Forest Pathology最新文献

Cryphonectria carpinicola, the most recently described species in the genus Cryphonectria, is gaining research interest due to its involvement in common hornbeam (Carpinus betulus) decline. So far, no symptoms of hornbeam decline have been observed in Croatian forests. However, following a chance observation of a Cryphonectria-like stromata on the bark of a dead hornbeam branch, we conducted a targeted sampling campaign to verify the presence of C. carpinicola, determine its distribution and assess its potential impact on the host. We confirmed the presence of C. carpinicola in four out of five sampled populations and isolated pure cultures from 28 out of 53 sampled trees, making it the largest collection of C. carpinicola in Europe to date. The population network analysis inferred from nucleotide sequences of C. carpinicola ITS region, including this and previous research, has grouped them all in a single cluster with only a few isolates differing by a single nucleotide polymorphism. The isolation of C. carpinicola was possible only from bark samples with visible sporulation. The majority (24) of C. carpinicola isolates were obtained from dead stems or branches. However, in two different populations, we isolated the fungus from branches on four living trees that had died off distally to the area of the observed fungal sporulation, suggesting the fungus to be at least a weak pathogen on susceptible hornbeam trees.

The cover image is based on the article Infection Severity of Arceuthobium oxycedri (Viscaceae) in Two Protected Areas in the Alborz Mountains, Iran: A Case Study by Davoud Kartoolinejad et al., https://doi.org/10.1111/efp.70000.

Phytophthora cinnamomi is one of the world's most invasive plant pathogens, requiring accurate detection in both plant and soil samples for effective disease management. This study compares existing qPCR assays with newly developed assays targeting the internal transcribed spacer (ITS) gene for improved detection. Our findings revealed that few current primers reliably distinguish P. cinnamomi from closely related species, and even those that did showed inadequate sensitivity. To address this, we designed novel primers and a species-specific probe targeting the ITS region, achieving consistent amplification with a detection limit of 10 fg. The new assay successfully detected P. cinnamomi in both artificial and symptomatic samples, ensuring rapid and precise identification. This optimised qPCR assay detects and quantifies P. cinnamomi in soil, providing superior sensitivity and specificity over existing methods and supporting more accurate pathogen management.

Verticillium nonalfalfae has been studied for > 20 years as a potential fungal bioherbicide for Ailanthus altissima. A specific isolate from Pennsylvania, VnAa140, has desirable virulence properties and demonstrated host specificity. However, it has yet to be tested outside Pennsylvania, and the potential for regional variation in the host–pathogen interaction and possible environmental limitations are unknown. The range of VnAa140 was expanded for the first time by inoculating A. altissima across 10 sites in Virginia that spanned three physiographic provinces and four USDA hardiness zones with the intent of quantifying disease progression in inoculated trees and the spread of the pathogen throughout A. altissima stands. However, initial inoculations resulted in very little disease development. Reinoculations the following year induced much higher levels of disease and mortality, including 52.3% ± 4.2% increase in disease levels of inoculated trees and a 27.2% ± 10.2% increase in symptom development among uninoculated trees, a marker of pathogen spread. However, results ranged widely along macro and microclimatic gradients, with higher site average temperatures and warmer microsite conditions correlating negatively with disease levels. While VnAa140 remains a strong bioherbicide candidate for the control of A. altissima, it appears that variability by culture and attenuation of virulence traits also contributed to the different levels of host disease development we observed in the field, suggesting that procedures to prevent and screen for these issues will be required as the fungus is propagated for bioherbicide formulation on a commercial scale.

Corymbia calophylla (marri), an iconic keystone species in the northern jarrah forest of southwestern Australia, is suffering from a stem canker disease caused by an endemic fungus, Quambalaria coyrecup. It is unusual for an endemic pathogen to have such a detrimental effect on a co-evolved host, unless host defence mechanisms have been compromised. This study investigated the role of Phytophthora cinnamomi root infection and water shortage in predisposing C. calophylla to this canker disease, and whether these two stresses work synergistically to intensify the effect of the canker pathogen on C. calophylla. The roots of two-year-old C. calophylla plants were inoculated with P. cinnamomi in pot infestation trials, and 8 weeks later in the stems with the canker pathogen Q. coyrecup. Half of the plants were exposed to a water shortage treatment for the duration of the trial. Biophysical variables related to plant responses to the treatments were measured at harvesting. Reflectance spectroscopy measurements with a portable high-resolution spectroradiometer were also taken weekly. The normalised difference spectral index (NDSI) was calculated for every combination of reflectance values between 350 nm and 2500 nm for all time points, correlated with treatment effects, and displayed as heat maps. Fifty-seven vegetation indices (VIs), using wavelengths from different regions in the electromagnetic spectrum, were also calculated from the spectral data. Neither P. cinnamomi nor the water shortage treatments exacerbated the effect of the canker pathogen on the plants. The canker treatment increased plant stem diameter and canker volume significantly (p < 0.001). The NDSI heat maps indicated that wavelengths in the electromagnetic spectrum's visible and shortwave infrared portions displayed the strongest correlations with the P. cinnamomi and water shortage treatments. For the canker treatment, it was the shortwave infrared portion. Six of the VIs responded significantly to the water shortage treatment: Carter index 1 (p < 0.001), renormalised difference vegetation index (p < 0.001), normalised difference water index (p = 0.012), normalised phaeophytinization index (p < 0.001), photochemical reflectance index (p < 0.001) and red-green ratio index (p = 0.018). The renormalised difference vegetation index was also sensitive to the canker treatment (p < 0.001), and the Carter index 1 to the P. cinnamomi treatment (p < 0.001). Reflectance spectroscopy was able to track biochemical changes in C. calophylla leaves due to inoculation with P. cinnamomi, Q. coyrecup, and the water shortage treatment. However, more work must be done to identify optimum wavelengths specific to C. calophylla and its responses to pathogens.