I planted some zinna's recently in a raised bed. They have grown well except that the stems seem to be deformed with about half of them bending downward. The foliage seems to be developing well. They receive full sun and have been well hydrated. I have fertilized them with neptunes fish emulsion and I did spray some spinosad and used diatomaceous earth for a caterpillar infestation. I planted them in some composted cow manure. I have read of herbicide carry over in manure from pyridine carboxylic acids could this be the cause of the bending/twisting stems?