Studies on the Determination of Optimum Amount of Broodlac Requirement for Crop Inoculations

Crop yields depend on the timely use of proper quantity of broodlac, and its proper distribution on the branches of the trees. Investigations were undertaken to determine the optimum requirement of broodlac for inoculations of kusum for both the Jethwi and Aghani crops and the present paper r~ports the results of investigations carried out for four years. Four brood rates, so as to give lat'val settlement on twigs over about 6-7, 12-13, 25 and SO times the length of brood sticks used for inoculation, were compared. The following observations could be made : (1) density of larval settlement increased with the brood rate used but not in direct proportion, (ii) the percentage of larval mortality was inversely proportional to the density of settlement indicating that certain minimum density is essential, (iii) there was a tendency towards higher percentage of males as the brood rates were increased, (iv) the yield per tree in both Jethwi and Aghani seasons increased with the increase in the quantity of brood used but not in same proportion as the brood rate. Yet it is more profitable to use more brood per tree on fewer trees than to use less brood per tree on a larger number of trees, because the slightly increased total yield obtained in the latter case will not adequately compensate for the much increased costs of operation with a larger number of trees. Further heavier brood rates within reasonable limits ensure better success of lac crops particularly in adverse seasons, (v) brood rate for crop inoculations should be such that it gives larval settlement on shoots nearly 10 times the length of broodlac sticks used for the Jethwi and 8 times the length of brood sticks used in the case of the Aghani crop.