Storing Pesticides

Diluted pesticides should never be kept

Bill Sevier: Ask a Master Gardener

Saturday, October 17, 2015

Q: Is it OK to store my unused herbicide in my sprayer? Ted, Tulsa

A: No, once a concentrated pesticide has been diluted, it should not be stored under any circumstance in any type of container. There are good reasons for this.

First, like most people, we tend to forget. The name and type of a chemical in a sprayer after it has been used and set aside may be misremembered. You easily can end up applying a harmful chemical to your vegetable garden, putting those who eat the veggies at risk. Or a possibility of less-severe consequences is killing a desirable ornamental or vegetable plant by spraying an herbicide inappropriately.

Chemical pesticides are stable while in the original container as a concentrate. However, once diluted with water, many pesticides deteriorate — some rapidly — over a few hours. This information is usually not available on the label, and one must assume any diluted pesticide will not be stable.

Pesticides that come already diluted and ready to use are usually mixed in a way that makes them stable but only for the duration listed on the label. If there is no time of best use on the label, discard the mixture after one season.

The work-around to this problem involves planning ahead and mixing only the amount of pesticide you anticipate using. Any left in the sprayer should be applied to the area sprayed originally. One thing that should never be done is to pour the pesticide into the street gutter; this adds toxins directly to our waterways.

Related to this is how to handle pesticides that are old or have lost their label. These should not be used and should be stored in a safe place until the Tulsa M.E.T. has its twice yearly Pesticide Collection Event at the Tulsa Fairgrounds. The next collection event is Nov. 7-8 at the Tulsa Fairgrounds gate No. 7 from 10 a.m. to 3 p.m. All pesticides are accepted and disposed of in a safe manner.

Empty pesticide containers may be recycled but only after rinsing vigorously three times. The rinse water should be applied to the landscape area that received the original spray.

Most of us prefer not to use pesticides, or if we do, use the “soft” organic types that have less risk to you and the environment. There are many ways to avoid, or minimize, pesticide risk. This falls under the heading of IPM, or Integrated Pest Management. This widely used technique encourages the prevention of pests and their damage by managing the ecosystem. This involves careful monitoring of your plants and the correct identification of the insect or disease to decide if any management is needed. If so, it recommends steps that have low impact on the environment and also suggests accepting the fact that some damage due to pests is inevitable but acceptable.

Garden tips

·       Plant container-grown trees and shrubs this month. Fall is generally the best time to plant. At this time, the plants have no energy burden of producing leaves and can concentrate on growing a root system until the soil cools in winter. They are then better prepared for growth the following spring.

·       Check and treat houseplants for insect pests before bringing inside. Look at the roots and re-pot those that are root-bound. Irrigate the soil thoroughly before bringing inside.

·       There is still time to plant radishes and mustard in the fall garden.