matteolab.org
Disclaimer: Mention of any company, trade name, or commercial product does not constitute endorsement by the University of California or recommendation for use. Always follow the manufacturer’s directions, restrictions, and precautions on the product label.
Cleaning tools in SOD-infested areas.
Can tools become infectious when used on trees infected by SOD? Yes, in particular when dealing with infected foliage, infested soil, and marginally with infected wood. The risk of spreading SOD is higher if soil or infected leaves are present on tires, shoes or tools. Wood is generally, not as infectious
Differently from other pathogens which produce invisible microscopic and often sticky spores that can remain viable even on apparently clean tools, the SOD pathogen produces spores that are normally lodged in plant debris, organic matter, and plant or soil residue.
Note: it is important to ensure all parts that came in contact with infected plant material are visibly clean and that no organic matter remains. This is particularly crucial for tools like chainsaws or machinery like chippers. The physical cleaning step (above) is critical, and can be effective even without washing although the application of a disinfectant may help). Washing first and then cleaning will be ineffective. Always wear safety glasses and protective equipment as recommended by the manufacturer and always follow the manufacturer’s directions, restrictions, and precautions on the product label.
To test the effectiveness of tool cleaning on the transmission of P. ramorum, a chainsaw and handsaws were “contaminated” with SOD-infected wood chips and saw dust. The saws were treated by different methods in an attempt to “decontaminate” them including, removing the visible organic matter with a wire brush or brushing followed by a disinfectant rinse. The disinfectants used were 10% ethanol, 5% bleach, and lysol (diluted as instructed on the label).
After cleaning, the saws were examined under magnification, any remaining bits of plant or organic matter plated on selective agar Petri dishes. The percentage of infectious propagules that grew on the agar plates is graphed below. Click to rebigulate the pdf.
Disclaimer: Mention of any company, trade name, or commercial product does not constitute endorsement by the University of California or recommendation for use. Always follow the manufacturer’s directions, restrictions, and precautions on the product label.
 |
 |
California Agriculture Vol 63, Jan-Mar 2009
What’s in a name? Two of the most serious wood pathogens of conifers worldwide have been renamed by U.C. Berkeley and US Forest Service scientists. Because of the significant economic and scientific importance of these organisms, and because one of them was introduced in Europe by US soldiers during World War II, this is a long-awaited publication.
The U.C. Berkeley Forest Pathology Lab directed by Matteo Garbelotto and the Gonthier Lab at the University of Turin, Italy, have jointly discovered the US military transported H. irregulare from North America to Italy in 1944, and have spearheaded most of the research on its invasion process. In October 2013, thanks to their efforts, Heterobasidion irregulare was included in the alert list of fungi by the European and Mediterranean Plant Protection Organization (EPPO). The H. annosum species complex comprises necrotrophic pathogens regarded as the most destructive disease agents of conifers. In the past 40 years, H. annosum s.l. has been the object of more than 1,700 scientific papers, which makes it one of the most intensively studied forest fungi. The complete genome sequence of the fungus is now available, making H. annosum s.l. the first sequenced plant pathogenic homobasidiomycete. Furthermore, it is one of the few examples of a forest pathogen that can be and has been controlled in managed forests. The understanding that two sister allopatric species are now sympatric because of a human-linked intercontinental movement of one of the two, provides the scientific community with the opportunity to understand in-depth the ecological similarities and differences among species within the complex.Pertinent publications from the Berkeley-Turin groups: Giordano, L., Gonthier, P., Lione, G., Capretti, P., M., Garbelotto, M. (2013) The saprobic and fruiting abilities of the exotic forest pathogen Heterobasidion irregulare may explain its invasiveness. Biol Invasions DOI 10.1007/s10530-013-0538-4 PDFGarbelotto M., Gonthier, P. (2013) Biology, Epidemiology, and Control of Heterobasidion Species Worldwide. Annu. Rev. Phytopathol. 51:39-59. PDFGarbelotto M., Guglielmo, F., Mascheretti, S., Croucher, P., Gonthier, P. (2013) Population genetic analyses provide insights on the introduction pathway and spread patterns of the North American forest pathogen Heterobasidion irregulare in Italy. Molecular Ecology, 22: 4855-4869 doi: 10.1111/mec.12452. PDF Gonthier, P., Lione, G., Giordano, L., Garbelotto, M. (2012) The American forest pathogen Heterobasidion irregulare colonizes unexpected habitats after its introduction in Italy. Ecological Applications 22(8) 2135-2143. PDF Gonthier, P. & Garbelotto, M. (2011) Amplified fragment length polymorphism and sequence analyses reveal massive gene introgression from the European fungal pathogen Heterobasidion annosum into its introduced congener H. irregulare. Molecular Ecology 20, 2756-2770 PDF Otrosina, W. & Garbelotto, M. (2009) Heterobasidion occidentale sp. nov. and Heterobasidion irregulare nom. nov.: A disposition of North American Heterobasidion biological species. Mycological Research, doi:101016/j mycres 2009.09.001 PDF Garbelotto, M., Linzer, R., Nicolotti, G., & Gonthier, P. (2009) Comparing the influences of ecological and evolutionary factors on the successful invasion of a fungal forest pathogen. Biol Invasions, doi: 10.1007/s10530-009-9514-4 PDF Linzer, R. E., Otrosina, W. J., Gonthier, P., Bruhn, J., Laflamme, G., Bussieres, G., & Garbelotto, M. (2008) Inferences on the phylogeography of the fungal pathogen Heterobasidion annosum, including evidence of interspecific horizontal genetig transfer and of human-mediated, long-range dispersal. Mol. Phylogenet. Evol., 46, 844-862. PDF Gonthier, P., Nicolotti, G., Linzer, R., Guglielmo, F., & Garbelotto, M. (2007) Invasion of European pine stands by a North American forest pathogen and its hybridization with a native infertile taxon. Molecular Ecology, 16, 1389-1400. PDF |
|
Selective removal and pruning of California bay laurel (Umbellularia californica) trees as a strategy to protect oaks and tanoaks from SOD infection.
For oaks between 3″ (8cm) and 32″ (80cm) diameter at breast height (DBH), remove small and medium sized bay laurels for a distance of 30ft (10m) around the tree. If large bays are present it may be useful to prune large branches that fall within the 30ft (10m) buffer zone. For oaks larger then 32″ (80cm) DBH, increase the bay-free buffer zone to 50-65 ft (15-20m).
Bays are persistent landscape plants that re-sprout quickly and produce lateral tillers in abundance. As a result they are difficult to remove permanently. Useful techniques include adding a spreader to the herbicide or applying the herbicide with a “hack and squirt” technique (see links below). For best results, apply the herbicide when the tree is alive, wait approximately a month for the chemicals to be distributed throughout the tree, killing the roots, and then cut it down
Managing the presence of bays, the primary carrier of P. ramorum, around high-value oaks and tanoaks can reduce the number of infectious spores in the environment. However, bays are important species in their own right and care must be taken not to disrupt their role in the environment, particularly along streams where they are particularly important.
