Needle Cast Research Articles

Repeated Lophodermium needle cast has a cumulative impact on the growth of Scots pine for up to 12 years

Repeated Lophodermium needle cast has a cumulative impact on the growth of Scots pine for up to 12 years

Effects of Swiss Needle Cast on the Profitability and Optimal Management of Douglas-fir Plantations in Western Oregon

Abstract This study conducts an economic analysis to evaluate the impact of Swiss needle cast (SNC) caused by Nothophaeocryptopus gaeumannii on Douglas-fir (Pseudotsuga menziesii) plantations at the stand level in western Oregon. We examine timber and nontimber benefits across varying degrees of SNC severity considering timber benefits and carbon sequestration benefits. By comparing these values with unaffected Douglas-fir stands, our aim is to quantify the economic losses associated with SNC in terms of the land expectation values. The total land expectation value for a stand affected by SNC ranges from $556 to $2,179/ac, representing an average decrease of 50% ($1,066/ac) in economic revenues compared with a Douglas-fir stand without SNC infestation. Engaging in cost-effective annual management activities, with maximum costs of $43–$56/ac, could offset the profitability decline. On average, the total losses in profits for the current plantations affected by SNC are estimated to be around $206.5–430 million. Study Implications: In this study, we examine the economic impacts of Swiss needle cast (SNC) on the profitability of western Douglas-fir in Oregon. Our results reveal that profits for landowners can be, on average, reduced by $1,066/ac when their stand is infested by SNC, representing a 50% loss in profitability. Landowners could potentially mitigate these losses by engaging in annual management activities aimed at preventing Douglas-fir infestation, incurring a cost ranging between $43–56/ac, which could offset the reduction in profitability.

BIOLOGICAL EFFECT OF CHEMICAL PREPARATIONS AGAINST THE MAIN DISEASES OF PINE

In the article Duplet TT 22,5% em.c. the drug was used in the growth period of 0,5 l/ha against phomoza and needle cast diseases in pine. The biological effectiveness of the drug against diseases was 84,7% for phomoza, 83,8% for needle cast, and other information were given.

Genomic and culture-based analysis of Cyclaneusma minus in New Zealand provides evidence for multiple morphotypes

Cyclaneusma needle cast, caused by Cyclaneusma minus, affects Pinus species world wide. Previous studies suggested the presence of two distinct morphotypes in New Zealand, ‘verum’ and ‘simile’. Traditional mycological analyses revealed a third morphotype with clear differences in colony morphology and cardinal growth rates at varying temperatures. Genome sequencing of eight C. minus isolates provided further evidence of the existence of a third morphotype, named as ‘novus’ in this study. To further analyse these morphotypes, we predicted candidate effector proteins for all eight isolates, and also characterized a cell-death eliciting effector family, Ecp32, which is present in other pine phytopathogens. In concordance with their distinct classification into three different morphotypes, the number of Ecp32 family members differed, with patterns of pseudogenization in the ‘simile’ morphotype, and some members being found exclusively either in the ‘simile’ or ‘verum’ morphotypes. We also showed that the Ecp32 family proteins trigger cell death in non-host Nicotiana species, and, as previously demonstrated in other plant pathogens, the Ecp32 family proteins in C. minus adopt a β-trefoil fold. These analyses provide further evidence that the three morphotypes might be distinct species that need formal descriptions. Understanding the geographical range of different Cyclaneusma species and variations in virulence and pathogenicity will provide a better understanding of pine needle diseases and enable the development of more durable methods to control this disease.

Effects of needle cast diseases on the growth of a 33-year-old Douglas-fir provenance plantation in northwestern Bulgaria

Abstract In this study, the effects of defoliation caused by fungal pathogens on the tree vitality and growth of a 33-year old Douglas-fir (Pseudotsuga menziesii) provenance plantation in northwestern Bulgaria was presented. The results of the conducted surveys in 2011 and 2020 showed that there were significant differences between the individual provenances of Douglas-fir concerning their susceptibility to the needle cast diseases, caused by the fungal pathogens Rhabdocline pseudotsugae and Phaeucryptopus gaeumannii. The extent of damage, expressed as the amount of Douglas-fir needles cast, varied among provenance groups in individual years. A serious degree of defoliation was assessed among all continental provenances. In 2011, all examined trees from the group of continental provenances had severe symptoms of the needle cast disease. In 71.5% of them, the defoliation of the crowns was over 25% – moderately to severely affected. The average degree of defoliation varied from 18.3% (32 Wаrm Springs) to 89.3% (55 Alamogordo). In 2020, severe defoliation was found among all continental provenances. Both fungal pathogens were found as causes of the defoliation of 64.3% of the trees. The growth indicators: average height, average diameter at breast height, average height- and diameter increment for survived provenances in 2011 (at age 24) and 2020 (at age 33) were evaluated. The loss of needles and the reduced physiological function of the trees affected their vitality in the following years. Relationships between the average current annual height and diameter increment by provenance groups for 2003–2011 and 2011–2020 were calculated. It was found that with an increase in the degree of defoliation, the height and diameter increment of the provenances decreases.

Genetic architecture of disease resistance and tolerance in Douglas-fir trees.

Understanding the genetic basis of how plants defend against pathogens is important to monitor and maintain resilient tree populations. Swiss needle cast (SNC) and Rhabdocline needle cast (RNC) epidemics are responsible for major damage of forest ecosystems in North America. Here we investigate the genetic architecture of tolerance and resistance to needle cast diseases in Douglas-fir (Pseudotsuga menziesii) caused by two fungal pathogens: SNC caused by Nothophaeocryptopus gaeumannii, and RNC caused by Rhabdocline pseudotsugae. We performed case-control genome-wide association analyses and found disease resistance and tolerance in Douglas-fir to be polygenic and under strong selection. We show that stomatal regulation as well as ethylene and jasmonic acid pathways are important for resisting SNC infection, and secondary metabolite pathways play a role in tolerating SNC once the plant is infected. We identify a major transcriptional regulator of plant defense, ERF1, as the top candidate for RNC resistance. Our findings shed light on the highly polygenic architectures underlying fungal disease resistance and tolerance and have important implications for forestry and conservation as the climate changes.

Which Cyclaneusma minus morphotypes are responsible for needle cast of Pinus spp. in Slovakia?

Cyclaneusma needle cast (CNC) is a needle disease which caused deterioration of vitality and reduction in the growth of pines. The disease is caused by the ascomycetous fungus Cyclaneusma minus, which has two well-described morphotypes; C. minus simile and C. minus verum. The distribution and host range of C. minus simile and verum was determined from needle samples and isolates collected throughout Slovakia from 2014 to 2020. Samples from 111 localities, 11 pine host species and 245 trees collected in different types of planting were analysed. It was found, that both morphotypes are present, but C. minus verum is predominantly responsible for CNC in urban and forest plantings in Slovakia. C. minus verum was positively detected in more than 88% of collected samples, whereas C. minus simile was only in four samples from three localities. Morphotype-specific primers were sufficiently sensitive even for new pine-host species. The host range of C. minus simile and C. minus verum was enriched worldwide. C. minus verum was observed in nine host species, whereas C. minus simile was identified only in one. Cyclaneusma niveum was also recorded and its presence was confirmed through DNA sequencing.

Early Prediction of Regional Red Needle Cast Outbreaks Using Climatic Data Trends and Satellite-Derived Observations

Red needle cast (RNC), mainly caused by Phytophthora pluvialis, is a very damaging disease of the widely grown species radiata pine within New Zealand. Using a combination of satellite imagery and weather data, a novel methodology was developed to pre-visually predict the incidence of RNC on radiata pine within the Gisborne region of New Zealand over a five-year period from 2019 to 2023. Sentinel-2 satellite imagery was used to classify areas within the region as being disease-free or showing RNC expression from the difference in the red/green index (R/Gdiff) during a disease-free time of the year and the time of maximum disease expression in the upper canopy (early spring–September). Within these two classes, 1976 plots were extracted, and a classification model was used to predict disease incidence from mean monthly weather data for key variables during the 11 months prior to disease expression. The variables in the final random forest model included solar radiation, relative humidity, rainfall, and the maximum air temperature recorded during mid–late summer, which provided a pre-visual prediction of the disease 7–8 months before its peak expression. Using a hold-out test dataset, the final random forest model had an accuracy of 89% and an F1 score of 0.89. This approach can be used to mitigate the impact of RNC by focusing on early surveillance and treatment measures.

Phytophthora pluvialis maintenance, spore production and detached needle assays.

Phytophthora pluvialis is an oomycete that primarily infects Pinus radiata and Pseudotsuga menziesii causing the destructive foliar disease red needle cast (RNC). Recent observations show that P. pluvialis can also infect western hemlock inducing resinous cankers. High-throughput and reproducible infection assays are integral to find key information on tree health and oomycete pathogenicity. In this protocol, we describe the propagation and spore induction of P. pluvialis, followed by detached needle assays for verification and quantification of virulence of P. pluvialis in P. radiata needles. These needle assays can be employed for high-throughput screening of tree needles with diverse genetic backgrounds. In downstream analysis, Quantitative PCR (qPCR) was utilized to assess relative gene expression, as exemplified by candidate RxLR effector protein PpR01. Additional techniques like RNA sequencing, metabolomics, and proteomics can be combined with needle assays and can offer comprehensive insights into P. pluvialis infection mechanisms.

Monitoring of the phytosanitary condition of Larix decidua Mill. plants in the Modryna tract of the Zviahel Forestry branch of the State Enterprise Forests of Ukraine

Phytosanitary monitoring of forest stands is currently a relevant and important area of scientific research that ensures observation, assessment, and forecasting of the dynamics (changes) of the quantitative and qualitative (including sanitary) state of forests and underlies the development of an effective system of tree protection. The purpose of this study was to identify the species composition and distribution of dominant phytopathogen species in the Modryna tract of the Zvyagelske Forestry branch and to identify the primary factors of Larix decidua Mill. decline. This study employed phytopathological, entomological, forest inventory, and comparative methods. The study identified and registered typical symptoms of damage and the consequences of the harmful effects of pests of L. decidua trees in the Modryna tract, leading to a general weakening of their sanitary condition. Symptoms of larch needle cast (meria needle blight) and browning were recorded on the needles; on the trunks – typical manifestations of cankers and fruiting bodies of a unique basidiomycete – Lariciphomes officinalis. Apart from infectious pathologies, sporadic wind and storm damaged larch trees, as well as other negative effects of wind exposure, were recorded in the study areas. The species composition of the pests of the surveyed larch trees included the following insect species: Cephalcia lariciphila, Sacchiphantes viridis Ratz., Coleophora laricella, Zeiraphera diniana Gn., Lasiomma laricicola Karl. It was generalised that the main threat to the centuries-old larch trees is the complex effect of anthropogenic, abiotic, and biotic (including parasitic) environmental factors that constantly and to varying degrees affect the sanitary and physiological state of ancient larch trees. The findings of this study provide information for predicting the risks of spreading pathogens and pests, which allows managing these risks and preventing their further spread

Genome sequences of three genetic lineages of the fungus Nothophaeocryptopus gaeumannii, the causal agent of Swiss needle cast on Douglas-fir trees.

Here, we present the nearly complete genome sequences of the three main genetic lineages of Nothophaeocryptopus gaeumannii, an endophytic ascomycete fungus responsible for Swiss needle cast, a foliar disease that is emerging as a significant threat to the Douglas-fir tree in its natural distribution range.

Automatic Detection of Phytophthora pluvialis Outbreaks in Radiata Pine Plantations Using Multi-Scene, Multi-Temporal Satellite Imagery

This study demonstrates a framework for using high-resolution satellite imagery to automatically map and monitor outbreaks of red needle cast (Phytophthora pluvialis) in planted pine forests. This methodology was tested on five WorldView satellite scenes collected over two sites in the Gisborne Region of New Zealand’s North Island. All scenes were acquired in September: four scenes were acquired yearly (2018–2020 and 2022) for Wharerata, while one more was obtained in 2019 for Tauwhareparae. Training areas were selected for each scene using manual delineation combined with pixel-level thresholding rules based on band reflectance values and vegetation indices (selected empirically) to produce ‘pure’ training pixels for the different classes. A leave-one-scene-out, pixel-based random forest classification approach was then used to classify all images into (i) healthy pine forest, (ii) unhealthy pine forest or (iii) background. The overall accuracy of the models on the internal validation dataset ranged between 92.1% and 93.6%. Overall accuracies calculated for the left-out scenes ranged between 76.3% and 91.1% (mean overall accuracy of 83.8%), while user’s and producer’s accuracies across the three classes were 60.2–99.0% (71.4–91.8% for unhealthy pine forest) and 54.4–100% (71.9–97.2% for unhealthy pine forest), respectively. This work demonstrates the possibility of using a random forest classifier trained on a set of satellite scenes for the classification of healthy and unhealthy pine forest in new and completely independent scenes. This paves the way for a scalable and largely autonomous forest health monitoring system based on annual acquisitions of high-resolution satellite imagery at the time of peak disease expression, while greatly reducing the need for manual interpretation and delineation.

First report of Cryptocline taxicola (Helotiales: Helotiaceae) causing needle cast disease on common yew in Algeria

AbstractThis short report describes the occurrence of Cryptocline taxicola (Allesch.) Petr. causing needle cast on Taxus baccata L. trees in natural stands in Algeria. Symptoms of fungal infection were observed on the trees' crowns. Closer inspection of collected needles showed the presence of dark brown fungal fruiting bodies on the upper and the lower sides of the needles. The visual symptoms and the microscopical study allowed the fungus to be identified as C. taxicola. This is the first report of this pathogen in Algeria. A detailed description of the fungus is given.

Tree diversity reduces co-infestation of Douglas fir by two exotic pests and pathogens

The number of non-native invasive pests and pathogens has increased dramatically in recent years, with disastrous consequences for the health of forests worldwide. Multiple studies have shown that mixed forests may suffer less damage from insect pests than single species forest. This “associational resistance” can be notably explained by the fact that heterospecific neighbours make it more difficult for herbivores to locate and then exploit their host tree. However, the validity of these findings in the case of non-native, invasive pests and pathogens remains to be demonstrated. In this study, we monitored over two hundred Douglas firs in pure and mixed plots of a tree diversity experiment to assess the damage from the non-native gall midge Contarinia pseudotsugae and the non-native needle cast Nothophaeocryptopus gaeumannii. The probability of Swiss needle-cast infection was lower in Douglas fir trees surrounded by heterospecific neighbours. Gall midge damage was lower on Douglas firs surrounded by taller neighbours, consistent with the hypothesis of reduced host Apparency. Douglas fir trees that were more damaged by C. pseudotsugae were also more often infected by N. gaeumannii. Our study thus provides partial support of the associational resistance hypothesis of mixed forests against exotic pests and pathogens. Promoting forest species diversity at the stand level could, therefore, offer interesting prospects for reducing the impact of biological invasions, especially those involving both pests and pathogens.

Site-level estimates of Douglas-fir foliage retention from climate, soil, and topographic variables

Cohort-based live foliage retention of Douglas-fir (Pseudotsuga menziesii), repeatedly shown to be directly related to tree growth, was estimated for areas in western Oregon and Washington by correlating nearly 1000 plot-level estimates of foliage retention with variables of climate, soils, and topography. Sampling of Douglas-fir foliage retention, motivated by the Swiss needle cast-induced loss of foliage (causal agent Nothophaeocryptopus gaeumanii) in western Oregon and Washington, covered the period from 1998 to 2021, with estimates collected from the Oregon Coast Range near the California border to the Olympic Peninsula and the foothills of the northern Oregon Cascades and the foothills near the border of Washington and Canada. Douglas-fir foliage retention was found to be correlated with average June/July relative humidity, December maximum temperature, and May precipitation averaged for the periods of budbreak for the 2–4 yr old needle cohorts, a transformation of slope and aspect, the number of meters above 400 m elevation, topographic position index, and soil cation exchange capacity. Using the constructed equation, foliage retention was estimated across a systematic grid of points in western Oregon and Washington and combined with a regional growth model to estimate potential volume growth loss across the region. The greatest implied average growth losses (∼23%) were in the zones closest to the Pacific Ocean between 46° and 48°N. Premature loss of Douglas-fir foliage in the Pacific Northwest has been primarily associated with Swiss needle cast, and this work may help explain conditions that favor Swiss needle cast or describe additional foliage retention drivers.

The Pathological Status of Pinus sylvestris L. Understory Affected by Anthropogenic Air Pollution Stress (Case Study of Forests near Krasnoyarsk)

Air pollution is the major anthropogenic factor in urban and industrial areas. Forests play the most important role in improving environmental quality in such areas. Long-term air pollution has an adverse effect on the entire biota in such forests and determines the nature of plant–pathogen interactions. The purpose of the present research was to study the pathological status of the understory in Pinus sylvestris L. stands subject to long-term anthropogenic air pollution. The study was conducted in the pine forests near Krasnoyarsk. Research methods included a detailed pathological inspection of the understory (including saplings and self-sown trees) in stands (mainly forest-steppe pine forests) growing from 10 to 30 km from the city and macroscopic and microscopic diagnostics of plant diseases, and the analysis of the data obtained was carried out using statistical criteria (Kolmogorov–Smirnov test (dK-S), Student’s t-test). Pathogens affecting young pines (nine species identified) are micromycetes of different parasitic strategies (semi-parasites predominate). The most common pathogens are Lophodermella sulcigena (causes needle cast), Cenangium ferruginosum (necrosis of branches), and Sarea difformis (stem and branches canker). The pathogens causing necrosis and canker are the most harmful for pine understory. As young plants mature, pathogen diversity and disease manifestations increase. In stands closer to the city, understory infestations with dominant diseases significantly decrease as the degree of their contamination with heavy metals and fluorine increases. The activity of pathogenic micromycetes is likely to be suppressed by the chemicals found in the plants.

Development of PCR-based markers for the identification and detection of Lophodermella needle cast pathogens on Pinus contorta var. latifolia and P. flexilis

Morphological similarities and fastidious development of increasingly emerging fungal needle pathogens impede accurate disease diagnosis and early detection. This study analyzed the specificity and sensitivity of polymerase chain reaction (PCR)-based markers developed for emerging needle cast pathogens Lophodermella concolor and L. montivaga co-occurring on Pinus contorta var. latifolia, and Bifusella linearis and L. arcuata on P. flexilis. To design primers, we utilized sequences of the internal transcribed spacer (ITS) region and single-copy gene (RH_2175) of the TCP-1/cpn60 chaperonin family searched through genomes of related species. In addition to the DNA of target and non-target fungal species that were used for primer assays, environmental samples with next generation sequencing data were used to evaluate primer sensitivity. Direct amplification using ITS primer pairs generated 248–260 bp amplicons and successfully differentiated the needle pathogens used in this study. Nested amplification of single-copy gene RH_2175 primer pairs which produced 409–527 bp amplicons detected Rhytismataceae species and discriminated both Lophodermella pathogens on P. contorta var. latifolia, respectively. While ITS-based primers had higher sensitivity than the 2175-based primers, both primer sets for L. concolor and L. montivaga detected their respective pathogens in asymptomatic and symptomatic needles. These molecular tools can help monitor and assess needle diseases for forest management and phytosanitary regimes.

Efficacy and optimal timing of low-volume aerial applications of copper fungicides for the control of red needle cast of pine

Background: Red needle cast (RNC) is a foliar disease of radiata pine (Pinus radiata D.Don), caused by Phytophthora pluvialis Reeser, Sutton & E.Hansen and occasionally Phytophthora kernoviae Brasier, Beales & S.A.Kirk. The disease has impacted plantations in New Zealand since at least 2008. To develop management recommendations for red needle cast, research has focused on identifying chemical control options and understanding pathogen epidemiology to guide optimal timing of spray application. The objectives of this study were to: (1) assess the efficacy of aerial copper fungicide application for the control of red needle cast in mature radiata pine plantations; and (2) investigate optimal spray timing. Methods: To address these objectives, three operational-scale field trials were undertaken in successive years between 2017 and 2019 at a forest in the Central North Island of New Zealand. RNC severity was assessed in canopies of forest blocks exposed to cuprous oxide applied at 0.855 kg ha-1 active ingredient in low-volume aerial spray at different times of the year (November, February and April (or May)). Needle cast from plantation trees and infection levels on trap plants were also assessed in some years. Results: Application of cuprous oxide significantly reduced RNC severity in all three trials. As well as reducing disease severity, application of cuprous oxide also tended to reduce needle cast from plantation trees and infection on trap plants in years when these were also assessed. No consistent effect of spray timing was observed. Generally, all three spray timings reduced disease severity compared to the unsprayed control, but differences were not always significant, and few differences were detected between different spray timings. Conclusions: The results reported here are the first to show that low-volume aerial applications of cuprous oxide applied at 0.855 kg ha-1 active ingredient can reduce the severity of RNC in commercial radiata pine plantations. No consistent effect of spray timing was detected. These findings support the development of management recommendations for RNC.

Infection periods of Phytophthora pluvialis and Phytophthora kernoviae in relation to weather variables and season in Pinus radiata forests in New Zealand

Background: Red needle cast caused by Phytophthora pluvialis Reeser, Sutton & E. Hansen, and less frequently P. kernoviae Brasier, Beales & S.A.Kirk, is an important foliar disease of Pinus radiata D.Don (radiata pine) in plantations throughout parts of New Zealand. Significant growth loss occurs following years when severe outbreaks occur. Aerial spraying with a copper-based fungicide has potential for disease control. Research is being carried out to optimise application timing, supported by complementary studies to understand RNC epidemiology. Methods: In order to determine the pathogen infection periods, a field trial was conducted over two years at two forests in the Central North Island of New Zealand. Batches of potted radiata pine seedlings were placed beneath diseased pine stands at fortnightly intervals, before returning them to an open nursery area for assessments of infection every two weeks (based on visual symptoms and qPCR) over a period of three months. A hybrid modelling approach was employed to establish relationships between the proportion of plants showing symptoms and weather conditions during the fortnight of exposure and previous fortnights. Gradient boosting machine learning analyses were used to identify the most important weather variables, followed by analysis of these by generalised mixed effects models, generalised least square models and ordinary least square models. Results: Development of RNC symptoms and detection of Phytophthora pluvialis and P. kernoviae on exchange seedlings was greatest for those exposed between April and September (Southern Hemisphere mid-autumn to early-spring). At this time, temperatures, solar radiation and evapotranspiration were lower, and rainfall and foliage wetness were plentiful. Modelling identified temperature and relative humidity several months before the date of exposure as the most important weather variables explaining infection. Conclusions: Because of autocorrelation, it was not possible to determine those variables that drive sporulation, dispersal, infection and symptom development. This will require more detailed exchange plant studies together with controlled environment inoculation experiments. Nevertheless, results of this and earlier work complement recent research indicating that it may be possible to manage RNC by fungicide applications made in late summer or autumn, early in the annual disease cycle.

Transitions of foliar mycobiota community and transcriptome in response to pathogenic conifer needle interactions

Profiling the host–mycobiota interactions in healthy vs. diseased forest ecosystems helps understand the dynamics of understudied yet increasingly important threats to forest health that are emerging due to climate change. We analyzed the structural and functional changes of the mycobiota and the responses of Pinus contorta in the Lophodermella needle cast pathosystem through metabarcoding and metatranscriptomics. When needles transitioned from asymptomatic to symptomatic, dysbiosis of the mycobiota occurred, but with an enrichment of Lophodermella pathogens. Many pathogenicity-related genes were highly expressed by the mycobiota at the necrotrophic phase, showing an active pathogen response that are absent in asymptomatic needles. This study also revealed that Lophodermella spp. are members of a healthy needle mycobiota that have latent lifestyles suggesting that other pine needle pathogens may have similar biology. Interestingly, Pinus contorta upregulated defense genes in healthy needles, indicating response to fungal recognition, while a variety of biotic and abiotic stresses genes were activated in diseased needles. Further investigation to elucidate the possible antagonistic interplay of other biotic members leading to disease progression and/or suppression is warranted. This study provides insights into microbial interactions in non-model pathosystems and contributes to the development of new forest management strategies against emerging latent pathogens.