Weeds are one of the most serious problems faced by the American farmer. Losses due to weeds are estimated at 3 billion dollars annually. The. inroads on farm income brought about by reduction in yields resulting from weed infestations, and expenses involved in control measures constitute a major factor in the economical production of crops.

The best way to control weeds is to stop them before they reach our farms; this is particularly true of noxious weeds which still have a rather limited distribution. It is much easier and cheaper to prevent these pests from establishing themselves than to eradicate them. The seeds of a few kinds of weeds can be carried long distances by natural means; for instance, dandelion seeds are wind-transported, cockleburs and stickseeds are carried by the hair of animals. However, the seeds of most weeds are spread by human agencies, most commonly in mixtures with agricultural seed.

Many individuals can recognize our worst weeds by appearance. If these weeds show up in agricultural fields their presence is soon noted, and the necessary control measures are taken. It would seem even more desirable that the seeds of these weeds be recognized when found in agricultural seed and control be effected before they get into the soil. The identification of weed seeds is admittedly, in many cases, a more difficult job than knowing the. plants themselves and is primarily the responsibility of seed analysts. Nonetheless, many farmers would be benefited by knowing some of these weed seeds, or at least having a general impression of them so that suspicious material might be sent to specialists for examination.