Survey of the presence and methods of control of wild oat, black grass and couch grass in cereal crops in the United Kingdom during 1977

Abstract

In summer 1977 a random survey was made of 2250 fields on 1153 farms selected throughout the United Kingdom. Wild oat, Avena spp., was surveyed in all countries; black grass, Alopecurus myosuroides, was surveyed in England and Wales; and couch grass, including Agropyron repens and other perennial grasses, in Scotland and N. Ireland.Wild oat was reported by farmers on 95 % of farms in England, 34 % in Wales, 65% in Scotland and 30% in N. Ireland; the areas of infestation in the different countries were 67, 13, 37 and 16 % respectively. The majority of wild oat was A.fatua. Only 6 % of the cereal area of U.K., including sprayed and unsprayed fields, contained more than one wild oat seed head/m 2 (10000/ha), the majority had less than one/20 m 2 . Black grass was reported on 50 % of farms in England (22 % of cereal area) mainly in East and South, and on 2 % of farms in Wales. Couch grass occurred on 92 % of farms in Scotland and 68 % in N. Ireland: areas of infestation were 88 and 67 % respectively. Most of the infestations of all three weeds had been present for longer than 5 years.Most farmers intended to eliminate or reduce wild oat and few proposed to hold the weed at its present level or do nothing. [Herbicides were used against wild oat on approximately half of the infested area in England and Wales, with proportionately more use in Wales and much less in Scotland and N. Ireland. A third of the black grass infested area of England was treated with a herbicide. There was little spraying against couch grass in Scotland and N. Ireland. Details of dose, time of application and mixing of chemicals were obtained. Wild oat was subsequently found on most of the area treated against this weed, similar observations were made of black grass and couch grass. Most farmers considered herbicide performance good or excellent and those in East and South England believed wild oat to be decreasing as a problem; farmers elsewhere thought the problem to be increasing.Hand pulling of wild oat (roguing) had occurred on only one tenth of the infested area but a greater area was intended to be rogued after the survey visit. Much of the land that had been rogued was found subsequently to contain few wild oats.The survey provided information on associations between weed presence, soil type and cropping system, the types of herbicide used and farmers' impressions of their performance. Comparisons are made with previous surveys in 1972, and information on the disposal of the 1976 crop of straw and on types of cultivation used in different regions is provided. The implications of the results are discussed.

Buried seeds in arable soils in Scotland

“…/74 1974/75 1975/76 1976/77 1977/78 Mean Potygonum persicaria 1972/73 1973/74 1974/75 1975/76 1976/77 1977/78 Mean Spergula arvensis 1972/73 1973/74 1974/75 1975/76 1976/77 1977 Mean Comparisons with previous surveys are difficult to make beeause of differences in objectives and methodology. The species found in this survey are, however, to a great extent the same as those in other surveys done on weeds growing in crops in Scotland (Elliot, Cox & McDonald, 1965;O'Leary, 1973;Phillipson, 1973;Elliott et al, 1979;Carnegie, 1974). The six species found most often, Chenopodium album, Poa annua, Polygonum avieulare, Polygonum persiearia.…”

“…Beauv.) which is a serious weed in Scottish cereals (Elliott et al, 1979) was found only in the last 2 years of the survey and only in three samples. It tends to spread by vegetative means rather than by seed (Anon., 1971).…”

“…Although Phillipson's (1973) survey showed that 25% of the cereal acreage in the east of Scotland had wild oats present, only a small proportion of that was of heavy infestation. Elliott et al (1979) found that 37% of the cereal area had wild oats present, but only one area had an infestation in excess of 50 000 panicles ha~'. It may be that there is no substantial bank of Avena fatua seed in the soil, and infestations are still below levels that could be detected at the sampling intensity adopted in the present survey.…”

“…Surveys of weeds in crops in Scotland have been carried out as part of joint U.K. exercises. Accordingly, Anon (1968), O'Leary (1973), Elliott & Attwood (1970), Phillipson (1973), Elliott et al (1979) surveyed the weeds in cereal crops and an estimation of the weeds in potato soils was given by Elliott, Cox & McDonald (1965). A survey ofthe dicotyledonous weeds in spring-sown cereals in north-east Scotland was made by Carnegie (1974).…”

Influence of tillage, straw disposal system and seed return on the population dynamics of Alopecurus myosuroides Huds. in winter wheat

“…Alopecurus myosuroides Huds. ('black-grass') is one of the commonest grass weeds of winter cereal crops in England (Froud-Williams & Chancellor, 1982) where it is estimated that it infests over 650 000 ha of cereal crops (Elliott et al, 1979). A knowledge of the population dynamics of the weed is essential in the formulation of long-term control strategies.…”