Large scale destruction of mature mandarin orange groves due to root rot has occurred in Central Malaya. During the course of an investigation on the aetiology of this malady, Phytophthora nicotianae var. parasitica (Dast.) Waterhouse was isolated, and a test on the susceptibility of nine common citrus species to Phytophthora root rot was carried out by a modified water-culture inoculation technique. This appears to be an efficient and rapid screening method suitable for tropical conditions. The results showed that none of the species tested was resistant, although the degree of susceptibility varied significantly among species and between groups of species.

Scientific papers must be accurate and readable. Writers must deliberately arrange their information in a way that will interest and be useful to readers, and write clearly and directly, in the simplest possible English. There is no need for scientific writing to be ponderously overformal. Key features of style are short sentences, a minimum of jargon, use of familiar words, active rather than passive constructions, and personal, direct statements.

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.

The apparent success of overdrilling in improving poor grazing pasture in other temperate climates led to an investigation of the technique under British conditions. With the development of a suitable machine, both for controlling competition and for drilling seeds and fertilizers simultaneously into established pasture, field trials were initiated in 1961 and 1962. Despite the achievement of satisfactory furrows for germination, the subsequent emergence and establishment of improved grasses and white clover was poor. This was thought to be due to various factors, particularly to competition from the short vigorous lowland swards, but also to unsatisfactory furrow environments where difficulties were experienced in covering seeds adequately, and in protecting seedlings from desiccation. Even when an overall application of herbicide was used to control competition, the seedlings were slow to colonize the bare ground and appeared to be particularly vulnerable to desiccation where vegetation was absent. Under the conditions of sward and climate at Aberystwyth, overdrilling by itself appears to offer no promise as a means of grassland improvement.

Although all methods of planning for the maximization of farm profits require knowledge of the basic ‘input-input’ and ‘input-output’ relationships, particularly detailed information is required when using linear programming. Specially designed crop experiments are one major source of such information, but it is important that each experiment should include all major interacting variables, since the response curves estimated from the data, and the relationships extracted from these curves, will otherwise be of little use for determining economic optimum input combinations. Where the matter of interest is the most likely production response, under the planning conditions envisaged, the best available estimate will usually be the average response estimated from a sample of experiments distributed randomly within the conditions. In each experiment of such a sample, the variables being examined should be at the same series of input levels, whilst other variables which are not of interest, but can be controlled, should be held constant at the same general level. With respect to the design of experiments established to generate production relationships, complete factorial and composite or rotatable arrangements are considered to be most suitable, although each of the types has certain disadvantages. Regarding the derivation of ‘input-input’ and ‘input-output’ relationships from the response curve fitted to the data obtained from such experiments, it is felt that this curve should first be ‘scaled down’, to allow both for the more favourable experimental conditions and for losses between the field and the point of use. After this, a number of individual production relationships should be selected, on that portion of the curve expected to be of economic interest. The relationships can then be employed in a linear programming procedure designed to generate a farm plan incorporating that combination of enterprises likely to earn the maximum profit.