However, in severe cases, a general lack of vigorous plant growth is obvious from time of transplanting. The injury can show up on seemingly healthy, vigorous plants in late June or early July following a heavy rain. Diagnosis and Identification To determine the specific problem, collect leaf samples of the affected plants along with soil samples from their rooting area. Analyze the leaf tissue specifically for Mg and Mn, and the soil specifically for pH and Mg.
Diagnosis is made on the basis of analytical values found in the tissue and soil.
The problem is one that is best corrected for the following crop, due to the requirement for thorough mixing of lime with soil. The Mn toxicity is corrected by adjusting soil to pH 6.0 or above with lime application. The soil analysis provides a lime requirement value that indicates the amount of lime required to raise soil to pH 6.0-6.5. Apply lime only on the basis of soil test and lime requirement value. Magnesium deficiency is corrected with the addition of Mg to increase exchangeable Mg to 75 pounds Mg per acre.