J_Kushanswered grow question 2y ago More likely a nutrient surplus. If the concentration in the soil is too high, the plant's selection mechanisms get overwhelmed and too much fertilizer enters the plant. Right before harvest, I would only give them water. You can save a lot of money on fertilizer and increase yields both quantitatively and qualitatively. Because growth reduction already occurs before chlorosis and necrosis. If you're interested, check out "ion toxicity.