While it’s best to get the smallest container of insecticides that fits your needs, sometimes you end up with more than you need. Can you use the insecticide next summer? How long is the shelf life? And is it dangerous to use expired insecticide?
Yes, insecticides expire, even if the package doesn’t have an expiry date. Eventually, they undergo a chemical change and can turn into crystals that make them impossible to use in sprayers. Don’t use old insecticides on plants! They won’t protect against pests and will harm your plants from phytotoxicity. If there’s no expiry date on the package, then assume 2 years from the purchase date.
What Is The Shelf Life Of Insecticide?
The shelf life, the time that you can safely store insecticide, depends on the primary ingredient and the storage conditions. If the insecticide has an expiry date, then the expiry date depends on ideal storage conditions. If it doesn’t have an expiry date, and you stored it correctly, you can assume it’ll last two years (handy tip: write the purchase date on the container so you don’t forget).
Avoid buying in bulk. You won’t save money in the long run. You will only end up with a bunch of expiring products you’ll need to dispose of properly. A better practice is to buy only the amount of insecticide you plan to use each year. If you have proper storage, you can buy insecticide in the fall when retailers put it on sale — it’ll still be in good shape come summer.
To extend the shelf life of insecticide:
- Store insecticide in its original, tightly sealed container
- Keep in a dry (40-50% humidity) room
- Keep at moderate temperatures around 55F – 65F (13C – 18C) — or at least prevent it from freezing or getting hot
- Place away from direct sunlight.
- Always read the label for additional storage information.
- Check older insecticides before use, and use up older insecticide before newer (unless it’s past its expiry date).
In short, keep it in its original container, keep it from freezing or boiling, and keep it dry and shaded. It’s the same process for extending the shelf life of fertilizer.
Does The Type (Formula) Of Insecticide Change Its Shelf Life?
Yes, an insecticide’s formulation affects its shelf life. Dust and wettable powders have a shorter shelf life than liquids because they’re more affected by humidity and high temperatures.
The concentration and stability of the active ingredient (the chemicals used to control pests) also affects shelf life. The lower the concentration, the faster it will lose its effectiveness. Organophosphates have a low stability, so naturally have a short shelf life.
However, manufacturers can add inert ingredients (any additional ingredients besides the active ones) that can prolong the shelf life, so make purchasing decisions based on your needs and by the manufacturer’s expiry date.
Natural insecticides like neem oil, spinosad, and bacillus thuringiensis also expire, but not any faster than most synthetic insecticides. Neem oil lasts the shortest at up to 2 years with proper storage, while spinosad can last up to 5 years.
What Are The Signs That Insecticide Is Gone Bad?
Before using older insecticides, check for the following signs:
Wettable powders: clumps and/or will not mix with water.
Dusts and granules: caking or clumping.
Emulsifiable concentrates: adding water does not produce a milky solution.
Oil sprays: sludge and/or solution separates.
Aerosols: clogged nozzle or the propellant no longer works.
Neem oil: discoloration or cloudiness.
Other general signs include:
Foul smells! As an insecticide deteriorates, it can give off an obvious stronger smell, especially if there’s a leak, spill, or improperly sealed container.
Missing or degraded label. If you can’t read the label anymore, don’t use it and properly dispose of it.
Is It Dangerous To Use Expired Insecticides?
Yes, it’s dangerous to use expired insecticides. As time passes, the chemicals in the insecticides break down and change composition. This makes them less effective as insecticides and also much harder to apply, as they get chunky, flaky, or form crystals. Liquid pesticides may turn into gas as it deteriorates, which can cause the container to rupture and explode when handled. And even if you can use it, expired insecticides will directly harm your plants!
Phytotoxicity is plant damage from something the plant was exposed to, like insecticides and herbicides. The symptoms include:
- Leaf speckling
- Leaf margin necrosis (browning) or chlorosis (yellowing)
- Brown or yellow leaf spots or patches
- Leaf cupping or twisting
- Plant stunting
- Plant death
Some plant species are more sensitive to phytotoxicity than others, and the amount of sprayed insecticide will change how much they’re affected. The best way to prevent this is by only using insecticides as intended, making sure they’re still good before use, or avoiding insecticide use when not needed.
How Do You Dispose Of Insecticides Properly?
If you have leftover or expired insecticide that you need to safely dispose of:
- Follow all the disposal instructions on the pesticide label (it’ll be under “Storage and Disposal”)
- Check with your local waste management authority for household hazardous waste collection programs. They can also advise you on the best way to dispose of insecticides according to municipal and state regulations.
Avoid these solutions:
- Never reuse empty pesticide containers, as the residue can contaminate the new contents.
- Never pour pesticides down the drain, as municipal drinking water and wastewater treatment systems can’t remove all pesticides, and if they reach waterways, they will harm the local environment.