Monday, July 13, 2009
Potassium and Nitrogen Deficiencies in Tomatoes - submitted by Mark Kepler
On July 10, 2009 Liz Maynard, vegetable specialist and myself (Mark Kepler) went to Titus Oberholtzer’s two high tunnels in which he is growing fresh market tomatoes. Liz brought along meters used for analyzing leaf petioles for Potassium and Nitrate levels. We tested plants that have a yellow shoulder problem.
Levels in these plants were substantially lower in Potassium (1400 ppm in plants with yellow shoulder disorder vs. 2200 ppm in normal plants). Leaves in another greenhouse were compared for nitrogen levels. The stunted plants had nitrate levels of 360 ppm and those larger plants had a reading of 2500 ppm nitrate, confirming suspicions of a nitrogen deficiency.
These results were consistent with recent tissue test results for entire leaves performed by a commercial lab. It is my opinion this is a good tool to use in greenhouse situations to monitor plant fertility levels.