The magnitude of the problem created by wild oats (Avena fatua L.) is one that warrants intensive study not only from the practical but also from the biological standpoint. A knowledge of the entities or taxa present in the wild oats population is a logical beginning to more extensive phases of investigation. The purpose of this paper is to report taxonomic and genetics studies carried out on the wild oats population of the Prairie Provinces. It is hoped that the information obtained may be of use to other investigators interested in the biology of wild oats.

In weed control, soil sterilization is that process whereby the soil is altered so that it will no longer sustain the higher forms of plant life. In most common use the term refers to the application of chemicals to the soil surface. The sterile effect obtained is not instantaneous but develops as the chemical is carried down through the soil with water or after mixing the chemical with the soil by tillage. The sterile effect obtained is not permanent as leaching, fixation, or decomposition by microbes reduce the toxic effect with time. The length of time chemicals will remain active as soil sterilants varies. Highly soluble materials will be removed much more rapidly than will relatively insoluble compounds.

One of the cultural practises used to control weeds in wheat fields is the application of 2,4-D sprays. The spray is applied as a post emergent selective after the wheat and the weeds have made some growth. The success of selective weed control in wheat depends upon the relative resistance of the wheat plants and the relative susceptibility of the weed plants to the 2,4-D spray. Major factors affecting successful weed control in wheat fields are the stage of growth of both wheat and weed plants, the quantity and formulation of 2,4-D applied, the solvent or carrier for the 2,4-D, the variety of wheat, and the species of weeds present.

The mesquite tree (Prosopis spp.) has been invading southwestern ranges to an alarming degree during the last half century, and has become a serious competitor for available moisture and light with perennial grass—the principal forage of livestock in this area. Its distribution in Arizona, New Mexico, and Texas has been estimated at over 70 million acres. Of the three varieties of mesquite found in these States, velvet mesquite (P. juliflora var. velutina (Woot.) Sarg.) is essentially limited to Arizona, and is the most common variety found therein.

The herbicide, isopropyl N–(3–chlorophenyl) carbamate (CIPC), has proved to be efficient in eliminating certain weeds from several crops. The toxic mechanism of this herbicide is still somewhat doubtful. In order to further determine the reaction of plants to this herbicide the carbohydrate content of corn plants sprayed with CIPC was investigated.

The distribution of 3 (p–chlorophenyl)–1,1–dimethyl urea (CMU) in the soil horizon is an important factor to consider in using the material since it is a soil active herbicide. It has been reported that the persistence and toxicity of CMU vary considerably with soil type, temperature, and moisture conditions.

Halogeton glomeratus, a weed poisonous to animals, was first observed in the United States near Wells, Nevada, 1934–5. Dayton has given a detailed historical sketch concerning its European-Asiatic habitats and species. The ecology of halogeton has been discussed by Cook and Stoddard, Fenley and Tisdale and Zappettini. Very little is known in the English-speaking world about the present status of Halogeton glomeratus in Asia, where this species is reported to be endemic.

With the introduction of new chemicals for weed control, a tremendous effort has been expended toward finding a chemical weed control method for soybeans. Some of this research has been reported in the Research Reports and Proceedings of the North Central Weed Control Conference from 1946 to date. Much of the effort has been devoted to pre-emergence treatments on soybeans because of the apparent sensitivity of soybeans to foliage sprays of the present day herbicides.