Competition for sulphur in a grass-clover association

Summary A 3 × 3 factorial experiment with nitrogen and sulphur fertilizers was carried out on a grass-clover association in an area where there is little if any cyclic return of sulphur. In the absence of sulphur, grass took up 98 per cent of the total uptake of sulphur, and nitrogen fixation by associated clover was negligible. In the absence of fertilizer nitrogen, dressings of sulphur as gypsum stimulated clover growth; at a low rate of application of sulphur, nitrogen fertilizer increased grass growth and clover was suppressed. This suppression was largely overcome with a higher dressing of sulphur. Sulphur therefore must be added to the group of elements (phosphorus, nitrogen and potassium) for which grass may compete intensely when grown with clover and when nitrogen fertilizers are applied to a grass-clover association adequate supplies of sulphur must be assured in order to minimise suppression of clover. Sulphate of ammonia may stimulate clover growth under these conditions. Solubility of gypsum was low in a dry season and residual effects were pronounced.     

Dominating species of entomophilous ascomycetes anamorphs in West Siberia,Primorsky krai,and Kyrgyzstan

The paper studies mycobiota of the dead insects in West Siberia, Primorsky krai, and Kyrgyzstan. Ascomycetes anamorphs of 13 genera are revealed. In all regions Beauveria bassiana (Bals.-Criv.) Vuill. dominated comprising on average 68% of the total number of isolates. The fungus hosts list the insects of 7 orders and 32 families with Coleoptera, Lepidoptera, and Hemiptera dominating. The rarely found entomopathogens include Tolypocladium inflatum Gams (primarily on Lepidoptera), Metarhizium anisopliae (Metschn.) Sorokin (on Coleoptera). The mortality rate of the insects due to micromycetes is observed mainly on enzootic level. The study of the pathogenic properties of the dominating species (B. bassiana) show the absence of specificity of its environmental isolates for a number of representatives of Orthoptera, Lepidoptera, Coleoptera, and Diptera.