Every year it seems there is an epic struggle to decide which glyphosate product to purchase. Luckily, glyphosate is not a very complicated product, and with the high uniform quality of today’s products it is not too difficult to have a high success rate if used in the proper solution within good application parameters.
There are three basic ingredients involved in any glyphosate formulation; the parent acid in the formula is the most important part. This is the actual active glyphosate ingredient that kills the weeds. Different brands of the chemical come in different concentrations of the parent acid, with a focus lately on higher concentrations of active ingredient. There is no difference between the formula of the acid between chemicals, between concentrations or brands. As long as the solution has enough parent acid in it for the required concentration, this aspect of the chemical should not have any effect on how well the tank-mix works. Lower concentration of active ingredient just means you have to deal with a larger amount of product, as compared to a formula with a higher concentration.
The second main ingredient is a salt of some sort. This salt is used to stabilize the product making it easier to handle as well as making it easier to tank-mix effectively. There are only three different salts that are used between products, and this information can be found on the product label.
The last ingredient is the proprietary components. This includes surfactants, de-foaming agents and other ingredients added to make the product more effective or easier to work with. These ingredients are sometimes hard to find because all of them are not placed on the label. Knowledge of the salt used and what other ingredients are included in a glyphosate product does have a bearing on getting the most out of the product.
KEYS TO EFFECTIVENESS
One of the major factors for glyphosate effectiveness is clearly identifying the weeds present and their staging, and then applying the correct amount of glyphosate needed to properly control those weeds for their size. The most common mistake made is not using enough chemical to properly control weeds present or using a product concentration that is below the recommended rate on the label. For example, on my farm I know glyphosate doesn’t do a great job on wild buckwheat. If it’s there, I make sure to juice up my rate and use a tank mix I know will work. Even then sometimes it takes a much longer time for the wild buckwheat to die than the more susceptible weeds.
Another important factor not to be overlooked is the water used and its qualities that could negatively impact how well the glyphosate works. Many rural town wells contain water that is very high in dissolved salts. The more salt in the water the higher the likelihood that it will impeded product effectiveness. When mixed in solution the natural salts in the water, usually calcium or magnesium salts, attract the glyphosate molecules. These salts are much different than the salts in the glyphosate product. If you’re seeing reduced glyphosate effectiveness, check your water first.
Water volume is also an important factor to how well the glyphosate works. Research suggests that a solution sprayed at under ten gallons an acre work best. This is in part because as the amount of water goes down the higher the concentration of active ingredient in the solution, reducing dilution of the glyphosate. However, reduced spray volume increases drift and could hamper weed coverage. A happy medium of around five gallons an acre seems to be the consensus of maximum efficiency depending on weed size and population.
Just about every farmer has been in the middle of spraying and had the weather turn on them. A sudden change in the environment while spraying has a significant impact on product effectiveness, but we’re not just talking about rain — weeds can really respond during the day to large swings in temperature. Spraying when temperatures are predicted to stay relatively constant should mean best results, but this can be hard to accomplish because work just needs to get done when it needs to get done. However, spraying through the hours when the weeds are most actively growing will go a long way in making sure that the control can be greatest.
As it turns out the actual formulation or concentration of the glyphosate is not the largest factor in how well it works. These factors come down more to the little things that the applicator can sometimes control and sometimes cannot. Being aware of your water quality is one thing I personally think goes by the wayside when one gets busy. Yet being aware of this and making sure it’s the right quality can go a long way in making sure your glyphosate stays effective. It is also important to scout out your fields so you are getting the proper amount of chemical on each field. A generic rate may not work on every field so being flexible in your chemical solution for each application can help assure clean fields. This is also true in making sure that there is enough chemical present to control tough to kill weeds as well as large weeds at the time of spraying.
Environmental factors play a key role in spraying success. There is no real scientific data out there yet on things like the impact of dew, for example, so commit to taking good notes and trying to repeat what works for you. Glyphosate is one of the most used tools to control weeds so a greater understanding hopefully means greater success in your use of it.