Hello! I work in a hydroponics greenhouse and our cherry tomato plants are dying at the very top of the main stems. They seem to shrivel up and turn brown. I was hoping someone could assist me in identifying this. The fruit have no problems and suckers grow further down the plant, but they then tend to follow the same pattern of shriveling up and dying. All the other tomato plants in the row as well as the cucumbers and peppers are thriving using the same recirculating nutrient solution and substrate.