WILL SPRAYING DO ANY GOOD?
The very first step in dealing with a sick plant is to find out why the plant is sick. 60-70% of plant problems sent to WSU Extension have cultural or environmental origins. Spraying pesticides will not help and may actually cause
additional problems.
Pesticides are for specific pests on specific plants. Using them on the wrong plant could cause further damage to the plant.
Some plants are sensitive to some pesticides. If you apply a proper pesticide for a pest but the plant is sensitive to the chemical, you can severely damage the plant, sometimes causing more damage than the pest itself would have caused.
Insecticides do not affect fungi – and fungicides don’t kill insects. Know what the problem is and use the correct solution for the problem.
Beneficial “good” insects that eat or kill pests such as aphids, caterpillars, or slugs (and therefore naturally keep these pests under control) are often more sensitive to pesticides than the pests themselves.
Different pests have different life cycles and different tolerances to insecticides. You have to apply a pesticide when the pest is in a vulnerable life state – and while it is still present at the spray site.
Spraying could be a waste of time and money and could be hazardous to the ecological balance in your yard if the proper amount and timing of the spray are not followed for a given pest. READ THE LABEL CAREFULLY!
Some pesticides – especially fungicides – are only preventive. Plants won’t heal the damage from mildew or other damage already present, but if the spray is timed properly it may prevent new infestations.
PEST IDENTIFICATION RESOURCES
There are many resources to help you know what is making your plant sick. If you need to identify a pest, first obtain a specimen of the pest/problem. Then refer to pest identification and control publications available from WSU Extension, the US Dept. of Agriculture, or from commercial publishers or public libraries. You can also take the sample to a Master Gardener clinic or a local nursery, a WSU Extension office, a university, an arboretum, or a commercial pest control business.
ALTERNATIVES TO SPRAYING
Knowing the plant and meeting its cultural needs helps prevent many plant problems. A healthy plant can survive attacks by insects and diseases – frequently with no spraying or intervention on the part of the homeowner.
Consider that a certain amount of damage from insects or disease is normal and that natural forces are working against the pest. The plant can usually sustain a fair amount of damage before its health is adversely affected. A small amount of damage may be more of an aesthetic issue than one of the health of the plant. If damage is slight, the affected leaves could be hand-picked or just left alone. Being able to tolerate some holes in your rhody leaves or other small amounts of damage could be looked upon as your contribution to the natural balance in
your yard – and you still have the option to spray if they start to get out of hand later.
Consider less toxic means of controlling smaller infestations: hand-picking or pruning out infested leaves or branches; trapping; spraying insects off with the spray of water from a hose; practicing good garden sanitation
by getting rid of infected leaves, etc. When choosing new plants for the garden, seed out the pest-resistant varieties.
CONSIDERATIONS (WHEN SPRAYING IS JUSTIFIED)
You are liable for any damage your spray causes to neighboring property caused by wind drift or the carrying of the pesticides off your property by water runoff. You are also negligent if you do not use the pesticide labeled for a specific pest on a specific plant with the specific dilution of the chemical listed on the label.
Any use or dilution not specified on the label is a violation of federal and state laws.
Make sure that the pesticide label specifies the plant you are spraying (such as rhododendron) and the site (leaves, soil, and garbage can). Do not let spray drift onto food crops (fruits, vegetables, herbs, berries, etc.) unless it is labeled for those crops and the number of days before harvest is adhered to.
Do not let the spray drift into neighboring yards unless you have consulted with them in advance, and toys, barbecues, picnic tables, etc. have been moved indoors or covered. Make sure children and pets are safely inside
and follow label instructions carefully concerning when they can safely be allowed back in the sprayed area. Homeowners can be fined for pesticide misuse in some states. Don’t spray on windy days or allow spray to
drift onto blooming plants or weeds where bees might encounter it. Bees can carry the toxins back to the hive with the pollen and kill off the entire hive.
Slug bait can be attractive to dogs and can make dogs and pets sick if eaten directly or accidentally (as when preening themselves after having rolled in the bait in the garden). Slug bait is also toxic to birds and other wildlife. Birds feeding on treated areas may be killed. It is best to put the slug bait under a board or other shelter to keep birds and animals from eating it.
Don’t over-apply pesticides. Many of the pesticides are easily carried by runoff water into groundwater, streams, ponds, lakes, wetlands, and even Puget Sound where birds, fish, and other wildlife can be killed.
Don’t dispose of unused chemicals in sewers, or dump them down the drain. Sewage treatment does not filter out pesticides and the chemicals eventually make it into Puget Sound. Take unused, old, or unwanted chemicals to a hazardous household waste pickup point for disposal.
BEFORE YOU SPRAY – CHECKLIST
- Do you know which insect/disease you are spraying for?
- Is the pesticide you’ve chosen registered for use on that plant for that pest/disease?
- Is the pest/disease you are spraying for listed on the label?
- Is the level of damage substantial enough to warrant spraying or will the problem take care of itself naturally?
- Is the pest present an in a stage that will be killed by the pesticide at the time you are planning to spray?