As the tomato plants grew larger, they slowly developed mild symptoms of auxin herbicide damage. Today, I discovered that it is very common for manure to be contaminated with the herbicide, aminopyralid. See
https://en.wikipedia.org/wiki/Aminopyralid . I suspect that aminopyralid in the manure stimulated the early growth of tomato seedlings.
While the plants were still in pots, I had some success in reversing the leaf distortions by spraying with 10 ppm Thidiazuron (TDZ).
Now, all of my tomato plants are doing fine outdoors in the ground. On some of these, I tried duplicating damage from spray drift of 2,4D by spraying 5 ppm 2,4D on the entire upper surfaces of the leaves of several tomato plants. It took more than one spray to produce mild leaf distortions. I sprayed one plant with TDZ and the distortions worsened but growth is faster than normal.
There doesn't seem to be much literature about why different synthetic auxins affect plants differently. For example, why does quinclorac, but not 2,4D, kill crabgrass?
Interestingly, at very low concentrations, many herbicides improve the growth of some plants. See
https://www.researchgate.net/publica...e_plant_growth
http://www.ask-force.org/web/Herbizi...osate-2008.pdf
An Error Occurred Setting Your User Cookie
http://www.public.iastate.edu/~taber...003/DevTom.pdf