Comparative sequencing of a microsatellite locus reveals size homoplasy within and between european oak species (Quercus spp.)

Tubakia dryina (Sacc.) Sutt. (teleomorph Dicarpella dryina Belisario & Barr) is a widespread leaf pathogen in northern temperate zones and is mainly associated with Quercus spp. During 2000, T. dryina was isolated from seasonal samplings of endophytic fungal communities of Turkey (Q. cerris L.) and English (Q. robur L.) oaks. Samples were taken from healthy and declining trees showing no symptoms of T. dryina in a coppice with saplings in Piedmont (northwestern Italy). Fragments of freshly opened buds (1-year-old shoots) and leaves were surface-sterilized by immersion in 75% ethanol for 1 min, in a NaClO solution (3 to 4% active ingredient) for 3 min, and in 75% ethanol for 30 s, then plated on potato dextrose agar. T. dryina was found in all sampled tissues. Its frequency in buds was higher in healthy trees than in declining trees (≈25 versus 12%; analysis of variance test P < 0.05), whereas no difference was found in shoots. T. dryina was also isolated from asymptomatic leaves, but more often from declining trees than from healthy ones (≈40 versus 10%; P < 0.05). No differences were observed when comparing the two oak species. The fungus was previously reported in buds of Q. nigra L. in North America (2), and it has also been isolated from symptomatic leaves of Q. cerris in a 5-year-old plantation (1). T. dryina was found in other studies in leaves and dead twigs of Q. robur. To our knowledge, this is the first report of T. dryina in buds and shoots of European oak species, suggesting an important role of this fungus as either an endophyte or a latent pathogen associated with oak decline. References: (1) A. Belisario. Plant Dis. 77:647, 1993. (2) Y. C. Zhang and J. T. Walker. Plant Dis. 79:568, 1995.

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Biscogniauxia (Hypoxylon) Canker or Dieback in Trees

EDIS ◽

10.32473/edis-fr407-2017 ◽

2017 ◽

Vol 2017 (6) ◽

Author(s):

Claudia Paez ◽

Jason A. Smith

Keyword(s):

Water Stress ◽

Tree Species ◽

Soil Compaction ◽

Urban Areas ◽

Root Disease ◽

Poor Health ◽

Green Spaces ◽

Opportunistic Pathogens ◽

Wide Range ◽

Quercus Spp

Biscogniauxia canker or dieback (formerly called Hypoxylon canker or dieback) is a common contributor to poor health and decay in a wide range of tree species (Balbalian & Henn 2014). This disease is caused by several species of fungi in the genus Biscogniauxia (formerly Hypoxylon). B. atropunctata or B. mediterranea are usually the species found on Quercus spp. and other hosts in Florida, affecting trees growing in many different habitats, such as forests, parks, green spaces and urban areas (McBride & Appel, 2009). Typically, species of Biscogniauxia are opportunistic pathogens that do not affect healthy and vigorous trees; some species are more virulent than others. However, once they infect trees under stress (water stress, root disease, soil compaction, construction damage etc.) they can quickly colonize the host. Once a tree is infected and fruiting structures of the fungus are evident, the tree is not likely to survive especially if the infection is in the tree's trunk (Anderson et al., 1995).

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Oak trees (Quercus spp.) as a source of extracts with biological activities: A narrative review

Trends in Food Science & Technology ◽

10.1016/j.tifs.2021.01.029 ◽

2021 ◽

Vol 109 ◽

pp. 116-125

Author(s):

Diego Morales

Keyword(s):

Biological Activities ◽

Narrative Review ◽

Oak Trees ◽

Quercus Spp

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Assessment of Stem Volume on Plots Using Terrestrial Laser Scanner: A Precision Forestry Application

Sensors ◽

10.3390/s21010301 ◽

2021 ◽

Vol 21 (1) ◽

pp. 301

Author(s):

Dimitrios Panagiotidis ◽

Azadeh Abdollahnejad ◽

Martin Slavík

Keyword(s):

Norway Spruce ◽

Laser Scanner ◽

Estimation Methods ◽

Coefficient Of Determination ◽

Stem Volume ◽

Small Scale ◽

Terrestrial Laser Scanner ◽

Precision Forestry ◽

Total Tree ◽

European Oak

Timber volume is an important asset, not only as an ecological component, but also as a key source of present and future revenues, which requires precise estimates. We used the Trimble TX8 survey-grade terrestrial laser scanner (TLS) to create a detailed 3D point cloud for extracting total tree height and diameter at breast height (1.3 m; DBH). We compared two different methods to accurately estimate total tree heights: the first method was based on a modified version of the local maxima algorithm for treetop detection, “HTTD”, and for the second method we used the centers of stem cross-sections at stump height (30 cm), “HTSP”. DBH was estimated by a computationally robust algebraic circle-fitting algorithm through hierarchical cluster analysis (HCA). This study aimed to assess the accuracy of these descriptors for evaluating total stem volume by comparing the results with the reference tree measurements. The difference between the estimated total stem volume from HTTD and measured stems was 2.732 m3 for European oak and 2.971 m3 for Norway spruce; differences between the estimated volume from HTSP and measured stems was 1.228 m3 and 2.006 m3 for European oak and Norway spruce, respectively. The coefficient of determination indicated a strong relationship between the measured and estimated total stem volumes from both height estimation methods with an R2 = 0.89 for HTTD and R2 = 0.87 for HTSP for European oak, and R2 = 0.98 for both HTTD and HTSP for Norway spruce. Our study has demonstrated the feasibility of finer-resolution remote sensing data for semi-automatic stem volumetric modeling of small-scale studies with high accuracy as a potential advancement in precision forestry.

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