Picture this: You’ve planted some milkweed, bee balm or California lilac, and you’re delighted to see bees and butterflies fluttering about your garden. You feel good about nurturing pollinators and love the life that plants attract to your yard.
As you move through your beds to examine your tomatoes, you notice that they are covered in black dots. Upon closer inspection, it becomes clear that your plants are infested with aphids.
If your tendency is to reach for a chemical pesticide – stop. Although this may put an end to your aphid problem, it will also threaten the beneficial insects, which pollinate the plants and keep the pests under control. Instead, apply the principles of Integrated Pest Management, or IPM.
The practice begins with acknowledging that a certain insect presence is tolerable. Control should be considered only when that limit is exceeded. Your first defense should always be the most gentle method available. This is where common sense prevails, and it should apply in the home as well as in the garden.
Take My Basement: Every spring, the ants arrive in March, but instead of spraying the perimeter of my house with insecticide, I set up ant traps wherever I see activity. After a few days, the colony collapses, and the problem is resolved.
All butterflies emerge as caterpillars, and all caterpillars chew on plants. That’s why I consider any plant that doesn’t have at least a few holes in its leaves to be useless to the ecosystem. Bear with munching some leaves and let nature run its course.
Back to your tomatoes: IPM will instruct to wash off the aphids with a strong stream of hose water. It usually works. But if they keep coming back after several tries, and you feel like you need to move on, take baby steps.
In this case, the next step would be insecticidal soap, a nontoxic insecticide that is safe for people, beneficial insects (when dried) and most plants (read the label to make sure your plant isn’t one of those few who are sensitive to the product) )
As a rule, prevention is the best treatment. Inspect the plants — including the undersides of their leaves — before bringing them home from the nursery. Reject anyone showing signs of illness or infection.
Discard instant gratification and space plants appropriately to allow for their mature size. Overcrowded plants retain moisture and promote mildew, mildew and fungal diseases.
Practice good hygiene by regularly cleaning up fallen leaves, fruit and plant debris that allow insects, rodents and pathogens to live on the ground.
When you see pests like aphids, wash them off. Dab scale insects with a cotton swab dipped in rubbing alcohol. Hand-pick tomato hornworms and cabbage worms (unless they are covered with the white eggs of brachnid wasps, which are tiny parasitic hitmen who will kill for you).
Traps can be used to catch slugs. Set shallow containers of beer around affected plants or place small wooden boards on the surface of the soil overnight. You’ll have a jar full of submerged slugs—or a congregation of live ones under the board—to dispose of in the morning.
If you decide that an insecticide is necessary, choose it carefully and follow the directions and precautions on the label. Avoid using any insecticides in extreme heat, on windy days or when the plants are damp, and apply them only in the morning or at night, when the pollen grains are dormant. It can hurt, but consider removing the flowers from the plant to reduce the exposure of beneficial insects to pollen and nectar. In most cases, more flowers will come.
These insecticides are generally considered safe for pollinators when applied correctly:
Insecticidal soap is a non-toxic alternative that kills aphids, adelgids, lace bugs, leafhoppers, mealybugs, thrips, scale, sawfly larvae, spider mites and whiteflies by suffocation rather than poisoning. It must be sprayed directly on insects and its effectiveness diminishes once it dries.
Horticultural oil, another suffocation, is effective against adelgids, aphids, leafhoppers, mealybugs, mites, scale, spider mites, thrips, and whiteflies. The product must come into direct contact with insects when wet and, once dry, is safe for beneficial insects (and ineffective against pests).
Neem oil, an insecticide derived from the seeds of the neem tree, is effective against aphids, adelgids, beetles, borers, leafhoppers, leafminers, mealybugs, scale, tent caterpillars, thrips, webworms, weevils, and whiteflies.
Bacillus thuringiensis (Bt) is a naturally occurring soil bacterium used as an insecticide. Several strains are available, each targeting different pests, so read the label to make sure the product you buy is suitable for your needs. Some strains are poisonous to monarch butterfly caterpillars, so do not plant them on or near milkweed, which is their only food source.