Roadside vegetation management final report for the period July 1986 to June 1991 (FHWA-OK-91-10) 2147

Abstract

The information contained within this report addresses: (1) Research -- involving the use of herbicides and plant growth regulators for roadside vegetation management; (2) Maintenance -- implementing research results into an operational phase of the Oklahoma Department of Transportation (ODOT) maintenance program; and (3) Training -- conducting pesticide applicator certification programs and providing continuing educational programs for these certified applicators. The following are recommendations and/or conclusions based upon the research results. (1) Roundup rates may be reduced from 0.75 to 0.62 lb. ai./A in the western and central portions of Oklahoma while maintaining 90% control of johnsongrass. In the eastern one-third of the state, rates of Roundup should be maintained at 0.75 lb. ai./ A to achieve the 90% level of control. (2) When applied at equal rates, SC-0224 and Roundup provide equal con tro l of johnsongrass. (3) The additive Frigate, significantly increases the activity of Roundup and Roundup plus Oust treatments. (4) A single application of Arsenal applied at 1.2 lb. ai. in combination with Oust at 0.047 lb. ai. applied in 40 gallons of water per acre will effectively control bermudagrass encroachment into paved roadside shoulders and seams when applied in late May or June to actively growing bennudagrass. (5) Musk this tle can be effectively controlled with Transline at 0.125 to 0.25 lb. ai. in 25 to 50 gallons of water per acre applied during March through April when thistle plants are actively growing and prior to bolti ng (flowering). (6) Vision, a plant growth regulator, applied under an EUP label suppresses of bermudagrass growth along roadsides. S everal larg e-scale demonstrations were initiated throughout the duration of this project and are described as follows: Musk thistle control with Transline; johnsongrass control with Roundup+ Oust and/or Frigate; c on trol of Kudzu with Arsenal; bermudagrass encroachmen t control with Arsenal; silver bluestem control with Roundup, alone, or in combination with Oust and/or Frigate; bermudagrass canopy height su ppression with Vision or Poast plus a crop oil. Training activities included certification of 59 1 new ODOT herbi cide applicators and providing continuing educational programs for 1354 ODOT certified applicators.