How To Safely Use Pesticides In The Garden, Part II

When we talk about pesticide safety there are two critical areas to consider. The first is personal safety as in yours and those around you. The second is environmental safety and that encompasses how to use pesticides with the lowest possible environmental risk, knowing how to avoid those risks and what to do if and when you screw up.

For your personal safety there are some things you should always do and some things you should always have. When handling these materials, liquids or granules, always wear protective gloves. These gloves can be as simple as disposable latex gloves (5 mil. are best) or rubber gloves. Never use cloth gloves, lined or flocked gloves, as these will absorb the materials you’re trying to protect yourself from. Wear the gloves when handling any type of liquid, powder or granular material. When using liquids always wear safety glasses to prevent any spilled or splashed material from getting in your eyes. These should be the wrap-around type of glasses or goggles that give you the best protection. You may even want to wear a respirator but be sure that the respirator you use is certified for use with pesticides as others will provide ineffective protection.

When applying granular pesticides with a spreader be aware of the correct spreader setting and how far your spreader will throw the material to the sides. Never allow the material to land on sidewalks, driveways or in gutters and don’t apply the material to areas where it may wash or dissolve into streams, ponds or waterways. Try to fill the hopper with only the amount you think you’ll need based on the total square foot area of application. It’s better to need to add more than to have to try and pour it back into the bag as this is where and when most spills occur. Read the label to see if there is a waiting period before you can re-enter the space you’ve treated and if it needs to be watered in. Every few years you should calibrate your spreader. You can find instructions on how to do this online.

When applying liquids never make applications when there is wind and check to see when rain is expected. Some sprays need to be on the foliage for a certain amount of time to be effective. Never allow your spray to drift. You should always have complete control of the pressure and spray pattern. Never open the sprayer while it is attached to a hose or while the container is pressurized and never, ever, look at a pressurized sprayer’s filling area or neck (pump type) when you’re draining and depressurizing. Mix only as much material as you calculate you will need and have a plan for disposing of any that might be left over. Never allow any spray to drift near streams, ponds or other water sources. When spraying herbicides for weeds remember that these can also kill other non-target plants like shrubs, garden annuals, perennials and nearby vegetables.

Keep your tank sprayer, the type you pump with a handle, clean and free of debris. It seems that dust and dirt just can’t wait to get inside the tank and clog the nozzle. One of the most dangerous times when using a pump sprayer is when the nozzle gets clogged. You have to release the pressure—never a safe procedure—remove the nozzle and find a place where you can clean it out. Every time you fill the sprayer make sure there’s no debris at the filling neck and after each use fill it with some clean water, pressurize the tank and let the clean water pass through the nozzle for a minute or so to clear it.

Never use the same sprayer for pesticides and herbicides. Even a small amount of herbicide mixed in with your pesticide can result in a garden calamity. If you can, have one sprayer that you mark with an “I” (insecticide) and a second that you mark with an “H” (herbicide).

Don’t mix different pesticides together unless you are absolutely certain that they are compatible. Such mixes can cause unforeseen consequences to you and your plants. And when the label says to mix a tablespoon of material with a gallon of water never, ever assume that 2 tablespoons will kill twice as much or twice as fast. It may just end up killing everything.

Be aware how your pesticide reacts to both heat and sunlight. Many botanical-based pesticides like pyrethrins degrade very quickly in sunlight and can be ineffective when it’s too warm. You’ll also see that some pesticides like Spinosad should be applied only a certain number of times a year to avoid insects building up a resistance to it. In fact, it’s always best to rotate among several pesticides to avoid any resistance issues. Some pesticides contain a synergist. That’s an ingredient that makes the pesticide work better. A good example is a pyrethrum-based insecticide that contains piperonyl butoxide, or PPO. PPO actually excites the insects and makes the insecticide more effective. On the down side though, PPO is not an organic material. When PPO is listed on the label of a pyrethrin insecticide, the product is not considered an organic pesticide.

Another consideration when applying liquids is pressure and droplet size. As you increase the pressure in your sprayer you can also be making the droplets that come out of the nozzle smaller. In some cases, like leaf coverage, a fine mist like this can be good. But it can also be bad because the smaller the droplet size the more likely it is that the pesticide will drift with the slightest breeze. Larger droplet sizes are best for herbicide applications. Droplet size and stream pattern can usually be adjusted at the spray nozzle tip and you can buy nozzle replacements for some pressure (pump) sprayers that control both the droplet size and the spray pattern from a cone, which is good for insecticides, to a flat pattern which is good for herbicide applications.

Don’t store pesticides in anything other than their original containers. Every year I read about children and adults who are poisoned—often fatally—when they splashed or ingested a pesticide that was in the wrong or unmarked container. And if you have bottles and bags of pesticides that you’ve stored in your garage or shed, get rid of them. They lose their effectiveness over time and the liquids should never be allowed to freeze. Don’t store them where kids will have access like along the basement stairs or under the kitchen sink. Every municipality has either a pesticide disposal day or they can tell you where and when the county has one. That’s where your extra bottles and bags should go, not out in the woods or down the drain.

It’s a good idea to know how insecticides work. Some disrupt reproduction, some destroy the insects’ nervous system, some, like the oils, simply smother them while others introduce a fungus or bacteria that eats the insect while others destroy their stomachs. Some work on certain insects like beetles while others work only on soft-bodied insects like aphids and others work only on mites. You also should know if the insect has to feed on the plant to ingest the insecticide or if the insecticide works on contact, or both. And you may also find it helpful to know if you need to spray the entire plant or just one surface. Translaminar insecticides like Spinosad are absorbed by the one side of a leaf and is then passed through the leaf so the other side becomes toxic as well. Knowing these things adds to your arsenal, in addition to the materials you use.

Lots to know and probably more than your realized. But knowing all this, and more, makes you a more effective gardener and environmental steward. Keep growing.