Yellowing after herbicide use

The yellowing observed in RR (Roundup Ready) soybean after glyphosate application may be associated with momentary manganese (Mn) deficiency.

This deficiency is one of the most commons nutritional problems in soybean fields.

It is often and can occur without showing visible symptoms, and even so reducing crop yields.

Researchers have analyzed the relationship between the use of some herbicides and the decrease on Mn availability and absorption in genetically modified crops. Some studies have pointed out changes on population of microorganisms responsible for providing manganese to plants. Over a period, the plant could not absorb manganese, even though it may be abundant in the soil.

The higher is the glyphosate rate; the lower is the manganese absorption.

Number of organisms responsible for manganese reduction and oxidation in rhizosphere, three weeks after glyphosate application on RR soybean.

An application of 3 l/ha of YaraVita Glytrel MnP tankmixed with glyphosate gave an 18% increase in seed yield compared to the untreated control. 2 x 3 l/ha YaraVita Glytrel MnP, the first tankmixed with glyphosate and the second applied alone 14 days later gave a 19.1% increase in seed yield compared to the nil. YaraVita Glytrel MnP applied as a tank mix was safe to the crop and did not affect the ability of the glyphosate to control weeds at the site.