Identify - - the pest problem. Is it a disease, weed or insect? Different pesticides are needed to control different pests. Insecticides control insects, herbicides control weeds and fungicides control fungal diseases. They are all pesticides. You should always identify the pest problem before you use a pesticide. If there are no obvious signs of a pest, have the soil tested to ensure that the problem is not because of a nutrient deficiency or low soil pH.
Do you have a problem? - Sometimes pesticide applications are not practical or effective. Sometimes the problem may be too much or too little water, winter kill, frost damage, wind damage, or even a lack of sunlight. There is a tendency to reach for the sprayer first and ask questions later, especially with insect pests. Determine first, if the number of pests warrant using a pesticide. There are many beneficial insects that do not harm plants and some that actually feed on pest insects. These should be preserved in the garden. Many diseases are caused by poor nutrition rather than pests.
Btk.(insecticide) is a bacterial insecticide that works in the stomachs of caterpillars and stops them from feeding. Depending on the size of the caterpillar, it may take a week to kill them but they stop feeding immediately. Btk. only harms caterpillars and has no effect on beneficial insects such as bees. Btk. has a low toxicity to people and pets.
Boric Acid Baits (insecticide) are toxic to ants, but have a low toxicity to people and pets. Ants take the bait back to the nest and it eventually kills all the ants in the nest.
Insecticidal Soap (insecticide) has a low toxicity to humans. It breaks down cell membranes, causing dehydration of the insect's body. It must come in contact with the insect to be effective.
Glyphosate (herbicide) kills most plant material. It is NOT recommended for weed control on lawns as it will damage grasses. If you use it for spot treatment on your lawn, reseed the treated spots to prevent new weeds from getting established. It has a low toxicity to people and pets. This herbicide moves inside the plant from the leaves down to the roots. It is effective on many perennial weeds.
Bordo (fungicide) is commonly used to control plant diseases, especially blights. Check the label for sensitive plants. Depending on the disease you are trying to control this product may have to be applied more than once, sometimes starting early in the season, even before leaves have budded out.
Lime Sulphur (fungicide) is commonly used to control many plant diseases. The dust may be irritating to the skin and eyes. Wear protective clothing and goggles. Depending on the disease that you are trying to control, this product may have to be applied more than once, sometimes starting early in the season, even before leaves have budded out.