In-Vitro Evaluation of Antagonistic Trichoderma Strains for Eradicating Phellinus Noxius In Colonised Wood

[EN] The aim of the present in vitro studies was to identify Trichoderma strains from Hong Kong with highly antagonistic potential against the basidiomycete Phellinus noxius (Corner) G. Cunn. Dual culture and interaction tests using samples of balsa wood (Ochroma lagopus Sw.), as well as studies on fungal growth at different temperatures and water activities, were conducted. The impact of Trichoderma strains on wood colonisation and decomposition by three P. noxius isolates were quantitatively analysed by measuring dry weight loss and the rate of eradication of the pathogen from the test wood. Most Trichoderma strains revealed antagonistic potential against P. noxius in these in vitro studies. In the wood blocks incubat-ed with P. noxius and then treated with Trichoderma T-TMS1 for 24 weeks, 100% eradica-tion of three P. noxius isolates was recorded. The results indicate that the application of Trichoderma strains may be a promising and environmentally benign method of eradicating P. noxius from wood debris in soils.We thank Muni Arborist Limited for assisting in the preparation of wood materials, use of facilities and support. Financial and technical support for project WQ/054/12 provided by The Chinese University of Hong Kong and Tree Management Office of the Development Bureau (Works Branch) of Hong Kong Government is gratefully acknowledged.Ribera Regal, J.; Tang, A.; Schubert, M.; Lam, R.; Chu, L.; Leung, M.; Kwan, H.... (2016). In-Vitro Evaluation of Antagonistic Trichoderma Strains for Eradicating Phellinus Noxius In Colonised Wood. Journal of Tropical Forest Science. 28(4):457-468. http://hdl.handle.net/10251/150303S45746828

Development of disease-suppressive organic growing media

Vigorous seedlings are an important base for vegetable production. Beside the availability of appropriate amounts of nutrients, the health of seedlings is decisive. Soil-borne diseases are a challenging problem in organic seedling production. Here, we present results on the development of disease-suppressive growing media. Three aspects were examined: (i) use of different components of growing media (peat, coconut fiber, wood fiber, compost), (ii) influence of selected organic nitrogen fertilizers and (iii) use of different microorganisms (including commercial biocontrol agents (BCA)). Three plant-pathogen systems were used in this study: cucumber-Pythium ultimum, cress-Pythium ultimum and basil-Rhizoctonia solani. Green waste compost showed a good capability to protect cress against P. ultimum. This effect was improved by using a chitin-containing N-fertilizer. However, an inappropriate storage of the compost diminished its efficacy. In contrast to coconut fibers, wood fibers showed a suppressive activity against P. ultimum when used as partial substitutes of peat. None of five tested commercial BCAs could improve the suppressiveness of the substrates against P. ultimum. However, one of newly tested strains of Trichoderma sp. was very suppressive against P. ultimum. The tested growing media showed only small differences in suppressiveness against R. solani on basil. In contrast, two of the new strains of Trichoderma sp., which were intermediately active against P. ultimum, could efficiently protect basil against R. solani. At the moment, we test combinations of different Trichoderma strains, compost, different types of peat and peat substitutes. The aim is to determine whether it is feasible to manufacture growing media which allow the production of healthy and robust seedlings also in the presence of high levels of pathogens

The DESI experiment part I: science, targeting, and survey design

DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data. We will measure luminous red galaxies up to $z=1.0$. To probe the Universe out to even higher redshift, DESI will target bright [O II] emission line galaxies up to $z=1.7$. Quasars will be targeted both as direct tracers of the underlying dark matter distribution and, at higher redshifts ($2.1 < z < 3.5$), for the Ly-$\alpha$ forest absorption features in their spectra, which will be used to trace the distribution of neutral hydrogen. When moonlight prevents efficient observations of the faint targets of the baseline survey, DESI will conduct a magnitude-limited Bright Galaxy Survey comprising approximately 10 million galaxies with a median $z\approx 0.2$. In total, more than 30 million galaxy and quasar redshifts will be obtained to measure the BAO feature and determine the matter power spectrum, including redshift space distortions

The DESI Experiment Part II: Instrument Design

DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. The DESI instrument is a robotically-actuated, fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. The fibers feed ten three-arm spectrographs with resolution $R= \lambda/\Delta\lambda$ between 2000 and 5500, depending on wavelength. The DESI instrument will be used to conduct a five-year survey designed to cover 14,000 deg$^2$. This powerful instrument will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak, Arizona, along with a new optical corrector, which will provide a three-degree diameter field of view. The DESI collaboration will also deliver a spectroscopic pipeline and data management system to reduce and archive all data for eventual public use