Researchers with the USDA’s Agricultural Research Services have been studying the effects of crop production with climate change.  Specifically, they have looked at soybean yield production against weed pressure.  Marty Williams is an ecologist with the A-R-S and says his findings over the last few decades show slightly warmer temperatures with drier conditions.  He says yields were compromised when there was weed pressure.  Williams says over the years, more weeds were able to build up resistance with traditional herbicides, making it more difficult to control the weed pressure, resulting in lower soybean yields.  Williams says some weeds, such as water hemp, have become more problematic through the years.  The USDA ecologist doesn’t see any new and innovative herbicides being developed and marketed in the near future, so he says farmers will need to look at other methods to control weed seeds.