Cereals weeds

Barnes JP, Putnam AR (1986) Evidence for allelopathy by residues and aqueous extracts of rye (Secale cereale). Weed Sci 34 384-390... 

H. Trozelli, Fluroxypyr-a new herbicide in cereals, Weeds and Weed Control 27 (1) (1986) 65-75. 

Black, I. D. and Dyson, C. D. (1993). An economic threshold model for spraying herbicides in cereals. Weed Research, 33,279-90. 

Plants can also be pests that need to be controlled, particulady noxious weeds infesting food crops. Prior to 1900, inorganic compounds such as sulfuric acid, copper nitrate, sodium nitrate, ammonium sulfate, and potassium salts were used to selectively control mustards and other broadleaved weeds in cereal grains. By the early 1900s, Kainite and calcium cyanamid were also used in monocotyledenous crops, as well as iron sulfate, copper sulfate, and sodium arsenate. Prom 1915 to 1925, acid arsenical sprays, carbon bisulfate, sodium chlorate, and others were introduced for weed control use. Total or nonselective herbicides kill all vegetation, whereas selective compounds control weeds without adversely affecting the growth of the crop (see Herbicides). 

In general, triazines are pre- and post-emergence selective herbicides particularly effective on annual and perennial broadleaf and grassy weeds in corn, sorghum, cotton, soybeans, sugar cane, and a host of other fruit and cereal crops. Some have anti-fungicidal properties (e.g., anilazine), and some (e.g., simazine) can be used for... 

Pyraflufen-ethyl was primarily developed as a cereal herbicide to control a broad spectrum of broadleaf weeds. Pyraflufen-ethyl applied in early postemergence at 12 g a.i. ha provides excellent control of some important weeds such as Anthemis arvensis, Lamium purpureum and Sinapis arvensis and good suppression of Matricaria chamomilla, Stel-iaria media, Veronica persica and Viola spp. 

E. Kerber, G. Leypoldt, and A. Seiler, CGA 163,935, A New Plant Growth Regulator for Small Grain Cereals, Rape and Turf, Presented at the 1989 Brighton Conference-Weeds, Brighton, UK, November 20-23, 1989. 

Another approach is the utilization of allelopathic rotational crops or companion plants in annual or perennial cropping systems (19). Living rye (Secale cereale L.) and its residues have been shown to provide nearly complete suppression of a variety of agroecosystem weeds (33). Similarly, residues of sorghums, barley, wheat and oats can provide exceptional suppression of certain weed species Q ). Although some progress has been made on identifying the allelochmicals from these plants, much remains to be accomplished. 

The total monetary loss resulting from weed competition in the cereal crops was 1.3 billion annually. The most frequently reported weeds were mustards (Brassica spp.) followed by wild oats (Avena fatua L.), bromes (Bromus spp.), and wild garlic (Allium vineale L.) (11). Losses in vegetables was 5% of the total while in fruit and nuts the loss was 7% of the total. Crabgrass, bermudagrass [Cynodon dactylon (L. )... 

Rye (Secale cereale L.) and Wheat Triticum aestivum L.) Mulch The Suppression of Certain Broadleaved Weeds and the Isolation and Identification of Phytotoxins... 

In fields where some weeds were cleared using herbicides, other, more herbicide-resistant, species have appeared, such as common horsetail, coltsfoot, foxtail, wild oats, false wheat, etc. As a result of herbicide use, scratchweed, which cannot be destroyed by any herbicide, is making inroads into cereal crops, and chamomile has taken over rapeseed [6]. Using herbicides on rice fields caused the spread of wild, pesticide-resistant, low-yield forms of red-grain rice. 

Leeson, J.Y., Thomas, A.G., Hall, L.M., Brenzil, C.A., Andrews, T., Brown, K.R. and Van Acker, R.C. (2005). Prairie Weed Surveys of Cereal, Oilseed and Pulse Crops from the 1970s to the 2000s, Weed Survey Series Publication 05-1 (and CD), Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, 395 pp. 

An example, when intercropping suppressed the weed growth more than sole, is a leek (Allium ampeloprasum var. porrum (L.) J.Gay) - celery (Apium graveo-lens L.) intercrop sown in a row-by-row layout decreased relative soil cover of weeds by 41%, reduced the density and biomass of groundsel (Senecio vulgaris L.) by 58% and 98%, respectively, and increased the total crop yield by 10% (Baumann et al. 2000). Increased weed suppression and the crop yield were also demonstrated in cereal-legume intercrops in many different environments (Ofori et al. 1987). 

Chase WR, Nair MG, Putnam AR (1991) 2,2 -Oxo-l,l -azobenzene Selective toxicity of rye (Secale cereale L.) allelochemicals to weed and crop species II. J Chem Ecol 17(1) 9—19... 

Rasmussen IA (2004) The effect of sowing date, stale seedbed, row width and mechanical control on weeds and yields of organic winter wheat. Weed Res 44 12-20 Reddy KC (2001) Effects of cereal and legume cover crop residues on weeds yield, and net return in soybean (Glycine max),. Weed Tech 15 660-668 Reynolds LB, Potter JW, Ball-Coelho BR (2000) Crop rotation with Tagetes sp. is an alternative to chemical fumigation for control of root-lesion nematodes. Agron J 92 957-966 Rice EL (1984) Allelopathy. Academic, New York, p 317... 

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