Variation in Rates of Spore Deposition of Fusarium circinatum, the Causal Agent of Pine Pitch Canker, Over a 12-Month-Period at Two Locations in Northern California

Abstract

Patterns of spore deposition by Fusarium circinatum, the causal agent of pine pitch canker (PPC) of Monterey pine (Pinus radiata) and other conifers, were studied between May 2003 and April 2004 at two sites in Northern California using a novel spore trapping method combined with a real-time polymerase chain reaction (PCR) approach. At each study site, two plots were sampled by placing spore traps at 100 m intervals along transects 600 m in length. The air was sampled continuously by exchanging the spore traps every 2 weeks. The spore deposition rate (DR), ranged from 0 to 1.3 x 10(5) spores m(2). Spores were detected throughout the year, with higher trapping frequencies (TF) during the rainy season (November to April), than during the dry season (May to October). The detection of spores on traps at distances larger than 200 m from any Monterey pine, suggests at least midrange aerial dispersal. Finally, different inoculum loads were associated with trees displaying different levels of disease symptoms, suggesting infectiousness of the pathogen varies as the disease progresses. This study represents one of the first documenting continuous inoculum pressure values over an entire year for a forest pathogen, and provides important epidemiological information that will be invaluable in the development of disease progression models.

Spore Dispersal Patterns of Fusarium circinatum on an Infested Monterey Pine Forest in North-Western Spain

“…The most striking difference was noted in July, when the sampling at the beginning of July was negative and the sampling at the end of the month showed a positive result with the highest value of the year. Similar patterns were shown by Garbelotto et al [28] in San Francisco in July-August. However, results of the present study are not reliably comparable with those of Garbelotto et al [28] due to the length of the sampling time, which was two weeks and continuous in the American study and 48 h twice a month in ours.…”

“…Similar patterns were shown by Garbelotto et al [28] in San Francisco in July-August. However, results of the present study are not reliably comparable with those of Garbelotto et al [28] due to the length of the sampling time, which was two weeks and continuous in the American study and 48 h twice a month in ours.…”

“…Similar results with the constant presence of F. circinatum throughout the whole year were obtained in other areas such as northern California [28] and South Africa [39]. This finding means that F. circinatum in Galicia can develop the infection at any time of the year whenever suitable environmental conditions and susceptible hosts are available for spore germination, as was expected from the calculation of models of spread [26,40].…”

“…Garbelotto et al [28] first applied a passive air sampling system using filter paper to collect deposited spores of F. circinatum. These authors suggested, however, the use of active air sampling spore traps to obtain more precise results in aerobiological studies of the inoculum of F. circinatum, especially for the study of its spatial spore dispersal.…”

Assessment of Pathogenic Variation against Pitch Canker Pathogen, Fusarium circinatum in Pinus thunbergii and Responses of Natural Selection Pinus × rigitaeda to Branch Inoculation in a Seed Orchard

“…In the recent study, 2 of 6 pine species or hybrid seedlings, P. echinata and P. virginiana, were the most susceptible to infection by Korean isolate of F. circinatum (Kim et al, 2008). However, some studies provided solid evidence on the seasonal and weather-related variations in levels of spore deposition rates of F. circinatum (Garbelotto et al, 2008;Schweigkofler et al, 2004).…”