Pre-Harvest Prophylaxis for Infestation Control in Stored Food-Grains
STORED food-grains suffer from considerable losses due to insect infestations in the tropical and subtropical regions of the world1. During post-harvest storage, cross-infestation by insect pests and the multiplication of pests as a result of field-infestation occur in stored grains even within a storage period of a few months in warehouses2–3. Fumigation with noxious gases such as methyl bromide, carbon disulphide, carbon tetrachloride, hydrocyanic acid, ethylene oxide and others, although of use in the control of most infestations, is not easy for the producer or the warehouse-man to apply2. Parkin1 observed that application of such measures unfortunately lags behind the advance of knowledge in all but the most highly developed countries, and even in those is not always so widespread or up-to-date as it could be. A new approach has therefore been made to replace the fumigation treatment with a relatively simpler prophylactic spray treatment of the grain under pre-harvest condition, using a chemical of low toxicity for mammals, for the control of pest infestation during post-harvest storage.
A provisional assessment of malathion for stored‐product insect control
Malathion has properties which make it generally suitable for use for stored products, but the non-persistent disagreeable odour evident during mixing and application is a disadvantage. Its stability to heat, moisture, and alkalinity needs more detailed assessment. It has low mammalian toxicity and outstanding toxicity to Oryzaephilus surinamensis and Tribolium castaneum, beetles which are often not easily controlled under practical conditions by other insecticides suitable for use in food stores. It also shows promise of value for the control of several other species of stored-product insects, but Ptinus tectus beetles have been found to be resistant to it.
Investigations on the rôle of organic matter in plant nutrition
1. As the result of decomposition of green manure in a swamp soil, the coarse fractions (including coarse and fine sand) of the surface layer (first 3 inches) decreased by 11·2 per cent. while the fine ones (silt+clay) increased by 9·8 per cent. in the course of 43 days. The effect was less pronounced in the manured soil maintained at 60 per cent. saturation, while no alteration was to be noticed in the case of the unmanured specimens. 2. Treatment with dilute hydrochloric acid prior to dispersion had no appreciable effect on the estimates of mechanical composition obtained in the different cases. Loss in solution was also comparatively small. 3. The silica-sesquioxide ratio increased slightly as the result of decomposition of green manure in swamp soil. The composition of the fine fractions was also altered, the total percentages of the oxides of iron, aluminium and silicon increasing from 90·5 to 99·3 in the course of 71 days. 4. The practical significance of the above and related observations has been discussed.