NEIGHBORHOOD GARDEN FOR JUNE 30, 2012

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DON’T KILL YOUR BENEFICIAL INSECTS PART #2

BY GEORGE EDGAR

 

          On June 1, 2012, Gladys and I received the “Environmental Leadership Award” in Agriculture/Horticulture for 2012 from the Lincoln-Lancaster County Health Department. We were honored for promoting public awareness and concern for the enhancement and protection of the environment. Both Gladys and I have tried to write articles that encourage readers to practice good stewardship of the land, to conserve water, to use insecticides, fungicides, and herbicides only when absolutely necessary, and to practice IPM (Integrated Pest Management).

          Integrated Pest Management is the combination of appropriate pest control tactics into a single plan to reduce pests and their damage to an acceptable level. Relying only on pesticides can cause pests to develop resistance. There are a number of choices on how to control your garden insect pests. These include natural controls, host resistance, biological control, cultural control, mechanical control, and chemical control.

          HOST RESISTANCE is selecting plants that are less prone to serious insect and disease problems. 

          Biological control involves the introduction or conservation of natural enemies including predators, parasitoids, and pathogens to suppress insect pest infestations. This approach includes applying an insecticide only when it will be most effective, and as selectively as possible, so as to promote the natural activities of the beneficial insects.

          Cultural control includes altering the environment, the condition of the host plant, or the behavior of the pest to prevent or suppress an infestation. It also includes practicing good sanitation in your garden as many insect pests overwinter in plant debris, and includes using proper watering, fertilizing, and good growing practices so you have healthy plants.

          Mechanical control is a great option and includes physically removing insects and eggs from your plants and destroying them, physically removing weeds from your garden, and preventing certain insects from attacking your plants. Nets (row covers) over plants during periods of high pest activity are very beneficial. This can avoid chemical use.

          Chemical control should be used only when needed and only as one component of your insect management plan. Remember, insecticides need to be used properly and always follow the instructions. When using insecticides, start with the least toxic, such as insecticidal soap, so you don’t kill the beneficial and other good bugs.

         Use the right insecticide, at the right rate, at the right time, on the right insect.

         What is the right insecticide? Do you know that Sevin is highly toxic to the ladybugs that eat aphids? And Sevin is highly toxic to bees that pollinate your flowers, cucumber, squash, and many other plants. If you did not get your season long control on and you have noticed grub damage, Dylox and other short residual insecticides will kill grubs but needs to be applied when the grubs are small and present. This is usually from mid-August to about mid-September. Again, adequate irrigation after treatment is essential for acceptable control. Remember, the bag may say the product inside will kill grubs, but not specify how well, and usually does not say when to apply in Nebraska. Some chemicals get tied up in the thatch and never reach the grubs which are feeding below the soil surface. Milky spore is advertised as an organic control of grubs, but it does not work in Nebraska and the Midwest where our primary species is the masked chafer grub.

         When controlling aphids I use insecticidal soap first as this product does not injure the beneficial predators (lady beetles). Insecticidal soap is also good for spider mites and many other destructive insects. It can be used in the vegetable garden up to the day of harvest.

         Use the right insecticide, at the right rate, at the right time, on the right insect.

         If you have applied too high a rate of insecticide, or applied an insecticide when not needed, you have probably killed many of the beneficial insects that are helping keep your insect pests under control. Not all inhabitants of your landscape are hurting your plants, or your lawn.           Many people want to kill the night crawlers in their lawn. They don’t want to be bothered with those worms on their driveway or sidewalk after a heavy rain, or don’t like the bumps in their yard from the night crawlers. But these worms are nature’s aerators. We pay people to core aerate our lawn, but then apply chemicals to kill off nature’s workers. Sometimes our behavior just does not make any sense.

         Use the right insecticide, at the right rate, at the right time, on the right insect. Remember, not all insects are bad.

References: “The Gardener’s Guide to Common-Sense Pest Control” by William Olkowski, Sheila Daar, and Helga Olkowski. Published in 1995 by Taunton Press: Newtown, CT. Chapter #4 is on “Meet the Beneficials”.

          “Insects and Gardens” by Eric Grissell, published in 2001 by Timber Press: Portland, Oregon.

         “Growing Plants to Attract Beneficial Insects” by Fred Birdsall, Colorado Master Gardener, and Carl Wilson, horticulturist, Colorado State University Cooperative Extension. Copyright by CSU/Denver Cooperative Extension Master Gardener 1999-2006.

Copyright 2012