Peak fungal spore dispersal coincides with peak needle shedding, which takes place between mid-May to mid-June in southern New England. acicola are dispersed by rain and wind from older, diseased needles to the developing, current season's needles in late spring and early summer (Sinclair and Lyon 2005). Therefore, the higher frequency of rain events during the spring and early summer, when newly developing pine needles are most susceptible to infection, is a driving force in the WPND epidemic. acicola can germinate and infect pine needles only when they are wet and the pathogen largely goes dormant during extended dry periods. Specifically, mild temperatures, high overnight humidity and a higher frequency of rain events from May through July are stimulating disease development. Research has shown this increase in disease incidence and severity is due to a change in regional climate that has created ideal conditions for disease development (Wyka et al. Historically, lower canopy branches and small trees were most susceptible (Sinclair and Lyon 2005), but since the WPND outbreak started in 2009, mature trees are diseased throughout the entire canopy.
2018).īSNB can first develop in the lower or interior canopy where shade and moisture is abundant. acicola is one of two fungi (along with Septorioides strobi) primarily responsible for WPND in the northeast (Broders et al. Studies and surveys have concluded that L. In these cases, needles may be retained in the canopy for longer periods of time as the base remains green. Symptoms can also appear as brown, blighted needle tips. Once these symptoms develop, diseased needles are quickly shed from the canopy. Symptoms of infection by Lecanosticta often first appear as yellowing to browning of older needles in late spring and early summer.
White pine needle damage (WPND) was first documented in 2009 and is a chronic stress for eastern white pines throughout eastern North America (Broders et al. For a broader list of known hosts, see Sinclair and Lyon (p. Lecanosticta acicola is distributed widely throughout the northern hemisphere, attacking pines in North America, Europe and Asia. sylvestris), and Japanese black pine ( P. Based on samples submitted to the UMass Plant Diagnostic Laboratory, additional hosts in southern New England include (but are not limited to): Japanese red pine ( P. HostsĮastern white pine ( Pinus strobus) is the primary host in New England, but numerous five-, three- and two-needle pines are also infected. Brown spot needle blight (BSNB) is caused by the fungal pathogen Lecanosticta acicola (formerly Mycosphaerella dearnessii).
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