Fungicides and Insecticides
Almost every gardener has, at one time or another, been faced with having to look to insecticides and fungicides for help with problems on their plants. Pesticide is the general term for anything that kills animal "pests" of any kind in lawns, gardens and on indoor plants. Insecticides specifically target insects, and fungicides target diseases caused by fungi. Herbicides are also pesticides. They target unwanted plants/weeds. It is important to know a little about pesticides before making them a part of your life. Whenever possible, try to use cultural methods to alleviate problems before using chemicals.
How do I know when I really need an insecticide or fungicide?
It is important to try to identify what specifically is causing your problem before applying any chemicals. Once you know what's causing the trouble, you can look for the best way to treat it. Often, you can solve your problem through cultural methods and not have to spray or dust. Sometimes you'll find the damage is only cosmetic and what caused it has already gone.
How can I get a specific problem identified?
Bachman's will be glad to help identify what is bothering your plants. Bring a sample of the damage and/or pest (in a zip-lock bag) to one of Bachman’s garden centers. If a horticulturist is not available to look at the sample right away, we'll get back to you with an answer as soon as we can. You can also get help through your county extension agent or by calling Dial U at 1-900-988-0500. Sometimes it may be necessary to have an expert make a house call to your yard.
When would it be worth having a professional visit my yard to look at the problem?
If the cause of your problem cannot be determined and the plants in question are of significant value to you and your landscape, it may be worth your time and money to have an expert consult with you on the site. Although Bachman's does not offer this service, we recommend Rainbow Tree Care. Rainbow Tree Care specializes in tree and turf health programs. Seeing the problem on site can be the key to understanding what is happening.
Once I know what is causing my problems, how do I choose the right product?
First, make sure you use an insecticide for an insect problem and a fungicide for a fungus disease. After you do this, find out what specific chemical is best for that insect or disease. The information you need is on the label of the product. Ask a Bachman’s staff member for specific recommendations and double-check the labels.
How do insecticides work?
Insecticides work in various ways, depending on what type they are. Some disrupt the insect's nervous system, others affect their cell membranes, and some give the insects a disease. Not all work immediately; it may be a day or two before you see results.
Do fungicides work the same way?
While fungicides can do a good job preventing disease, they are not very effective treatments. Applying fungicides to a diseased plant will, at most, minimize the spread of the disease. Fungicides will not affect what is already damaged. Fungicides work by killing the causative agents and/or by creating changes that keep the diseases from taking hold.
What about danger to the environment?
Chemical labels are required to list environmental hazards. It may list a caution against use near water, birds or other wildlife. Be sure to read this information and follow its precautions when using the product and when storing or disposing of it.
Is there an easy way to know how dangerous a chemical might be?
The law requires that all chemicals be clearly identified by one of three words: Danger, Warning or Caution. These indicate the level of toxicity to people, based on the most hazardous means of exposure. In some cases, this would be ingesting the chemical; others may be through the skin or inhalation.
Danger is the most highly toxic and is sometimes also labeled as poison.
Warning applies to moderately toxic chemicals.
Caution refers to chemicals that are considered fairly safe for people. Whenever possible, choose the least toxic chemical.
Do many plants need insects for pollination?
Bees are especially sensitive to many common insecticides and are the primary pollinator of fruit trees. To avoid killing your pollinators, do not spray while the plants are blooming or choose an insecticide that isn't toxic to bees (such as Bt or Pyrethrins).
Once I have the right chemical for the problem, is there a best time to apply it?
Many insects and diseases are only susceptible to pesticides at certain stages of their life cycle. Most insects are sensitive while young and actively growing, but the same chemical that would kill a young whitefly may not affect it in the egg or pupal stage. Be sure to check labels to make the most effective use of pesticides.
Do I need to worry about the weather?
Many pesticides can cause damage to plants when they are applied under conditions that are either too warm or sunny. Some are not effective below a certain temperature. If it rains right after application, it is likely that it may wash off before accomplishing its job. Check the weather along with the label to make sure your timing is right.
Some of the chemicals seem to be available in different forms. Which is best?
Pesticides are available as dust, concentrated liquid, wettable powder, granule, pellets and ready-to-use. Each form has its advantages and disadvantages. See our Chemical Basics for additional information.
Do the chemicals stay in the plant, affecting fruits and vegetables?
Many insecticides and fungicides leave a residue in the plants. The label will tell you how much time must elapse between application and harvest. As an additional precaution, be sure to thoroughly rinse anything you intend to eat.
What should I do with old bottles and bags of chemicals that I am not going to use?
Every community has a procedure for proper disposal of old chemicals and chemical containers. Please follow their recommendations. Locally, you can call the Minnesota Pollution Control Agency at 1-800-652-9747.
Additional Bachman's Information
How to Use Garden Sprayers
Calculating, Measuring and Spacing
Bonide™ Insecticides and Fungicides
Hose-End Sprayers and Misters
All-Season Horticultural Oil
Safer's™ Insecticidal Soap
© Bachman's 2007