Pests and diseases cause appreciable loss to tea in north-east India, but their incidence and intensity of attack vary widely from district to district, and within districts with variation in climate, elevation and the jat (seed-source) of tea. For example, blister blight is a serious disease in Darjeeling and looper catepillar is mainly localized in certain tea estates of the Assam valley. Thus recommendations regarding pesticides and their application in a particular region must be based on a thorough knowledge of the distribution of the diseases or pests in the region. This can best be obtained through sample surveys, planned in representative estates of the region and carried out with the help of trained investigators. Such surveys will also provide basic data on jat, environment and disease, as a guide to experimentation.

The results are recorded of three field experiments, designed to investigate the effects of plant population and nitrogen fertilizer on growth and yield of maize. High yields of grain can be obtained in Trinidad provided plant populations are at least 20 000 plants per acre, nitrogenous fertilizer is added at the rate of 5–6 cwt per acre, weed and insect pests are controlled, and water is not a limiting factor at any stage of crop growth. Growth analysis has shown the importance of high leaf area indices in the production of high grain yields.

The incidence of rotting among three varieties of yams (Dioscorea rotunda, D. alata and D. cayenensis), stored in a yam barn at Ibadan for about four months, was between 0·6 and 68·5 per cent. The micro-organisms which caused rotting on experimental re-inoculation into yam tubers were the fungi, Botryodiplodia theobromae, Penicillium sp., Marcophomina phaseoli, Hendersonula toruloidea and a motile gram-negative orange-red pigmented bacterim, probably Serratia sp. This is the first record of the ability of M. phaseoli, and H. toruloidea to cause rotting in yam.

The nature of the soil, the influence of previous natural grassland, ley, fallow or cultivation, and the weather conditions before and after planting are shown to affect the yield of wheat, and its response to fertilizers, especially nitrogen. Out of seventeen experiments over four seasons, involving nitrogen top-dressings on wheat, thirteen gave economic increases after the application of I cwt per acre of ammonium sulphate nitrate (A.S.N.). Such applications to the first, second or third wheat crops after Rhodes grass (Chloris gayana) ley, or to land continuously cropped for a number of years, nearly always gave an economic increase in grain yield, but on continuously cultivated land, with normal rainfall after planting, an economic return to a second cwt per acre was probable. Following a one-season fallow, economic responses to nitrogen only occurred when the pre-planting period was very wet. Yields of wheat after ley, both with and without applied nitrogen, tended to be superior to those on continuously-cropped land. Responses to phosphorus only occurred in one area, where the importance of applying both N and P, particularly to newly-ploughed grassland, was very evident. Loss of organic matter, and structural deterioration accompanied by lower efficiency in the utilization of water and nitrogen, are probably the main causes of falling yields on soils cultivated for many years. The use of grass/legume leys is suggested as the best means of maintaining these naturally fertile soils in a highly productive state, even though the present returns from the legs themselves may be less profitable than wheat cropping.

Certain statistical techniques, useful in collecting and interpreting ordinal data, are described and their applicability in plant breeding explained. It is suggested that these statistical techniques may be particularly valuable to plant breeders in determining taste Preferences. A series of experiments are described, investigating the taste Preferences of the Itero of Uganda, who show a strong preference for a mixture of cassava, sorghum and Eleusine millet for food. They do not apparently prefer white sorghum grains for food, nor coloured grains for beer, although such Preferences have been recorded elsewhere. They dislike maize and Pennisetum millet. It is suggested that an experimental approach to quality in the breeding of tropical food crops is both desirable and possible, using rank correlation techniques.

Repeatability estimates of milk yield and length of lactation of local, ½ Anglo-Nubian × local and ¾ Anglo-Nubian × local cross-bred goats were calculated. There were highly significant differences in the effect of dams on milk yields for the third, fourth and fifth lactations for local goats, when considered together. No significant differences were found for the first two lactations. For the ½ Anglo-Nubian cross-bred goats significant differences were also found for the first and second lactations, but not for the third lactation. No significant differences were found for the two lactations in the case of the ¾ Anglo-Nubian cross-bred goats. The effect of lactation periods were not significant for the three types of goats. The mean repeatability estimates for local goats were 0·47, 0·42 for ½ Anglo-Nubian and 0·54 for ¾ Anglo-Nubian cross-bred goats, which were comparable to those reported for cattle. The between-dam effect was highly significant when three lengths of lactations were combined in local goats, and the interval between lactations were also significant, but these two effects were not significant for the ½ Anglo-Nubian and ¾ Anglo-Nubian cross-bred goats. The estimates of repeatability for length of lactation averaged 0·29 for local goats, 0·17 for ½ Anglo-Nubian and 0·53 for ¾ Anglo-Nubian cross-bred goats. The correlation coefficients between milk yield and length of lactation were positive and statistically significant for all the three types of goats, ranging from 0·59 to 0·93. The similarity of the genetics of goats to those of cattle and sheep is mentioned.

The productivity of climax and serai grassland in South Africa was compared at three stocking rates with steers. On climax grassland, over nine years, gains per head at one steer per morgen (= 2·12 acres = 0·86 hectare) were not significantly greater than at two steers per morgen. Liveweight gains per morgen were 70 per cent higher at the heavier stocking rate and were 162 lb and 273 lb at one and two steers respectively. On serai grassland, over three seasons stocked at two steers and three steers per morgen, the liveweight gains per steer were significantly less at the higher stocking rate but there was no significant difference in the gains per morgen, which were 366 lb and 318 lb at two and three steers respectively. The liveweight gains on the seral grassland were significantly higher than on the climax grassland at the same stocking rate Calculation of the total digestible nutrients (T.D.N.) has shown that with heavier stocking more T.D.N. per morgen may be harvested on both grassland types. However, with heavy grazing the efficiency of conversion of T.D.N. into liveweight was less. The quality of the sward, measured in per cent crude protein, P2O5 and crude fibre was better at the heavier stocking owing to delayed maturity of the grass when it is continually grazed short.

Four depth of tillage treatments were given by ploughing to 7 cm. depth by bullock-drawn plough and 14, 21 and 28 cm. depth with a tractor-drawn mouldboard plough in 1962–63. A significant decrease in bulk density was observed with the 21 and 28 cm. ploughing, negatively correlated with dry matter of crop roots and yield of grain. The effectiveness of 28 cm. tillage in reducing the population and dry matter of weeds was significant when compared to tillage at 7 and 14 cm. and there were significant relations between dry matter of weeds and yield of grain. Crop roots under tractor tillage were significantly greater than with 7 cm. tillage. Grain yield was maximum under 28 cm. tillage followed by 21, 14 and 7 cm. deep tillage in that order. The higher grain yields were associated with a greater number of fertile tillers per metre of row and higher yields per tiller.

Propagules of five tall fescue genotypes, planted monthly, from April to December, made the greatest growth in April and September and the least in December. Despite the diverse geographic origin of the genotypes, there was no indication of interaction between genotypes and daylength. Propagules grew more vigorously when cut just above the basal leaf sheath then when cut to two or three inches in length. The complete removal of roots, which would facilitate planting, did not reduce growth and appeared to enhance the development of new roots. Propagules consisting of two or three culms grew more vigorously than those consisting of a single culm. Accordingly, if propagules were fragile or if survival was poor, two-culm propagules would become established more readily. Genotypes differed in growth rate even when planting weights were kept uniform. Results of this study could be used to reduce the time and cost of vegetative propagation of tall fescue.

Propagules of 74 genotypes of tall fescue, consisting of parent and progeny groups, were grown in a glasshouse. The number of surviving propagules were determined after one month and at that time, increment weight (growth) and leaf and root weights were determined. Broad-sense heritability estimates were calculated on the whole population and on two individual parent and progeny groups. The criteria measured varied in heritability between groups, but for the 74 genotypes the values had a more limited range from 57 per cent for root weight to 70 per cent for increment weight. Capacity to survive vegetative propagation was dependent on leaf growth and not on root growth or size of propagule. Because of the variation in survival, this characteristic warrants consideration in a selection program where propagation will be utilized for commercial purposes.