The wildflower species typically planted in the highly disturbed environment of a tilled bed are not very competitive with the aggressive weedy species that inhabit the state. Weeds are not only unsightly but they also compete with wildflowers for growth inputs and reduce wildflower stands, growth, and bloom production. Hence, control of weeds is a necessity in successful establishment and maintenance of wildflowers. The most widely used weed control treatment for establishing wildflower beds in North Carolina has been soil fumigation, typically with the highly effective fumigant methyl bromide. This procedure is very expensive, and it necessitates the use of unsightly plastic tarping. Moreover, production of methyl bromide, classed as an ozone depleter, will cease at the end of 2004. The loss of methyl bromide will create a serious void in the weed management program for wildflowers. Chemical weed control (herbicides) is the only feasible means of managing weeds in roadside wildflower plantings in the absence of fumigation. There are no biological controls for weeds in wildflowers, and other non-chemical methods are much too labor intensive and costly.
The NCDOT is currently using a limited number of herbicides in wildflowers, but the herbicides used do not control many weed species encountered. There are likely other herbicides that could be used safely and effectively, as demonstrated by preliminary experiments currently underway by this proposal's author, but very little is known about the tolerance of wildflowers to most herbicides and the weed control possible. Research in this area is a critical need. Further, such research is needed to support registration of herbicides that have potential uses in wildflowers. Considering the multi-species plantings common along roadsides and the number of annual and perennial weeds encountered, it is quite likely that suitable herbicides cannot be found to handle every situation. Hence, research is also needed to investigate new fumigants, such as methyl iodide, as an alternative to methyl bromide. The proposed research will be designed to thoroughly investigate the use of herbicides and alternative fumigants in the establishment and maintenance of wildflowers. Results of the research will be used to develop weed management recommendations and educational programs for NCDOT personnel involved in wildflower management decisions.
