Vegetation management along roadside and railroad right-of-ways
Efficient transportation of freight as well as motorists requires effective control of vegetation on right-of-ways (ROW's). Traditionally on railroad ROW's, residual herbicides are applied early in the growing season with POST applications to restrict weed emergence. Field studies in central Illinois (three), Missouri (one), and Kansas (one) were established in 2015 and 2016 to compare fall single versus multiple application timings of residual herbicides from fall through the following summer. The objective was to optimize the timing of residual herbicides to minimize weeds over the greatest duration of the growing season. Residual herbicides were applied in the: fall (full rate), fall followed by spring (half-rates) spring (full rate), and spring followed by summer (half-rates). Spring/summer split applications resulted in consistent weed control throughout the growing season in four of five locations. Fall application at half-rates delayed the spring timing of spring half-rates up to 40 days compared to no fall application. Split programs extended the length of time that herbicides remained at active levels in the soil. In a separate study, management of an emerging invasive tree species along roadside ROW's was determined. Callery pear (Pyrus calleryana) has escaped cultivation and invaded undisturbed areas such as roadsides and pastures from the mid-west to eastern United States. Experiments were initiated in 2015-2017 to determine the response of herbicides delivered by foliar, basal bark, and cut-stump methods. Initiation of symptoms with foliar applied growth regulator herbicides was slow at 3 months after treatment (MAT); control at 12 MAT control ranged between 95 and 100%. Basal bark and cut-stump experiments were conducted on trees with a basal diameter between 10 and 15 cm. At 1 year after treatment (YAT) for basal bark treatments, triclopyr + aminocyclopyrachlor resulted in the highest control (57%). Remaining basal bark treatments resulted in 25 and 50% control. Cut-stump treatments involved application of herbicide on cambium tissue and effectiveness was high (95 to 100% at 1 YAT). In densely infested areas with small trees, a number of foliar herbicides can be effective. In areas with desirable species, Callery pear can be selectively removed using cut-stump applications. The use of basal applications may require different timing for initial application or sequential treatment.
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