Treatments usually have to be repeated to obtain and maintain good control. As 
soon after the first spraying as regrowth reaches full foliage, it should be retreated 
with the same herbicide and at the same rate as in the original application. In 
subsequent years, the regrowth should be treated when it reaches full foliage in 
the spring with a spray diluted to half the original herbicide concentration. 
Clearing away or burning the dead canes from the preceding year makes retreat- 
ment easier and improves control. However, the canes should not be removed from 
the plant until 6 months after treatment. Earlier removal encourages new shoots 
to start growing before they normally would. 
General Directions for Spraying 
General directions for applying sprays containing 2,4—D and 2,4,5—-T with vari- 
ous types of equipment follow: 
When a boom sprayer is used to control seedlings and young established weed 
roses in grass meadows and along roadsides and drainage ditches, the output and 
ground speed of the sprayer should be calibrated to deliver between 10 and 40 gal- 
lons of spray per acre. 
When a high-pressure sprayer with handgun is used to penetrate established 
hedges or large isolated plants, a pressure between 100 and 200 pounds per square 
inch is required to wet all the foliage well. It is not necessary to drench the plants, 
however. Because of the large amounts of spray used to wet the leaves, a relatively 
weak spray concentration—2 pounds, acid equivalent, of herbicide in 100 gallons of 
water—will do the job efficiently. 
When aerial spraying is used, the sprayer should be calibrated to deliver 5 to 10 
gallons of spray per acre. 
The hazard of drift in aerial spraying is minimized by using invert emulsions 
(those in which the herbicide is on the inside of the drop instead of the surface) or 
adding an agent that prevents formation of very fine droplets. Spray pilots know 
about these techniques. 
IN CONCLUSION 
Weed roses are not as noxious as certain other weeds, such as wild morning glory 
in small-grain fields or the Canadian thistle, for which no effective controls have 
been found. However, intensified effort on the part of farmers in affected areas will 
be needed to prevent weed roses from migrating further. Controlling seedlings and 
young established rose plants is much cheaper and easier than reclaiming land that 
is heavily infested. Preventing migration of weed roses into orchards is especially 
important, since treatments recommended in this report may damage the fruit 
trees. Tillage is therefore the only control. measure available to orchardists at 
present. 
Because of the strong tendency of Macartney, Cherokee, Woods, and multiflora to 
spread, a farmer cannot ignore the weed potential of these roses when they are 
growing on or near his land or when he considers planting them for a living 
fence or wildlife cover. 
