Identifying and correcting manganese deficiency
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Manganese deficiency is the most common micronutrient issue found in Michigan row crop production. Soybeans and wheat are the two field crops most likely to develop manganese deficiency, although deficiency may also be found in corn and sugar beets. Manganese deficiency appears as yellowing between the leaf veins (interveinal chlorosis) of corn, soybeans, and sugar beets, and as yellow-green striping in wheat. Manganese deficiency is most likely to be a problem on organic soils (mucks) with a pH greater than 5.8 or on dark colored lake bed and glacial outwash soils that have been limed to a pH greater than 6.5.
Due to the variability of our Michigan soils, often times the low depressional areas in a field will tend to be mucky and will show manganese deficiency when the rest of the field looks healthy. But, these areas may also be yellowing as a result of nitrogen deficiency stemming from denitrification or leaching. One distinction between nitrogen and manganese deficiency in crops is that manganese deficiency will show up in the younger, newest leaves of the plant, while nitrogen deficiency will appear on older tissue (lower leaves).
The best way to be sure what is causing the deficiency is through soil and tissue analysis. But, if your field has a history of manganese deficiency, these areas will tend to show the deficiency (and will need to be corrected) on an annual basis, since most of the manganese in our soils is in an unavailable form. Even when a soil-applied manganese fertilizer is applied, a large portion of the manganese will be very quickly tied up, or fixed, in the soil in an unavailable form.
Correcting Mn deficiency
If you have a field, or part of a field, that is manganese-deficient, it is important to correct the problem as soon as possible to reduce the risk of yield loss. Foliar fertilization with an inorganic or chelated manganese source is the most effective means by which to correct a manganese deficient field crop. The foliar manganese should be applied at a rate of 0.5 to 1.0 lb Mn per acre with at least 20 gallons of water (30 gallons recommended). Chelated manganese sources have not been shown to be more effective and should be applied at rates equivalent to inorganic salts (manganese sulfate). Many products, particularly multi-nutrient products, are often labeled at very low rates, and care should be taken to assure that appropriate rates to correct the deficiency are applied. In some cases, a second application may be needed at a later date to correct the deficiency. Use caution if you plan on tank-mixing manganese fertilizer products with glyphosate products, as research has shown antagonism between many manganese fertilizer formulations and glyphosate. More information about this antagonism can be found in the accompanying article by Kurt Thelen.