snap

  • Roses: Carefree Delight, David Austin English Roses, The Fairy, Meidiland roses, Red Fairy, rugosa roses, Town and Country Roses

  • Strawberries: Allstar, Cavendish, Delite, Guardian, Lateglow, Redchief, Scott, Surecrop

  • Tomatoes: Beefmaster, Better Boy, Big Beef, Celebrity, Enchantment, LaRossa, Mountain Delight, Roma, Sunmaster, Sweet Million, Viva Italia

  • Zinnias: Cherry Pinwheel, Crystal White, Orange Pinwheel, Rose Pinwheel, Salmon Pinwheel, Star Gold, Star Orange, Star White

Sometimes pesticides are the best tool to keep your plants healthy. Keep reading to learn about pesticide safety.

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