Manage Roundup ready resistant weeds in Soybeans

Fighting Weed Resistance in Indiana 01/21/2009by Gary Truitt
There will be more acres of soybeans planted this year in Indiana than last. And, as soybean growers learned last year, the earlier you plant your beans the better your yields. A number of companies have new products that allow growers to get into the fields early. Syngenta has a new product that not only lets farmers get an early start on soybeans but helps manage glyphosate resistance. Mark Kitt, Technical support representative with Syngenta, talked with HAT about new "Prefix “It can be applied 14 days pre-plant all the way up to pre-emergence and it has a lot of activity on many of the weeds that are becoming glyphosate resistant or even slightly tolerant.” These include lambs quarters, water hemp, and the ragweed complex. Kitt said Prefix also does well on annual grasses.

With the majority of the soybeans planted in Indiana being Roundup Ready, it is not surprising that our state is having a bigger and bigger problem with Roundup resistant weeds. Prefix has two modes of action which help fight the development of glyphosate resistant weeds. Kitt says Syngenta has been a leader in fighting the development of glyphosate resistant weeds, “We have worked with Purdue and other leading Universities to develop feasible programs to growers manage glyphosate resistance.” He said glyphosate is a technology that agriculture can not afford to lose.
Prefix consists of two proven chemistries, S-metolachlor and fomesafen, both of which work to protect yields by controlling highly competitive broadleaf weeds and grasses. Prefix consists of two proven chemistries, S-metolachlor and fomesafen, both of which work to protect yields by controlling highly competitive broadleaf weeds and grasses. S-metolachlor is a shoot growth inhibitor that prevents normal cell development so weeds cannot grow. Fomesafen controls weeds by causing rapid browning and tissue desiccation following exposure to sunlight. This combination provides a non-glyphosate, non-ALS herbicide option for controlling troublesome weeds such as common ragweed, waterhemp and Palmer amaranth (Palmer pigweed), which are known to be resistant to multiple herbicide modes of action. According to Purdue University research, weeds that reach 9 and 12 inches in height can cause 6 and 10 percent yield losses, respectively. According to Syngenta, it is important to control yield-robbing weeds early in the season because they compete for soil moisture, light and nutrients vital to soybean plants during the critical crop-establishment stages. Using a pre-emergence herbicide, such as Prefix, reduces weed density later in the season by providing residual control and also adds flexibility to weed management programs.