Suzanne Wainwright-EvansWhile we may not all agree on how to manage insect problems, we can all agree that reducing pesticide use is a good thing. How do you go about this? There are a few simple steps to take. Follow them, and you will see the savings in your wallet.
The first step is always to correctly identify your pest. Don’t guess. If you are not absolutely sure, take or send a sample to your local extension office or to an independent lab. Sometimes what you thought was a pest may turn out to be a beneficial. You may actually have beneficials that are feeding on your pests. If it is a true pest issue, be sure to select a product that has your specific pest on the label. Also be sure it is labeled for your location.
Correct pest identification is key to reducing pesticide use. Photo by ©iStockphoto.com/Arie J. JagerRates matter
Pesticide rates are not listed on labels as a suggestion. Application rates are something that should be followed very closely. Although a grower may be tempted to use a lower rate to make the pesticide dollars stretch a bit further, this will ultimately take a huge bite out of your bottom line. Instead, the pests will not die when sprayed, but will be exposed to what is called a sub-lethal dose. This exposure without killing allows the pests to develop resistance to the pesticide, making them harder to kill. The old saying “what doesn’t kill you makes you stronger” is true for lots of pest insects.
Of course this saying might tempt a grower to use a higher rate to be sure they achieve a full kill on the pest population. If mixed pesticide rates are too high, it can be a health hazard to both you and your plants, as well as a waste of money. There is no difference between dead, and really, really dead. The only difference is you spent more money for really, really dead pests.
Know your pH
One important aspect of mixing pesticide sprays is the water quality. Water is essentially the carrier for the pesticides, and if your spray water pH is too high, you might as well spray water alone.
When a pesticide is mixed with alkaline water (water that has a pH value greater than 7) a chemical reaction may occur, called alkaline hydrolysis. This reaction can cause the pesticide’s active ingredient to break down quickly. The active ingredient is the entire reason you purchased that pesticide in the first place. When the AI’s chemistry breaks down, it will not only become less effective initially, but will also inhibit residual efficacy. In extreme cases, the spray product may not be effective by the time you finish your application.
Ideally for many pesticides, the pH of the spray water should be around 5.5. The best way to test the spray water is with an accurate pH meter. There are many models available ranging from $20 to hundreds. A less expensive option is pH paper, but this method is not nearly as accurate. These paper strips can be purchased for around $8 a package.
If the pH is off, and correction is needed, what do you do? There is an easy-to-use product available called Indicate 5, available from many horticultural supply companies. It is a color-coded pH adjuster. The pink adjuvant is poured into the spray water until it reaches the desired pH (as indicated by the resulting color of the treated water). Additionally, Indicate 5 also acts as a buffer (holding the pH at the right level). It also contains a surfactant to evenly distribute the spray across the leaves and stems, normally resulting in better and more uniform spray coverage. Mix Indicators in the spray water to adjust the pH before you add the pesticide.
Not all pesticides are pH dependent (Table 1). Again check the label or ask your supplier.
If the spray water pH is acceptable, and no adjustment is needed, you may still need a sticker spreader (this is not always true with electrostatic sprayers). Check the label or ask your pesticide supplier if a sticker/spreader is needed for your intended pesticide.
One exception is when using MilStop. MilStop is a bicarbonate based formulation that raises the pH on a leaf surface when applied as a foliar spray. Since acids can neutralize bases, a grower should not adjust (lower) the pH of the water used to dissolve MilStop. Many active ingredients can become unstable at pH above 7, and mixing them with MilStop is not a good idea. MilStop is labeled as a fungicide for many types of foliar fungal diseases in and can also be used on soft-bodied insects. New York State has granted a FIFRA 2ee exemption for this use.
Cover the pests
Pesticide applications can be made a few different ways. Conventional sprayers are economical and rather low tech, but they get the job done. There are concerns with this method because of the large volume of spray that must be applied to get thorough coverage. This can lead to over-spray and pesticide runoff. An alternative is an electrostatic sprayer, but this is not a cheap option. The initial investment can be quite costly, but if you have large areas to treat, this option is a great way to go.
Electrostatic sprayers work by charging the spray solution, causing it to “stick” to the plant surfaces when it comes close. Think of a balloon sticking to your hair after rubbing it on your head. This charge allows you to get better under-leaf coverage, where many pest insects and mites often hide. Because the insecticides are “attracted” to the foliage, a grower will actually use less product because there is no over-spray or runoff. The rates may need to be adjusted because the same amount of insecticide needs to be applied, just with less water.
Proper storage will extend the shelflife of pesticides. Do not leave bags open.Pesticides and shelflife
Most pesticides have a shelflife of two to three years (some fungicides only one year). Over time the pesticides break down due to many factors such as temperature extremes, high humidity and light exposure. Sometimes liquid formulations settle out and won’t go back into solution. They may become murky or milky. Wettable powder formulations can clump due to humidity.
Once these products begin a degradation process, the effectiveness of the pesticide is proportionally reduced. Of course proper storage will extend the shelflife of pesticides, but at some point, even the most carefully stored chemicals will become next to useless, or even dangerous. If you are not sure about any older pesticides that have been on the back shelf for a while, ask the manufacturers about the shelflife. It could be that you have some very expensive paper weights. To add insult to injury, now you will have the cost of disposing of hazardous waste.
Follow a few simple guidelines to maximize your pesticides’ shelflife. Close all containers tightly and seal bags of dry products between applications. Date the containers as you receive them and try to rotate containers and use the older products first.
Pesticides can be very expensive — not only the cost of the products, but the application costs, too. By being wise about when you need them and how to apply them, you can save money in your pest management budget.