1. The fungicidal action of vegetable oils on the conidial stage of the hop powdery mildew, Sphaerotheca Humuli (DC), Burr., is a property common to glyceride oils. When applied with 0·25 per cent. Agral I, the various samples of vegetable and animal oils examined, with the exception of castor oil, proved fungicidal at a concentration of 0·5–1·0 per cent.

2. The fungicidal action of glyceride oils is associated with the glyceride structure and, in the presence of Agral I, is unaffected by the presence of those impurities of the oil which are removed by refinement.

3. Glycerol, at 4 per cent., is not completely fungicidal and, under the conditions of the experiments, causes leaf injury; oleic acid, at 1 per cent. is phytocidal; triolein, prepared by synthesis from glycerol and oleic acid, is fungicidal at 0·5 per cent. and causes no injury to the leaves.

4. The fungicidal properties of glyceride oils are affected by the type of emulsification used and the stable emulsions produced by the twosolution oleic acid method are less effective than the unstable emulsions obtained by agitation with dilute Agral I solutions.

Analyses of grass samples from seventeen fertilizer trials on acid soil showed that both the percentage phosphate in the grass and the amount of phosphate removed by the crop were significantly and directly related to the percentage saturation of the b.e.c. of the soil. The amount of acid-soluble phosphate by difference (Table 1, A — B) was also significantly and directly related to the percentage phosphate in the grass but not to the amount taken up by the crop. The amounts of exchangeable bases, exchangeable calcium and acid-soluble, adsorbed and watersoluble forms of phosphate showed no significant relationships with phosphate uptake and percentage phosphate in the grass.

The percentage saturation of the b.e.c. was found to be, on the average, about five times as effective a contributory factor to the percentage phosphate in the grass as the amount of acid-soluble phosphate by difference. The results confirm previous work, which indicated that in acid soils the main form of available phosphate is that associated with the exchangeable bases the effective presence of which is governed by the percentage saturation of the b.e.c. It is considered that phosphate availability and response in acid soils are best assessed by considering the percentage saturation of the b.e.c. rather than the amounts of some form or forms of phosphate in the soil.

The grass analyses also showed that when the amount of phosphorus (P) hi the dry grass exceeds 0·33% no response to phosphate is to be expected. When the percentage in the grass is less than 0·23% responses of 10% or more are likely.

It is generally recognized that there is a close relationship between the utilization of roughage feed and rumination behaviour in ruminant animals (Gordon, 1955, 1968; Pearce & Moir, 1964; Campling, 1966; Welch & Smith,1969; Sudweeka et al. 1975; Thomas, Kelly & Wait, 1976; Fujihara, 1981). Likewise, it is also well known that rumination behaviour is clearly affected by differences in the physical and/or chemical properties of the diet (Gordon, 1958; Campling, Freer & Balch, 1962; Balch, 1971; Ørskov, Fraser& Gordon, 1974; Osuji, Gordon & Webster, 1975; Morgan & Campling,1978; Harumoto & Kato, 1978a, b; Fujihara, 1980b). Recently, Fujihara (1980a, b) observed more efficient rumination in sheep offered fresh grass than hay, and suggested that the efficient rumination might induce an efficient utilization of dietary nitrogen when feeding fresh grass.

A tightly autumn-calving herd of British Friesian cattle, running throughout the year as a single group, received two different amounts of mineralized barley supplement per day during the winter of 1973/4. As they calved, alternate cows were allocated to one of two rates of supplementary feeding differing in the approximate ratio 2:3 which was applied according to the calendar and not specifically related to milk yield.

Average herd size for the year was 140 cows; average milk sales were 4680 kg/cow at a total supplementary concentrate use of 650 kg/cow. All cows had free access to selffeed silage reinforced with brewers' grains. Cows which received 50% more supplement from 8 September to 31 January (an extra 235 kg/cow) showed an improvement in total lactation milk yield of 248 kg/cow. Standard lactation curves were used to demonstrate a significant interaction between quantity of concentrates fed and season of production and showed that most of the improvement took place during the winter period.

Three sowings of marrowfat peas were made at about 20-day intervals at forty-seven centres in eastern England over 4 years. The sowing period ranged from late February to late April, varying with seasonal conditions. Bird damage caused considerable loss of sowings but satisfactory yield data were obtained from forty-one of the trials.

Highest yields were obtained from drillings made in the last 10 days of February. After mid-March each week's delay in sowing resulted in a yield loss of about 3/4 cwt. per acre. Quality fell off slightly from February onwards.

Early sowings suffered some loss of plant in tractor wheelings but were negligibly affected by cold weather.

Early sowings appear likely to encounter better harvest weather than late sowings and the chances of good harvest weather seem appreciably better in the centre and south of the pea-growing area than in the north. Early sowings mature before the cereal crop, enabling better attention to be given to the pea harvest.

It was concluded that the crop should be sown as soon after the middle of February as soil conditions allow.

1. Attention is drawn to the remarkable dissimilarity between the cacao and the grapefruit tree in their nutrient requirements, indicating that grapefruit is calcicolous in physiological habit. This conclusion is mainly based on a consideration of the results of chemical analysis of representative leaf material produced by trees grown on soil of known chemical and physical characteristics, under the same climatic conditions in Trinidad.

2. The nutrient relationships that obtain between the cacao and the grapefruit tree respectively and the soil in which they are growing have been gauged by means of chemical analysis of representative leaf material.

3. For this purpose, leaf material was obtained from trees growing on the differently manured plots of two large-scale field experiments in Trinidad.

1. The problems involved in conservation of fodder in Northern Rhodesia are discussed in relation to climate and present day practices. Special reference is made to the conservation of grassland herbage.

Climatic conditions do not appear suitable for haymaking.

2. A number of silage samples were collected from dairy farms in the territory and from Mount Makulu Research Station. Chemical analyses of these samples are given and their nutritional value is discussed with special reference to their crude protein contents. The majority of the silages were found to have low crude protein.

3. A type of miniature tower silo designed for experimental work is described.

4. Three crops commonly used for ensilage, i.e. maize, maize with legume and Napier grass, were compared with giant Rhodes grass (Chloris gayana Kunth.) when ensiled in these miniature silos. The type of fermentation and loss of nutrients was studied. Rhodes grass ensiled at the early flowering stage was found to compare favourably with the other three. Napier grass (Pennisetum purpurem) cut when over 6 ft. high did not ensile well and had a low crude-protein content.

5. Giant Rhodes grass was ensiled in miniature experimental silos at two different stages of growth. Cutting the grass at a height of 20 in., three times during the season, resulted in a higher yield of dry matter and crude protein per acre than cutting once at a height of 40 in. even when the resultant aftermath growth was included.

Field experiments were conducted in a zinc-deficient flood plain alluvial soil to study the effect of amounts, methods and sources of zinc application on the yield and uptake of zinc by wheat. Zinc was applied at 0, 5 and 10 kg Zn/ha as zinc sulphate and zinc oxide either broadcast and mixed in the soil or drilled below the seed. Spray application of zinc was also tested. Irrespective of the source, grain yield and zinc uptake significantly increased up to 10 kg Zn/ha. Soil-applied zinc was highly correlated with yield and zinc uptake in the two field experiments. Grain yield was also found to be significantly correlated with zinc content of grain (r = 0·78), straw (r = 0·72) and flag leaf (r = 0·66). When applied at the rate of 10 kg Zn/ha, broadcasting of zinc sulphate and drilling of ZnO below the seed were equally effective in increasing grain yield of wheat. Foliar spray of zinc sulphate was an effective emergency method, but in highly zinc-deficient soils it did not compare well with soil application of zinc.

1. Seed plots of five perennial rye-grass varieties, S23, S24, S321, Melle Pasture and an experimental type, Ba6280, were established in 18 in. rows.

2. Each variety was subjected to hard grazing by sheep in September, at ear initiation in spring, and 3 weeks following ear initiation; one series of plots was left ungrazed. Three levels of spring nitrogen, 2, 4 and 6 cwt./acre ‘Nitro-chalk’ (21%N), were applied to subplots.

3. S321 produced significantly more seed heads and Ba6280 gave significantly fewer heads than S23, S24 and Melle. September grazing increased head production by 15%, whilst the two spring grazings gave fewer heads than the ungrazed plots. An increase in the rate of nitrogen application in spring favoured head production.

Heterosis and combining abilities for yield, bollworm resistance, fruiting efficiency and photosynthesis were studied in a five-parent diallel involving cotton (Gossypium hirsutum) strains differing in their resistance to the bollworm complex (Heliothis zea and H. virescens).Substantial magnitudes of useful heterosis (over the commercial cultivar ‘Coker 304’) were observed for yield and other agronomic characters. Useful heterosis for yield ranged from 1 to 32·7%. The highest yielding hybrid was Coker 304 × PD 695. The strain PD 695 is moderately resistant to bollworms.

All the hybrids having at least one resistant strain as their parent suffered less damage from bollworms than Coker 304. The resistant strains (BW 76–31, PD 695 andred leaf cotton) had desirable general combining ability (GCA) effects for bollworm damage. Relative yield (yield without protection expressed as percentage of yield with protection) was used as a measure of bollworm resistance. The high gossypol strain BW 76–31 had desirable GCA effects for relative yield, bollworm damage to buds, number of live worms and for bolls per plant. The fruiting efficiencies and photosynthetic rates of some bollworm-resistant strains were similar to those of a high-yielding, moderately susceptible cultivar.

Combining-ability analysis indicated BW 76–31 to be a desirable parent for use in hybridization programmes for improving agronomic performance, fruiting efficiency, photosynthetic rate and bollworm resistance. It was also observed that bollworm-resistant cottons do not always have lower fruiting efficiencies and photosynthetic rates and it might be possible to combine this resistance with high yields.

An analysis of the breeding of 130 kinky-tailed pigs of Large White and Wessex origin indicates that the character is genetic in nature and is of variable penetrance and expressivity. The hypothesis is put forward that pigs, in general, may be charcterized by a slight tendency to this defect which is exhibited when the appropriate accidents of development occur. In addition, there may be genes which raise the overall frequency and severity of the defect. In the Large White inbred strain studied, it is thought that there were minor genes with a recessive effect as well as a major gene with incomplete dominance. In the inbred strain several litters were obtained which included no normal pigs although both parents were apparently normal. In outcrosses, kinky tails appeared less frequently. Inbred, kinky-tailed pigs were difficult to rear and of those kept for breeding most proved sterile. Post-mortem examination of a number of affected pigs showed a high incidence of abnormalities of the kidneys, ureters and genitalia. The suggestion is made that kinky tails are but a minor manifestation of an early developmental disorder.

Hoof, formalized hoof, formalized casein, leather wastes and dried blood were compared with ammonium sulphate for vegetables in several field experiments which were continued for a number of years. Residual effects were measured in one experiment at Rothamsted.

For crops which had a high requirement for nitrogen, hoof and formalized casein tended to give somewhat lower yields than equivalent ammonium sulphate. Organic nitrogen fertilizers tended to be slightly superior to ammonium sulphate for less responsive crops, and also in experiments where the high rate of ammonium gave lower yields than the medium rate.

Crushed hoof and a formalized casein product gave similar yields of most crops. There were no marked gains from treating hoof with formalin; a coarse (5·7 mm.) sample of formalized casein did not give materially different yields from the ordinary fine (2 mm.) product.

One leather product made by simple roasting was inferior to ammonium sulphate and to hoof. Other leather wastes processed by alkalis did not behave very differently from crushed hoof or from ammonium sulphate. Dried blood was tested in a few experiments, there were no significant differences between yields given by blood and by ammonium sulphate.

In experiments on a light soil, spring cabbages planted in autumn were very sensitive to the time of applying nitrogen fertilizer; there were much larger gains in yield from ammonium sulphate applied half at planting and half in spring, than from either ammonium sulphate or organic nitrogen fertilizers applied wholly at planting.

The effect of short leys and arable cropping on the yields of the following arable crops has been tested since 1937 at Woburn Experimental Farm, Bedfordshire. The leys were a 3-year grazed ley and 3 years of lucerne cut for hay and the arable cropping was potatoes, winter cereal and either a 1-year ley or a third tillage crop. The effects of these crop sequences were measured by test crops of potatoes and barley, uniformly treated except that 15 tons farmyard manure was applied on one-half of each plot for potatoes.

Without farmyard manure, the yield of potatoes after the grazed ley was higher than after three tillage crops by an average of about 3 tons per acre; after lucerne it was about 2 tons per acre more than after the tillage crops and after the 1 -year ley under 1 ton per acre more. With farmyard manure the benefit from leys was less (about 2 tons per acre for both lucerne and the grazed ley). The average effect of the farmyard manure was about 2·8 tons except after the grazed ley, where the increase was only 1·6 tons per acre.

Effects of the previous cropping on the yield of barley were small in the early years of the experiment, but in the last 5 years the yield after ley and lucerne has exceeded that after the tillage crops by about 15%.

Part of the difference in potato yield between the ley and arable sequences can be attributed to the differential incidence of potato-root eelworm, which has reached a high level of infestation on some of the arable plots. Much of the remainder may be ascribed to the low level of basal manuring which has affected the yield of all plots, but particularly those under tillage crops. How far the observed differences can be explained by these considerations remains a matter for speculation, but may to some extent be clarified when further results are obtained from a revised scheme of cropping and manuring.

Perkins & Jinks's (1971) analysis was used to detect and measure the interactions between the environment and the additive, dominance and epistatic effects of the genes for final plant height, spike length, 100-grain weight and yield per plant in three barley (Hordeum vulgare) triple test crosses (DL 3 × IB 226, DL 3 × Jyoti and Jyoti × P 113) raised in two environments (normal irrigation and no irrigation). The j- and I- type epistasis was more sensitive to environmental differences than the i-type epistasis. Similarly, additive gene action responded more to the different environments than did the dominance action of the genes.

The true and apparent metabolizable energy (TME and AME) of a range of indigenous feedingstuffs and finished feeds were determined by rooster bioassay techniques adapted to suit a small nutrition laboratory.

The AME and TME of some common feedingstuffs were similar to the values published elsewhere. The AME of two finished feeds were similar to their zero-N corrected metabolizable energy values determined by the conventional total collection method. The mean ±S.E. endogenous and metabolic excreta energy per bird for 24 h was 70·4 ± 2·94 kJ.

Tubers from nine cultivars grown in four plantings over 3 years at two sites in Scotland were tested for resistance to cracking by squeezing between two flat surfaces. The force was applied by a lever to which a steel plate was fixed, pressing the tuber against a wooden base. The weight on the lever was recorded when wet hair-line cracks appeared on the tuber surface.

There were significant differences between cultivars from the same planting. The rank positions of some cultivars were relatively stable but others differed widely between plantings. The grouping of cultivars into the upper, middle or lower parts of the range for squeezing resistance was similar to that for resistance to external damage based on Potato Marketing Board farm surveys. The test could be used to help breeders identify genotypes highly susceptible to external mechanical damage. If combined with tests of resistance to other types of mechanical abuse common in the bulk handling of tubers a more accurate estimate of damage resistance on the farm should be possible.

Four grass species, three hybrids and three mixtures were grown in field swards near Aberystwyth. All swards were amply supplied with nutrients and were cut at 5-week intervals during the year of sowing (1989) and during the following 4 years. The order of the grasses in rate of establishment was: Westerwolds ryegrass > Italian ryegrass (Lolium multiflorum) > Italian ryegrass × perennial ryegrass, Italian ryegrass × meadow fescue, perennial ryegrass (Lolium perenne) > perennial ryegrass × meadow fescue, meadow fescue (Festuca pratensis) > tall fescue (Festuca arundinacea). During the sowing year as a whole, Italian ryegrass was the highest yielding grass, followed by Westerwolds ryegrass. During the remaining period (1990–93), as a whole, the highest yields were obtained from perennial ryegrass sown alone or in a mixture with tall fescue. Tall fescue sown alone was one of the lowest yielding grasses in the year of sowing, but developed to be the highest yielding in 1992 and 1993. Westerwolds ryegrass persisted least well, although some plants did survive until 1992. Italian ryegrass persisted better than Westerwolds and Italian ryegrass × meadow fescue persisted better than Italian ryegrass. Hybrid ryegrass and perennial ryegrass × meadow fescue persisted satisfactorily but with fewer tillers/m2 than perennial ryegrass or tall fescue. The yield of tall fescue in March was as high as that of Italian ryegrass in 1990 and 1991 and higher than that of any of the other grasses in 1992 and 1993; the tiller density of tall fescue was particularly high in March. The yield of mixtures (Italian ryegrass with perennial ryegrass, Italian ryegrass with tall fescue and perennial ryegrass with tall fescue) was, on average, 2·5% more than the mean of the component species when sown alone. When grown with ryegrass, tall fescue was not prominent initially but its proportion in the sward gradually increased.

1. Piglets reared in a cold building but in pens provided with electrically warmed or wooden beds weighed considerably more at 8 weeks old than piglets reared in pens with solid concrete floors covered with thin permeable cork-tar bricks. At 3 days and 3 weeks old there were no differences in live weight between the three groups.

2. Before weaning at 8 weeks old the piglets reared on concrete floors had very much poorer appetites for solid food than had those from the other two groups.

3. Although the blood haemoglobin concentrations of piglets on warmed and wooden floors rose between 3 and 8 weeks of age, the haemoglobin concentrations in the group on concrete floors fell. The differences in concentrations between groups at weaning just failed to be statistically significant at P = 0·05.

4. Under the conditions of this experiment the provision of electrically warmed or wooden floors diminished but did not eliminate the incidence of a pathological liver condition in pigs which has been attributed to poor housing conditions.

5. The low weaning weights, poor appetites, low haemoglobin concentrations at weaning and the presence of the liver disease in piglets born on concrete floors were probably interdependent, but the mechanism and direction of this interdependence could not be explained from the data collected.

Throughout the 21st century, livestock diseases will impact upon the productivity of domesticated livestock and compromise the ability to feed a growing global population. The focus of the present review is to outline how the recent rapid expansion of genetic sequence data available for both pathogens and hosts can be exploited to develop new tools to improve the ways in which livestock diseases can be controlled. In the post-genomics era of the future, there will be a more intimate understanding of the way in which pathogens interact with their hosts and the key molecules that define host–pathogen relationships; knowledge that can be utilized to generate novel diagnostics and vaccination strategies. However, experience from the global rinderpest eradication programme highlights that effective disease control is a multifactorial process. Clearly, appropriate new therapeutic and diagnostic tools can play a critical role in our ability to monitor and limit the spread of diseases. However, adequate resources are also required: these are principally financial and also include the availability of trained personnel and veterinary infrastructure; international cooperation, transparency between different countries and sharing of epidemiological data and ownership of disease; acceptance of the difference in perception of importance of diseases in the developed world v. the developing world.

Sugar-beet crops, Beta vulgaris spp. vulgaris (L), suffer from premature bolting and flowering as a consequence of prolonged exposure to cold conditions (vernalization). This reduces crop yield and quality and could be avoided if bolting-resistant varieties were available. Traditionally, development of bolting-resistant varieties has relied on selection against the annual growth habit associated with the bolting gene B. However, this has failed to deliver crops that can be reliably sown in early spring or grown over winter without the risk of bolting. New breeding targets and selection strategies are required and have become tractable with the recent development of the vernalization-intensity model. This model uses parameters for the intensity and duration of vernalization (vernalization hours) to predict bolting responses and discriminates between varieties by the minimum number of vernalization hours needed to induce bolting (vernalization requirement (VR)) and by the increase in bolting incidence for each extra vernalizing hour once the VR has been satisfied (bolting sensitivity (BS)). Since the vernalization-intensity model was developed from variety-assessment trials data, the present work sought to refine and test it through controlled environment (CE) experiments in which seven sugar-beet varieties were exposed to differing levels of accurately defined vernalization treatments and scored for bolting rates to determine their VR and BS values. The results confirmed and improved the model and showed that VR, not BS, has more potential for developing bolting resistant varieties. It was also observed that there exist in current varieties, the genetic potential to breed for higher VR. Further experiments assessed the correlation of attainment of VR with changes in gene expression and shoot apical meristem (SAM) morphology to identify potential markers for this trait. It was found that the time when VR is attained correlates with up-regulation of gibberellin biosynthetic genes and floral transcription factors in leaf and shoot apices; most prominently, GIBBERELLIN 20-OXIDASE 2 (BvGA20ox2) and FLOWERING LOCUS T 2 (BvFT2). To integrate the results with weather data, temperature records for the past 47 years from the Broom's Barn weather station were used to develop a tool for predicting accumulated vernalization hours based on sowing date. The results, together with data from the CE experiments, were used to establish VR-breeding targets for bolting-resistant varieties for spring- and autumn-sown sugar-beet crops. The present paper shows that integration of weather, VR and genetic data provide useful tools to aid both cultivation and breeding selection. For growers, it provides a weather data tool to assist with the selection of suitable sowing dates. For breeders, it provides the first identification of molecular genetic factors that correlate with VR and the physiological changes associated with vernalization responses in sugar beet. The results suggest that gene-expression profiles can be developed into tools for quantifying bolting resistance in beet, thereby providing a cost-effective, high-throughput and simple method for breeders to apply the vernalization-intensity model.