Manganese deficiency in winter wheat
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EmailEditor’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.
Many
stands of winter wheat in the state have taken a good beating this
spring due to early growth followed by a mid-April cold spell. The
variable weather affecting wheat growth has also prompted the appearance
of manganese (Mn) deficiency in some fields. Manganese deficiency is
the most common micronutrient problem in Michigan, and wheat is highly
responsive to Mn. Manganese exists in many forms in the soil, most of
which are unavailable to the growing crop. An adequate level of Mn2+,
the primary plant-available source in our soils, is influenced closely
by soil pH. Manganese issues most often occur on organic peats or mucks
with pH >5.8, but can occur on mineral lakebed and glacial outwash
soils with pH > 6.5. Manganese deficiency in wheat generally shows up
in patchy areas within a field, and appears as generally stunted plants
with yellowing of the upper leaves, slight striping of the leaves and
whitish or colorless spots. In some wheat fields, sprayer or tractor
tracks will appear noticeably healthier through an area of Mn deficient
plants. This phenomenon results from the slightly compacted, more
anaerobic (wetter) conditions under the tracks where bacteria convert Mn
oxide to plant-available Mn2+. Often times, Mn deficiency shows up
early in the spring as a result of limited root activity from
environmental conditions (weather, compaction, disease, N deficiency,
etc.), even though there may be sufficient Mn2+ in the soil. If limited
root growth is driving the deficiency, the crop will often grow out of
the Mn deficiency when conditions become more favorable. If you’re not
willing to wait and see, foliar applications of Mn fertilizer can be
effective at correcting the deficiency. Spray grade carriers of Mn
sulfate are the recommended source, applied at a rate of 1 to 2 lbs of
actual Mn per acre with 30 gallons of water and a sticker. (Always be
sure products are compatible prior to tank mixing.) Chelated sources of
Mn generally tank mix better, but are much more expensive and are
generally no more effective than inorganic sources.
A detailed discussion of Mn deficiency in wheat, including deficiency photos, can be found at: http://www.omafra.gov.on.ca/english/crops/field/news/croppest/2005/04cpo05a2.htm
