22

H.—29

Cobalt Deficiency. The top-dressing trials have been continued at Mamaku, and a third generation of lambs have now been reared on the cobalt-deficient areas on this farm. The value of cobaltized superphosphate in controlling bush sickness has been definitely established, and considerable data has been accumulated concerning the uptake of cobalt after top-dressing with various rates of application in both autumn and spring. Bone Diseases. A special investigation of bone-diseases has been initiated at Wallaceville, and a careful study has been made of the pathology of rickets in hoggets, fragile bones in suckling lambs, and of pigs and poultry suffering from both calcium or Vitamin D deficiencies. Pulpy Kidney. A further study has been made of the different types of vaccine available for use. The value of vaccinating ewes where the disease occurs in lambs under six weeks of age has been confirmed, but it has been demonstrated that where the disease occurs in lambs more than six weeks old, ewes should not be vaccinated as this renders the vaccination of the lambs themselves less effective. Arthritis in Pigs. A bacteriological survey of abattoir specimens has been made to determine the organisms responsible for condemnations for arthritis. Osteopetrosis in Fowls. This has been shown to be an infectious disease, and a study is being made to determine the means of its transmission. Zinc Poisoning in Pigs. Experiments have been initiated to determine the toxic dose and the contributing effect of other factors in zinc poisoning, and to obtain information concerning the rate of solution of zinc from galvanized piping. Toxicity of Ergot for Sheep. The experimental feeding of rye-grass ergot to sheep has indicated that the symptoms produced do not resemble those of any of the important diseases of sheep encountered in New Zealand. Serpentine Superphosphate. Magnesium has been estimated in crops and pastures grown in experiments conducted by the Fields Division with serpentine superphosphate, and magnesium sulphate and superphosphate topdressings. Potash from Seaweed. The Chief Agricultural Chemist has collaborated with the Fields Division and the Marine Department in exploring the possibilities of seaweed as a source of potash for manurial purposes. Chemical Control of Ragwort. Work on the effect of sodium chlorate has been completed and information obtained concerning the rates and methods of application. It has been shown that the best results are obtained by treatment during summer or early autumn. Unfortunately, where infestations are heavy the applications necessary to kill the plants result in considerable pasture deterioration, but good results can be obtained with lighter infestations. Conclusion. Professional, technical, and farm staffs have worked conscientiously, often under special difficulties. Workers on the same problems are sometimes situated in widely separated research stations, and under war conditions do not meet as often as they should ; nevertheless, collaboration has been maintained, and good team spirit is being developed.