By George Silva
Soil and leaf tissue tests suggested low soil pH, magnesium deficiency and, to a lesser extent, sulfur were causing leaf striping on corn.
In 2017, several corn fields in Michigan’s Ingham and Eaton counties are showing excessive leaf striping, or interveinal chlorosis (see photo). Striped areas are sometimes interspersed with patches or rows of almost normal looking corn. A certain amount of leaf striping in new growth is noticeable every year, but plants generally grow out of it as the season progresses.
Scientific literature suggested corn striping can be caused by several nutrient deficiencies. These nutrients included magnesium (Mg), sulfur (S), zinc (Zn) and manganese (Mn). Non-nutrient factors are also implicated, such as herbicide injury, root damage, cold temperature, hybrid genetics, soil pH and soil type. With no clear cut evidence, there has been much speculation as to what is causing these symptoms.
Corn leaf striping at V8 in Michigan corn, 2017.
Some limited research was conducted in 2015 with tissue and soil analysis comparing striped areas and normal areas of the field (see “What is causing striped corn? – Part 1” and “What is causing striped corn? – Part 2” by Michigan State University Extension). Soil test data indicated the soil in the striped area was lower in organic matter, cation exchange capacity and pH compared to normal area. The striped area had below optimum magnesium levels in soil. Sulfur levels were considered low in both areas, even though the soil test is not a reliable indicator for sulfur.
Leaf tissue analysis indicated magnesium uptake was below the sufficiency range in the striped area compared to the normal area. The sulfur uptake was identical in both areas, but at the lower end of the sufficiency range. The nitrogen to sulfur ratio in the striped area was 29:1, indicating an imbalance and a greater likelihood of sulfur deficiency in the leaf tissue. The uptake levels of zinc and manganese were in the sufficiency range in both areas.
This study was limited in that only one composite soil and tissue sample representing good and striped areas of the field were analyzed. However, soil and leaf tissue tests pointed toward lower pH, magnesium deficiency and, to a lesser extent, sulfur deficiency as causing the leaf striping in this region.
Magnesium deficiency in low pH and coarse-textured soils is a concern in Michigan. In this instance, the soil test recommendation for the striped area was 2 tons per acre dolomitic lime. A rescue application of 20 pounds of magnesium sulfate (Epsom salts) as a foliar spray is also an option if field conditions permit.
MSU Extension recommends getting a soil and tissue test to identify potential causes. Fields that exhibit leaf striping symptoms will likely benefit from grid sampling and variable rate fertilizer and lime application program.