Gordon Johnson, Extension Ag Agent, Kent Co.; gcjohn@udel.edu
I recently looked at several snap bean plantings with symptoms of salt injury from starter fertilizer. Leaves had large areas that were dried from the margin inward, other areas were light green and showing signs of dessication. Symptoms were field wide and did not show up until after the plants had germinated and emerged. It was likely that fertilizer salts had moved toward the seedlings with water from rain and irrigation in high enough concentration to cause the injury. The grower had changed starter fertilizer to a higher analysis from previous years. Other crops were not affected. Caution should be taken with starter fertilizers, especially in crops that are sensitive to salts, such as beans. Choose low salt index fertilizers and limit the total amount of nitrogen and potassium (a general guideline is no more than 80 lbs total of N + K). Adjust fertilizer applicators to deliver the band no closer than 2″ to the seed and 2″ deep. If higher amounts of starter are required, move the fertilizer band farther from the seed.