Timing of Chopper herbicide site preparation on bedded sites.

摘要

Vegetation control after different application dates of Chopper herbicide (active ingredient imazapyr) relative to bedding was examined at four lower coastal plain study locations. Four locations in USA were selected to cover a range of soil conditions and vegetation complexes. Vegetation at the two locations with sandy surface soils (Tenille and Yulee in Florida) was dominated by gallberry (Ilex glabra), bluestem grasses (Andropogon spp.) and low panicgrass (Dichanthelium spp.). Two locations with finer textured soils (Oakdale (Louisiana) and Whiteville (North Carolina)) were characterized by a wide range of species including arborescent hardwoods. Two bedding regimes: midseason (23 May and 25 July) and late season (25 September and 19 November), were examined at each location. Results indicated that many of the past application date limitations on imazapyr are not necessary. Chopper herbicide in combination with methylated seed oil can be applied as early as February and as late as November, up to the day before bedding and immediately after bedding. Seasonal application was found to significantly affect pine (Pinus elliottii) growth. For those treatments that provided good vegetation control, earlier season treatments resulted in the best pine growth. The optimum application dates were (1) June through September at least 3 weeks after midseason bedding; (2) February to the day before midseason bedding; and (3) February through July followed by late season bedding. An exception is that if deciduous woody species such as hardwood or blackberry (Rubus spp.) are targeted, early season applications (February-April) should not be employed until these species have initiated its leaves' emergence. The optimum timing windows allow forest managers plenty of flexibility in scheduling operations. The use of optimum timing windows has the potential to substantially increase productivity without increasing costs..