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.

A survey of barley crops on 166 west of Scotland farms in 1969 indicated a more widespread distribution of Avena fatua L. than had previously been recognized. Whilst only 0-8% of the barley area was infe.sted with A. faiua, the weed wa.s found on 16% ofthe known barley-growing farms. A. fatua was associated with arable farming situations and with fields where there was a recent history of cereal eropping. Only on four ofthe sample farms where A. fatua was found had any attempt been made to control the weed. It is concluded that there is a strong case for eradicating or at least containing the weed before it becomes a major problem.The distribution of Avena strigosa Schreb. and Agropyron repens (L.) Beauv. is also given. Distribution rf'Avena fatua L., d'Avcna. strigwa Schreb. et rf'Agropyron repens (i.) Beauv. dans les cultures d'orge de I'ouest de VEcosse Resume. Un cxamen des cultures d'orge dans 166 fermes de I'ouest de TEcoasc en 1969 a montrii que la distribution A'Avena faiua L. ^tait plus (5tendue qu'il n'avait i:tt constate antirieurement. AJors que 0,8 % de la surface des cultures d'orge itait infestiie autrefois par A. fatua, cette adventice a 6t^ trouv6e dans 16% des exploitations connues cultivant de I'oi^e. Avena fatua 6tait assod^e avee des syst^mes d'exploitation ou des champs qui avaient un pass(5 recent dans la culture c^r^ali^re. Parmi les fenncs ^chantillonnt^es oil Avenafatua itait pr^sente, quatre seulement avaient fait quelque tentative pour lutter contre la mauvaise herbe. 11 en a &l& conclu qu'il y a un g[rand int<5rrt k d^truirc ou tout au moins & Umiter la mauvaise herbe avant qu'elle ne eonstitue un probi^me majeur. La distribution A'Avena strigosa Sehreb. et d'Agropyron repens (L.) Beauv. est aussi indiqude. Die Verbreitung von Avena fatua {L.), Avena strigosa Schreb. und Agropyron repens {L.) Beatw. in Gerste in WestschottlandZusammenfassung. Die Aufnahme von Gerstesaaten in 166 westschottischen landwirtsrh;ifilirhon Betrieben ergab, daB Avenafatua (L) eine weit groBerc Verbreitung hat als bisher bekannt war. Wahrend nur 0,8% der Gerstenflache mit A. fatua verseueht war, wurde das Ungras in 16% der Gerste anbauenden Betriebe gefunden. Das Auftreten von v4./

The benefits to establishment and growth of white clover cvs Aberystwyth S.184 and Grasslands Huia of inoculation with three strains of Rhizobium trifolii, using the peat or liquid inoculum techniques, were investigated during 1975-8 on improved hill soils ranging from brown earth through dry and wet peaty podzol to deep peat.Inoculation induced positive response in either number of seedlings, plant cover or dry-matter production in 18 out of 139 comparisons, had no effect in 118 and produced a negative response in three. Most of the positive responses to inoculation were at sites with wet peaty podzol or deep peat soils but of the five sites where increase in clover D.M. production was found in the first harvest year one was a brown earth. The positive agronomic responses occurred only when the proportion of plants with nodules was high and where a substantial proportion ( > 50 %) of the latter contained introduced Rhizobium strains at least in the year of sowing. The three negative responses were in numbers of seedlings on one brown earth and two dry peaty podzol soils and with the Huia cultivar only. Despite lack of statistical significance at individual sites the dominant overall trend was for inoculation to enhance seedling establishment and the early growtli of white clover in all soil types.On one brown earth and one dry peaty podzol soil there was some evidence that spraying the Rhizobium on to emerging white clover seedlings was more beneficial, at least in microbiological terms, than the customary peat inoculum procedure.The incorporation of even a small amount of nitrogen (30 kg/ha) into the seed bed at the time of sowing adversely affected germination, establishment and growth of white clover in some soils. Sometimes the effects of this nitrogen persisted into the first harvest year.

SUMMARYBetween 1972 and 1976 a series of 15 trials was carried out at various climatically favoured sites throughout Scotland to assess the potential of new hybrid maize varieties of European origin under Scottish conditions. No meaningful differences were found between varieties in respect of dry-matter yield or maturity.Seed rates ranged from 100 to 200 × 103 seeds/ha giving final stands from 40 to 194 × 103 plants/ha. Regression analyses for the variety Dekalb 202 included in 54 treatments indicated that the relationship between plant population density and dry-matter yield was partly linear with an important quadratic function, suggesting an optimum of 179 × 103 (± 80 × 103) plants/ha. Plant population density accounted for 65·9% (P < 0·01) of the variance in dry-matter yield but was not significantly related to dry-matter content.Climatic variation between years had no overriding influence on growth and development. Dry-matter production for the variety Dekalb 202 sown in mid-May ranged from 2·86 (1972) to 14·54 t/ha (1975) with associated dry-matter contents of 15·1 and 24·1% respectively. In a few instances slightly higher dry-matter contents (maximum 28·6%) from mid-May sowings were associated with lower yields.Neither date of sowing nor accumulated temperature to harvest measured as Ontario Heat Units was significantly related to yield but date of sowing accounted for 29·5% (P < 0·01) of the variance in dry-matter content. Accumulated Ontario Units at harvest were not significantly related to dry-matter content.An interesting relationship between dry-matter yield and the date on which the crop had received 1379 Ontario Units was found. This relationship may be useful in selecting sites at which maize may be grown or to predict maximum potential final yield in any given season.

Summary. Two techniques for the comparative evaluation for the control of couchgrass (Agropyron repens (L.) Beauv.) were tested in 1960, and it was concluded that the more practicable was the one in which known lengths (96 in.) of couchgrass rhizome fragments were planted in a plot of 10 × 2 ft. The rhizomes were allowed to grow and herbicides were applied when the shoots were 6–9 in. high. Two to 3 months later the rhizomes were carefully dug up, weighed, measured and dried. Dry weight of rhizomes was used as a measure of the quantity of couchgrass present. Four trials of spring applications, and two of autumn applications are reported. Of the commercially available herbicides, amitrole‐T, TCA and dalapon were effective in that order, and presented no insuperable problems of persistence in the soil. Fenac and atrazine showed little promise. Spring applications of herbicides were considerably more effective than autumn treatments. Essai d'herbicides pour la lutte contre Agropyron repens