Insights into the Host Specificity of a New Oomycete Root Pathogen, P1: Whole Genome Sequencing and Comparative Analysis Reveals Contracted Regulation of Metabolism, Protein Families, and Distinct Pathogenicity Repertoire.

P1 Stanghellini, Mohammadi, Förster, and Adaskaveg is an oomycete root pathogen that has recently been characterized. It only attacks plant species belonging to family, causing root necrosis, stunting, and yield loss. Since P1 is limited in its host range, this prompted us to sequence its whole genome and compare it to those of broad host range spp.

Deep injection and the potential of biochar to reduce fumigant emissions and effects on nematode control.

Reducing fumigant emissions is essential for minimizing the environmental impacts of pre-plant soil fumigation. Low permeability plastic films are effective at reducing emissions but have high initial purchase, installation, and disposal costs. The objective of this study was to evaluate if deep fumigant injection and biochar soil amendments can reduce emissions, improve fumigant distribution in soil, and provide acceptable control of plant parasitic nematodes.

Pythium brassicum sp. nov.: A Novel Plant Family-Specific Root Pathogen.

Roots of stunted broccoli plants (Brassica oleracea) from the Palo Verde Valley, CA, were observed at various stages of decay. A species of Pythium with large spiny oogonia was microscopically observed and consistently isolated from decayed roots. Isolates produced spherical, intercalary sporangia (average 34.

Emission and transport of 1,3-dichloropropene and chloropicrin in a large field tarped with VaporSafe TIF.

Tarping fumigated fields with low permeability films such as commercial Totally Impermeable Film (TIF) can significantly reduce emissions, but it can also increase fumigant residence time in the soil such that extended tarp-covering durations may be required to address potential exposure risks during tarp-cutting and removal. In an effort to develop safe practices for using TIF, a large field study was conducted in the San Joaquin Valley of California. Comprehensive data on emissions (measured with dynamic flux chambers), fate, and transport of 1,3-dichloropropene and chloropicrin were collected in a 3.

Olpidium bornovanus-mediated germination of ascospores of Monosporascus cannonballus: a host-specific rhizosphere interaction.

Monosporascus cannonballus, a host-specific root-infecting ascomycete, is the causal agent of a destructive disease of melon (Cucumis melo L.) known as vine decline. Ascospores germinate only in the rhizosphere of melon plants growing in field soil.

Viability of Oomycete Propagules Following Ingestion and Excretion by Fungus Gnats, Shore Flies, and Snails.

Sporangia of Phytophthora capsici and P. nicotianae, as well as hyphal swellings of Pythium splendens, P. sylvaticum, and P.

Colonization of cantaloupe roots by Monosporascus cannonballus.

Penetration of Monosporascus cannonballus into and growth within cantaloupe roots was studied using light and electron microcopy. Germ tubes penetrated the epidermis, and hyphae grew, without branching, almost directly to the xylem. The hyphae traversed the endodermis into protoxylem cells, and then grew extensively within the lumen of metaxylem vessels.