Pini Hulbary Research Articles

New data on the spread of the invasive species Dothistroma septosporum (Dorogin) M. Morelet in Belarus

Red band needle blight, or Dothistroma needle blight is one of the most common and harmful diseases of pine. The causative agents of the disease are pathogenic micromycetes Dothistroma septosporum (Dorogin) M. Morelet and Dothistroma pini Hulbary. Dothistroma needle blight was firstly detected in Belarus in 2012 year, but till now information about this disease in the republic is fragmentary. The article presents the results of a survey of different pine trees, carried out in the period 2016–2020 years in botanical and dendrological gardens, forest nurseries and mini-arboretums at forestry enterprises, urban stands, nurseries of decorative plants, garden centers, for the presence of Dothistroma needle blight. The species identification of the causative agent of the disease was carried out by mycological and molecular genetic methods. In this study, Dothistroma needle blight was revealed on individual trees of Pinus mugo, P. nigra and P. ponderosa in the stands of the Central Botanical Garden of the NAS of Belarus, the dendrological garden of the Glubokoe experimental forestry enterprise, in the nurseries of decorative plants in the Grodno and Minsk regions. In the collected samples of needles, the invasive species Dothistroma septosporum was identified. The frequency of occurrence of the pathogen was 4.8–7.2 %, the proportion of observation sites in which this disease was detected at 60 %. The detection of Dothistroma needle blight on pine trees, mainly on planting material imported from abroad, indicates a transboundary route of D. septosporum entering the country. Analysis of literature data indicates the potential danger of Dothistroma needle blight for pine stands in the republic, which in turn requires the organization of regular monitoring of the disease and the development of methods to limit the spread of D. septosporum in the republic.

Development of a Rapid Loop-Mediated Isothermal Amplification Assay for the Detection of Dothistroma septosporum

A Loop-Mediated Isothermal Amplification (LAMP) assay was developed for the detection of the pine pathogen Dothistroma septosporum (G. Dorog.) M. Morelet. The specificity of the LAMP assay was tested using a selection of pine needle fungi, including Dothistroma pini Hulbary, and Lecanosticta acicola (Thüm.) Syd.; only D. septosporum DNA was amplified by the test. In terms of sensitivity, the assay was able to detect as little as 1 pg of total D. septosporum DNA. This assay enables DNA extracted from diseased host needles to be rapidly tested for the presence of D. septosporum using relatively simple to operate equipment away from a fully equipped molecular biology laboratory.

DNA-barcoding identification of Dothistroma septosporum on Pinus contorta var. latifolia, P. banksiana and their hybrid in northern Alberta, Canada

The ascomycete fungi Dothistroma septosporum (Dorogin) M. Morelet and D. pini Hulbary are both responsible for Dothistroma needle blight disease (DNB) on pines. Using a DNA-barcoding approach, we confirmed that the DNB infection of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), jack pine (P. banksiana Lamb.) and their hybrid in four research sites in northern Alberta (Canada) was caused by D. septosporum, confirming that the range of D. septosporum extends east of the Rocky Mountains into Alberta. Analysis of mating-type (MAT) genes showed the presence of both mating types in each of the pine plantations, indicating that the pathogen has the potential to complete its lifecycle in this region. Controlled inoculation confirmed that the two native pines found in this area (P. contorta var. latifolia and P. banksiana) and their hybrid are susceptible to D. septosporum, suggesting that continuous monitoring of the disease needs to be carried out to prevent any future outbreak in natural stands.

First Record of Dothistroma pini on Pinus nigra in Switzerland.

The mitosporic ascomycetes Dothistroma septosporum s.s. (Dorog.) Morelet and D. pini Hulbary are closely related species (1) causing red band needle blight on Pinus spp. D. septosporum (teleomorph Mycosphaerella pini Rostr.) is considered as a cosmopolitan species, whereas D. pini (no teleomorph known) seems to have a more restricted distribution area. Detected in the United States on Pinus nigra for the first time, it was later found in Russia, Ukraine, Hungary, and France on different pine species (P. radiata, P. mugo, P. pallasiana) (3). In Switzerland, Dothistroma sp. (species not further determined) was recorded in 1989 for the first time and since then only damages on planted pines (mainly P. mugo and P. nigra) in urban areas were reported (R. Engesser, personal communication). In September 2012 and in April 2013, several planted mature trees and naturally regenerated young trees of P. nigra with Dothistroma needle blight were detected on a climatically mild forest site on limestone at the shore of Lake Walensee (47°07'48.0″ N, 9°13'54.4″ E, 420 m asl). In 2012, symptomatic needles were collected from the litter under one planted mature P. nigra tree and in 2013, symptomatic needles were collected from green twigs from a 2 m tall naturally regenerated P. nigra specimen. Conidiomata were frequently observed in the red bands but no conidia were detected. For fungal isolation, the surface of infected needles was shortly disinfected with 95% ethanol. The epi- and hypo-dermis covering the still closed conidiomata was removed and small tissue samples from the mesophyll (less than 0.5 mm length) were placed on malt extract agar (15 g/liter agar, 20 g/liter malt extract) amended by 50 mg/liter oxytetracycline. Conidia were observed after one year at 4°C in the resulting pure colonies (3 to 4 cm diameter on malt extract agar medium). The conidia formed by strain OH_120923_2_1_1 (KJ878557 = D. pini) were hyaline, smooth, thin-walled, 2- to 4-celled, and 31.6 (22 to 37) × 2.8 (2 to 3.5) μm. While conidial morphology of both Dothistroma species overlap, DNA was extracted and the internal transcribed spacer (ITS) region (primers ITS 1 and ITS 4) sequenced (KJ878557 to 81). From the 25 obtained ITS sequences, seven were identical with AY808275 (D. septosporum from P. radiata, South Africa, CMW 684), three were identical with AY808302 (D. pini from P. nigra, Michigan, CMW 10951), and 15 were identical with DQ926964 (D. pini from P. pallasiana, Ukraine, CMW 23767). The North American and Ukrainian D. pini sequences (AY808302 and DQ926964) showed only 1 bp difference. In addition, mating type genes were amplified using the method described by Groenewald et al. (2) for D. pini and scored using gel electrophoresis. Analyses showed that both D. pini ITS-sequence variants (e.g., KJ878557 and KJ878558) and both mating types were sometimes present in the same needle. In two cases, both mating types and ITS-sequence variants were also present within the same lesion. Interestingly, D. pini and D. septosporum were found on the same tree but not on the same needles. This is the first report of D. pini in Switzerland. Although symptoms of red band needle blight (species not determined) were repeatedly observed on this site during the last 20 years, the disease level always remained low and no tree mortality was noted. However, due to the presence of two ITS-sequence variants and both mating types, the incidence of D. pini in Switzerland deserves attention.

Four New Host and Three New State Records of Dothistroma Needle Blight Caused by Dothistroma pini in the United States.

During 2010 and 2011, Dothistroma needle blight (DNB), also known as red band needle blight, was observed for the first time in Cass and Pembina counties in North Dakota (ND). In Pembina Co., DNB was observed in two sites in the Jay V. Wessels Wildlife Management Area (JWWMA). In September 2009, yellow spots on green needles were observed on some trees along the western edge of one planting. By June 2010, DNB was found on third- and fourth-year needles in both JWWMA plantings. Symptoms had developed into dark brown bands or spots on necrotic needles that contained erumpent black acervuli. In June 2011, similar DNB symptoms were observed on Pinus nigra, P. flexilis, P. ponderosa, P. cembra, and P. albicaulis in the Dale E. Herman Research Arboretum, Cass Co., ND. DNB was collected in July 2011 in Brookings Co., South Dakota (SD), from a seed source provenance planting of P. ponderosa. To identify the species causing the infections, symptomatic needles were collected in 2010 from both sites in JWWMA and then again from all four locations in 2011 on all pine species infected. Needles of P. nigra from a private residence near Fairland in Shelby County, Indiana (IN), were also included in the sample set. The rDNA-ITS was PCR-amplified either directly from conidia obtained from acervuli on the needles or from cultures obtained from isolations. Amplicons were sequenced and a BLAST search was performed in GenBank. The sequences of samples obtained from P. nigra, P. flexilis, P. cembra, and P. albicaulis in ND, P. ponderosa in SD, and P. nigra from IN showed 100% sequence homology with Dothistroma pini (Accession No. AY808302). These isolates were identical to all previously assayed isolates of D. pini from Nebraska, Minnesota, and Michigan in the United States. The P. ponderosa isolates from all three sites in ND differed from the other isolates and contained a 1-bp point mutation from a C to a T at site 72 (sequence deposited in GenBank, accession KJ933441). Mating type was determined using species-specific mating type primers for D. pini (3). All 26 samples from ND and SD were of the MAT-1 idiomorph, while the sample from IN contained the MAT-2 idiomorph. All cultures are maintained at FABI, University of Pretoria, South Africa. The two species that cause DNB, D. septosporum (G. Dorog.) M. Morelet and D. pini Hulbary, are morphologically indistinguishable and molecular characterization remains essential for correct species identification (1). Host and geographical distribution range determinations of Dothistroma spp. made without molecular methods are not valid. To date, species confirmed using DNA sequences in the United States include D. septosporum in the Pacific Northwest states of Oregon and Idaho on P. ponderosa, in Montana on P. contorta v. latifolia, and D. pini in the North Central states of Nebraska, Minnesota, and Michigan on P. nigra (1). This study documents the presence of D. pini in three additional states, including a first report of DNB in ND and SD. It also includes new records of D. pini infecting P. flexilis, P. cembra, P. albicaulis, and P. ponderosa. Results of this study have expanded the documented host range of D. pini in the United States from one (P. nigra) to five species. Globally, D. pini is now known to infect a total of 10 pine hosts (2,4,5).

First Report of Dothistroma pini, a Recent Agent of the Dothistroma Needle Blight, on Pinus radiata in France.

Dothistroma needle blight (DNB), also known as red band needle blight, is an important fungal disease of Pinus spp. that occurs worldwide. On the basis of molecular and morphological studies of the anamorphic stage, Barnes et al. (1) showed that two closely related species were involved in DNB: Dothistroma septosporum (Dorog.) Morelet and D. pini Hulbary. D. septosporum (teleomorph: Mycosphaerella pini Rostr.) has a worldwide distribution and is reported as the species that caused past epidemics of DNB. This species is reported on more than 80 different pine species, and Pinus radiata D. Don (Monterey pine) is classified as a highly or moderately susceptible species, depending on the published sources (4). D. pini (telemorph: unknown) was initially found on needles of P. nigra J. F. Arnold collected from 1964 to 2001 in the north central United States (Minnesota, Nebraska, and Michigan). It was subsequently found in Ukraine and southwestern Russia, where it has been associated with the emergence of DNB on P. nigra subsp. pallasiana (Lamb.) Holmboe, in Hungary on P. nigra, and in Russia on P. mugo Turra (1). In France, D. pini was reported for the first time on P. nigra, and was sometimes found in association with D. septosporum on the same needles (3). Later on, a more intensive survey of DNB was launched in France and 216 stands of Pinus sp. were studied. D. septosporum and D. pini were detected in 133 and 123 stands, respectively. Both species co-occurred in 40 stands but D. pini was only found on P. nigra (subsp. laricio and austriaca) (2). Up to now, D. pini was therefore only reported on European pine species, mainly on the different allopatric subspecies belonging to the black pine complex and on one occasion on P. mugo, which belongs to the same section and subsection as P. nigra. In March 2011, typical symptoms of DNB (needles with orangey-red brown distal ends, dark red bands, and green bases; small and black fruit bodies within the bands) were observed in a 50- to 60-year old P. radiata stand of ~3 ha located in Pyrénées Atlantiques close to the Spanish border (1°36'08″ W, 43°19'51″ N). The density of pine was relatively low and patches of natural regeneration were present. Although nearly all of the trees showed DNB symptoms, less than 50% of their needles were affected by the disease. In this stand, needles showing typical DNB symptoms were randomly taken from four pines and mixed together to form a single sample for analysis. Total DNA was extracted from symptomatic needle pieces. The presence of D. pini was confirmed by a specific multiplex real-time PCR analysis using the D. pini-specific primers/probe combination DPtef-F1-/R1/-P1 (3), and by sequencing a D. pini-specific amplicon generated by another conventional PCR (3) using DPtef-F/DPtef-R primers (GenBank Accession KC853059) (3). D. septosporum was not detected in the sample. To our knowledge, this is the first report worldwide of D. pini on P. radiata, a pine species largely planted in Spain and in the Southern Hemisphere. This is also the first report of this pathogen on a non-European pine species. The original native range and the host range of D. pini remain unknown and there is currently no data about host preferences or aggressiveness on different pine species.

Scientific Opinion on the risk to plant health posed by Dothistroma septosporum (Dorog.) M. Morelet (Mycosphaerella pini E. Rostrup, syn. Scirrhia pini) and Dothistroma pini Hulbary to the EU territory with the identification and evaluation of risk reduct

Scientific Opinion on the risk to plant health posed by Dothistroma septosporum (Dorog.) M. Morelet (Mycosphaerella pini E. Rostrup, syn. Scirrhia pini) and Dothistroma pini Hulbary to the EU territory with the identification and evaluation of risk reduct

Dothistroma needle blight and pitch canker: the current and future potential distribution of two important diseases of Pinus species

Globally, pitch canker and Dothistroma needle blight are two of the most important diseases of pine species caused, respectively, by the pathogens Fusarium circinatum Nirenberg & O’Donnell and Dothistroma spp. ( Dothistroma septosporum (Dorog.) Morelet and Dothistroma pini Hulbary). The potential distributions of these two diseases under current global climate have previously been modelled and contrast strongly with each other. In this study, we used the process-based niche model CLIMEX to estimate the potential distribution of both diseases in the 2080s under six scenarios that include three contrasting global climate models, each with moderate and high CO2 emissions. For both diseases, under the future climate scenarios, there was a global reduction in the potentially suitable area. Among the three global climate models, this reduction ranged from 11% to 22% for Dothistroma needle blight and from 39% to 58% for pitch canker. The projected potential ranges of both diseases were significantly reduced for Africa, South America, and Australia. In Asia and North America, substantial reductions in potential area were generally projected for pitch canker, while little change to moderate levels of expansion were projected for Dothistroma needle blight. For Europe and New Zealand, expansion of suitable climate was projected under all climate change scenarios for both diseases.

The hosts and potential geographic range of Dothistroma needle blight

Dothistroma needle blight, one of the most important foliar diseases of Pinus spp., is caused primarily by the fungus Dothistroma septosporum (Dorog.) Morelet, and to a lesser extent by Dothistroma pini Hulbary. The potential distribution and abundance of Dothistroma spp. was determined by (i) developing a process-oriented model of potential distribution of Dothistroma spp. from known locations, (ii) compiling a comprehensive list of susceptible host species from existing scientific literature and (iii) determining the distribution of susceptible hosts in areas predicted to be suitable for range expansion of Dothistroma spp. Using these three sources of information regions at risk were identified as those that were predicted to be suitable for range expansion by Dothistroma spp. and included significant areas of susceptible host species. The process-oriented distribution model, CLIMEX was used to infer the climatic requirements of Dothistroma spp. from laboratory based measurements and 248 disease records in North America and Asia. When validated against 7594 disease observations from Europe, Africa, South America and Oceania, the model correctly predicted that all observations had a suitable climate for Dothistroma spp. The model indicated that the fungi can persist in climates ranging from sub-arctic through temperate, Mediterranean, continental, subtropical to dry tropical regions. The low level of disease detection in many regions projected to be climatically suitable may be due to the low occurrence of susceptible hosts. When areas that were not suitable for susceptible hosts were excluded results suggest that Dothistroma spp. could further extend their range into south east China, Vietnam, Ireland, Western Australia, Venezuela, Guyana, Suriname, Panama, Turkey, Albania and many countries bordering the Mediterranean Sea.

Mycosphaerella dearnessii and Mycosphaerella pini

<i>Mycosphaerella dearnessii</i> and <i>Mycosphaerella pini</i>

First Report of Dothistroma septospora on Native Limber and Whitebark Pine in Montana.

Dothistroma septospora (Doroguine) Morelet (= Dothistroma pini Hulbary), the anamorph of Mycosphaerella pini Rostr. in Munk, has been reported to cause needle blight in 29 Pinus species and hybrids in North America, including limber pine (P. flexilis James) in plantings in Kansas, Nebraska, and Ohio. We are unaware of any reports of D. septospora on limber or whitebark pine (P. albicaulis Engelm.) growing within their native ranges in the western United States. In June 1997, limber and whitebark pine in Montana were observed with severe defoliation and symptoms typical of those caused by D. septospora: affected second- and third-year needles were green at the base with brown tips or reddish-brown spots or bands, and black fruiting bodies in discolored portions of needles. Symptomatic needles were collected in natural stands of limber pine at 22 locations representing 15 counties in central, south-central, and southwestern Montana, and whitebark pine at three locations representing two counties in the Crazy Mountains in south-central Montana. Approximately 20 needles and five stromata from each location were examined with dissecting and compound microscopes to observe morphological features. Stromata were black, linear, 150 to 1450 μm (average 650 μm) by 65 to 450 μm (average 190 μm), subepidermal, and erumpent. Conidiophores were hyaline and unbranched. Conidia were 16.0 to 23.5 μm (average 18.5 μm) by 3.0 to 4.1 μm (average 3.4 μm), hyaline, 3 to 5 septate, blunt at the ends, and slightly falcate. The fungus described above was found at all sample locations. The teleomorph, M. pini, was not observed. Symptom expression and mycological characteristics were consistent with Hulbary's lectotype (1) of D. pini (= D. septospora). This is the first report of D. septospora on limber and whitebark pine within the hosts' native ranges. Reference: (1) R. L. Hulbary. Ill. Nat. Hist. Surv. Bull. 21:231, 1941.

A note on the effect of temperature and relative humidity on the germination of Conidia of a New Zealand isolate of Dothistroma pini Hulbary

Summary Conidia of a New Zealand isolate of Dothistroma pini Hulbary germinated at temperatures between 5° and 30°C with an optimum at 17°C. Liquid water was not essential for spore germination which occurred at humidities down to 96% R.H. This isolate was more closely related to D. pini var. keniensis than to the other two varieties of the fungus. However, further work is necessary before the varieties present in New Zealand can be determined with certainty.

Spore germination and growth in culture of Dothistroma pini var. Keniensis

Spore germination of Dothistroma pini Hulbary var. keniensis Ivory is shown to require trace quantities of organic nitrogenous substances in the germination medium. Germination occurs within the pH range 2·2–5·5 and the temperature range 8–25°C, with optima of pH 3·5 and 18°C respectively. Light was found to exert no significant effect. In liquid culture the fungus is non-specific in its nutrient requirements and does not require additives such as vitamins or minor elements. Growth is very slow but occurs within the pH range 2·0–7·0 and the temperature range 6–28°, with optima of pH 3·5 and approx. 15° respectively. Growth is not affected significantly by light. Attempts to induce the formation of the perfect state of the fungus in culture and on infected needles were unsuccessful.

A new variety of Dothistroma pini in Kenya

Three varieties of Dothistroma pini Hulbary are distinguished by their spore dimensions. The two varieties described by Thyr & Shaw are retained, with amended values for their conidial dimensions. A third variety, with conidia of intermediate length, is described as var. keniensis . The length of conidia is shown to differ significantly (P linearis and slowest in var. pini .

Dothistroma needle blight of pines: Effect and etiology

SUMMARYThe defoliating needle blight of pines caused by Dothistroma pini Hulbary (perfect state Scirrhia pini Funk &amp; Parker) is severely damaging to plantations of Pinus radiata D. Don., P. ponderosa Laws, and P. nigra Am. Symptoms and studies on P. radiata are reported.Disease severity has a linear relationship to stunting in very young trees, and a sigmoidal relationship to losses of height and diameter increments in 3‐year‐old trees, the most rapid losses occurring at disease severities between 25 and 75% blighted foliage. Height, independently of age, reduces disease severity. Maximum infection occurs at 0–5 ft. above ground level, while above 18 ft. there is significantly less attack.Rainfall of less than 1/2 in. weekly has little effect on disease increase and a mean weekly temperature of 65° F. or greater seems to be necessary for large disease increases; but the general environmental relations are too complex to be explained entirely quantitatively from the present data.

SCIRRHIA PINI N. SP., THE PERFECT STATE OF DOTHISTROMA PINI HULBARY

The perfect state of Dothistroma pini Hulbary was found on native and exotic pines in British Columbia. It is described as a new species of Scirrhia Fuckel, and the name S. pini is proposed. The life history, cultural characteristics, and distribution are presented.

Dothistroma pini Hulbary: A New Disease on Pine in Britain

Dothistroma pini Hulbary: A New Disease on Pine in Britain

Kansas Mycological Notes: 1952

The 1952 season was not particularly favorable for the development of fructifications of fungi as compared with the season of 1951 which had almost ideal moisture conditions. A deficiency of rainfall occurred throughout most of the season with drought conditions existing from the latter half of August through the remainder of the year. The saprophytic flora was curtailed and the collections of fleshy fungi were few. Several of the plant pathogenic fungi which in 1951 threatened to build up to epiphytotic proportions were completely checked by the dry conditions of 1952. For example, Dothistroma pini Hulbary, which is believed to be the cause of the serious needle-blight disease of pines, was not observed on any of the new needles produced in 1952 although abundant fruitbodies and spores were present on the 1950-51 meedles. Apparently the dry conditions, especially during May and June (3 inches of rainfall in 1952 compared with 17 inches for the two months in 1951), prevented infection of the developing needles. Fruitbodies of Dothistroma pini were found on two additional species of pine which were formerly thought to be resistant. On white pine (Pinus strobus L.) needle-blight symptoms were similar to those on the other susceptible pines (Austrian, western yellow, lodgepole and Swiss mountain pines), but on table mountain pine (Pinus pungens Lamb.) yellowish spots on only a few needles were noted. This is the first report in the United States of Dothistroma pini on these two species. Perhaps the most interesting fungus record new for Kansas was Ascoidea rubescens Brefeld & Lindau, a primitive ascomycete found in the slime flux of American elm (Ulmus americana L.). A brownish feltlike mat of mycelium was developed on the moist slime flux in which broad hyphae bore terminal cells (the asci) containing many hat-shaped ascospores similar to those produced in some yeast fungi. Single-celled, hyaline conidia were also produced on stout, erect conidiophores. The fungus was first collected in October on an old elm tree along Wildcat Creek. Later the fungus was found by S. M. Pady to be fairly common on elm trees on the Kansas State College campus and along the streets of Manhattan. Dr. Pady was able to culture the organism but only the