Recent Papers

Volume 14 - 2024

3. A comprehensive checklist of fungal species associated with Shorea robusta (Sal tree) in South Asia: taxonomic diversity and ecological insights
Tarafder E et al. (2024)

2. Checklist of pests and diseases of fruits and vegetables in Bamenda, North West Region, Cameroon
Kinge TR et al. (2024)

1. Farmers’ knowledge and perception of late blight of potato and its management strategies in Kailali and Banke districts of Nepal
Tiwari S, Srivastava A (2024)

Volume 13 - 2023

11. Evaluation of cabbage varieties for resistance to clubroot pathogens, Plasmodiophora brassicae woronin in Dhankuta, Nepal
Thapa A et al. (2023)

10. Characterization of infection patterns of common bean rust (Uromyces appendiculatus) under different management practices
Bhandari S, Srivastava A (2023)

9. First report of Podosphaera sp. (Fibroidium sp.) causing powdery mildew on Erigeron bonariensis L. in India
Thite SV et al. (2023)

8. Validation of a generic model for predicting garlic rust
Mallmann G et al. (2023)

7. Ampelomyces quisqualis – a remarkable mycoparasite on Cucucrbita maxima powdery mildew from Satara (M.S.) India
Thite SV et al. (2023)

6. First report of Pyrrhoderma noxium from rice in northern Thailand
Absalan S et al. (2023)

5. Biological characteristics of Diplodia sapinea f. sp. cupressi infecting Cupressus sempervirens L. in Tunisia
Hlaiem S, Ben Jamâa ML (2023)

Volume 9 - 2019 -

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1. Pith necrosis associated with Pseudomonas viridiflava in tomato plants in Brazil

Authors: Monteiro FP, Ogoshi C, Becker WF, Wamser AF, Valmorbida J

Recieved: 03 October 2018, Accepted: 23 December 2019, Published: 09 January 2019

This is the first report of the bacterium Pseudomonas viridiflava as the aetiological agent of tomato pith necrosis (TPN) in Brazil. The strain was identified by a scheme of tests for bacteria that emit fluorescence, known as LOPAT, and by sequencing the 16S rDNA region.

Keywords: fluorescent bacteria – Solanum lycopersicum – vascular disease

 

2. Disease prevalence and severity assessment of Pratylenchus coffeae on an infected banana in Peninsular Malaysia

Authors: Paiko AS, Ahmadu T, Rashed O, Ahmad K, Sijam K, Alsultan W

Recieved: 07 August 2018, Accepted: 27 December 2018, Published: 10 January 2019

Pratylenchus spp. cause considerable damage to the banana plant (Musa spp.) globally and although reported extensively in Malaysia, disease prevalence and infection severities have not been defined. The objective of this research, therefore, was to determine the prevalence of Pratylenchus coffeae and the extent of their damage on Musa spp. Of the 13 banana fields sampled, Pratylenchus nematodes were found in 76% of them. Proportions of root cortexes occupied by reddish brown lesion were significant in all the states. All the sampled areas exceeded the threshold limit, which is a 1% increment above 5% and is considered highly significant damage. The pathological reaction of P. coffeae against Pisang Berangan multiplications was observed after 12 weeks of growth in a glasshouse experiment. There were significant differences in vegetative growth within the various pathogen inoculation levels evaluated. Pisang Berangan showed a high level of susceptibility through the activity of polyphenol oxidase and peroxidase-induced resistance at all days after inoculation with P. coffeae compared to the control, except at week 12 where it declined or was non-significant from the control. Educating banana growers on the prevalence of this pathogenic parasite is therefore imperative for management decisions.

Keywords: disease evaluation – Musa spp. – nematodes – root lesion

 

3. Control of black rot disease in cabbage by integration of mulching, pruning and hot water treatment of seeds

Authors: Ombuna GJ, Nyangeri BJ, Maobe SN

Recieved: 13 October 2018, Accepted: 09 January 2019, Published: 22 January 2019

Black rot disease of cabbage caused by Xanthomonas campestris pv. campestris has been a major hindering factor to cabbage production in Kisii County, Kenya. The conventional technique for controlling this disease has been the use of chemicals. However, this method of control has not been effective as the disease is seed borne. In addition, most chemicals pollute the environment and make it unconducive for the survival of other important organisms such as decomposers. In this paper, the integration of hot water treatment of seeds, mulching, pruning and plant debris management was considered as an approach that can effectively manage this disease. To achieve this objective, seeds of Gloria Hybrid cabbage were inoculated with a bacterial suspension of X. campestris pv. campestris isolated from leaf segments obtained from plant leaves with characteristics symptoms of black rot disease. A portion of the inoculated seeds were treated with hot water at 50oC for 25 minutes and later planted in the field to evaluate the effects of mulching, pruning and plant debris management on black rot disease. Another portion of the inoculated seeds were not treated with hot water and were planted to serve as a control. Disease was scored on a scale of 1–9 based on the length of the V-shaped lesions developed on the margin of plant leaves. The results obtained show that integration of hot water treatment of seeds, mulching, pruning and plant debris management led to 76.1% less black rot disease and a 78.3% increase in marketable yields. Hence such treatment is recommended as the best approach to manage black rot disease of cabbage in the field.

Keywords: disease score – Gloria Hybrid – integration – severity – significant difference – Xanthomonas campestris

 

4. Molecular diversity and distribution of arbuscular mycorrhizal fungi colonizing peach (Prunus persica) and apple (Malus pumila) trees in a sustainable small market garden

Authors: Winther J, Aldrich K

Recieved: 09 October 2018, Accepted: 08 December 2018, Published: 01 March 2019

We characterized the molecular diversity and distribution of arbuscular mycorrhizal fungi (AMF) in the roots of apple and peach trees found at Grand Valley State University’s Sustainable Agriculture Project small market garden. Arbuscular mycorrhizal fungal root colonization observed in cleared and stained roots ranged from 11–43%. The molecular identity of the fungal symbionts was determined based on phylogenetic analyses of isolated small subunit ribosomal DNA sequences. Twenty-seven arbuscular mycorrhizal fungal sequences in the phylum Glomeromycota were isolated from roots of apple and peach trees with 96% of those sequences in family Glomeraceae including the genera Rhizophagus and Sclerocystis, and 4% of the sequences share identity with fungi in the family Paraglomeraceae. Four of the isolated arbuscular mycorrhizal sequences were shared between different apple and peach trees. Peach tree roots had the highest arbuscular mycorrhizal richness of trees sampled. Our analyses suggest that apple and peach trees in small gardens may form arbuscular mycorrhizal associations with different fungi than apple and peach trees of larger scale agricultural operations. Furthermore, the presence of shared AMF sequences between different fruit trees suggests the presence of common mycorrhizal networks that may serve an important function in the health and productivity of small market gardens. 

Keywords: agriculture – Glomeraceae – mutualism – symbiosis – 18S

 

5. Efficacy of selected fungicides against mycelial growth of Colletotrichum spp. causing anthracnose of chilli

Authors: Nuraini MN, Latiffah Z

Recieved: 13 September 2018, Accepted: 15 December 2018, Published: 06 March 2019

Many Colletotrichum spp. are associated with chilli anthracnose, and fungicides remain one of the important means to manage the disease. The present study evaluated the effectiveness of two contact fungicides, mancozeb and propineb, and two systemic fungicides, benomyl and difenoconazole to inhibit mycelial growth of seven Colletotrichum spp. causing chilli anthracnose using poison food and agar disc diffusion assays. In vitro tests of the fungicides showed that the two systemic fungicides effectively inhibited mycelial growth of C. fructicola, C. siamense, C. truncatum, C. scovillei, and C. fioriniae. The study provides preliminary information on the types of fungicide that are suitable for managing anthracnose of chilli fruits in Malaysia.

Keywords: Capsicum sp. – chilli – Colletotrichum spp. – contact fungicides – systemic fungicides

 

6. Assessment of Botryosphaeria stevensii detection by DNA barcoding

Authors: Wang Y, Gao RF, Zhang GM, Cheng YH, Shi YQ, Li FR, Pan G, Xiang CY

Recieved: 24 May 2018, Accepted: 07 October 2018, Published: 12 March 2019

Botryosphaeria stevensii is a fungus that infects several tree species and causes cankers. In this study, 139 strains of 12 species in the genus Botryosphaeria isolated from infected apple trees were selected for assessing feasibility of identifying Botryosphaeria stevensii using DNA barcoding method with three potential marker genes: translation elongation factor 1alpha (EF-1α), the internal transcribed spacer (ITS) and β-tubulin. By means of intraspecific and interspecific interval and cluster analysis and Wilcoxon rank sum testing, the ranking of the three tested genes for distinguishing intraspecific and interspecific genetic distance in B. stevensii is as follows: EF-1α > β-tubulin > ITS. DNA barcoding using the three tested genes was shown to be suitable for detection of three Botryosphaeria stevensii strains isolated from the United States and New Zealand. Therefore, DNA barcoding based on the sequence of the EF-1α gene could be used to rapidly identify B. stevensii infecting apple trees.

Keywords: apple trees – Botryosphaeria stevensii – fungus identification

 

7. Fungal Epiphytes for Biological Control of Rice Blast Fungus (Pyricularia oryzae)

Authors: Paraiso L, Dela Pena F, Capacao R

Recieved: 08 November 2018, Accepted: 20 January 2019, Published: 12 March 2019

Fungal epiphytes are microbes residing on plant surfaces. However, their use has not been exploited in contrast to fungal endophytes in which a number of studies had been conducted in relation to plant protection. This study describes the potential of epiphytic fungi that can antagonize the rice blast fungus, Pyricularia oryzae. Ten epiphytic fungi isolated from rice leaves were used to challenge the rice blast fungus in vitro. Dual culture test of the fungi showed three modes of antagonism: (1) pathogen mycelia overgrown by fungal epiphytes mycelia [Penicillium sp. GM15 and Fusarium sp. LM1], (2) suppression by colonizing half of the plate [Curvularia sp. GM11, Penicillium sp. GT1, GM20, GM7, GT19, and GT27], and (3) through antibiosis as shown by zone of inhibition [Aspergillus sp. GT29 and Penicillium sp. GM6]. However, only Penicillium sp. GM15 and Fusarium sp. LM1 had parasitized the mycelia of P. oryzae after seven days. Extracellular activities of fungal epiphytes were screened. Eight of ten isolates produced endoglucanase while six of the isolates showed proteolytic activity on plate method. This study proved the potential of fungal epiphytes from rice leaves as biocontrol agents against P. oryzae.

Keywords: antagonize – endoglucanase – mycoparasitized – proteolytic – zone of inhibition

 

8. New host reports of rust fungi (Pucciniales) from Khyber Pakhtunkhwa, Pakistan

Authors: Fahad M, Fiaz M, Ullah Z, Shariq M, Ullah S, Rehman Hu, Shah R, Ahmad S

Recieved: 22 July 2018, Accepted: 01 March 2019, Published: 18 March 2019

During a survey of rust fungi from Shangla District of Khyber Pakutunkhwa, Pakistan, two species of Puccinia were found parasitizing two plant species. Puccinia purpurea was found on Sorghum halepense, and P. caricis-filicinae was found on Carex filicina. Sorghum halepense is reported as new host from Pakistan while P. caricis-filicinae is a new record from District Shangla (KP) Pakistan.

Keywords: Cyperaceae – grass – Poaceae – Puccinia – rusts

 

9. Statistical analysis of foliicolous fungal biodiversity of Konkan region, Maharashtra, India: A novel approach

Authors: Dubey R, Pandey AD

Recieved: 28 November 2018, Accepted: 12 February 2019, Published: 19 March 2019

Foliicolous micro-fungi are the microscopic fungi inhabiting leaf surface as asymptomatic mutualists, benign commensals or latent pathogens. Maharashtra being the largest state in terms of area in peninsular India shows wide variety of ecosystems. With a view of studying the foliicolous fungi in such a diverse array of habitats, a project entitled “Foliicolous fungi of Maharashtra” was undertaken and various areas were visited in different forest ecosystems of Maharashtra. The present paper deals with the analysis of foliicolous micro-fungal diversity of Konkan region of Maharashtra. A total 191 foliicolous micro-fungi were found. In order to analyse difference in biodiversity across the districts ordinary least squares (OLS) and count data regression models were developed with Species Count as a dependent variable. Both approaches yielded identical results in terms of overall significance of regression and statistical significance of estimated coefficients: there was highly statistically significant (p < 0.01) difference in mean Species Count across the districts. To analyse the similarity in species composition Jaccard similarity Index (JSI) was calculated. Maximum JSI was 7.927%, for Greater Thane and Sindhudurg districts. No species was common in all districts; only 4.396% species were common in maximum three districts (i.e. Greater Thane, Ratnagiri, Sindhudurg).

Keywords: Foliicolous fungi – Jaccard similarity Index – Konkan – Mycobiota – Negative Binomial Regression Model (NBRM) – Ordinary Least Squares – Poisson Regression Model (PRM)

 

10. Cultural Variability of Fusarium oxysporum f. sp. elaeidis Isolates from Oil Palm in South Western Cameroon and Sensitivity to Four Plant Extracts

Authors: Kinge TR, Moforcha ZL, Mih AM

Recieved: 26 November 2018, Accepted: 27 March 2019, Published: 30 April 2019

Oil palm (Elaeis guineensis Jacq.) of the Arecaceae is a perennial monocot of great importance in both small and large scale farming in most countries in the world. Vascular wilt caused by Fusarium oxysporum f. sp. elaeidis is one of the most damaging diseases of oil palm in Cameroon. It displays enormous cultural variability leading to difficulty in its control. This work aimed to study the cultural variability of Fusarium oxysporum f. sp. elaeidis isolates responsible for vascular wilt of oil palm in five Cameroon Development Corporation oil palm estates in South Western Cameroon and verify the bioactivity of five plant extracts to the fungus. A total of 107 isolates from oil palm rachis and rhizospheric soils of five estates were characterized culturally. These isolates showed variation in colony characters in Potato Dextrose Agar and Rose Bengal media. Neem and Tithonia leaf extracts showed inhibitory effects on the fungal isolates in vitro. This work therefore confirms the variability within the Fusarium oxysporum complex and the potential of producing anti-fungicidal sprays from Tithonia and neem leaf extracts in the control of this phytopathogenic fungus.

Keywords: Elaeis guineensis– In vitro Control – Occurrence – Vascular wilt

 

11. Podosphaera lini (Ascomycota, Erysiphales) revisited and reunited with Oidium lini

Authors: Braun U, Preston CD, Cook RTA, Götz M, Takamatsu S

Recieved: 25 April 2019, Accepted: 07 May 2019, Published: 29 May 2019

Podosphaera lini (Erysiphaceae) has recently been detected on linseed, Linum usitatissimum var. crepitans, in England and represents the first unequivocal record of this powdery mildew species from Great Britain. The history of powdery mildew on linseed/flax in the UK is critically discussed. DNA sequence data (ITS + 28S rDNA) have been retrieved, from the British material and a specimen from Germany, to be used for phylogenetic analyses. The position of P. lini as a species of its own in the genus Podosphaera, close to P. macularis (hop powdery mildew), was confirmed in the ITS-based phylogeny. The phylogenetic results, in concordance with the morphological traits of the flax powdery mildew (small peridial cells of the chasmothecia), place this species in Podosphaera sect. Sphaerotheca subsect. Sphaerotheca. Oidium lini, described from Croatia by Škorič in 1926, was later erroneously reduced to a synonymy with Golovinomyces orontii. Oidium lini has been reassessed and is now regarded as a synonym of Podosphaera lini. Oidium lini, cited in the literature as a name published by Bondartsev in 1913, is critically discussed and reviewed. The name O. lini was most likely never validly introduced and is doubtful.

Keywords: powdery mildew – Linum – phylogeny – taxonomy – Oidium

 

12. The plant pathogenic genus Neocordana

Authors: Samarakoon SMBC, Wanasinghe DN, Jeewon R, Tian Q, Jayawardena RS, Chomnunti P

Recieved: 28 December 2018, Accepted: 27 May 2019, Published: 06 June 2019

Neocordana species mainly causes leaf spots on Musa spp. (banana and plantain) and on Canna denudata (an ornamental plant). Leaf spots on Musa spp. reduce the quality of the commodity and result in significant economic loss. Based on molecular and morphological data, the genus accommodates seven species at present with a worldwide distribution. Most of the taxonomic work has been conducted on Neocordana musae. In this study, updates on the diversity, distribution, and morpho-molecular taxonomy of Neocordana are provided. In addition, important aspects such as pathogenicity, disease control, antagonistic activity and association with other pathogenic fungi are discussed. The phylogenetic relationships of Neocordana with other genera in the family Pyriculariaceae based on LSU and ITS DNA sequence data are investigated. Our results support the monophyletic nature of Neocordana which is sister to Barretomyces. This study provides the first comprehensive account on diversity, taxonomy, and pathogenicity of Neocordana.

Keywords: antagonistic – banana – controlling – endophytic – pathogens – Pyriculariaceae

 

13. In vitro evaluation of Trichoderma harzianum strains for the control of Fusarium oxysporum f.sp. cubense

Authors: Napitupulu TP, Ilyas M, Kanti A, Sudiana IM

Recieved: 14 January 2019, Accepted: 31 May 2019, Published: 11 June 2019

Tricoderma harzianum have been widely used as a biocontrol agent for the suppression of soil-borne pathogens. The objective of this work was to evaluate the potential of T. harzianum strains to control Fusarium oxysporum f.sp. cubense (Foc), a well-known soil-borne pathogen that associated with banana wilt disease. In this study, ten isolates of T. harzianum strain isolated from various regions in Java were evaluated through two in vitro antagonistic approaches, dual culture test and volatile organic compound (VOC) producing test. All strains showed antagonistic activity against Foc according to the dual culture test with various degree of antagonism from efficient antagonism to highly efficient antagonism. Observations after five days, the antagonists overgrew 63% until 88% of medium surface. Similarly, all strains produced toxic volatile metabolites that having significant effects on the growth and development of the Foc. After seven days of exposure with antagonists, the mycelial growth of the test pathogen was inhibited by 24% until 44%. These results indicate that different strains showed variability in the level of antagonism.

Keywords: antagonism – dual culture – Foc – VOC

 

14. First record of the powdery mildew fungus Erysiphe polygoni on the introduced coral vine Antigonon leptopus (Polygonaceae) in Taiwan

Authors: Wang CT, Yeh YW, Lin LD, Kirschner R

Recieved: 03 April 2019, Accepted: 19 June 2019, Published: 21 June 2019

Antigonon leptopus has been naturalized in Taiwan for about 100 years, but hitherto no fungal species was recorded on this plant in Taiwan. A powdery mildew fungus collected on A. leptopus in central and northern Taiwan was identified as Erysiphe polygoni based on internal transcribed spacer sequence comparison and morphology of the anamorph.

Keywords: Erysiphaceae – ITS – new host record – pathogenic Ascomycota – pest insects

 

15. Checklist of order Capnodiales in Thailand

Authors: Rathnayaka AR, Jayawardena RS

Recieved: 08 May 2019, Accepted: 20 July 2019, Published: 01 August 2019

Capnodiales fungi are associated with plant and human as pathogens, endophytes, saprobes and epiphytes. Order Capnodiales consist with 15 familes and 245 genera. The aim of the present study is to prepare a checklist for Capnodiales species which are recorded in Thailand. USDA database (latest accessed 09/01/2019) and related research studies are used to gather the information for the checklist. In total, 272 Capnodiales species are included in this checklist. The fungi recorded in this paper are distributed in five families and 29 genera. Most of the fungi species are belong to family Mycosphaerellaceae. According to this study, Capnodiales species are recorded in plant leaves, branches, fruits and decaying pod. Among them most of the capnodiales species are associated with plant leaves. This work will be used to estimate the diversity of Capnodiales species in Thailand.

Keywords: Acacia – Eucalyptus – Leaves – Mycosphaerellaceae – Plant Pathogens

 

16. New record of Nyssopsora thwaitesii on Schefflera leucantha and its colonization

Authors: Phetruang W, Haituk S, Kankavee P, Cheewangkoon R

Recieved: 29 July 2019, Accepted: 29 August 2019, Published: 02 September 2019

A pathogenic rust was found on Schefflera leucantha during a routine survey conducted in Chiang Mai province, Thailand in November – December 2018. Morphological studies based on compound and scanning electron microscopy revealed the pathogen to be a new geographical and host record of Nyssopsora thwaitesii on Schefflera leucantha from Thailand. In addition, the development of rust pustule and the colonization of mycelia of Nyssopsora thwaitesii are provided.

Keywords: Pucciniales – Raveneliaceae – Rust – Thailand

 

17. Heterotruncatella spartii causal agent of dieback disease on Pinus pinea in Tunisia

Authors: Hlaiem S, Zouaoui Boutiti M, Ben Jamaa ML

Recieved: 27 June 2019, Accepted: 18 September 2019, Published: 26 September 2019

Disease is a syndrome of complex origin due to dynamic interactions between the plant host and several abiotic and biotic causes. Fungal infections are the main cause of diseases in forest trees. Decline symptoms are visible at canopy, trunk and branch levels: Canopy transparency gradually increases; plants show necrosis and canker on twigs. Since 2012 symptoms of dieback were observed on Pinus pinea, located in the forest of “Henchir Kort” northeast of Tunisia in the region of Nabeul mixed with other species of shrubs. The causal agent obtained from symptomatic tissues was identified as Heterotruncatella spartii based on morphological features and genomic DNA sequences of the ITS region. The Koch’s postulates have been verified.

Keywords: Canker – Fungal infections – ITS region – Syndrome

 

18. Effect of resistance inducers on in vitro inhibition of mycelial growth and sporulation of Fusarium solani causing root rot of fenugreek

Authors: Ramteke PK

Recieved: 10 August 2019, Accepted: 14 November 2019, Published: 20 November 2019

Fenugreek is a leafy vegetable plant known for its medicinal, pharmaceutical and nutraceutical properties. The root rot of fenugreek is more severe in recent years. Controlling this disease depends mainly on use of fungicides. The use of resistance inducers is an effective and non-fungicide alternative with antimicrobial properties and also induces resistance in plant. All isolates of Fusarium solani had potency to cause root rot disease but the isolate from Jaygaon locality was found highly virulent one and was selected for in vitro studies. The inhibitory effect of plant resistance inducers viz. chitosan (1-15 mg/ml), methyl jasmonate (1-20 mM) and salicylic acid (20-80 mM) on linear growth and sporulation of F. solani was evaluated by poisoned food technique. The obtained results showed that chitosan had significantly reduced linear growth and sporulation of F. solani with increase of concentrations when compared to control. The complete inhibition of both linear growth and sporulation was observed at 15 mg/ml and 10 mg/ml concentrations respectively. Methyl jasmonate (MeJa) had also significantly reduced linear growth in a concentration dependent manner. The highest fungal growth reduction (76.37 %) was observed with 20 mM concentration. It was interesting that MeJa had halted spore formation of fungus at10 mM concentration. The increasing concentrations (20, 40 and 60 mM) of salicylic acid (SA) were found to promote linear growth. However, 80 mM of SA had totally suppressed the growth of fungus. But, reduction of sporulation was found as SA concentrations increased over control. The results of current study showed the possibility of using resistance inducers to control Fusarium root rot of fenugreek.

Keywords: antifungal – chitosan-methyl jasmonate – salicylic acid – fenugreek – root rot

 

19. Metabolic profiling to discriminate the biochemical basis of Powdery Mildew resistance in Green Gram (Vigna radiata)

Authors: Soundhiriyan PV, Kamlakannan A, Paranitharan V Jeyakumar P, Latha TKS

Recieved: 19 September 2019, Accepted: 14 November 2019, Published: 26 November 2019

Knowledge of the complexity of mechanisms responsible for resistance to powdery mildew infection of green gram cultivar TARM-18, is necessary for strategies to be defined which will improve resistance in highly susceptible crop species. Metabolic profiles of resistant and susceptible cultivars were analysed by Gas Chromatography /EI-TOF-Mass Spectrometry. The metabolites were identified manually using AMDIS software integrated with NIST library 2014. Different metabolites elaborated under compatible and incompatible interactions have been tentatively identified as the top five spectral hits with the NIST-05 and GMD libraries, using retention times as reference. Out of 20 metabolites identified, found 6 metabolites viz., Hexadeconic acid, alanine, validane, dimethyl amino benzaldehyde, putrescine and methy ethyl trisulfide were up-regulated in resistant green gram genotypes upon pathogen inoculation and contributed for resistance.

Keywords: Erysiphe polygoni – GC-MS – Metabolomics – Susceptibility

 

20. The Genus Cronartium Revisited

Authors: Wijesinghe SN, McKenzie E, Wanasinghe DN, Boonmee S, Jayawardena RS

Recieved: 18 June 2019, Accepted: 13 November 2019, Published: 03 December 2019

Cronartium is a prominent rust pathogen (Pucciniales, Basidiomycota). The type species of the genus was Cronartium asclepiadeum, which is currently synonymized under C. pini. Cronartium species infect branches, cones and stems of Pinus species, which are economically and ecologically valued crops in many countries in North and Central America, Asia and Europe. Cronartium species show host specificity alternating between two unrelated hosts such as Pinus and Ribes species. In this macrocyclic, heteroecious lifecycle, the five different spore stages are produced. They are the causal agent of numerous blister rust diseases such as cone rust disease, gall rust disease and limb rust disease on pine forests worldwide. Mainly, Cronartium comptoniae causes sweet fern blister rust, C. ribicola causes white pine blister rust, C. comandrae causes comandra blister rust, C. pini (=Peridermium pini) causes resin-top disease, C. quercuum causes gall rust disease in pine-oaks, C. arizonicum causes limb rust disease and C. strobilinum and C. conigenum cause cone rust disease. All species of Endocronartium have been synonymized and transferred to Cronartium. The updated phylogenetic analysis for the genus Cronartium is performed based on ITS sequence data from GenBank. This study is focused on morphology, phylogeny, pathogenicity and mitigation methods as well as future directions for research on the genus Cronartium.

Keywords: Five spore stages – pathogens – rust diseases

 

21. First report of Pythium deliense causing root and crown rot on Catharanthus roseus in Thailand

Authors: Intaparn P, Noireung P, Maumoon R, McGovern RJ, Unartngam J, Tapingkae T, To-anun C

Recieved: 06 October 2019, Accepted: 24 December 2019, Published: 27 December 2019

Pythium sp. was isolated from the roots, crowns and rhizosphere soil of Catharanthus roseus (L.) G. Don. (common name; vinca) showing symptoms of root and crown rot disease in plantation areas in Chiang Mai Thailand. The pathogen was studied by morphological and molecular analysis based on internal transcribed spacer (ITS) sequence. The Pythium isolate was confirmed as Pythuim deliense. The pathogenicity of the isolate was tested by inoculating with an agar disc containing mycelium of the fungus on detached C. roseus leaves compared with an agar disc alone as the control. It was found that P. deliense infected the vinca leaves causing a brown rot. Moreover, P. delicense infected and caused rot symptoms on plant crowns 5 d after inoculation with a mycelial suspension. This is the first report of P. deliense as pathogenic to C. roseus in Thailand.

Keywords: Pythiaceae – Phylogeny – Soil betting –Vinca