THE AVOIDANCE OF EXCESSIVE SUPERHEATING DURING STEAM STERILIZATION OF DRESSINGS

SUMMARY: During the steam sterilization of dressings some degree of superheating occurs. With dressings normally hydrated, that is with about 5% moisture content, the small degree of superheating which occurs is unlikely to be of consequence; but if dressings contain less than 1% of moisture before sterilization, a significant degree of superheating may occur. The use of drums is neither an advantage nor a disadvantage in regulating superheating, which occurs to the same degree whether the air is removed initially by vacuum pump or by downward displacement. The use of a high initial vacuum does not increase the risk of superheating.     

THE USE OF SEED DRESSINGS CONTAINING γ-BHC IN THE ESTABLISHMENT OF SUGAR-BEET SEEDLINGS

From 1949 to 1952 field trials were made to determine the effect of seed dressings containing γ-BHC, with and without the addition of organic mercurial compounds, upon the establishment of sugar-beet seedlings. Most of the trials were made in fields where no serious pest problems were anticipated. The 1949 trials established the concentration of γ-BHC non-phytocidal to sugar-beet seedlings. Later trials tested the effect on pre- and post-singling plant populations of dressings applied to natural or rubbed seed sown at standardized rates. Parallel tests of dressed seed were made on farms representing a variety of soil types, It was found that the phytotoxiCity of γ-BHC varied with season and soil type, but that a dressing containing 40 % was usually safe. In these trials, the benefits from seed dressing were, as a rule, slight. Generally the combined mercury-γ-BHC seed dressing gave the best pre-singling stand of plants. Most of the improvement was attributable to the organic mercury rather than to the γ-BHC, but where pest attacks occurred, γ-BHC gave marked improvements in stand. Wireworm appeared to be the chief pest controlled: control of pygmy mangold beetle was only partial.