VEGETATION MANAGEMENT — EGLER 305 



to desirable plants. Ammate is also applied in powder form to cups 

 notched in the bases of trees. Although this practice has been adopted 

 for control of weed trees in timber forests, it is relatively unusable 

 on rights-of-way, where the individual stems are usually too small 

 for cupping. Stump treatment on rights-of-way where the forest 

 has been newly cut is another possibility, but here also comparative 

 data with D-T treatments are lacking. 



SPRAYING 



Techniques of D-T spraying are sharply divided into opposing 

 groups. There is dormant-season vs. growing-season spraying; pack- 

 sack vs. power spraying; blanket spraying vs. selective spraying; 

 and foliage vs. basal spraying. Most treatments are either (1) sum- 

 mer foliage blanket-power spraying, or (2) winter basal selective 

 pack-sack spraying. Neither of these is a panacea for all ills, but 

 both have their roles. Nevertheless, it is the former which, though 

 giving relative relief from the high costs of hand-cutting and show- 

 ing quick visual results, is unsupported by impartial vegetation- 

 management data; whereas the latter is primarily responsible for 

 results that point to the lowest long-term costs and the highest public 

 benefits. 



Foliage sf raying involves large quantities of spray mixture ( 100 to 

 250 or more gallons per acre) at relatively low concentrations (in 

 ratios of 1 part of commercial chemical, at 4 pounds acid equivalent 

 per gallon, to 99 parts of solute, usually water). The actual physio- 

 logical action on the plant is unknown. At one time it was widely 

 believed that the chemical is absorbed through the leaves and then 

 moves down through the stems and into the roots, to kill the entire 

 plant. This theory had its origin in university studies indicating a 

 downward movement from the cotyledons of herbaceous seedlings 

 grown in greenhouses. Nevertheless all field evidence, except in a very 

 few anomalous situations, indicates no downward movement in the 

 stems of mature woody plants. The only (unpublished) study at- 

 tempting to find traces of the chemical at significant distances in the 

 roots was negative ; and other studies indicate that the chemical disin- 

 tegrates in the leaves and never moves out of them. The kill-to-ground 

 effects of foliage spraying may be due in part to the chemical that 

 accidentally gets on the stems. In any event, the effects of foliage 

 spraying are rapid and striking. Within a week the foliage begins to 

 turn color and soon browns to a crisp. By the next spring all woody 

 plants and broad-leaved herbs appear dead ; only the grasses survive 

 (if there were grasses to begin with; otherwise the land is bare and 

 may remain bare of grasses) . In the second year those same root sys- 

 tems usually resprout, and in 2 years may be as high as 5 or 6 years 

 of growth preceding spraying. It is true that three or four annual 



