Either Ca or Mg deficiencies often cause deformities in the shape of cupping (did you add dolomite to your mixes? does your fertilizer contain Ca/Mg?). Deficiencies of zinc and molybdenum can also cause the same distortions. Too much or not enough water can do it, too.

Any chance the plants caught any herbicide over spray? What Osmocote formulation did you use? Selecting a product that matches your zone and plant requirements can have a considerable impact on what benefits are gained by your plants.

Al

Al, thank you for your response. You are the foundation of this forum. I did not add dolomite to the mixes, as my water has plenty of Ca (78 mg/L) and Mg (30 mg/L). To the mix I added Florikan MIV Meg-Iron, which has .09% Zn and .06% Mo. I added 1 lb./ cu. yd, or about 1/6 tab per gallon of mix. The Osmocote in the mix was Classic 18-6-12 (I know you like this ratio) in 8-9 months. There is little chance of herbicide spray, as the plants are in a high tunnel. Could it be too much or too little water? The problem with plants seems to be that too much or too little water can result in similar symptoms.

Unless I come up with a definitive answer, I am hoping an experiment will shed some light. I am placing two similar plants side by side. For one I am cutting back on water. For the other I will increase the watering amount slightly. We will see which looks better over time. I hope they both do not die!

Thank you again,
Marc