Economic Losses Caused by Weed Competition in Manitoba Grain Fields. I. Weed Species, Their Relative Abundance and Their Effect on Crop Yields

Abstract

ABSTRACT

Propanil for Control of Green Foxtail in Wheat and Barley

“…Despite the presence of a very dense infestation of green foxtail in the check plots and excellent control with propanil, there were no significant differences in grain yield of the field plots. This is in agreement with the results of Friesen and Shebeski (1960) …”

“…Competition from green foxtail at high densities can cause yield reduction ofcereafs (Friesen and Shebeski 1960 …”

THE BIOLOGY OF CANADIAN WEEDS.: 60. Polygonum convolvulus L.

“…most viable achenes that will germinate do so in their first year (Chepil 1946), but some germination can occur in subsequent years (Forsberg'and Best 1964) and as late as 5 yr after seed set (Chepil 1946 in barley (Friesen and Shebeski 1960 (Arnold and Dosland 1967;Gruenhagen and Nalewaja 1969 (Hume 1982 (Simmonds 1946) and Lepidopteraz Mamestra oleraceae L. has been found on wild buckwheat plants in Bulgaria (Dochkova 1969 (Wiesner 1962), cucumber mosaic virus (Ksiazek 1916a), alfalfa mosaic virus (Ksiazek 1916b), and tobacco rattle virus (Cooper and Harrison 1973).…”

The economics of herbicide use in cereal crops in New Zealand

“…2 Histograms of percentage yield losses from weeds, plus the corresponding fitted normal curves, for (a) weeds other than wild oats in wheat, (b) weeds other than wild oats in barley, and (c) wild oats in wheat. The data is from Friesen & Shebeski (1960). The means (m) and standard deviations (s) used to construct the curves are as follows: (a) m =11.7%, s=10.2%; (b) m=l1.9%, s=8.6%; (c) m=22.7%, s=15.5%.…”

“…However, most of these reports describe losses in only one or a few selected fields in a region, and often suffer from the same deficiencies as the New Zealand data. Only one paper (Friesen & Shebeski 1960) is known to the authors where yield losses have been surveyed randomly over a region to provide an unbiased estimate of regional crop losses.…”