Infection of Pinus radiata needles by Dothistroma pini

The role of weather and topography in the development of Dothistroma septosporum.

“…A period of 10 hours or more of needle wetness is usually required for successful infection, and long dry periods after infection generally lead to less severity and slow development of stromata (Bulman 1993;Bradshaw 2004). One or more germ tubes emerge from a germinating spore, though whether their direction of growth is targeted or random is conflicting in the literature (Peterson 1966, cited in Gadgil 1967Gadgil 1967;Muir and Cobb 2005). Germ tube growth may follow water gradients from spores to stomata .…”

“…Within a lesion hyphal growth is restricted to necrotic tissue, and extension of necrosis beyond the infected area indicates that host cells are killed by a toxin or host defense response (Gadgil 1967;Bradshaw 2004). Adjacent to the red lesions are yellow areas of necrotic tissue, sometimes flanked by areas of dark green tissue containing highly lignified cells (Franich et al 1986).…”

“…Adjacent to the red lesions are yellow areas of necrotic tissue, sometimes flanked by areas of dark green tissue containing highly lignified cells (Franich et al 1986). The change from green to red can be sharp or interposed with yellowish areas between green area and red band (Gadgil 1967).…”

“…Infection severity has been found to increase with increasing light intensity, suggesting there is an interaction between dothistromin and photosynthetically-active tissue (Gadgil and Holden 1976;Shain and Franich 1981). Dothistromin is broken down to oxalic acid and CO2 more efficiently in light (80% breakdown) compared to dark (5-10% breakdown) (Franich et al 1986).…”

The relationship between climate and outbreak dynamics of Dothistroma needle blight in northwest British Columbia, Canada.

“…During the early stages of infection, the germ tube undergoes a precise and genetically programmed series of morphological changes. There are conflicting reports about whether the direction of growth is random or targeted towards a stomatal pore , Gadgil 1967. The resulting morphogenic events form an appressorium, a swollen structure that adheres strongly to the leaf surface and facilitates penetration .…”