“The problem was urgent. I had two greenhouses full of plants — about $50,000 worth,” Harmuth said. “I knew I had to do something quickly or I wouldn’t have a saleable product.”

Harmuth carried a flat of discolored plants directly to the Agronomic Division’s Plant/Waste/Solution/Media laboratory. Staff gathered around and suggested a battery of tests: soilless media, irrigation water, nutrient solution and plant tissue.

Agronomist Aaron Pettit asked to see a fertilizer label.

 “It was like an emergency room,” Harmuth said. “I got undivided attention. About four people stopped to help me. They recognized the urgency . . . the potential economic disaster. My situation mattered to them.”


Pettit decided to zero in on the nutrient content of the media and the fertilizer. He had Harmuth bring in a sample of the original growth media. He analyzed that sample and a sample from the flat with the discolored plants.

Test results showed that the media originally contained 13 parts per million sulfur, but there was no sulfur left in the media the plants were growing in and none in the fertilizer.



Meanwhile Harmuth had gone home to research the problem online and had settled on sulfur as the possible cause of the problem as well. He felt vindicated the next day when Pettit called him with test results that confirmed his hunch.

Pettit recommended a modification of the fertility program and provided all the necessary calculations.



“Harmuth had been using a fertilizer that did not contain sulfur,” Pettit said. “He had also been applying iron and calcium nitrate as an extra nitrogen source to see if that would help the problem.

“I suggested he add Epsom salt (magnesium sulfate) and omit the iron application. It was also necessary to eliminate calcium nitrate, which chemically reacts with Epsom salt to form a precipitate that could clog the drip system.”



“Within two days, I saw marked improvement. Within four days, the change was incredible. It was a miracle turnaround,” Harmuth said.

“I had a real problem; I found a real solution; and it was real quick.”