Heart Rot Research Articles

Pathological Characterization and Management of Lasiodiplodia theobromae, a Hemibiotroph with an Interkingdom Host Range.

Heart rot disease, caused by Lasiodiplodia theobromae, is destructive for date palms and other woody plants. The disease was reported in several oases in Egypt, and the pathogen was found in association with infected trees suffering dieback and rachis blight. Seven phylogenetically distinct fungal isolates were selected, and their pathogenicity was confirmed on date palms. The isolates exhibited variable degrees of virulence on inoculated leaves, which confirms the variation. We examined the antifungal effect of microbial bioagents and plant extracts on heart rot disease. The isolates of Trichoderma spp. gave moderate reduction of the pathogen's linear growth (40 to 60%), whereas their exudates were ultimately ineffective. Bacillus spp. isolates, except for B. megaterium, were more effective against spore germination, giving 80 to 90% reduction on average. Among the examined plant extracts, garlic sap gave 98.67% reduction of linear growth followed by artemisia (15.5%) and camphor (24.8%). The extraction methods greatly influenced the antifungal efficiency of each extract because exposure to organic solvents significantly decreased the efficiency of all extracts, whereas hot water extraction negatively affected garlic sap only. Successful bioagents and plant extracts were further assayed for the suppression of heart rot disease on date palms. Both T. album and T. harzianum gave comparable degrees of suppression as by commercial fungicides. In addition, treatment before or during pathogen inoculation was the most effective because it significantly enhanced the expression of defense-related enzymes. Our findings suggest biopesticides possess a dual role in disease suppression and defense boosters for date palms suffering heart rot disease.

Screening actinomycetes as biological control agents against the Dickeya zeae, causal agent of bacterial heart rot of pineapple

Screening actinomycetes as biological control agents against the Dickeya zeae, causal agent of bacterial heart rot of pineapple

СОКОПРОДУКТИВНОСТЬ КЛЕНА ВЫСОКОГОРНОГО

In the North Caucasus are presented data on the intensity of sap production and sap productivity of the Trautvetter maple. Experimental tapping was carried out in an old-growth maple forest in the forest fund of North Ossetia-Alania, the Koban tract. Maple tapping was carried out by laying drill channels with a diameter of 10 mm and a depth of no more than 30 mm. From 1 to 4 channels were laid on one trunk. A polyvinyl chloride tube with an outer diameter of 10 mm was used as a sap line. Plastic containers with a volume of 5 and 10 liters served as juice collectors. The volume of secreted juice was determined with an accuracy of 10 ml. It has been established that the intensity and duration of juice secretion depends on the weather conditions at the beginning of the growing season. The sap productivity of the Trautfetter maple also depends on the size of the tree and its condition. A direct and strong dependence of the intensity of juice secretion on the diameter of the trunk has been proven - the larger the diameter, the more juice. At the same time, there are cases when the intensity of sap production by trees with a small trunk diameter is higher than that of trees with a trunk diameter of about 1 m. It is noted that the presence of heart rot and hollowness of the trunk affects both the intensity of sap production and sap productivity. An interesting feature was revealed in individual Trautfetter maple trees: when 2-4 sapling canals are laid on one trunk, sap flow from one, or less often from two canals at once, quickly stops. The period of rapid decrease in juice secretion takes from 30 minutes to several hours. A characteristic phenomenon for alpine maple is the growth of trees in nests, when from 2 to 10-12 trunks develop from a single root system. It is indicated that the intensity of sap production does not depend on the number of trees in the “nest”, and the overall sap productivity of the “nest” is higher than that of individual trees.

Economically Imperative Ananas comosus Diseases, Status, and Its Control Measures Documented in Producing Countries

Ananas comosus, commonly known as pineapple, is a fruit with a large potential market as a commodity and commercial fruit. Numerous pests and diseases affect pineapple, directly or indirectly, by lowering the quality and quantity. The fungal causative agents, namely Fusarium ananatum and Thalaromyces stolii (previously named Penicillium funiculosum), cause fruitlet core rot (FCR) and fusariosis by Fusarium guttiforme. Bacteria heart rot (BHR) is an infection by Erwinia chrysanthemi, newly known as Dickeya zeae. Nevertheless, the mealybug wilt of pineapple (MWP) is another pineapple treat to susceptible pineapple varieties caused by pineapple mealybug wilt-associated viruses (PMWaVs). Other diseases include destruction caused by pathogenic nematodes. This review discusses the status of these diseases and the control measures that greatly affect the economy of pineapple-producing countries due to the economic significance of these crops. Growers need up-to-date information on the identity of the diseases that affect pineapple crops in the various countries that produce them to effectively manage the diseases in the field.

A new pathogenic polypore on urban trees: The first record of Rigidoporus ulmarius (Rigidoporaceae, Hymenochaetales) in Hungary

AbstractThe Giant Elm Bracket (Rigidoporus ulmarius) is a widely-distributed necrotrophic polypore species that causes white heart rot in deciduous trees. Despite its recognition as one of the largest species known for forming basidiomata, this perennial polypore had not been documented in Hungary. However, in recent years, two specimens macroscopically resembling this species were collected on old horse chestnut (Aesculus hippocastanum) trees from two different places in Hungary by amateur mycologists. In this study, subsequent morphological and molecular-genetic analyses of these fungal samples confirmed their identity as R. ulmarius. This study represents the first documented occurrence of this plant pathogenic polypore species in Hungary.

Characterizing the Palm Pathogenic Thielaviopsis Species from Florida.

Thielaviopsis paradoxa sensu lato is a soilborne fungal pathogen that causes Thielaviopsis trunk rot and heart rot in palms. The loss of structural integrity resulting from trunk rot can cause the palm trunk to collapse suddenly and poses a serious threat to life and property. Even though rudimentary knowledge about the Thielaviopsis infection process in palms is available, nothing is known about the T. paradoxa species complex in the US. The aim of this study was to characterize T. paradoxa s. lat. isolates collected from diseased palms grown in Florida. Multi-locus phylogeny using three genes, ITS, β-tubulin, and tef1-α, revealed that the isolates separate into two distinct clades with high bootstrap support. The majority of the isolates clustered with the species T. ethacetica, while two isolates formed a separate clade, distinct from T. musarum, and might represent an undescribed Thielaviopsis species. One representative isolate from each clade, when grown on three distinct media and at four different temperatures, showed differences in gross colony morphology, as well as growth rates. The T. ethacetica isolate TP5448 and the Thielaviopsis sp. isolate PLM300 grew better at opposite ends of the temperature spectrum tested in this study, i.e., 35 °C and 10 °C, respectively. In pathogenicity assays on whole plants, the T. ethacetica isolate proved to be more aggressive than Thielaviopsis sp. isolate PLM300, as it produced larger lesions when inoculated on wounded leaflets. An unequal distribution was observed for the mating-type locus of T. ethacetica, as 12 isolates carried the MAT1-1-1 allele, while the status for four isolates remained undefined. Variation in mycelial growth in response to different fungicides was also observed between the two clades. These results demonstrate the existence of two Thielaviopsis clades that can infect palms in Florida and underscore the need for targeted sampling to help uncover the diversity of Thielaviopsis species across palm-growing regions in the US.

Bacillus safensis filtrate-based ZnO nanoparticles control black heart rot disease of apricot fruits by maintaining its soluble sugars and carotenoids.

Black heart rot is a serious disease of apricot and it has been reported to be caused by Alternaria solani, around the world. The present research was designed to control this disastrous disease using zinc oxide nanoparticles (b-ZnO NPs). These NPs were synthesized in the filtrate of a useful bacterium (Bacillus safensis) and applied to control black heart rot of apricot. After synthesis, the reduction of b-ZnO NPs was confirmed by UV-visible spectroscopy, at 330nm. Fourier transform infrared (FTIR) spectra ensured the presence of multiple functional groups (alcohols, phenols, carboxylic acids, nitro compounds and amines) on the surface of b-ZnO NPs. X-Ray diffraction (XRD) analysis elucidated their average size (18nm) while scanning electron microscopy (SEM) micrograph described the spherical shape of b-ZnO NPs. The synthesized b-ZnO NPs were applied in four different concentrations (0.25mg/ml, 0.50mg/ml, 0.75mg/ml, 1.0mg/ml) under both in vitro and in vivo conditions. These NPs were very efficient in inhibiting mycelial growth (85.1%) of A. solani at 0.75mg/ml concentration of NPs, in vitro. Same concentration also performed best, in vivo, and significantly reduced disease incidence (by 67%) on self-inoculated apricot fruit. Apart from this, application of b-ZnO NPs helped apricot fruit to maintain its quality under fungal-stress conditions. The decay of apricot fruit was reduced and they maintained greater firmness and higher weight. Moreover, b-ZnO NPs treated fruits controlled black heart rot disease by maintaining higher contents of ascorbic acid, soluble sugars and carotenoids. These b-ZnO NPs were produced in powder form for their easy carriage to the farmers' fields.

Heart Rot Disease of Walnut Caused by Nothophoma juglandis sp. nov. and Its Endophytic Biocontrol Agent.

English walnut (Juglans regia L.) is an economically important hardwood tree species cultivated worldwide. Walnut heart rot disease leading to heartwood decay of trees has been frequently observed in a number of plantations in China. To identify the causal agent, 29 diseased stem samples were collected from walnut plantations in Beijing, and 54 fungal isolates were obtained. Koch's postulates were developed, and the results showed that Nothophoma juglandis, a species new to science, was the causal agent of walnut heart rot disease. Granulobasidium vellereum, a notable biocontrol agent, was coisolated with N. juglandis. An antagonistic assay on dual culture and walnut stems (both in the field and detached branches) proved that G. vellereum acted as a potential biocontrol agent against N. juglandis, as it could significantly inhibit the expansion of N. juglandis. The optimal temperature for mycelial growth and pathogenicity of N. juglandis was 26.6 and 27.0°C, respectively, which frequently occur in the summer of the walnut-growing regions in China.

Survey on the natural resistance to decay of five hundred tropical wood species

The natural durability of wood species against rot has again become a matter of interest for the uses of wood as a natural material, while the use of synthetic fungicides is being debated. In the mid-20th century, many experimental studies were performed in Europe and North America, using different standardised protocols. More than five hundred tropical wood species were tested in France between 1955 and 1990, with a total of 9,842 wood samples tested. It would seem useful to allow free access to all the data from these tests in the interests of a more comprehensive study of the natural durability of large wood panels. The great majority (68%) of all these tests used two slightly different protocols with only a change in woodblock test dimensions. Roughly half of the species were tested under one of the two protocols, and the other half under the second. In addition, certain species were tested with both protocols. The dimensions of the test blocks, the fungal strain used, and the wood type (sapwood or heartwood) all give significantly different results, but the mean mass loss due to the 4 main fungal strains is a good predictor of the wood resistance to rot. Overall, mass loss for sapwood with each protocol is 45% higher than for heartwood of the same species. There is a significant positive correlation between the rot resistance of the sapwood and the heartwood, but the decrease in heartwood compared to sapwood is greater in durable wood species than in non-durable ones. Heartwood rot resistance was observed to be highly variable between trees of the same species, except in those classified as “very durable” and “non-durable”. This opens up possibilities for a classification of natural rot resistance for numerous useful types of timber that are often regarded as only moderately resistant because they include a small proportion of species with poor resistance. Each protocol group included over one hundred species for which density and chemical composition data were available. Density, lignin content, and extractive content have a similar and very significant influence on the rot resistance of the wood (R² around 0.25).

Non-destructive detection of tree deterioration due to termite attack in plant conservation areas

Cibodas Botanic Gardens (CBG) is an ex-situ conservation area in tropical highlands. Termites are one of the nuisance organisms in the collection that have conservation value. The number of attacks and the intensity of termite attacks require more strict attention. The main problem in tree health analysis is the difficulty in detecting internal weathering due to attacks by wood-destroying organisms which causes damage to the tree’s core (heart rot) and butt rot. Arborsonic is a tool used and developed to detect and assess tree damage, especially to the trunk. This study aimed to analyze the deterioration of the main trunk of a living tree with visual signs of termite attack using a non-destructive method. Termite observation plots were made in 4 replications to determine the type of termites that attack. Observations on termite baits in 4 plots showed no attack on the baits. Observations on 12 sample trees tested in 4 plots showed low-intensity damage. Visual signs of termite attack can be used as a sign of wood decay, but the effect is minor.

Profiling phytochemical compounds, antibacterial activity and mechanisms of action of ginger essential oils-nanobactericides against Erwinia chrysanthemi causing heart rot disease of pineapple

Profiling phytochemical compounds, antibacterial activity and mechanisms of action of ginger essential oils-nanobactericides against Erwinia chrysanthemi causing heart rot disease of pineapple

Detection and incidence of pineapple heart rot disease caused by Phytophthora nicotianae in commercial farms of Puerto Rico

Pineapple heart rot disease (PHRD) caused by Phytophthora spp. is one of the most important diseases of pineapple. This disease is characterized by soft rot and water-soaked lesions. In severe cases plant mortality is 100%. During a one-year survey, conducted from March 2018 to March 2019, a total of 29 pineapple hectares were evaluated from five commercial pineapple fields located in the Puerto Rican municipalities of Guánica, Lajas, Manatí and Santa Isabel, and at the Agricultural Experiment Substation of the University of Puerto Rico in Isabela. Symptoms of PHRD were observed in all fields evaluated, except at the Agricultural Experiment Substation in Isabela. Diseased plant tissue was surface disinfected and plated on PARPH-V8 selective media for Phytophthora spp. Aerial photography using a DJI Phantom 3 drone was used to corroborate PHRD incidence in the field. Approximately eight hectares were infected by P. nicotianae with an average of PHRD disease incidence of 28.82%. The highest percentage of PHRD incidence was observed in fields located at Guánica, Lajas and Manatí with 40%, 40% and 30%, respectively. Eleven isolates of Phytophthora nicotianae were collected from pineapple fields in Guánica, Lajas, Manatí and Santa Isabel and identified using morphology and phylogeny of sequences of the mitochondrial cytochrome oxidase subunit I region (COI). The estimation of the incidence of P. nicotianae as the causal agent of PHRD is important as a first step in developing specific control measures in the pineapple fields of Puerto Rico.

Estimation of the occurrence, severity, and volume of heartwood rot using airborne laser scanning and optical satellite data

ABSTRACT Rot in commercial timber reduces the value of the wood substantially and estimating the occurrence, severity, and volume of heartwood rot would be a useful tool in decision-making to minimize economic losses. Remotely sensed data has recently been used for mapping rot on a single-tree level, and although the results have been relatively poor, some potential has been shown. This study applied area-based approaches to predict rot occurrence, rot severity, and rot volume , at an area level. Ground reference data were collected from harvester operations in 2019–2021. Predictor variables were calculated from multi-temporal remotely sensed data together with environmental variables. Response variables from the harvester data and predictor variables from remotely sensed data were aggregated to grid cells and to forest stands. Random Forest models were built for the different combinations of response variables and predictor subsets, and validated with both random- and spatial cross-validation. The results showed that it was not possible to estimate rot occurrence and rot severity with the applied modeling procedure (pR2: 0.00–0.16), without spatially close training data. The better performance of rot volume models (pR2: 0.12–0.37) was mainly due to the correlation between timber volume and rot volume.

The Effectiveness Test of Trichoderma harzianum, Mycorrhiza and Bacteria B8 on the Growth of Phytophthora nicotianae in Pineapple Plants (Ananas comosus L. Merr) at PT.Great Giant Pineapple

This study aims to determine the potential of biological agents to inhibit the pathogen P. nicotianae that causes liver rot and the effect of biological agents on the growth of pineapple plants at PT. Great Giant Pineapple. The research was carried out at the Experimental Field and Research and Development Protection Laboratory of PT. Great Giant Pineapple, Terbanggi Besar, Central Lampung from September to November 2022. The research was carried out in several stages, namely the preparation stage and the implementation stage. The preparation stage includes land preparation, breeding and application of T. harzianum, preparation of liquid culture of T. harzianum and B8 bacteria, dipping crowns, and selection of crowns and tagging. While the implementation phase includes planting, application of T. harzianum, mycorrhiza, and B8 bacteria, observation of disease occurrence level, antagonist test, observation of new leaf growth, and plant observation. The data obtained were analyzed using the T-test, which compared the control plot with the treatment plot (T. harzianum, mycorrhiza, and B8 bacteria). The results showed that the application of the biological agent T. harzianum had a significant effect on suppressing the pathogen P. nicotianae that causes heart rot in pineapple plants in vitro. In addition, the application of T. harzianum, mycorrhiza, and B8 bacteria significantly affected the growth of the number of tillers, d-Leaf height, and d-Leaf index.

Морфологический анализ и оптимизация технологического процесса продольного раскроя круглых лесоматериалов

Coniferous sawn timber is extensively used in construction. However, the dimensional and qualitative composition of the round timber for lumber production has recently deteriorated significantly. The number of sawn logs with a diameter of 14–20 cm represents barely 50 % of the total supply of raw materials for sawmills. Besides that, large-diameter logs frequently have some signs of decay, which is mostly heartwood rot. Thus, the sawlog must be handled with caution. The problem is to intensify the sawing process, especially when logs have a presence of heartwood rot. This is possible to achieve with the implementation of modern technological sawing processes and specified equipment. A method of morphological research is used to select flowsheet diagrams of sawing and construction solutions for rip cutting equipment. The completeness of the morphological table is determined by the sum of all properties of the concept objects and is evaluated by obtaining effective technological and constructive solutions. According to the morphological method, a procedure of search systematization is developed. The patent search identified the main protective and published application documents concerning programs about ripping machines for round timber. The flowsheet diagrams for rip cutting of round timber and operational schemes for the equipment are adjusted according to the discovered regularities. A new sawing program is proposed in order to improve the efficiency of the equipment. It was licensed under a national patent of the Russian Federation. The evaluation of the possibility of implementing the technological process is made by analyzing the target costs for the production arrangement, the production rate per shift, and the quality of the final products. The proposed method for selecting directions to intensify the rip cutting of round timber gives the possibility to determine the effective technological and technical decisions at a project’s preliminary problem-solving stage. For citation: Toropov A.S., Byzov V.E. Morphological Analysis and Optimization of Technological Process for Rip Cutting of Round Timber. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 132–145. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-132-145

Genetic architecture of terpene chemistry and growth traits and the impact of inbreeding on these traits in western redcedar (Thuja plicata).

Western redcedar (WRC; Thuja plicata) is a conifer of the Pacific Northwest of North America prized for its durable and rot-resistant wood. WRC has naturally low outcrossing rates and readily self-fertilizes in nature. Challenges faced in WRC breeding and propagation involve selecting trees for accelerated growth while also ensuring enhanced heartwood rot resistance and resistance to ungulate browsing, as well as mitigating potential effects of inbreeding depression. Terpenes, a large and diverse class of specialized metabolites, confer both rot and browse resistance in the wood and foliage of WRC, respectively. Using a Bayesian modelling approach, we isolated single nucleotide polymorphism (SNP) markers estimated to be associated with three different foliar terpene traits and four different heartwood terpene traits, as well as two growth traits. We found that all traits were complex, being associated with between 1700 and 3600 SNPs linked with putatively causal loci, with significant polygenic components. Growth traits tended to have a larger polygenic component while terpene traits had larger major gene components; SNPs with small or polygenic effect were spread across the genome, while larger-effect SNPs tended to be localized to specific linkage groups. To determine whether there was inbreeding depression for terpene chemistry or growth traits, we used mixed linear models for a genomic selection training population to estimate the effect of the inbreeding coefficient F on foliar terpenes, heartwood terpenes and several growth and dendrochronological traits. We did not find significant inbreeding depression for any assessed trait. We further assessed inbreeding depression across four generations of complete selfing and found that not only was inbreeding depression not significant but that selection for height growth was the only significant predictor for growth during selfing, suggesting that inbreeding depression due to selfing during operational breeding can be mitigated by increased selection intensity.

First Report of Bacterial Pineapple Heart Rot Caused by Dickeya zeae in Puerto Rico.

In Puerto Rico, the agricultural production of pineapple (Ananas comosus (L.) Merr.) comprises nearly 5,000 tons harvested annually from over 250 ha (USDA 2018). With an annual income of approximately $3 million USD, pineapple ranks fourth in importance among Puerto Rican crops (USDA 2018). Recently, the pineapple industry on the island underwent a change from growing a local cultivar known as "Cabezona" to cultivar MD2, introduced from Hawaii around 1996 (SEA 2015), because this cultivar produces fruit more than once during a single growing season. In August 2018 (when the rainy season normally starts in Puerto Rico), soft rot symptoms appeared at commercial fields in Manatí (WGS 84 Lat 18.42694, Lng -66.44779) and persisted through 2019. Symptoms observed in the field included foliar water-soaked lesions with gas-filled blisters, especially at the base of the leaf. Leaves exhibited brown discoloration and a fetid odor (rot) at the basal portion of the plant. Finally, leaves collapsed at the center of the pineapple crown, effectively killing the apex and preventing the fruit from developing. Disease incidence ranged from 25% to 40% depending on the weather and season; when there was more rain, there was higher disease incidence. Symptomatic leaves were collected in February 2019, disinfected with 70% ethanol, and rinsed with sterile distilled water. Tissue sections (5mm2) were placed in nutrient agar. Bacterial colony-forming units (CFU) were a translucent cream color, circular, with a flat convex surface and wavy edge. Biochemical analysis showed that bacteria were Gram-negative, oxidase positive, catalase positive, and facultatively anaerobic. Pathogenicity was tested on leaves of one-and-a-half-year-old pineapple seedlings in humid chambers. Bacteria were grown on sterile nutrient agar for 3 days at 25 ± 2°C. Inoculation assays (three replications) were performed using 1X108 CFU/ml of bacteria suspended in sterile water and applied with a cotton swab to leaves wounded with a needle. The inoculated tissue was incubated at 28°C and kept in a dark environment. Negative controls were inoculated with sterile water. Five days after inoculation, foliar water-soaked lesions were observed, followed by the formation of brown leaf tissue and gas-filled blisters, the same symptoms observed in the field. A partial DNA sequence of the 16S rRNA gene of the bacterial isolate and the re-isolated bacteria were amplified using primers 27F and 1492R (Lane et al. 1985) and sequenced. The isolate was determined to the genus Dickeya through a BLAST® search against sequences available in the database of the National Center for Biotechnology Information (NCBI). This partial 16S rRNA sequence of the bacterial isolate was deposited in GenBank® at NCBI (Accession no. MT672704). To determine the identity of the Dickeya species, we sequenced the genes dnaA, gyrB, dnaX, and recN (Marrero et al. 2013) for the bacterial isolate (GenBank accession nos. OM276852, OM276853, OM276854, and OM276855) and conducted a Multilocus Sequence Analysis including reference Dickeya sequences of Marrero et al., 2013. The Phylogenetic analysis (using WinClada) resolved the Puerto Rican isolate as belonging to a clade broadly ascribable to D. zeae, most closely related to strains isolated from earlier Hawaiian pineapple bacterial heart rot outbreaks. Dickeya zeae was responsible for bacterial heart rot of pineapple in Malaysia and was later reported as the causal agent for outbreaks in Costa Rica and Hawaii (Kaneshiro et al. 2008; Sueno et al. 2014; Ramachandran et al. 2015). D. zeae had not previously been reported as causing bacterial heart rot in pineapples in Puerto Rico and this study points to a close relationship with strains first detected in Hawaii and which should further be explored to determine the precise nature of this relationship. This information should facilitate the adoption of effective control measures for this disease on the island, promote more effective methods of preventing future introductions of pathogens, and encourage further investigations into the occurrence of D. zeae on the island.

Incidence and Effect of Heart Rot in Marayur Sandalwood (Santalum albumL.) Reserve, Kerala, and Its Natural Durability Against Fungi

AbstractIndian sandalwood (Santalum album L.) is a semi-parasitic tree, well known for its valuable sandalwood oil extracted from heartwood and roots. Extensive loss of heartwood as a result of its decay is observed in living trees and this has inspired the current study, to investigate the health of sandalwood in Marayur sandalwood forest reserves. Located in Kerala, India, the majority of the trees in Marayur are facing high mortality with the loss of heartwood. The current study evaluated the health status and heartwood-rot disease severity of each tree, which revealed that only 16.67 % of the total trees were healthy and 1.5 % of them were dead. Statistical analysis revealed increasing girth class of trees has a significant positive association with increased disease severity at a 0.05 level of significance. Laboratory analysis confirmed the presence of the major wood-rotters Allophoma tropica, Xylaria berteroi, Diaporthe sp., Fomes sp., Ganoderma appalanatum, and Trametes sp., and that they are collectively responsible for the heart rot. A durability assessment revealed sandalwood is highly resistant (durability class I) to white-rot fungi (viz., Trametes hirsutus and T. [Coriolus] versicolor) and moderately resistant (durability class II) to brown-rot fungi (Oligoporous placenta and Fomitopsis meliae).Study Implications: This study highlights the health status and heart-rot disease severity of sandalwood trees in Marayur Forest Reserves. Of the total trees surveyed, about 1.5% mortality was observed and only 17% of the trees were devoid of any heart-rot symptoms. Allophoma tropica, Ganoderma applanatum, Xylaria berteroi isolate SR52, Diaporthe sp., Fomes sp., G. appalanatum, and Trametes sp. are typical species collectively responsible for the heart rot and this was found to be the case in our study. These findings will sensitize forest managers to the loss of valuable sandalwood and death of the trees due to the heart rot, thereby enabling them to take appropriate preventive measures. Also, the natural durability of sandalwood against brown- and white-rot fungi is reported for the first time, indicating that sandalwood falls in the resistance class I (highly resistant) against white-rot fungi (Trametes hirsutus and T. (Coriolus) versicolor) and resistance class II (resistant) against brown-rot fungi (Oligoporous placenta and Fomitopsis meliae).

The effect of xylotrophic basidiomycetes on the photosynthetic pigments of small-leaved trees

Xylotrophic basidiomycetes are an essential component of any biogeocoenosis. It is due to these organisms that one of the most important processes occurs throughout the biosphere, namely the decomposition of organic substances and, first of all, cellulose, which is synthesized by producers. However, these phytopathogens bring significant losses to forestry, making wood unsuitable for industrial use. At the same time, sufficiently effective methods for diagnosing and assessing wood damage by heartwood rot, which are caused by xylotrophic basidiomycetes, have not been developed. The paper studies the peculiarity of the influence of these phytopathogens on the pigment apparatus of valuable small-leaved tree species using the methods of spectroscopy and electrophotocolorimetry, while comparing the rate of degradation of the main pigments of photosynthesis chlorophylls a and b to pheophytin, as well as assesses the content of chlorophyll, and auxiliary pigments such as carotenoids and xanthophylls in healthy trees and trees with signs of damage by pathogenic xylotrophs. A significant number of effects of phytopathogens on leaf pigment apparatus of small-leaved tree species have been identified. Among those are rapid degradation of primary and secondary pigments, distortion of chlorophyll a concentration data caused by filter properties of photoelectric colorimeter and higher chlorophyll b concentration in affected trees in comparison to control sample. These methods and the results obtained can be actively used both in forestry to assess the phytosanitary state of small-leaved trees, and to further study the features of the interaction of xylotrophic basidiomycetes with woody plants.

Селекционные испытания факториальных гибридов Populus tremula L. в ювенильном возрасте

The aspen is known for its rapid growth, unpretentiousness to growing conditions, valuable timber and some other useful properties. The largest areas on the Eurasian continent are occupied by Populus tremula L. Unfortunately, it is susceptible to heart rot Fomes igniarius Fr., which is a significant drawback. Considering this drawback many scientists had carried out selection of rot-resistant stands and individual aspen trees in natural forests, and later proceeded to artificial hybridization. Besides different crossing options, factorial hybridization, in which several females are crossed with several males, is of interest. The resulting hybrids provide an opportunity to determine the best parental individuals or their pairs. Factorial hybridization of P. tremula in Russia was first carried out in the Central Chernozem region in 2015–2016 within the framework of international cooperation with the Institute of Forest Genetics of the Johann Heinrich von Thünen-Institute (Germany) under the MARussiA project. The purpose of the work was to carry out hybridization, create a field experiment on variety testing of the resulting hybrids and observe them to identify the best hybrids and parents. The hybrids were tested at experimental field sites in the Voronezh and Lipetsk regions. This paper presents the results of field testing at the Latnoye variety test plot in the Semiluky district of the Voronezh region (51°42’ N, 38°56’ E; total area – 2,160 m2). Survival of plants of different hybrid families in the 4-year field experiment ranged from 67 to 100 %; on average, it was 88 %. The average height of plants at this age in individual families varied from 349±38.7 to 510±30.0 cm, being on average 419 cm in the experiment. The average diameter at breast height (1.3 m) was 3.4 cm with fluctuations by families from 2.4 to 4.6 cm. The average size of species cylinders of aspen hybrids by families was 3.5 dm3 with fluctuations from 1.7 to 7.7 dm3. The general and specific combining abilities of the parental forms had been preliminarily found. The results have been compared with the results obtained in other countries. Performed laboratory and field experiments on hybridization of P. tremula L. in the Central Chernozem region will allow to determine the best parental forms and select a number of economically valuable hybrids.