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Comparison of Herbicides by Mario Villarino



Recently I got a request from one of our producers related to herbicide applications and the role of generic products today. After asking several questions related to the topic, I came to the conclusion that cost per application was the main concern.  According to F. Menalled, MSU Extension Service Cropland Weed Specialist there has been a proliferation of generic herbicides, look-alike products with different commercial names but the same active ingredient, which is the component responsible for its ability to control the target pest. Generic herbicides are the fastest growing sector in crop production chemicals, but will they work well for you and save you money? There are three main reasons of why generic herbicides have become so popular in recent years. The main reason for the proliferation of look-alike products is the expiration of patents. Agricultural chemical formulations are patented for only 17 years. During those years, only the company that has developed the product is allowed to produce and commercialize it. After that period, any company can synthesize the herbicide and commercialize it under a different name. In addition, because of the cost of development, registration and commercialization of new products has increased so much in recent years, companies may collaborate on some projects. So, when the product is finally released into the market, each company has the new technology available for sale. An example is that some herbicide resistant crops have been produced as a joint venture of several agri-chemical companies. Another reason for multiple brands of the same herbicide is technology licensing. To obtain quicker return for their investment, agri-chemical companies may license their technology and allow more than one company to produce the same active ingredient. One advantage of generic products is their cheaper price. Because generic manufacturers did not pay the cost of developing the herbicide, they are able to sell the generic products cheaper than the brand name alternative. Regardless, of what company makes the herbicide, the core issue is whether generic herbicides are as good as brand-name ones. Generic products have same active ingredients than the original brand name herbicides. Thus, generic and brand name herbicides should have the same performance. However, generic and brand name herbicides are not required to have the same inactive ingredients. For soil applied herbicides, the inactive ingredients would only influence handling and mixing properties of the formulation. Thus, performance should not be affected. Inactive ingredients of post-emergence products have a broader influence, including how well the product sticks to the leaf surfaces as well as other factors. The inactive ingredients of post-emergence products include solvents, stabilizers, emulsifiers, surfactants and other additives. These additives can make a difference in the performance of the product you are buying and are usually lumped in the labels as inert ingredients with no additional information revealed to the buyer. Nevertheless, products are extensively tested before release, and differences should be minimal unless one of the inactive ingredients is missing altogether. Another difference between generic and brand name herbicides could be the physical form of the active ingredient. Although several herbicides might get recommended at using at the same rate, they might not exactly be the same product. Although they have the same chemical formula the elements of the molecules are arranged slightly differently; they are “isomers” of each other. The concept of isomers is easy to be understood if we think in a pair of gloves. At casual glance the right and the left glove look identical. However, the fingers are arranged differently and the right glove does not perfectly fit on the left hand and vice versa. So it is with the two isomers of the same molecule. Specifically, the s-isomer is more active than the r-isomer, because it fits the herbicide binding site better .In conclusion, generic products tend to perform as good as their brand-names counterparts, provided that they have the same inactive ingredients and isomer structure. When evaluating whether generic products fit your farm, you should compare their cost, safety and relative performance. The bottom line is that you should not use a significantly inferior product, even if it is cheaper.

For more information on this or any other agricultural topic please contact the Hopkins County Extension Office at 903-885-3443 or email me at m-villarino@tamu.edu.




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