Be careful of chemicals in the garden

This week we focus on our indiscriminate use of chemicals as we delve into part two of a five-part series on the biggest mistakes we make in our landscapes and gardens.

How many times have we resorted to pesticides or applied fertilizer without really knowing what the problem was to begin with? At what point did we decide that every problem in the landscape and garden could be solved with a chemical? In our busy lives it just seems like the expedient thing to do. Unfortunately, little heed is given to the potential consequences of these conveniences.

Americans love a flawless lawn and garden and have little patience for imperfections in the landscape. Unfortunately, our lack of understanding of how, when and where to use chemicals is killing beneficial insects, poisoning pets and wildlife, polluting soil and water, and disrupting fragile ecosystems.

The first step to using chemicals properly is to determine specifically what the problem is. Then seek to find the most effective yet benign solution.

In many cases, satisfactory controls can be achieved without chemicals. If you find it necessary to use pesticides, look for selective controls first. These target a specific type of pest without killing non-target or beneficial insects. Keep in mind that non-selective controls can't tell the difference between a Japanese beetle and a lady beetle. Indiscriminate spraying is lethal to both.

Proper timing refers to two separate issues. The first pertains to the insect's life cycle. Timing insecticide applications to coincide with the most susceptible life stage helps control pests and breaks their cycle of infestations. It's also the best way to choose a control option that minimizes the impact on other insects and the environment. Modern non-selective pesticides are often engineered to take out offending insects at any stage of their life cycle. Unfortunately, their persistence in the environment and widespread reach come with a price.

Timing also refers to the time of day when chemicals are applied. The quick and dirty is that if you're going to apply non-selective chemicals, wait as late as possible after beneficial insects have retired for the evening. When pollinators return to the garden by morning, direct contact will be reduced. The worst mistake is to actively spray non-selective controls from morning into the afternoon when the garden is buzzing with insects.

Applying chemicals to non-affected areas can result in undesired consequences. Common garden insecticides have killing power beyond the pests they were applied to control. Insect pests have preferred diets and rarely stray. Seeing hornworms on your tomatoes or peppers doesn't mean they'll take over your entire garden, so you don't need to treat them as though they will.

The same rule applies to herbicides and fertilizers. Look at the label on most consumer weed-killing products. Note the warning about toxicity to aquatic invertebrates and non-target plants. Off-target fertilizers pose similar problems. Common ingredients include nitrogen and phosphorus. When these make their way into streams and other water systems, they cause problems. Excess nitrogen runoff promotes the growth of organisms that deplete available oxygen needed for other aquatic life, including fish. High levels of phosphorus support aggressive growth of algae, leading to a significant reduction in water quality and an adverse impact on plant and animal life.

Too often, consumers take for granted the potency of synthetic chemical products. In our age of excess, it is natural to assume that if some is good, more is better. But information like application rates on packaging is very specific to provide maximum efficacy while providing a reasonable level of safety to people, pets and the environment.

Author Joe Lamp'l, host of "Fresh from the Garden" on the DIY Network and "GardenSMART" on PBS, is a master gardener. For more information, visit www.joegardener.com and www.DIYnetwork.com. DIY Gardener