Roundup or Touchdown? Banvel or Clarity? Prowl or Repose?
Buctril or Bromox? In recent years, 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 postemergence products have a broader
influence, including how well the product sticks to the leaf surfaces as well
as other factors. The inactive ingredients of postemergence 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. For example metolachlor is the active
ingredient of Dual II Magnum, a product labeled for corn, potatoes, safflowers,
grains or forage sorghum and soybeans. Recently, Sipcam started to
commercialize metolachlor under the name of Stuart C. Although both herbicides
recommend using the same rate, they are not exactly 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 metolachlor.
Specifically, the s-isomer is more active than the r-isomer, because it fits the
herbicide binding site better. The difference between the two metolachlors is
that Dual II Magnum has a higher concentration of the s-isomer than the generic
counterpart. Thus, for the same concentration of active ingredients, it
effectiveness could be higher in situations where grasses are dense or multiple
flushes could occur.
A similar idea applies to glyphosate, the active ingredient of Roundup.
Generics may differ in chemical form, i.e. potassium, diammonium, or
monoammonium salts. Nevertheless, several studies showed that only minor
differences were observed between the glyphosate formulations and these
differences were most likely due to variations in the weed populations from
plot to plot.
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.
Disclosure. Common chemical and trade names are used in this publication for
clarity by the reader. Inclusion of a common chemical or trade name does not
imply endorsement of that particular product or brand of herbicide and
exclusion does not imply non-approval.
Categories: Weed, Integrated Weed Management, Herbicide label
Date: 05/12/2005