ALBERT

Notes: Three groups of 8 Polled Dorset Iambs were weaned at 8 weeks of age and were fed dried grass, a 50–50 mixture of dried grass and protein-supplemented barley and protein-supplemented barley. All rations were completed. Digestibility trials were also conducted and the effect of level of feed intake on nutrient digestibility investigated.The dried grass resulted in rates of gain comparable to those produced by the pelleted barley ration. Feed conversion efficiency was lowest for the grass and highest for the barley ration. An interaction between the dried grass and barley was observed in nutrient digestibility. Increasing the level of feeding from approximately maintenance to appetite tended to result in slight depressions in the digestibility of energy and protein of all rations.The results suggest that dried grass can be used successfully for intensive feeding of early weaned lambs and little nutritional advantage appears to be gained from combining dried grass with barley.

Notes: For spaced plants of Lolium perenne cv. S24 at the Welsh Plant Breeding Station, Aberystwyth, and at the National Institute of Agricultural Botany, Cambridge, linear relationships were obtained between the recorded heading dates and (a) mean March earth temperatures at 30 cm depth and (b) mean March plus mean April earth temperatures at 30 cm depth. The residual standard deviations were ±2.97 days and ±2.65 days, respectively, A mean March earth temperature of 8°C predicted heading on 5 May, 6° C predicted heading on 12 May, and 4°C predicted heading on 20 May. For sites with an average April temperature significantly below 8.7°C a correction of +2 days per degree mean temperature difference in April had to be applied to these dates. These equations could be used to predict dates for 50% ear emergence in swards with a 50% confidence limit of ±22 days for sites in Central and Southern England and Wales. In certain years, cold, wet weather in May appeared to delay heading considerably at two Scottish sites.

Notes: Book reviewed in this article:BEST, K. F.; LOOMAN, J.; CAMPBELL, J. B. Prairie grasses identified and described by vegetative charactersSHLYK, A. A. Chlorophyll metabolism in green plantsDEVLIN, R. M.; BARKER, A. V. PhotosynthesisEVANS, L. T. (Editor). The induction of floweringMACHLIS, L.; BRIGGS, W. R.; PARK, R. B. (Editors). Annual review of plant physiology.

Notes: A grazing experiment using four stocking rates of sheep, equivalent to 34, 45, 57 and 68 sheep/ha on an assumed 200-day grazing season, was conducted using a portable grazing corral technique. Plots were subjected to fotir grazing periods between mid May and early September. The effect of stocking rate on herbage yield and quality and the influence of these factors and feed intake on liveweights of the sheep were recorded.The mean daily herbage organic matter available over the trial was 9.6, 5.8, 3.3 and 23% of the total liveweight of the sheep at each of the four stocking rates. The highest grazing pressure led to the production of high-quality herbage, but also led to reduced productivity, low feed intake and liveweight losses. The most lenient grazing pressure failed to provide adequate herbage utilization. Even at the most intensive stocking pressure, only 66% of the herbage available to ground level was utilized in grazings after July.Intake results suggested that sheep of 45 kg liveweight required 1000–1200 g digestible organic matter per day to maintain body weight. Despite the higher in vitro digestibility of herbage on offer at the higher stocking rates, intake was limited through lack of herbage; a high degree of correlation existed between herbage availability and herbage intake over the four stocking rates and at all grazings.It is concluded that the portable corral technique is well suited for grazing studies and the assessment of sward response to varying stocking rates and is particularly useful where facilities for more extensive studies are limited.

Notes: Groups of 8 steers weighing 300–400 kg (660–880 Ib) were rotationally grazed on a ryegrass-dominant pasture for 115 days. The systems compared were zero grazing (Z), field grazing conducted at the same stocking rate (FC), and field grazing conducted at a stocking rate varied with the intention of giving the same liveweight gain per uiimal as zero grazing (FV). Mean daily liveweight gains were: Z, 0.98; FC, 0.78; FV, 0.90 kg/animal (2.2, 1.7 and 20 Ib/animal), and liveweight gains/unit area were in the ratio 100:78:85. Organic-matter intake, measured on four occasions, was, on average, Z, 6.54; FC, 6.18; FV, 687 kg/head daily (14.4, 13.6 and 15.1Ib).From these results it appears that a comparison of zero grazing and field grazing made at the same stocking rate is likely to underestimate the potential of field grazing for beef production from grass.

Notes: An experiment was conducted in two successire years to measure the effect of two levels of fertilizer N, 50 and 300 kg/ha (45 and 270 Ib/ac) on the productivity of pastures grazed by young beef cattle. Two stocking rates were imposed at the lower N level and 4 at the higher level. The responses per kg fertilizer N were approximately 1 kg liveweight gain, 20–24 Meal ME and 8–9 kg DM. Maximal yields of about 1000 kg gain/ha (890 Ib/ac) and 19,000 Meal ME/ha (7700 Mcal ME/acre) were recorded.Animal performance was similar on the low and the high N pastures. There was evidence that the chemical quality of pasture was lower on the low N pasture in the first year, but there was no difference in the second year.The numbers of dung pats per ha and the refusal of herbage due to fouling were reduced by Increasing the stocking rate.

Notes: Ways of using nitrogen fertilizer and long growth periods to produce grass for summer milk production are described. To exploit the extra production obtained from long growth periods it is suggested that the grazing system should be flexible, integrating cutting with grazing.

Notes: Five substrates (high-quality brome grass, low-quality brome grass, lucerne pellets, lucerne cubes, and barley straw) were analyzed for DM disappearance in a two-stage in vitro system in nine consecutive runs. Samples for each run were inoculated in duplicate with four independent collections of rumen fluid from the same mature, non-lactating Holstein cow. Data repeatability was excellent for the two lucerne substrates, good for high-quality brome grass, and poor for low-quality brome grass and barley straw.

Notes: Winter (vernalized) and summer (non-vernalized) timothy tillers were grown to anthesis in day/night temperature regimes of 32/26°, 27/21°, 21/15°, and 15/10°C. Herbage and total plant yields, total leaf-blade number and area, and total plant growth-rate were highest, or very nearly so, in the 21/15°C regime for both the winter and summer plants. However, summer plants reached anthesis 13 to 14 days later than winter plants in each temperature regime. Even though virtually all primary shoots produced an infiorescence, summer plants had significantiy more leaves and leaf-blade area, produced significantiy higher yields of leaf blade, stem plus sheath, stubble, and root tissues and had a significantly higher total plant growth rate than winter plants in each temperature regime.

Notes: Fifteen out of 36 possible combinations of 3 cutting dates for hay, 3 rates of N application and 4 intervals between N application and cutting date were compared to study the effects of pre-harvest application of N on the N, P, K, Mg and Ca contents of the aftermath and the effectiveness of utilization of these elements.According to the method of calculation given by ARC (1), the control haycrop harvested on 16 June was deficient in N, Ca, P and Mg, and the aftermath which was given no further N after harvest was of low bulk, but adequate in mineral content. Earlier harvesting improved the quality of the hay, and increased the bulk and reduced the mineral content of the aftermaths. Applying 125.6 kg N/ha after harvest resulted in a satisfactory increase in bulk, plus an improved mineral content in the aftermath. Applying N before harvest resulted in increased uptake of N, K, Ca, P and Mg in the hay and in the increased percentage of N, K, and Ca in the DM of the hay. Very early application of pre-harvest N increased the percentage of Mg.The general effect of pre-harvest N on the aftermath was to reduce yield and uptake of N, K, Ca, P and Mg. Doubling the pre-harvest N raised the mineral uptake. Very early pre-harvest application resulted in low mineral uptake in the aftermath. The percentage of N, K and P in the aftermath was reduced by pre-harvest N applied at both levels and on both dates.Deferring the application of fertilizer N until 4 days after harvesting the hay crop produced the highest mineral contents in the aftermath, without reducing its bulk.Mineral uptake in the regrowths was linearly related to N uptake at 1.43 kg K, 0.34 kg Ca, 0.157 kg P, 0.006 kg Mg/kg N uptake.

Notes: This paper describes experiments carried out with different depths of topsoil and methods of cultivation on an ash lagoon at Besthorpe, near Newark. Good yields of grass were obtained even on bare ash with suitable rates of fertilizer application. In the conditions existing at Besthorpe, the optimum depth of soil appeared to be three in. (7.62 cm), but the depth of cultivation (three in. (7.62 cm) or twelve in. (30.48 cm), die latter resulting in mixtures of soil and ash, had no significant effect.B uptake by the growing plants was markedly lower in the third year of the experiment but, apart from its possible effect on yield, it produced no ill effects.

Notes: The acid-detergent fibre (ADF) contents of 50 grass samples of known in vivo and in vitro digestibility were determined by hydrolysing with acid for 1, 2, 3,4, 5, and 6 h. The 50 samples used consisted of 6 Lolium perenne, 9 Cenchrus ciliaris, 15 Chloris gayana, 10 Digitaria spp., and 10 Setaria spp. Regression and residual standard deviations (RSD) were calculated for each hydrolysis time for each grass and for all 50 samples.Increasing the hydrolysis time decreased the RSD for Lolium perenne and Setaria, had no effect on Chloris gayana and Digitaria and increased the RSD for Cenchrus ciliaris regressions. For regressions based on all 50 samples die RSD varied between ±4.8 and 5.0 digestibility units with only minor differences between hydrolysis times. Correcting the ADF for contaminating ash generally increased the RSD.Changing the acid strength from the 10 N recommended by van Soest (8) did not lead to any major improvement in the RSD for regressions based on Cenchrus ciliaris, but with Setaria the RSD was reduced from ±2.8 to 1.7 digestibility units when 2N acid was used and hydrolysis was extended to 2 h.It was concluded that unless the optimum conditions for determining ADF for each grass are known then the in vitro technique provides digestibility estimates with a lower error.

Notes: A coring technique (6), that may be used for estimating the mean amount of herbage on closely grazed pastures, has been adapted to include visual scoring. Two methods are described, both of which use sets of pasture cores from the sward as reference standards. The observers score the herbage on view at random sites against the standards. In the first method the scores are converted to herbage yields directly by reference to the yields of the standards. In the second method a double sampling regression technique is used and the set of standards is used as a visual guide only.

Notes: Soil samples were taken at 0–1 in. (0–2.54 cm) and 1–3 in. (2.54–7.62 cm) depths on five occasions over a period of 55 days from under (3 in. (7.62 cm) radius from centre) and around (9 in. (22.86 cm), 12 in. (30.48cm) and 18 in. (45.72 cm) radius from centre) dung patches deposited on pasture. The samples were analysed for available N, K and P. There was a significant increase in the level of all three elements in the 0–1 in. samples beneath the dung patch. The increase persisted throughout the experiment. K exhibited the greatest increase, but was not detected beyond the edge of the dung patch. The increase in soil N was smaller but was detected up to 6 in. (15.24 cm) from the edge of the dung patch. P also increased, but was more variable than either N or K. Soil N, P and K did not increase in the 1–3 in. samples.The weight and fibre content of the dung patch was also measured throughout the experiment. After high initial losses (25%) the dung patch decayed only slowly.The loss of ammonia from dung patches was followed over 13 days in a separate experiment During the relatively hot weather over this period approximately 5 % of the N iu the dung was lost as ammonia, mainly in the first five days. During the experimental period of 13 days 60% of the original weight of the dung patch was lost through evaporation.The results are discussed in relation to the growth of herbage surrounding a dung patch reported in the previous paper (12).

Notes: The seasonal pattern of DM prodaction of Lolium perenne, Cynosurus cristatus. Anthoxanthum odoratum. Festuca ovina and Agrostis stolonifera. cnt to 3 cm at 6-week intervals was studied on five sites, ranging from 49 to 303 m above sea level, in north-west Lancashire. Total annual production declined from a mean of 704 g/m2 on the lowest site, to 553 g/m2 on the highest, largely as a result of a severe depression in the spring peak of production, i.e. from 6.7 to 2.5 g/m2 per day. Later in the year, the daily rate of DM production was similar on all sites. Species varied in their response to increased altitude; Lolium was worst affected by this and Festuca least. The significance of these results, and possible reasons for the decline in spring production are discussed.

Notes: Tillering is examined in relation to the morphology and habit of growth of the perennial herbage grasses; particular reference is made to the effects of cutting and grazing. The importance of tillering in establishment and regeneration or perennation of a grass sward is considered; greater importance is attached to the role of tillers in the regrowth of swards cut for conservation at the reproductive stage of growth. Amounts of regrowth are related to both the number and size of vegetative tillers present at the base of reproductive tillers at the time of cutting. The probable inhibition of the replacement tiller buds by the developing inflorescence is suggested as a reason for the poor growth of grass swards in the favourable environment of midsummer.The physiological mechanisms which control tillering during reproductive development are examined. Spring and winter wheat (Triticum aestivum), Lolium temulentum and Phalaris tuberosa are used as physiological tools to demonstrate that tillering is restricted during reproductive development, and that stem extension may be more important than changes at the stem apex in controlling this restriction of tillering at the base of the inflorescence-bearing stem. It appears from results of the application of a range of growth regulators that substances derived from the meri-stematic centres, in either the elongating stem or the terminal meristem, indirectly control the metabolic activity of the lateral buds from which new tillers are derived. The degree of apical dominance is shown to depend on the light intensity in which the plants are grown. Finally, the physiological results are used to suggest reasons for the commonly found apparent inability of heavily fertilized perennial ryegrass (Lolium perenne) swards to regrow after cutting at the inflorescence-emergence stage of growth.

Notes: A study of the relationship between some farm and grassland management factors and milk production at the Hannah Dairy Research Institute in the period 1951–70 is reported. During this period various aspects of farm management were altered, and total annual milk production was increased from 28,400 to 63,900 gal. The major factors influencing total milk production, in order of declining importance, were: the overall rate of stocking, milk yield per cow, the numher of milking cows as a percentage of all animals, and the acreage of grass as a percentage of the total farm acreage. Stocking rate and milk yield per cow together explained 85% of the total variation in annual milk production. No significant relationship was found between total milk production and weight of concentrates fed/gal, the amount of fertilizer N applied/aC, rainfall and sunshine data. It is suggested that the lack of a direct relationship between milk prodnction and the amount of fertilizer N applied resulted from the contribution of N from clover and from grazing animals.

Notes: The loss of water from small bulk samples of five grass species was studied under constant conditions of humidity, temperature and lighting. A logarithmic curve was fitted to the data and the different species compared on the basis of a loss coefficient derived from the fitted curve. The species varied significantly in this aspect; those with high surface-area to dry-weight ratios generally lost water fastest The presence of stem material appeared to increase the rate of water loss considerably. High humidity during drying caused the grasses to lose water more slowly and to retain much more water at equilibrium with the surrounding air. Chemical treatments to speed water loss, using a solvent and a fungal toxin were tested. Both appear to have some promise. Selection for high water loss in grass breeding may also be possible.

Notes: Eighteen crossbred Aberdeen-Angus and six Shorthorn steers with an average liveweight of 382 kg were given silage (DM content 22.3%) ad lib., supplemented with 0, 1.2, 2.4 and 3.6 kg artificially dried grass, or 1.8 kg rolled barley, per day. A digestibility study carried out on the silage and dried grass showed that the concentration of the metabolizable energy was 52.7 and 45.6 kcal/100 kcal of food, respectively. Live-weight gain increased with each level of supplementation. Supplementation did not significantly affect the intake of silage DM, but differences in the intake of total DM were significant. The killing-out percentages of the steers were similar. The results suggest that dried grass pellets may be a usefid supplement for a silage diet. It was shown that 1.12 kg of dried grass was equivalent to 1.80 kg rolled barley as a supplement for silage.

Notes: Three groups of Hereford × Friesian steer calves, bom in early January 1969, were strip-grazed on eqoal areas of a sward of S321 perennial ryegrass from May to September inclusive, and received kibbled barley at the rate of nil, 3/4% or 1 1/2% of liveweight per day. Adjustments were made to the number of animals per group in order to maintain the same high grazing intensity (defined as 8 cm stubble height in grazed areas) on all treatments. The animals receiving supplementary barley gained weight at a rate 17–19% higher than the controls, but there was no significant difference in growth rate between the high and low levels of supplementation. The effficiency of conversion of barley was only 5–12 kg per animal liveweight gain/100 kg barley OM.The high level of supplementation resulted in an increase in stocking rate of 36 % over that of the control group, and an increase in liveweight gain per unit area of land grazed of 63%. The additional liveweight gain due to supplements, expressed per unit area of land grazed, was relatively constant at 21–24 kg liveweight gain/ 100 kg barley OM consumed.

Notes: Books review in this article:PERRING, F. [Ed.] The flora of a changing BritainWATER AND SOILS DIVISION, MINISTRY OF WORKS, NEW ZEALAND. Land use capability survey handbook. A New Zealand handbook for the classification of landNATIONAL ACADEMY OF SCIENCES, NATIONAL RESEARCH COUNCIL, COMMITTEE ON REMOTE SENSING FOR AGRICULTURAL PURPOSES. Remote sensing with special reference to agriculture and forestryHUGHES, D. E.; ROSE, A. H. [Eds] Microbes and biological productivity. Twenty-first symposium of the Society for General Microbiology held at University CoOege London April 1971

Notes: The average daily intake of drinking water of two groups of 10 spring-calved Ayrshire cows, one gronp on a paddock and the other on a Wye College system of grazing, was measured on 4 days/week for 20 weeks. Trends in water intake were similar on both systems, the average daily intake being 23.0 ±8.5 kg (5.1 ± 1.9 gal)/cow. The average DM content of the herbage was 17.8% and the mean air temperature 134°C (56 1°F). The weight of water drunk was positively related to the daily milk yield and the DM percentage of the herbage, and negatively related to daily rainfall and relative humidity. All of these relationships were significant. Possible changes in the provision of water for dairy cows at grass are discussed.

Notes: The ripening process in a tetraploid ryegrass is described in terms of seed moisture content changes. The heavier seeds of tetraploids appear to be shed at an earlier stage in the ripening process than those of diploid ryegrass. The seed moisture level at which a tetraploid ryegrass seed crop is harvested is shown to be a critical factor determining the yield and quality of from the crop harvested seed.

Notes: The two-stage in vitro digestibility technique was scaled down to use 0.1 g samples. The accuracy of predicting in vivo DM digestibility by the use of micro-samples was studied, using 35 samples of four grass species of known in vivo digestibility. When the sample size was reduced from the normal 0.5 g to 0.1 g, the residual standard deviation of the regression relating in vitro to in vivo DM digestibility was increased from ±2.5 to ±3.4 digestibility units. Grinding the samples more finely than through a 1.0 mm screen did not improve the accuracy of predicting in vivo digestibility.It was concluded that the in vitro method may be used with micro-samples where necessary, but with less accuracy than the macro-technique. For maximum accuracy, the use of standards of known in vivo digestibility is necessary.

Notes: A total of 228 separate dung pats voided by lactating dairy cows between May and October on a ryegrass/dover sward were studied for 2 years. The pats were on grazed swards receiving, on average, either 440 or 110 lb N/ac (492 or 123 kg/ha) per year. The mean area of the pats was 0.62 ft2 (0.058 m2) with no difference in area between the pats on the two N treatments. On average, the pats on the high- and the low-N treatments crumbled in 63 and 55 days, respectively, and disappeared in 115 and 113 days, respectively. Pats deposited in July disappeared significantly quicker than pats deposited in May. The average area of rejected herbage around the pats was 2.63 and 084 ft2 (0.244 and 0.078 m2), respectively, 1–2 months, and 1 year after they were voided; but after 2 years the affected areas were recolonized with ryegrass and clover and were grazed normally. It is concluded that the levels of N fertilizer applied had no differential effects on the breakdown of the dung and on the subsequent recolonization of the affected areas by pasture plants.

Notes: The agronomic value of Syn 1 tall fescue, a synthetic variety derived from North African parent material, was determined in three experiments. Herbage yield, sward purity and digestibility were measured under cutting treatments for incremental sward growth during autumn/winter, and for sward regrowths during autumn/winter, spring and a complete season. Similar data were obtained for sward regrowths during autumn/winter and spring under defoliation by grazing. Syn 1 was compared with several of the north-temperate region tall fescues, e.g. S170, Rozelle and Manade, also with S143 cocksfootSyn 1 showed yield superiority in autumn/early winter when there were comparable populations of tall fescue. Under cutting management, Syn 1 swards thinned out rapidly because of lack of winter-hardiness and yields were depressed in the second season; the effects were worst under the winter foggage-type management. Under grazing, with probably less severe defoliation, Syn 1 swards maintained yields for an additional season, but thereafter failed to persist Syn 1 swards had low spring- and annual-yields.The yield advantage of Syn 1 in autumn/early winter was not sufficient to be of great agricultural value and with its shortcomings in winter-hardiness and annual yield, it was considered unsuitable for West of Scotiand conditions. The main value of plant material such as Syn 1 may lie in ccmferring autumn/winter growth potential to winter-hardy north-temperate tall fescues in a breeding programme.

Notes: Three cutting heights, 1, 3 and 5 in. (2.5, 7.6 and 12.7 cm), and three cutting frequencies, 3, 6 and 10 weeks, were imposed on a pure sward of Italian ryegrass (Lolium multiflorum) cv. Irish. Lowering the cutting height increased the yield of DM, digestible DM, crude protein and crude fibre. Increasing the interval between cuts increased the yield of DM, digestible DM and crude fibre. The results are discussed in relation to other research findings and to the management of short-term leys of Italian ryegrass.

Notes: Books review in this article:SPEDDING, C. R. W.; DIEKMAHNS, E. C. (Editors) Grasses and legumes in British agricultureHYAMS, E. Plants in the service of man. 10,000 years of domesticationWAREING, P. F.; COOPER, J. P. (Editors) Potential crop productionDENT, J. B.; ANDERSON, J. R. (Editors) Systems analysis in agricultural managementTTVY, J. Biogeography. A study of plants in the ecosphereWESTERN, J. H. (Editor) Diseases of crop plantsCHORLEY, R. J. (Editor) Water, earth, and man. A synthesis of hydrology, geomorphology, and socioeconomic geography

Notes: The capacitance meters available in the past for estimating herbage yields have lacked sensitivity at the extremes of their range of measurement. The preliminary evaluation of a highly sensitive capacitance meter described here indicates that accurate measurement is possible in the range 0.1100 kg DM/ha. The implications of this development for the measurement of herbage of low availability are discussed.

Notes: Books review in this article:ROTHAMSTED EXPERIMENTAL STATION. Details of the classical and long-term experiments up to 1967NIX, J. Farm management pocketbook. Ed. 4WIESNER, C. J. Climate, irrigation and agricultureHARBORNE, J. B.; BOULTER, D.; TURNER, B. L. (Editors) Chemotaxonomy of the LeguminosaeNELSON, J. G.; CHAMBERS, M. J.; CHAMBERS, R. E. (Editors) Process and method in Canadian geography

Notes: An area of black currants in Kent, which had been cut for mechanical harvesting in July 1970, was observed in the following spring to be uniformly infested with larvae of Clepsis spectrana, whilst adjacent bushes which had been hand picked were practically free from larvae. This difference was attributed to adults preferring the post-harvest growth, which occurred only on mechanically harvested bushes, as a site for oviposition.

Notes: The incidence of leaf diseases was assessed in approximately 150 crops of spring barley in Cornwall, Devon and Dorset in 1967–69 inclusive. Estimates of the percentage area of the laminae of the two top leaves affected by each disease were inade at growth stage 11.1 (Feekes scale). Mildew, leaf blotch and brown rust were the main diseases, mildew being the most severe in two of the years. Disease incidence varied with location and cultivar. Leaf blotch was usually more severe in earlier than in later sowings but the effect of sowing date on mildew severity was not consistent. None of the diseases was significantly more severe in crops which immediately followed barley than in those which did not, but the level of mildew was significantly lower after barley than after other crops. Thousand-grain weight determinations, made on samples from a proportion of the crops surveyed, correlated well with the amount of total disease on the top leaf. The estimated loss in grain yield from all diseases ranged from about 19 to 22 per cent over the three years. Leaf blotch was more severe and mildew less severe in the three south-western counties than in England and Wales as a whole.

Notes: Field trials were condueted in 1967 and 1969 in south-west England to compare the distributions on potato plants of green and pink biotypes of Macrosiphum euphorbiae. In both trials, the green biotype was most abundant on the lower, older leaves, whereas the pink biotype was of similar abundanee on all leaves irrespective of their position on the plant. Furthermore, the numerical predominence of the green biotype was greater on older plants.

Notes: The results of a field experiment with winter barley in which severe mildew occurred early in the autumn are described. Where the disease was controlled with ethirimol (‘Milstem’)* seed dressing, the production of adventitious roots and tillers in the autumn was significantly increased and more of the tillers developed to maturity leading to higher grain yields.

Notes: The shell of wheat bulb fly eggs has plastron areas at either end and a few on the side; the central micropyle is surrounded by petal-like plastrons.

Notes: The electroscan microscope was used to show details of the external structure of the egg of cabbage root fly. The median area between the hatching lines differs from the more solid structure of the longitudinal ridges on the rest of the surface. On the pointed posterior end are small holes in the outer layer, but in contrast to wheat bulb fly, Leptohylemyia coarctata (Fall.), there are no distinct plastron areas around the micropyle at the blunt anterior end. The egg of cabbage root fly also lacks small plastron areas among the longitudinal ridges.

Notes: In a series of field trials during 1968–1970, 4 per cent methiocarb or 3 per cent metaldehyde baits, applied to plots before drilling winter wheat, effectively reduced the numbers of slugs found by various methods of trapping after treatment. In the dry conditions prevailing at most of the sites, there were few consistent differences between methiocarb and metaldehyde. Little grain damage occurred on the control plots at any of the sites as weather conditions after drilling did not favour slug activity. Small increases in plant stand were obtained on the treated plots but differences between treatments were not significant.

Notes: Some Fl progeny of crosses between resistant and susceptible cultivars of potato contain resistance to Heterodera rostochiensis pathotype E (British notation) supplementary to that conferred by genes H1 and H2. This resistance in hybrid K2/6 was equal to that of its parent D40 and could be incorporated in a useful resistant cultivar.

Notes: In a field trial in Bedfordshire, England, in 1970–71 aldicarb at 2–8 lb a.i./acre (2·2–9·0 kg/ha) and dazomet at 196–784 lb a.i./acre (220–879 kg/ha) significantly increased the yield of onions (cv. Robusta) in irrigated sandy loam inoculated with Ditylenchus dipsaci (stem nematode). Aldicarb and dazomet prevented D. dipsaci injuring onion bulbs, but yields were greater from treating with dazomet than with aldicarb, probably because dazomet made more nitrogen available to the crop and aldicarb damaged the seedlings.

Notes: Both in experimental plots and on a field scale in East Anglia better control of Tarsonemus fragariae Zimm. was achieved by application of endosulfan when strawberry plants (cv. Cambridge Favourite) had previously been mown off after harvest. Therefore, where this pest is a problem removal of foliage before spraying should prove beneficial.

Notes: Eggs collected from around the base of cultivated cruciferous crops in north-east Scotland were hatched on suitable media contained in petri dishes, or on plants grown in pots in an outdoor insectary. Breeding in petri dishes was more successful.It was found that Erioischia brassicae(Bouche), the cabbage root fly, and E. floralis(Fall.), the turnip root fly, occur together in swede crops, but only E. brassicae in crops of cabbage and cauliflower. Despite the eggs of both species overlapping in size and the chorion patterns being indistingtiishable, plotting mean egg sizes over short consecutive periods showed that the main egg-laying period of E. floralis was during August and September.The measurements of eggs collected before and after 1 August, when plotted on arithmetical probability paper, indicated an appreciable difference in the average size of eggs laid in the two periods, but only at those sites where both species were found.

Notes: On average, 180 samples of sugar beet seed grown in England between 1958 and 1970, and examined before being steeped in ethyl mercuric phosphate (EMP), had 39 per cent of clusters infected with Phoma betae. However, the fungus damaged few seedlings in commercial crops because this treatment controlled it. In 1969, Aphanomyces sp. was unusually prevalent in sugar beet crops. Treating EMP-steeped seed with a protectant fungicide did not, on average, significantly increase seedling emergence or final plant stand.

Notes: Post-harvest applications of relatively low concentrations of benomyl (0.0125 per cent a. i.), phenylmercuric chloride (0.005 per cent), thia- bendazole (0.0125 per cent a.i.) and triarimol (0.003 per cent a.i.) were effective in preventing the production of perithecia of Venturia inaequalis. Urea (5 per cent) was also effective. Phenylmercuric chloride was the only chemical effective as a spring application in preventing the release of ascospores.

Notes: Between 1967 and 1970, 19 insecticides in nine trials in southern and eastern England were evaluated for the control of pre-blossom pests on apple. Where sprays were applied at the green-cluster stage, azinphos- methyl, dichlorvos, ‘Dursban’, fenitrothion, methidathion and phos- alone gave an equivalent or better control than DDT of winter moth larvae, tortricid larvae and apple capsid. Iodofenphos, phosmet and trichlorphon were also as effective as DDT against tortricid larvae and apple capsid but gave more variable control of winter moth larvae. Carbaryl, Ciba C11042, cyanophos, monocrotophos and pirimiphos-methyl in single trials and Du Pont 1642 and ‘Torak’ also gave effective control of winter moth and tortricid larvae; no data were available on their effect on apple capsid.Dichlorvos, ‘Dursban’. fenitrothion, methidathion and phosmet were particularly effective against apple sucker. Cyanophos, Du Pont 1642, iodofenphos, monocrotophos and ‘Torak’ were also effective in single trials, but azinphos-methyl, phosalone and trichlorphon gave less effective control of apple sucker when infestations were heavy.In one trial, azinphos-methyl, dimethoate and fenitrothion effectively controlled apple-grass aphid. Where a bud-burst spray was applied, azinphos-methyl, DDT, Du Pont 1642,‘Dursban’ and iodofenphos in a single trial all gave some control of apple blossom weevil. Although green-cluster sprays are generally too late to prevent some damage by apple blossom weevil, some degree of control of larvae was achieved at that stage by azinphos-methyl, Ciba C11042, Du Pont 1642, pirimiphos-methyl and ‘Torak’.In a single trial on pear, azinphos-methyl or phosalone applied at green cluster or white bud, or methidathion at green cluster, gave a control of winter moth larvae equivalent to DDT.

Notes: Twenty-three pure culture isolates of Phytophthora fragariae were obtained from the cvs. Cambridge Favourite, Cambridge Rival, Gorella and Redgauntlet which had become infected at one site in Hampshire. All were race B66–11. When four isolates were compared, there was no evidence that they had been selected for pathogenicity towards their soiuce cultivar.

Notes: In a glasshouse pot test Meloidogyne naasi Franklin developed to the adult stage and produced eggs on 11 cultivars of oats. All cultivars were less susceptible than the spring barley control, and there were differences in susceptibility between them.

Notes: The prophylactic properties of Bayer 22555 (1,000 p.p.m. a.i.), beno- myl (333 p.p.m. and 1,000 p.p.m. a.i.), FUN 52.133 (160 p.p.m. and 320 p.p.m. a.i.) and the insecticide Du Pont 1410 (20 p.p.m. and 80 p.p.m. a.i.) were assessed in a pot experiment using pure culture inoculum of Phytophthora fragariae. Bayer 22555 applied either as a drench or as a dust resulted in a significant decrease in the percentage of infected roots. The effects with and differences between the other chemicals were non-significant.

Notes: Samples from 250–300 spring-sown barley crops including all popular cultivars were taken when the grain was milky ripe. The percentage of the leaf area affected by recognizable diseases was recorded for the top two leaves and sub-samples were tested for barley yellow dwarf virus. Mildew was the most severe disease in the first three years. In 1970, brown rust was most severe. Leaf blotch was the second most severe disease in 1969; in other years it was less severe than mildew and brovm rust. Estimated losses in yield due to mildew were revised in the light of recent data on disease progress. Annual losses of 7–11 per cent, with a mean over the four years of 9 per cent were estimated. Losses caused by leaf blotch infection were estimated to have been about 1 per cent in 1967, 1968 and 1969 and nil in 1970. No consistent annual pattern of distribution of mildew between geographical regions was apparent. Brown rust and leaf blotch infection levels tended to decrease from south to north. Disease severity was related to previous cropping only with respect to leaf blotch in 1969 when crops following a previous barley crop were infected more severely than those following another crop.

Notes: Summary. A resumé of the fate of introductions of Callimorpha jacobaeae (L.) into Victoria, Australia in the 1930s and 1955–62 is given. The problems of acclimatization In the Southern hemisphere and methods by which the pupal diapause can be broken at a time satisfactory for the release of adult moths into the field are discussed. A method is described which gave a high percentage of emergence of adults.Insects of English origin introduced between 1955 and 1959 were severely affected by disease which killed the larvae, but insects introduced in 1961 and 1962 from central Europe did not suffer epizootics. Breeding of the 1961 and 1962 insects in field cages and organdie sleeves attached to ragwort plants is described.The effects of C. jacobaeae on ragwort, the various predators and parasites of C. jacobaeae and their effects on the establishment of the species for the control of ragwort in Victoria are discussed. Essais de lutte contre te séçon jacobée, Senecio jacobaea L., au moyen d'un Léptdoptére de la famille des Arctiidés, Callimorpha jacobaeae (L. dans Vitat de VictoriaRésumé. L'auteur donne un resume du sort des introductions de Callimorpha jacobaeae (L.) dans rétat de Victoria (Australie) au cours des annees 1930 et 1955–62. Les probléemes de l'acclimatation dans I'hémisphére sud et les méthodes par lesquelles la diapose des pupes peut être rompue à un moment favorable pour le lâcher des adultes dans les champs sont discutés. Une méthode est décrite qui donne un pourcentage élevé de sorties d'adultes.Les insectes en provenance de l'Angleterre qui ont été introduits entre 1955 et 1959 ont été durement affecté par des maladies qui ont tué les larves, mais les inseetes introduits en 1961 et 1962 de I'Europe Centrale n'ont pas souffert d'épizooties. L'élevage des insectes de 1961 et 1962 dans des cages en plein air et dans des manches d'organdi fixées aux plantes de séneéon est décrit.Les effets de C. jacobaeae sur le séneçon, les prédateurs variés et les parasites de C. jacobaeae et leurs effets sur l'établissement des espèces pour la lutte contre le séneçon dans l'état de Victoria sont discutés. Untersuchungen zur Bekämpfung von Jakobskreuzkraut, Senecio jacobaea L., mit Callimorpha jacobaeae (L.) (Arctiidae: Lepidoptera) in VictoriaZusammenfassung. Es wird ein Überblick über den Ausgang von Versuchen zur Einführung von Callimorpha jacobaeae (L.) in Victoria, Australien, während der dreissiger Jahre und zwischen 1955–62 gegeben. Die Probleme der Akklimatisierung in der Südhemisphäre und Methoden zur Brcchung der Puppenruhe zu dem für den Flug der Schmetterlinge erwünschten Zeitpunkt werden diskutiert. Es wird eine Methode beschrieben mit der ein hoher Prozentsatz der Imagines zum Schlupfen gebracht werden konnte. Zwischen 1955–59 aus England eingeführte Insekten wurden stark von Krankheiten befallen, die die Larven abtöteten. Bei in den Jahren 1961 und 1962 aus Mitteleuropa eingeführten Insekten traten hingegen keine Epizootien auf. Die Aufzucht der Insekten in den Jahren 1961 und 1962 in Feldkäfigen und an mit Organzastoff umhüllten Kreuzkrautpflanzen wird beschrieben. Die Wirkung von Callimorpha jacobaeae auf das Jakobskreuzkraut, die verschiedenen Pradätoren und Parasiten von C. jacobaeae und deren Auswirkung auf die Ftablierung des Schmettertings zur Bekämpfung von Jakobskreuzkraut in Victoria werden diskutiert.

Notes: Zusammenfassung. Durch Blattapplikation des 14C-markierten Flurenol-n-butylesters an Phaseolus vulgaris wurde die Metabolisiening dieses systemischen Wirkstoffs unter-sucht. Die Struktur zweier isomerer β-Glucoside wurde aufgeklärt, und vier weitere polare Metaboliten wurden isoliert und charakterisiert.Metabolism of flurenol-n-butyl ester in higher plants

Notes: Summary. A dry film or p.-nitrophenyl-α,α,α:-trifluoro-2-nitro-2-tolyl ether (fluorodifen) decomposed rapidly under ultraviolet (2537 run) irradiation in the laboratory. Photolysis under growth chamber lights was slower. One major photolysis product (probably a polymer of fluorodifen) and several minor products were detected.Photolyse du flurodifeneRésumé. Un film sec de p-nitrophényl-α,α,α-trifluoro-2-nitro-p-tolyl äther (fluorodifènc) a été rapidement décomposé sous une irradiation dans l'ultra-violet (253,7 nm) au laboratoire. La photolyse sous l'éclairage des chambres elimatisées fut plus lente. Un produit important de la photolyse (probablement un polyméie du fluorodiféne) et plusieurs produits secondaires ont été détectés.Photolyse von FluorodifenZusammenfassung. Ein trockener Film von p-Nitrophenyl-α,α,α-trifiuor-2-nitro-p-tolyläther (Fluorodifen) zersetzte sich im Laboratorium schnell bei Bestrahlung mit ultraviolettem Licht (253,7 nm). Unter Klimakammerlampen war die Photolyse lang-samer. Es konnten ein Hauptprodukt der Photolyse (wahrscheinlich ein Polymer von Fluorodifen) sowie mehrere Nebenprodukte festgestellt werden.

Notes: Summary. Soil which had received nine previous field treatments of MGPA (33 kg/ha) at intervals of about 6 months, and which had become able to detoxify MCPA more rapidly than untreated control soil, was able to degrade MCPB with equal facility. In contrast, the disappearance rates of phytotoxic residues of dichlorprop (2-(2,4-dichloro-phenoxy)propionic acid), mecoprop (2-(4-chloro-2-methylphenoxy)propionic acid), fenoprop (2-(2,4,5-trichlorophcnoxy)propionic acid) and dicamba (2-methoxy-3,6-dichlorobcnzoic acid), as determined with a bioassay technique, were unaffected by previous treatments of the soil with MCPA.Indirect evidence from these studies suggests that β-oxidation of MCPB to MCPA did not occur to any significant extent either in the soil to which the roots of the indicator plant were exposed or in the roots themselves.Dégradation de quelques herbicides dans un sol préddenvnent traté avec le MCPARésumé. Un sol ayant reçu 9 traitements au MGPA (3,3 kg/ha) à des intervalles d'environ 6 mois et qui est devenu capable de dégrader le MCPA plus rapidement qu'un téntoin non traité, s'est montré capable de diégrader le MGPB avec la mêmefacilité. En revanehe, les taux de disparition de résidus toxiques déterminés par des testsbiologiques, du dichlorprop (acide 2-(2,4-dichlorophenoxy)propionique), du mécoprop(acide 2-(4-chloro-2-méthylphénoxy)propionique), du fénoprop (acide 2-(2,4,5-trichlorophénoxy)propionique) et du dicamba (acide 2-méthoxy-3,6-dichlorobenzoique) n'ont pas été affectés par les traitements antérieurs avec le MCPA.Comme conclusion indirecte de ces travaux il est suggéré que la β-oxydation du MGPB en MCPA ne se produit pas à un dcgré significatif dans le sol où les racines desplantes servant d'indicateurs sont plongées, pas plus que dans les racincs elles-mêmes.Abbau von verschiedenen Herbiziden in einem vorher mit MCPA behandelten BodenZusammenfassung. Boden, der auf dem Feld in Abstanden von sechs Monaten neunmal mit MGPA (3,3 kg/ha) behandelt wurde und dadurch in der Lage war, MGPA schneiler umzuwandeln als der unbchandelte Kon troll boden, konnte MCPB gleichermassen abbauen. Mit Hilfe von Biotests wurde ermittelt, dass vorausgehende Behandlungen des Bodens mit MCPA dagegen keinen Einfiuss auf die Abbaurate phytotoxischer Rückstände von Dichlorprop (2-(2,4-Dichlor-phenoxy)-propionsäurc), Mecoprop(2-(4-Ghlor-2-methyl-phenoxy)-propionsäure), Fenoprop (2-(2,4,5-Trichlorphenoxy)-propionsaure) und Dicamba (3,6-Dichlor-2-methoxy-benzoesaure) hatten.Die Ergebnisse lassen darauf schliessen, dass der β-Oxidation von MCPB zu MGPA weder im Boden, dem die Wurzein der Testpflanzen ausgesetzt waren, noch in den Wurzeln selbst Bedeutung zukam.

Notes: ‘Dowco 275’ (0,0-diethyl 0-(6-fluoro-2 pyridyl) phosphorothioate) at 2·5, 5 and 10 p.p.m. in pots of sandy loam controlled potato cyst nematode (Heterodera rostochiensis Woll.). At 5 p.p.m. the control was as effective as with aldicarb.

Notes: Commercial-scale field trials on farms in North Hampshire over four seasons (1963 to 1968) showed that nitrogen applied to wheat or barley stubble after harvest in the autumn failed to reduce the incidence of take-all and eyespot in the succeeding wheat or barley crop, or produced only minor reductions in the spring which were not maintained up to the stage of crop maturity. There were no consistent significant differences in levels of disease between rate or form of nitrogen applied as urea/ammonium nitrate spray at 0, 12, 24 or 48 units/acre (1 unit/ac × 1·25 kg/ha), ammoniacal gas liquor spray at 48 units/acre and anhydrous ammonia injected at 40 units/acre. Burning-off stubbles with high-output flame cultivators did not significantly reduce the incidence of either disease.

Notes: Verticillium wilt of Pelargonium x domesticum caused by Verticillium albo-atrum and Verticillium dahliae is recorded in the U.K. Naturally-infected plants showed severe symptoms during the summer but there was some recovery in the autumn and winter. In experiments, symptom severity increased at high temperatures but was not markedly in fluenced by day-length treatments. Isolates of V. dahliae from chrysanthemum and pelargonium readily infected either host. Benomyl drenches at 1·5 g/4·5 1. at the rate of 200 ml/plant suppressed symptom expression and resulted in a high proportion of healthy cuttings from infected stock plants.

Notes: Observations at a holding in south-west England in 1970 and 1971 have shown that the mite predator Phytoseiulus persimilis Athias-Henriot can effectively control red spider mite, Tetranychus urticae (Koch), on roses under glass where the grower is willing to dispense with sulphur fumigation.

Notes: Yields of apple fruits over 55 mm or 2 1/4 in. in diameter of CV. Cox's Orange Pippin in orchards studied in Kent were significantly decreased in only two out of five years between 1965 and 1971 by infestations of fruit tree red spider mite. In both these years, early peak populations of the mite occurred before mid-July.

Notes: An isolate of tomato bushy stunt virus was obtained from a tulip plant affected by a necrotic disease. The isolate differs from the type strain in virulence in some experimental hosts, and serologically is more closely related to a pelargonium leaf curl strain than to the type strain. When transmitted manually to tulip plants, both the tulip isolate and the type strain of tomato bushy stunt virus produced leaf symptoms indistinguishable from those caused by tobacco necrosis virus, but the tomato bushy stunt isolates had effects on the flowers different from those caused by tobacco necrosis virus.

Notes: A virus, code-named 52V, was obtained from 16 cultivars and seedlings of red raspberry by inoculation of sap to Chenopodium quinoa during spring or autumn. Some raspberry plants were infected with 52V after six months in the field, and more than 50 per cent of the plants of some cultivars were infected after four years. The virus was also obtained from Rubus occidentalis plants previously infected with virus from red raspberry by means of aphids (Amphorophora rubi and Aulacorthum solani). These aphids transmitted 52V from red raspberry to C. quinoa.52V was transmitted by inoculation of sap to six herbaceous species but induced symptoms only in Chenopodiaceae. In C. quinoa sap, 52V lost infectivity after dilution to 10−2, heating for 10 min at 52·5°C, storage at 18°C for 24 hr or treatment with n-butanol to 8·5 per cent (v/v). Preparations made by clarifying extracts with chloroform or ether followed by differential centrifugation contained a few isometric particles c. 30 nm in diameter which may be those of the virus.

Notes: Symptom production was recorded during a 31 month period in a commercial crop of carnations infected by Fusarium oxysporum f. dianthi. In the first year spread was slow but increased to approximately 12 in. (0·305 m) of bed length per month by the end of the crop.The degree of infection and colonization of the plants did not differ greatly at 18–20°C or 23–25°C, although symptoms appeared more rapidly at the higher temperature.Benomyl, applied as a drench to each plant at the rate of 1·5 g and 3·0 g/4·5 l./200 ml. suppressed symptom expression and was not markedly phytotoxic. Best results were obtained when the fungicide was applied within a week of planting into infested soil. Bioassay results of treated plants indicated a maximum level of activity within the plant 10–14 days after application.

Notes: Experiments using thiabendazole (2-(4-thiazolyl) benzimidazole) for thé control of Verticillium albo-atrum in lucerne are described. In in vitro tests thiabendazole completely inhibited fungal growth. In the glasshouse, spray treatments were ineffective but a soil drench treatment using 50 p.p.m. of active ingredient proved the most effective. In some other treatments phytotoxicity was observed. In most cultivars in a field trial there appeared to be a cumulative reduction in wilt development with further applications of fungicide: in cvs. Du Puits, Europe, Flamande and Provence the reduction occurred more quickly than in Cardinal, Emeraude, Eynsford and FD100.

Notes: Development of Cephalosporium aphidicola was inhibited in vitro by the fungicides benomyl and triarimol but not by dimethirimol. However, neither triarimol nor dimethirimol inhibited the fungus in individuals of the aphid. Aphis gossypii, that fed on cucumber plants treated with the fungicides. Plants treated with benomyl were aphicidal.

Notes: An attempt was made in 1968 to reduce a wheat bulb fly population in a field in northern England by means of insecticidal seed dressings on early and late-sown winter wheat. Ethion seed dressing reduced plant and shoot attack and also decreased the number of larvae within the plants on the late-sown plots but not on the early-sown. Chlorfenvin- phos seed dressing had no significant effect on either sowing. It is concluded that the control of wheat bulb fly populations by the use of these seed dressings on wheat crops in the previous year is not a promising means of control.

Notes: Summary. Copper sulphate (GUSO4.5H2O) and sodium hydroxide (NaOH) were used to test the performance of a split-root method for evaluating the effectiveness and phytotoxicity of root-active herbicides. This method involves a vertical separation of the root system of weeping willow (Salix babylonica L.) cuttings. One section is treated with the herbicide dissolved in half-strength Hewitt's medium while the other remains in medium without herbicide during the test period. Roots are assayed with 2,3,5-triphenyttetra-zolium chloride 24 h after treatment to determine their viability. Both herbicides satisfactorily reduced the viability of the treated roots as measured by the quantity of formazan extracted. Copper sulphate was systemic and injured untreated plant parts; sodium hydroxide affected only treated roots. The split-root tetrazolium method is relatively rapid and does not require sophisticated laboratory equipment.Méthode au tétrazolium sur portions de racines pour l'évaluation de l'efficacité et de la phytotoxicité des herbicides agissant par les racines

Notes: Summary. The root and shoot growth of oat (Avena saliva L.) and squash (Cucurbita maxima Duchesne) was reduced in proportion to propachlor concentration. Corn (Zea mays L.) root growth was inhibited only by concentrations of 16 ppm and higher. Cell division in onion (Allium cepa L.) root tips was reduced by propachlor and totally inhibited by 16 ppm. Auxin-induced cell elongation of oat coleoptiles was inhibited in proportion to propachlor concentration. Propachlor treatment prevented the normal senescence of squash cotyledons by inhibiting the autolysis of proteinaceous and lipid reserves.Effets morphologiques, anatomiques et biochimiques du propachlore sur la croissance des plantules Riisumi.

Notes: Zusammenfassung. Die Bekämpfung von Galium aparine L. mit Mecoprop im Nachauflaufverfahren ist abhangig sowohl von der Pflanzengrösse ab auch vor allem vom Boden, in dem die Pflanzen wachsen:〈list xml:id="l1" style="custom"〉1 Kleine Pflanzen werden leichter vernichtet als grosse.2 Pflanzen, die auf einem Boden mit hohem organischen Anteil wachsen, sind gegen Mecoprop widerstandsfähiger als solche, die auf einem Boden mit niedrigem C-Gehalt wachsen.3Ein Teil der im Nachauflaufverfahren gespritzten Herbizidmenge gelangt auf den Boden und wirkt zusätzlich durch Aufnahme über die Wurzeln.4Diese zusätzlichc herbizide Wirkung ist auf den Bodenproben I und II mit hohem organischen Anteil geringer als auf dem Boden mit niedrigem C-Gehalt. Als Ursache der geringeren Wirksamkeit ist eine verstärkte Adsorption des Mecoprop in den Bodenproben I und II gegenüber Boden III verantwortlich.5Als Adsorbens kommt nur die organlsche Substanz der Bodenproben in Frage.Der zu erzielende Gesamtbekämpfungserfolg hängt neben der Aufnahme des Mecoprop über das Blatt auch von der zusätzlichen Wirkung des Herbizids über den Boden ab. Control of Galium aparine with mecoprop in relation to soil type

Notes: Summary. IAA, GA, kinetin, 2,4-D and naptalam were applied at 100 or 1000 ppm in lanolin to wounds made at the top of the hypocotyl of Fraxinus pennsylvanica Marsh. seedlings. Formation of normal periderm was prevented in the hypocotyl below the wounded tissue by 1000 ppm IAA or naptalam and 100 or 1000 ppm 2,4-D. IAA or naptalam at 100 ppm and GA or kinetin at 100 or 1000 ppm retarded normal periderm development. Wound periderm development was prevented only by 1000 ppm 2,4-D. Wound-stimulated development of normal periderm in tissues near the wound was prevented by 1000 ppm kinetin and 100 or 1000 ppm 2,4-D. Anomalous growths which appeared morphologically similar to nascent roots developed in the wounded hypocotyl section of seedlings treated with 1000 ppm naptalam and 100 or 1000 ppm 2,4-D. Identical growths were found in unwounded portions of the hypocotyl of seedlings treated with 100 or 1000 ppm 2,4-D. The data emphasize differences in physiological control of normal and wound periderm development. Effets de substances de croissance et d'herbicides sur l'onlogénie du pérderme normal ou blessé dans des plantules de Fraxinus pennsylvanica.

Notes: Summary. The effects of 2,4-D, 2,4,5-T, IAA and GA on the germination behaviour of one-seeded pods of Psoralea corylifolia L. were studied. For each chemical, inhibition of germination of acid-scarified pods increased with increase in concentration. The inhibition was irreversible and led to death of the seed in the pod. Morality, expressed as percentage of dead pods, was highest for 2,4,5-T and IAA and lowest for GA. Impermeable or ‘hard’ pods were unaffected by the treatments. Though acid-scarified pods were significantly damaged by an 8 h chemical treatment, weathered pods were unaffected by treatments of less than 30 h duration. After scarification, dry pods were more susceptible than pre-imbibed ones. Rates of water uptake were determined for pods of both categories. Effets de quelgues produits chimiques sur la germination de Psoralea corylifolia L.

Notes: Summary. The selective action of triazine herbicides for control of wild canarygrass (Phalaris spp.) in wheat was studied in four field experiments. Canarygrass was controlled by pre- and post-emergence applications of methoprotryne and terbutryne. The phytotoxicity of methoprotryne to wheat was higher than that of terbutryne. Addition of small amounts of simazine to either one of the methylthiotriazines considerably increased damage to wheat. The most resistant stage of wheat after emergence was that of spike initiation, whereas the most sensitive stage was that of earing. Increase of yield as a result of control of canarygrass was higher in semi-dwarf wheat than in normal-height cultivars. Application of 625 g/ha of terbutryne to a semi-dwarf cultivar pre- and post-emergence increased grain yield by 56% and 29%, respectively. Action selective des triazines pour la lutte contre les Phalaris dans le blé

Notes: Summary. Freshly-collected seeds of twenty species of annual weeds were uniformly mixed with 2.5, 7.5 or 15 cm of soil confined in cylinders sunk in the ground outdoors. The soil was either cultivated four times a year or left undisturbed, seedling emergence was recorded, and after 5 years the numbers of viable seeds remaining were determined.Total seedling emergence from seeds incorporated to 2·5, 7·5 and 15 cm amounted to 75, 65 and 54% respectively of those added when the soil was cultivated, and 58, 36 and 21% where it was left undisturbed. The corresponding numbers of viable seeds remaining after 5 years were 2·3, 4·0 and 7·7% respectively for cultivated soil, and 6·8, 16·5 and 31·6% of the seeds initially added and then not disturbed. Individual species varied in their responses to increasing depth of incorporation and to cultivation; these differences are discussed in relation to the dormancy characteritics of the seeds.Devenir des semences de quelques mauvaises herbes annuelles à différentes profondeur dans un sol cultivé et non cultivé

Notes: Summary. Trifluralin (2,6-dinitro-NN-dipropyl-4-trifluoromethylaniline) pre-sowing, and carbetamide (d-N-ethyl-2-(phenylcarbamoyloxy)propionamide) and asulam (N-(4-aminobenzenesulphonyl)methylcarbamate) pre-sowing or post-emergence were evaluated for the control of Rumex obtusifolius L. in autumn-sown red clover (Trifolium pratense L.). All herbicides gave good control of if. obtusifolius from seed. Asulam at 2 or 4 kg/ha gave the best control of R. obtusifolius from rootstocks, followed by trifluralin at 1 kg/ha and carbetamide at 2 kg/ha. Poa annua L. was controlled by trifluralin and carbetamide but not by asulam. The results are interpreted in terms of the mode of action and method of application of the herbicides. La lutte contre la Patience sauvage (Rumex obtusifolius L.) dans un semis récent de trèfle rouge (Trifolium pratense L.) avec la trifluraline, le carbétamide et l'asulame

Notes: Summary. Chlorfenprop-methyl, the active ingredient of the selective herbicide BIDISIN®, induces autolysis in the leaves of Avena fatua L. During this process the cellular hydrolytic enzynnes, normally inactive, degrade the polymeric proteins, starch and nucleic acids, leading to breakdown of the plant. The basic metabolic processes of respiration, photosynthesis, protein synthesis and RNA synthesis are not inhibited by chlorfenprop-methyl but become inactivated during autolysis.Méemisme d'action de l'herbicide sélectif chlorfenprop-méthyle

Notes: Summary. Evidence is presented that blackcurrants show a considerable tolerance to simazine when the entire root system is exposed to a uniform concentration of the herbicide in sand and water culture. The tolerance of this species under field conditions does not therefore seem to be primarily due to root development being limited in the surface soil to which simazine is applied. Accordingly, experiments were carried out using simazine, labelled in the ring with 14C, to determine whether there were restrictions to the uptake of the herbicide by the roots and its translocation to the xylem sap and leaves, and whether there was extensive breakdown of simazine in the plant. The results of these experiments are compared with those on two susceptible species, barley and marrow.Although simazine appeared to be metabolized to a greater extent in blackcurrants, and was less readily translocated from the roots, than in the susceptible species, a substantial proportion of the labelled material in the leaves was present as unchanged simazine. Studies on the effects of simazine on the rate of transpiration of detached leaves of the three species suggested that in blackcurrants there was a restriction to movement of the herbicide from the conducting tissue in the leaves to the mesophyll; this was confirmed by autoradiographs. It is suggested that this restriction, combined with partial breakdown of the herbicide in the leaves, may be responsible for the tolerance of blackcurrants to simazine.Résistance du cassissier à la simazine

Notes: Summary. Vaucheria plants collected from a ditch near Crowland and from the River Cherwell at Oxford in the first week of October 1970 were identified as V. dichotoma Ag. A nutrient medium is described which allows the growth and the production of organs of sexual reproduction of this alga. Preliminary studies on the control with diquat show that it must be exposed to a concentration of 2 mg/1 for 6 h for the herbicide to be effective. The presence of mud reduces the rate at which chlorophyll disintegrates and hastens the inactivation of diquat. Etudes sur la biologie et la destruction de Vaucheria dichotoma. Ag. dans les eaux doucei de Grande-Bretagne

Notes: Summary. Early development of Cynodon dactylon (L.) Pers, was studied on one-node rhizome fragments planted at successive dates over a year. Aerial growth followed the changes in external temperature; in the cool season tops grew very slowly but remained alive. New rhizomes were formed only at temperatures exceeding 15–20°C. Flowering occurred in the warm season from May onwards. No relationship was found between flowering and rhizome formation. The age of plants forming new rhizomes decreased from 5 months for the January planting to less than 2 months for the May-September plantings. Rhizome bud germination was maximal between 23 and 35°C, slow below 20°C and inhibited at 10°C.The weight ratio of tops to subterranean parts of established plants was near 1 in winter, declined in March-April and remained at 0·5–0·6 from May onwards.An established sward of C. dactylon was sampled from September to November of the following year. Dry weight was lowest from January to mid-April, rose in spring and decreased in late summer. Almost no rhizomes were found deeper than 45 cm. Underground parts from the 0–15, 15–30 and 30–45 cm horizons constituted 62, 26 and 12% of the total weight, respectively; rhizomes formed more than 90% of the total underground dry weight. In the warm season the dry weight of the subterranean organs amounted to 2, 0·7 and 0·4 kg/m3 of soil in the three horizons, respectively.Percent dry matter in tops and subterranean parts was about 35–45% in the winter and 50–65% in the warm season. Up to 2% reducing sugars was found in various parts of the plants. The water-soluble sugar content of rhizomes was high in November-December, decreased in late winter, rose again in spring, and decreased in late summer.Percent germination of rhizome buds fluctuated greatly during the year, but complete dormancy was never recorded. Newly-formed rhizomes showed a high germinative capacity. Similar germination percentages were found on fragments with one node and those with several nodes. Développement du Cynodon dactylon (L.) Pers.

Notes: Summary. Direct contact of seeds and recently emerged seedlings with 2,4,5-T at 25 or 100 ppm caused abnormal development of Pinus resinosa Ait. seedlings. The first observed effect of 2,4,5-T treatment at 25 ppm was cessation of cell division and expansion in the roots. Subsequently the herbicide stimulated proliferation and expansion of parenchyma ceils in the stem and cotyledons, causing abnormal thickening of the seedlings. Parenchyma cells in the upper stem became disorganized and many of them collapsed. Callus tissue then formed in the region of tissue disintegration. The herbicide also inhibited formation of primary needle primordia and expansion of primary needles. In treated plants the cotyledons were fused to primary needles. Cell proliferation and formation of callus tissue were greater with 2,4,5-T at 100 ppm than at 25 ppm. Quelques effets histologiques du contact direct des semences et desjeunes plantules de Pintis resinosa avec le 2,4,5-T

Notes: Summary. Argemone mexicana L. and A. ochroleuca Sweet., two closely related species that often co-exist in the same habitat, showed different responses to nitrogen, phosphorus and potassium. Total yield, shoot: root ratios and nutrient uptake all differed. The significance of these results is discussed and it is concluded that the differences not only permit the species to exist in ecologically distinct habitats but also allow them both to survive in apparent co-existence. Facteurs de la nutrition influençant la distribution de deux espéces très voisines d'Argemone

Notes: Summary. The effects of pre-sowing treatments with terbutryne (4-ethylamino-2- niethylthio-6-t-butylamino-1,3,5-triazine) and with simazine (2-chloro-4,6-bisethyl-amino-1,3,5-triazine) on seedling mortality of wheat grown from regular seed and from seed containing about 40 ppm chlormequat (2-chloroethyl trimethylammonium chloride), due to a late chlormequat treatment of the seed-parent, were tested in two pot experiments. In another pot experiment the effects of pre-sowing and post-emergence treatments of terbutryne on dry matter accumulation and moisture content in SPT (= Seed-Parent Treated) and regular wheat seedlings were examined.No significant differences in simazine resistance between regular and SPT seed were found. However, there was a marked and significant increase in terbutryne resistance of SPT over regular seeds, which was expressed by a longer period to 50% seedling mortality as well as by a lower daily increase in mortality. Growth retardation, caused by pre- sowing as well as by post-emergence terbutryne treatments, was appreciably less in the SPT seedlings than in the regular ones. The higher terbutryne resistance of the SPT seedlings may be attributable to their higher moisture content induced by the chlormequat. Effet du traitement des pieds meres avec le chlorméquat sur la résistance des plantules de blé a la terbutryne et à la simazine

Notes: Summary. The effects of localized herbicide placement at different internodes of pea (Pisum sativum L. cv. Alaska) shoots below the soil surface after plant emergence were studied by removing the soil from around the shoots and replacing with herbicide-treated soil. The first internode proved insensitive to linuron, diuron, atrazine and simazine at 4·5 kg/ha, while treatment of the second and third internodes markedly reduced plant growth 4–6 days after treatment. Separate exposure of the first internode alone, and the second and part of the third together to 14C-labelled atrazine indicated no difference in herbicide metabolism. However, a two- to threefold increase in 14C uptake and movement to the foliar parts occurred when the second and part of the third internode was treated, as compared to first internode treatment. Thus the differential sensitivity of the internodes to atrazine, and possibly to the other herbicides, may be because the more mature first internode allows less uptake and subsequent movement to the foliar parts. Absorption dans la zone des tiges des herbicides appliqués dans le sol chez Pisum sativum L.

Notes: Summary. The presence of weeds during autumn and winter had no effect on the growth of transplanted spring cabbage provided they were removed before rapid growth of crop and weeds began in early spring. Weeds left beyond this time competed with the crop, resulting in smaller marketable heads. Increasingly severe competition affected internal head quality, reduced the numbers of plants producing heads and resulted in the death of a proportion of the crop plants. The main weed species responsible for crop loss was Stellaria media, which survived winter frosts and grew rapidly in early spring to fill all available ground space, dominating the weed flora and shading the crop foliage.Application of propachlor at planting time failed to give sufficient control of S. media to avoid crop loss, although the onset of competition was delayed. Trifluralin gave excellent control of S. media and resistant species were kept in check by the crop.Comparison of cropped and uncropped plots showed that the crop exerted considerable competitive pressure on the growth and development of weeds particularly where this had been reduced or delayed by herbicide treatment. The presence or absence of the crop did not, however, affect the relative proportions of the weed species, except on plots treated with trifluralin, where the crop suppressed Capsella bursa-pastoris. Compétition des mauvaises herbes dans les choux de printemps repiqués