Effects of fungicide residues on the survival, fecundity, and predation of the mites Tetranychus urticae (Acari: Tetranychidae) and Galendromus occidentalis (Acari: Phytoseiidae).

Representative fungicides from three or four families used for management of powdery mildew and other diseases in tree fruits were evaluated for their effects on a common spider mite and predator mite species, respectively. A modified Munger cell technique was effective in measuring the response of phytophagous and predaceous mites to fungicide residues on detached leaves in the laboratory. Demethylation-inhibiting (DMI) (imidazole [triflumazole] and triazole [myclobutanil]) and strobilurin (trifloxystrobin) fungicides were not toxic to female Tetranychus urticae Koch and Galendromus occidentalis (Nesbitt), and no sublethal effects were found on fecundity and predation rate after 3-5-d exposure to residues.

Establishment and Dispersal of Puccinia thlaspeos in Field Populations of Dyer's Woad.

Dyer's woad rust is being intensively studied as a biocontrol agent for the noxious weed dyer's woad. These studies report on methods to establish this fungus in woad populations and to obtain information about disease incidence and dispersal of the rust subsequent to establishment. Inoculum dosages as low as 1 mg/plant established disease in dyer's woad rosettes.

Seasonal Infection of the Weed Dyer's Woad by a Puccinia sp. Rust Used for Biocontrol, and Effects of Temperature on Basidiospore Production.

Potted dyer's woad rosettes exposed to natural rust inoculum at field sites became infected when exposed from late April through early July, depending upon the location. The latent period between exposure and symptom expression varied from 9 to 54 weeks. The length of this latent period was unrelated to either the age of plants at exposure or the exposure period itself.