A bacterial parasite (designated as BEV) of the leafhopper Euscelidius variegatus, which is passed transovarially to offspring, was transmitted from insect to insect via feeding of the insects in plants. The rate of bacterial infection of leafhoppers fed upon plants that had previously been exposed to BEV-infected leafhoppers declined with an increase in the time that infected leafhoppers had been off rye grass. Transmission of BEV also occurred on sugar beet and barley but not celery. The bacterium was also transmitted to and acquired from membrane-encased artificial diets. There was no evidence that the bacterium was transmitted via plant surfaces, but transmission and direct culture assays from plants indicated that the bacterium did not multiply or move within plants. This parasite-host relationship may represent a primitive stage in either the evolution of intracellular symbiosis with its insect host or to alternative parasitization of plant and insect hosts via insect transmission, as is the case for insect-vectored plant pathogens.

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Nursery trade plays a major role in the long-distance spread of Phytophthora ramorum, the causal agent of Sudden Oak Death (SOD) and ramorum blight of ornamental plants. Under federal regulations, nurseries found positive for P. ramorum must destroy infected plants and treat infested soils. The use of steam is an effective method to thermally inactivate P. ramorum from nursery soils as demonstrated at the National Ornamental Research Site at Dominican University (NORSDUC) and one commercial nursery in the Central Valley of California. Heating up the top soil layer (0-30 cm) to 50°C for 120 minutes resulted in complete thermal inactivation of P. ramorum. Consequently, the commercial nursery was released from federal quarantine. Steaming can be a fast, reliable and sustainable option for treating nursery soils. Accepted for publication 21 January 2014. Published 13 March 2014.

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