Stonerdanswered grow question 4 years ago Might be Manganese (Mn) or Zinc (Zn) deficiency or just a simple Nitrogen (N) deficiency, check the pH in your irrigation and make sure its in optimal range (5.5-6.5) if it's okay then just increase the micro-nutrient and Nitrogen fertilizers you use by 20% and monitor the plants' health closely, if it responds well then increase until plants are in full health and vigor.
Hope this helps! Good luck and happy growing :)