No abstract

Concentrations of 2,3-dihydro-5-carboxanilido-6-methyl-1,4-oxathiin lower than 8 parts per million prevented mycelial growth of a number of Basidiomycetes. By contrast, mycelial growth of various other fungi-Phycomycetes, Ascomycetes, and Deuteromycetes-was 50 percent inhibited only by concentrations of 32 ppm or higher. Two exceptions to this pattern of selective fungitoxicity were found:an isolate of Rhizoctonia solani was not as sensitive as other Basidiomycetes, and the deuteromycete Verticillium alboatrum was inhibited by lower concentrations than affected other fungi in this group. Spore germination of two Basidiomycetes, Uromyces phaseoli and Ustilago nuda, was inhibited 95 percent or more at 10 ppm.

Thirteen cover or forage crops, 14 vegetable crops, eight sativum), and pumpkin (Cucurbita pepo) roots also contomato (Lycopersicon esculentum) cultivars, and four tained large populations of P. penetrans, but none was found tobacco (Nicotiana tabacum) cultivars were examined in the in asparagus (Asparagus officinalis) roots. Differences in greenhouse for susceptibility to root penetration by root populations of P. penetrans occurred within cultivars of Pratylenchuspenetrans. Of the cover and forage crops tested, several crops. Neither root necrosis nor plant height, both Saranac alfalfa (Medicago sativa) and alsike clover indicators of damage by P. penetrans, were consistently (Trifolium hybridum) had the largest populations of P. correlated with P. penetrans populations within the roots. penetrans per total root mass, while timothy (Phleum Knowledge of a plant's interaction with P. penetrans may pratense) and reed canary grass (Phalaris arundinacea) had enable the management of P. penetrans populations in the the smallest. Cucumber (Cucumis sativus), pea (Pisum field by proper selection of crop plants.

Eliminating infected female mosquitoes by aerial applications of ultra-low volume adulticides is the intervention strategy currently recommended to interrupt the epidemic transmission of encephalitis viruses, including West Nile. The current research optimized pyrethrin formulations and evaluated their efficacy in the desert environment of the Coachella Valley, Riverside County, California. After seven trials during 2004, a 1:2 by volume mixture of Pyrenone 25-5 in BVA oil optimized particle size, droplet descent to ground level, and kill of sentinel mosquitoes. Three subsequent experiments used 3 aerial applications of the 1:2 Pyrenone 25-5:BVA oil mixture on alternate nights to suppress Culex tarsalis Coquillett host-seeking abundance over a 1-square-mile target area. Mortality patterns among caged sentinel mosquitoes varied among sites and replicate sprays, indicating variable particle dispersion at ground level within the target area. In addition, mortality was observed for sentinels up to 1 mile downwind from the target area, indicating considerable particle drift. Geometric mean abundance of host-seeking Cx. tarsalis females collected at dry ice-baited traps within each of 3 sprayed and 2 unsprayed negative control strata varied similarly over time, indicating that our sprays minimally impacted the target population or that drift combined with other factors led to widespread area control. Experiments during March and June when recruitment rates were minimal showed general area-wide suppression of abundance following spray, whereas an experiment during September when recruitment rates were high from newly flooded marshes failed to prevent an area-wide increase in abundance. Clearly additional research is needed to standardize the efficacy of aerial applications of pyrethrins in hot dry desert environments.