Date of this Version
UNIVERSITY STUDIES, VOL. XXXIX, 1939, No.2.
EXACT knowledge of the relations existing between weeds and cultivated crops is very limited. This is true also of the amount of viable weed seed present in arable soil. Impressions and observations have been recorded, but very few quantitative investigations have been made. The numerous circulars and bulletins about weeds, issued by many experiment stations, deal mostly with descriptions of species and methods of weed control. The present research was undertaken primarily to determine the relationship which exists between weeds and cultivated crops, but also to obtain an estimation of the number of viable weed seeds present in the soil. A third objective was to provide a record of species which compose the weed flora of cultivated soils. Opportunity was also afforded to observe the effects of extreme drought upon the weed population. A satisfactory definition of the term "weed" has never been given. A weed is frequently defined as "a plant out of place." This definition has been found unsatisfactory by Pieters (1935),1 who suggests a weed is "a plant that does more harm than good and has the habit of intruding where not wanted." Muencher (1935) states that "weeds are those plants with harmful or objectionable habits or characteristics which grow where they are not wanted, usually in places where it is desired that something else should grow." Only the weeds which occurred on arable land, as distinguished from meadow or grassland, were considered in this study. Even under constant cultivation certain weeds always appear among cultivated plants, and it is with these that this study is concerned.