If symptoms of fallow syndrome appear on corn, you must identify them early to attempt any rescue treatment.
Affected plants tend to show typical phosphorus deficiency symptoms.
They have purplish leaves and are smaller and more spindly than unaffected plants. Experiments evaluated post-plant applications of fertilizer phosphorus on research farms in Buchanan and Howard Counties in 1960 and in Buchanan County in 1961. Application of 30 lb P2O5 per acre was after the date of planting, not after the date of emergence. Fertilizer phosphorus was placed by hand 2 to 3 inches to the side of the row and 4 inches below the soil surface. In both experiments, corn yields increased 5 percent with an application 5 weeks after planting.