Occurrence and range of dicumarol concentrations in sweet clover

The dicumarol concentration in 272 cured sweet clover samples from 4 counties in North Dakota was determined. Dicumarol concentrations ranged from 0 to 164.7 mg/kg of sweet clover, with 64.6% of the 272 samples containing less than 10 mg/kg. Round bales were significantly (P less than 0.05) higher in dicumarol concentration (mean of 22.9 +/- 3.10 mg/kg) than were stacks or silage (means of 1.8 +/- -6.3 mg/kg and 0.6 +/- 2.1 mg/kg, respectively). The outer section of core samples taken from round bales contained significantly (P less than 0.0021) higher concentrations of dicumarol than did the inner section of the core, with means of 30.8 mg/kg and 16.6 mg/kg, respectively. A significant (P less than 0.0001) correlation existed between crude protein and dicumarol values (r = 0.44).     

Viability and stability of biological control agents on cotton and snap bean seeds

Cotton and snap bean were selected for a multi-year, multi-state regional (south-eastern USA) research project to evaluate the efficacy of both commercial and experimental bacterial and fungal biological control agents for the management of damping-off diseases. The goal for this portion of the project was to determine the viability and stability of biological agents after application to seed. The biological seed treatments used included: (1) Bacillaceae bacteria, (2) non-Bacillaceae bacteria, (3) the fungus Trichoderma and (4) the fungus Beauveria bassiana. Seed assays were conducted to evaluate the following application factors: short-term (< or = 3 months) stability after seed treatment; quality (i.e. isolate purity); compatibility with chemical pesticides and other biocontrol agents; application uniformity between years and plant species. For the bacterial treatments, the Bacillaceae genera (Bacillus and Paenibacillus) maintained the greatest population of bacteria per seed, the best viability over time and the best application uniformity across years and seed type. The non-Bacillaceae genera Burkholderia and Pseudomonas had the least viability and uniformity. Although Beauveria bassiana was only evaluated one year, the seed fungal populations were high and uniform. The seed fungal populations and uniformity for the Trichoderma isolates were more variable, except for the commercial product T-22. However, this product was contaminated with a Streptomyces isolate in both the years that it was evaluated. The study demonstrated that Bacillaceae can be mixed with Trichoderma isolates or with numerous pesticides to provide an integrated pest control/growth enhancement package.     

Genetic Regulation of Polerovirus and Luteovirus Transmission in the Aphid Schizaphis graminum

ABSTRACT Sexual forms of two genotypes of the aphid Schizaphis graminum, one a vector, the other a nonvector of two viruses that cause barley yellow dwarf disease (Barley yellow dwarf virus [BYDV]-SGV, luteovirus and Cereal yellow dwarf virus-RPV, polerovirus), were mated to generate F1 and F2 populations. Segregation of the transmission phenotype for both viruses in the F1 and F2 populations indicated that the transmission phenotype is under genetic control and that the parents are heterozygous for genes involved in transmission. The ability to transmit both viruses was correlated within the F1 and F2 populations, suggesting that a major gene or linked genes regulate the transmission. However, individual hybrid genotypes differed significantly in their ability to transmit each virus, indicating that in addition to a major gene, minor genes can affect the transmission of each virus independently. Gut and salivary gland associated transmission barriers were identified in the nonvector parent and some progeny, while other progeny possessed only a gut barrier or a salivary gland barrier. Hemolymph factors do not appear to be involved in determining the transmission phenotype. These results provide direct evidence that aphid transmission of luteoviruses is genetically regulated in the insect and that the tissue-specific barriers to virus transmission are not genetically linked.     

Electrostatic aspects of physical adsorption: implications for molecular sieves and gaseous anesthesia

The equations of electrostatics are applied to the adsorption of gases on molecular sieves; separations on sieves are caused not by the size of molecules but by electrostatic forces between the gases and the strong electric fields of the sieves. Electrostatic interactions can also explain the phenomenon of general anesthesia.     

Deoxycytidylate and deoxyguanylate kinase activity in pneumococci after exposure to known polyribonucleotides

Polycytidylic acid and to a lesser extent polyadenylic acid enhance the activity of deoxycytidylate and deoxyguanylate kinases in resting cell suspensions of encapsulated pneumococci. The active intracellular materials appear to be oligomers of A and C, respectively. The stimulation of the kinase activities is amino-acid dependent and can be abolished by the addition of chloramphenicol. The addition of all eight naturally occurring deoxyribonucleosides and deoxyribonucleotides to cell suspensions containing the homopolymers leads to a selective enhancement of DNA synthesis.