Pathogenicity and sporulation of Phytophthora pinifolia on Pinus radiata in Chile

Abstract

Phytophthora pinifolia causes the needle and shoot disease of Pinus radiata known as Daño Foliar del Pino (DFP) in Chile. The first pathogenicity trials with this organism utilized mycelial plugs placed on stem wounds. These resulted in lesions in the tissue, but did not reproduce the resinous bands on the needles, which are the most characteristics symptoms of the disease under natural conditions. In this study, stem inoculations were repeated, but to complete Koch's postulates fully, and to confirm that P. pinifolia causes the symptoms observed on naturally infected trees, zoospore/sporangial suspensions were used to inoculate pine foliage. This method produced the same symptoms observed on needles infected naturally. These results confirm that P. pinifolia is the causal agent of the Daño Foliar del Pino on P. radiata in Chile and successfully completed Koch's postulates for the first time. Pathogenicity tests on different Pinus spp. and hybrids showed a wide range of responses to inoculation with P. pinifolia mycelial plugs, from highly susceptible to resistant. Monitoring of sporulation revealed that the sporangia commonly remain on the needles for extended periods of time and their frequency of occurrence and dispersal appear to increase during the rainy season.

Pathogenicity of Phytophthora pluvialis to Pinus radiata and its relation with red needle cast disease in New Zealand

“…Despite our efforts to optimise inoculation, the level of infection remained variable between Pinus radiata clones and Phytophthora pluvialis isolates. These observations are consistent with the infection of Pinus radiata by Phytophthora pinifolia as reported by Ahumada et al (2013) and additional controlled inoculation studies which we have carried out using Phytophthora Phytophthora pluvialis isolates NZFS isolates 3613, 3713, 3719 or left uninoculated (control). Means ± SE, n = 3 blocks.…”

“…Our observations from field samples and controlled inoculation studies have been that very similar early needle symptoms can be produced by Phytophthora pluvialis and Phytophthora kernoviae to those reported for Phytophthora pinifolia infecting Pinus radiata in Chile (Ahumada et al 2013;Durán et al 2008). These observations may indicate a consistent response to Phytophthora spp.…”

Decline in vitality of propagules of Phytophthora pluvialis and Phytophthora kernoviae and their inability to contaminate or colonise bark and sapwood in Pinus radiata export log simulation studies

“…For instance, the ability to isolate Phytophthora kernoviae periodically after spraying oospores across the bark surface during Study 1 suggests that had colonisation taken place it should have been possible to recover this species adjacent to a single bark or sapwood inoculation point. Ahumada et al (2012) were also unable to demonstrate the survival of Phytophthora pinifolia in wood of Pinus radiata after artificial inoculation (50,000 zoospores mL -1 ) or exposure to natural inoculum in diseased plantations, even though this species is able to move from infected needles into the succulent cambial tissue in young branches (Ahumada et al 2012(Ahumada et al , 2013. The outcomes from our studies with Phytophthora pluvialis and Phytophthora kernoviae imply that the conclusions of Ahumada et al (2012) are also applicable to green radiata pine timber exported from New Zealand.…”

Alternative approaches for estimating missing climate data: application to monthly precipitation records in South-Central Chile

“…In forestry, there is an increasing interest to study the influence of climate on forest productivity (Álvarez et al 2013), forest hydrology (Dai et al 2011), soil water availability (Ge et al 2013), and wood quality (Xu et al 2013). Nowadays, climate data are also required for parameterizing process-based simulators of tree growth (Sands and Landsberg 2002) and for studying forest water balance (Huber and Trecaman 2002), phenology processes (Codesido et al 2005) and to carry out pest and disease research (Ahumada et al 2013). To perform these studies, complete and homogenous climate data that covers a sufficiently long period of time is required (Teegavarapu 2012;Khosravi et al 2015).…”