Dicamba (3,6-dichloro-o-anisic acid), I, I '-dimethyl- 4,4'-dipyridinium ion (paraquat), and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) were applied as foliar sprays to 4-year-old sweetgum (Liqu.idambar styracifiua L.), green ash (Fraxinu.s pennsylvanica Marsh.), water oak (Qu.ercus nigra L.), and loblolly pine (Pin.us taeda L.). For the three hardwood species the amount of herbicide absorbed and transloca ted, as measured 4 days after application, was correlated closely with tops killed 1 year later. Applications in May were more effective than those made later in the growing season. Loblolly pine was defoliated by all herbicides but recovered the second season after spraying.
Brady, Homer A. 1971. Spray date effects on behavior of herbicides on brush. Weed Science volume 19, number 3, pages 200-202. May 1971.