Crinkle-leaf is an abnormal condition of the leaf of coffee in Kenya, the cause of which is unknown. Preliminary observations showed that its symptoms are suppressed by spraying with captan and experiments were carried out to investigate whether this material would provide an economic coivtrol. Spraying at the rate of 4 lb per acre, when symptoms of the condition first appeared, gave good control but lower quantities were less effective. Means of predicting the severity of the condition have not yet been evolved and the spray programme must therefore be adjusted each season to meet the local conditions. The spraying of nurseries and young suckers is recommended as soon as early symptoms are noted, since the cost is low, whereas the spraying of large areas of mature coffee requires a careful assessment of the possible economic advantages. Susceptibility to crinkle-leaf was found to differ between cultivars.

Nitrogen is the most important, and usually the only, nutrient necessary for high yields of rice in the South Western Riverina of N.S.W. Inclusion of a legume pasture phase in the rotation is a very effective method of improving the nitrogen status of the soil, but small additions of artificial fertilizer at sowing may still be necessary for maximum yields. The addition of phosphatic fertilizers is rarely necessary, except on a few isolated virgin soils, and where pastures are included in the rotation ample phosphate for the rice crop is usually present as a residue from topdressing. Potash and trace-elements do not improve rice yields in this area.

It is suggested that irrigation should ideally be based on two sets of measurements, i.e. of conditions in the leaf and of cumulative evaporation rates respectively, on the assumption that the question 'When to irrigate ? ’ can best be answered from a knowledge of leaf water potential and the daytime behaviour of stomata, and the question ‘How much water to apply?’ from a knowledge of the current soil water deficit. It is emphasized that there is no unique or fixed relation between leaf water potential and soil water deficit, and since neither can be deduced from the other it is advisable to measure both in critical experimental work on irrigation. Various methods of measuring leaf water potential and evaporation rates are discussed, and their value in experimental work assessed.

A method is described whereby starch level in wood of Coffea arabica L. was estimated by means of visual scoring. The correlation between the amount of starch thus found and the quantity established by chemical analysis proved to be + 0.925, +0.932 and 0.819 in young, semimature and mature wood respectively. No satisfactory way was found for making a similar estimate of the amount of starch in the leaves.

The amount of starch in branches of Coffea arabica L. was studied by means of a method of visual scoring. In cropping branches, the variation in starch level was greatly, but not completely, determined by the growth of the crop. More knowledge of the formation and distribution of the products of photosynthesis is needed before a satisfactory explanation can be offered. Starch levels in non-cropping branches were higher than those in the cropping branches, but followed the same pattern of fluctuation. In general, translocation of starch occurred rapidly throughout the tree but some exceptions to this rule were found.

In a factorial experiment with two spacings, four numbers of seedlings per hill, and two levels of nitrogen the highest numbers of shoots were produced in high nitrogen and high plant density plots. Increasing the number of seedlings per hill led to a rise in the number of shoots per plot and this was more pronounced in high than in low plant densities. Significant differences in shoot number between high and low nitrogen plots occurred only at the higher plant density, but high nitrogen and wide spacing led to an increase in the number of shoots per hill and per plant. Increasing the number of seedlings per hill resulted in an increase in the number of shoots per hill but a decrease in the number of shoots per plant. The effects of treatments on leaf blade area at ear emergence and on grain yields were similar to those on shoot number. The percentage increase in the yield of grain per unit area due to increasing the number of seedlings to three and four were 12 and 9 respectively. The percentage shoot mortality was greater in plots with low than with high plant density. Plants were higher in high nitrogen plots, especially at high plant density, while high nitrogen supply and four seedlings per hill increased the number of days from seeding to ear emergence. The former treatment also increased ear length. Low plant density and three seedlings per hill increased the ear to shoot dry weight ratio. The best combination of treatments for high grain yield was high nitrogen, 15 cm x 15 cm spacing, and four seedlings per hill.

Measurements are reported on the influence of mulch on the chemical and physical characteristics of the soil and the chemical composition of the crop, together with growth measurements on an indicator crop in the greenhouse and on mature coffee in the field. Mulch reduced soil acidity; increased organic carbon, Kjeldahl nitrogen, exchangeable potassium and available phosphorus; and decreased exchangeable calcium and manganese. It increased total pore space, free-draining pore space and rate of rainfall acceptance in the top soil. Effects on the coffee were to increase phosphorus, potassium and in some cases nitrogen in the leaf, but reduce magnesium and calcium levels. Potassium and calcium levels were increased in feeder roots, whereas in the ripe cherry the phosphorus level was increased but nitrogen, calcium and magnesium levels were reduced. The soil effects were reflected in increased growth of the indicator crop and mulch improved the growth of the coffee tree in a year of seasonal drought.