The increasing presence of herbicide resistant weeds is partially related to a decline in the number of companies involved with herbicides (53 in 1974 versus 9 in 2004) and number of experimental herbicides available for research in our program at the Eastern Shore Agricultural Research and Extension Center (43 in 1974 versus 1, in 2004). Globally there are 174 herbicide-resistant weed species and 107 of these are found in the United States, where at least 11 glyphosate-resistant weeds have been documented. A list of these weeds include palmer amaranth, common waterhemp, common lambsquarters, common ragweed, giant ragweed, marestail (horseweed), Italian ryegrass, rigid ryegrass, goosegrass,...