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Do Your Beans have GIMD?

University research has determined Glyphosate Induced Manganese Deficiency occurs in glyphosate-tolerant soybeans in 2 ways. The first is caused by the glyphosate tolerant gene itself, interfering with the soil uptake of manganese into the plant. The second occurs after the application of glyphosate, and interferes with cation exchange, and the plant’s ability to metabolize manganese that is already in the plant tissue.

Factors that determine the severity of GIMD in soybeans are:

  • Soils that are known to be manganese deficient.
  • Soil pH values of 7.0 and higher.
  • “Yellow Flash” is seen after glyphosate application.
  • Physiological factors caused by glyphosate application.


MAN-GRO DF is a highly concentrated water soluble manganese powder designed for foliar application. 3 pounds of MAN-GRO DF applied to soybeans in the R1 to R3 stage of growth, 3-10 days after glyphosate application will correct GIMD. The addition of an adjuvant/water conditioner will assist in mixing and maximize uptake of manganese. MAN-GRO DF is compatible with most insecticides and fungicides.

Manganese Agronomics

Manganese is an essential micronutrient for crop production in general and for Legumes it is absolutely required. Traditional methods of applying Manganese to the soil have proven not to be consistently effective in supplying the amounts needed for maximum yields achievable today. Manganese in its plant available form as a divalent cation (MN++) is very easily “tied up” by other elements or factors in the soil. Soils with a pH of 7.0 and up will cause Manganese deficiencies as well as High Cation Exchange capacity (organic) soils. Other factors causing this phenomenon are high levels of Calcium, Iron and Magnesium which all share the same divalent status and compete for space on the soil particle. An excellent example of this problem is the area in the Southeastern United States where “Homogenous” fertilizers were sold for 40 years. Soybean special and Peanut Special fertilizers containing 2 to 3 per cent Manganese were applied at 400 to 600 pounds per acre (12-18 pounds of Manganese per acre per year) and crops still show visual Manganese deficiencies.

Manganese Sulfate is the best form of Manganese to apply for crop performance. It should be applied as an in-furrow application in the soil. This will provide sufficient Manganese to get the crop off to a good start and last until there is enough foliage for a foliar application. Manganese is one of the Micronutrients that are relatively immobile in the soil. It is taken up from the soil solution (must be soluble because plants drink there food, they don’t chew It.) and transported from root to shoot through the phloem. Once in place the Manganese is not translocated from older leaves to new growth, hence the reason foliar application is necessary. The increased use of Glyphosate Tolerant Crops such as Soybean, Cotton and Corn has accentuated the need for foliar applications. The same genetic addition that adds the tolerance of Glyphosate tolerance to plants also inhibits the production of enzymes that allow the plant to take up manganese a/or move it to the growing parts. In the early days of GMO crops before much research had been done this phenomenon was known as “yellow flash” or “Green Stem”. I usually occurred after an application of Glyphosate and resulted in reduced yield and delayed maturity.

Manganese is an activator or catalyst of enzymes such as dehydrogenases, transferases and decarboxylases. It is a part of the enzymes involved in respiration and protein synthesis. Manganese also activates the reduction of nitrites and hydroxylamine to ammonia. As an activator for enzyme reactions and oxidation/reduction hydrolysis it supplies the O2 for plant respiration. It has both direct and indirect effect on Chloroplasts and their conversion of sunlight to chemical energy. All of the above activity results in more nitrogen metabolized by the plant and since 50% of grain (yield) is the direct result of protein which are compounds of nitrogen the result is increased yield from applied nitrogen. The rule of thumb is 1 pound of actual Manganese per acre. Soil types, ph, temperature and crop will determine how much more should be applied.