scholarly journals An Emerging Strawberry Fungal Disease Associated with Root Rot, Crown Rot and Leaf Spot Caused by Neopestalotiopsis rosae in Mexico

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2054-2059 ◽  
Author(s):  
Angel Rebollar-Alviter ◽  
Hilda Victoria Silva-Rojas ◽  
Dionicio Fuentes-Aragón ◽  
Uriel Acosta-González ◽  
Merari Martínez-Ruiz ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Root Rot ◽  
Phylogenetic Reconstruction ◽  
Elongation Factor ◽  
Fungal Disease ◽  
Crown Rot ◽  
Internal Transcribed Spacer Region ◽  
Pathogenicity Tests ◽  
Vitro Effect

In the 2017 strawberry season, several transplant losses reaching 50% were observed in Zamora, Michoacán Valley, Mexico, due to a new fungal disease associated with root rot, crown rot, and leaf spot. In this year the disease appeared consistently and increased in the following seasons, becoming a concern among strawberry growers. Thus, the aim of this research was to determine the etiology of the disease and to determine the in vitro effect of fungicides on mycelial growth of the pathogen. Fungal isolates were obtained from symptomatic strawberry plants of the cultivars ‘Albion’ and ‘Festival’ and were processed to obtain monoconidial isolates. Detailed morphological analysis was conducted. Concatenated phylogenetic reconstruction was conducted by amplifying and sequencing the translation elongation factor 1 α, β-tubulin partial gene, and the internal transcribed spacer region of rDNA. Pathogenicity tests involving inoculation of leaves and crowns reproduced the same symptoms as those observed in the field, fulfilling Koch’s postulates. Morphology and phylogenetic reconstruction indicated that the causal agent of the described symptoms was Neopestalotiopsis rosae, marking the first report anywhere in the world of this species infecting strawberry. N. rosae was sensitive to cyprodinil + fludioxonil, captan, iprodione, difenoconazole, and prochloraz.

scholarly journals Pathogenicity and Mefenoxam Sensitivity of Pythium, Globisporangium, and Fusarium Isolates From Coconut Coir and Rockwool in Marijuana (Cannabis sativa L.) Production

2021 ◽  
Vol 3 ◽  
Author(s):  
Cora S. McGehee ◽  
Rosa E. Raudales
Keyword(s):  
Root Rot ◽  
Cannabis Sativa ◽  
Disease Incidence ◽  
Elongation Factor ◽  
Pythium Myriotylum ◽  
Internal Transcribed Spacer Region ◽  
Pythium Irregulare ◽  
Coconut Coir

Oomycetes and fungi were recovered from coconut coir and rockwool substrates where marijuana (Cannabis sativa L. cv. Silver and Citron) plants with root rot and wilt symptoms were grown in a commercial growing facility in Connecticut. The objectives of this study were to identify the isolates collected from these substrates, determine the pathogenicity of the isolates on hemp seedlings in vitro and in vivo, and evaluate the pathogens' sensitivity to mefenoxam. Pythium and Globisporangium isolates were identified by sequencing the mitochondrially-encoded cytochrome oxidase genes (COI and COII) and Fusarium sp. with the translation elongation factor (EF-1α) region and internal transcribed spacer region (ITS4 and ITS5) genes. Three isolates were identified as Globisporangium irregulare (formerly Pythium irregulare), 21 isolates were Pythium myriotylum, and one was Fusarium oxysporum. All the isolates tested were pathogenic to hemp plants in vitro and in vivo, with disease incidence between 6.7 and 100%. Inoculated plants were smaller by 32% or more compared with the non-inoculated control. On average, hemp plants infected with Pythium myriotylum produced the lowest biomass and relative greenness values. None of the Pythium and Globisporangium isolates were resistant to mefenoxam—all were sensitive to ≥5 μg·mL−1 mefenoxam. This is the first report of G. irregulare causing root rot on marijuana and hemp plants. The results of this study provide information about the characteristics of pathogens that can be found potentially in soilless substrates in controlled environment agriculture.

scholarly journals Biological control of strawberry crown rot, root rot and grey mould by the beneficial fungus Aureobasidium pullulans

BioControl ◽  
2021 ◽  
Author(s):  
Mudassir Iqbal ◽  
Maha Jamshaid ◽  
Muhammad Awais Zahid ◽  
Erik Andreasson ◽  
Ramesh R. Vetukuri ◽  
...  
Keyword(s):  
Root Rot ◽  
Fungal Pathogens ◽  
Aureobasidium Pullulans ◽  
Grey Mould ◽  
Lesion Size ◽  
Plant Diseases ◽  
Crown Rot ◽  
Whole Plants

AbstractUtilization of biocontrol agents is a sustainable approach to reduce plant diseases caused by fungal pathogens. In the present study, we tested the effect of the candidate biocontrol fungus Aureobasidium pullulans (De Bary) G. Armaud on strawberry under in vitro and in vivo conditions to control crown rot, root rot and grey mould caused by Phytophthora cactorum (Lebert and Cohn) and Botrytis cinerea Pers, respectively. A dual plate confrontation assay showed that mycelial growth of P. cactorum and B. cinerea was reduced by 33–48% when challenged by A. pullulans as compared with control treatments. Likewise, detached leaf and fruit assays showed that A. pullulans significantly reduced necrotic lesion size on leaves and disease severity on fruits caused by P. cactorum and B. cinerea. In addition, greenhouse experiments with whole plants revealed enhanced biocontrol efficacy against root rot and grey mould when treated with A. pullulans either in combination with the pathogen or pre-treated with A. pullulans followed by inoculation of the pathogens. Our results demonstrate that A. pullulans is an effective biocontrol agent to control strawberry diseases caused by fungal pathogens and can be an effective alternative to chemical-based fungicides.

The occurrence of root-infecting fungi and parasitic nematodes in annual Medicago spp. in Western Australian pastures

2000 ◽  
Vol 51 (4) ◽  
pp. 435 ◽  
Author(s):  
M. P. You ◽  
K. Sivasithamparam ◽  
I. T. Riley ◽  
M. J. Barbetti
Keyword(s):  
Western Australia ◽  
Root Rot ◽  
Pathogenic Fungi ◽  
Parasitic Nematodes ◽  
Fungal Isolates ◽  
As Species ◽  
Significant Damage ◽  
Pathogenicity Tests ◽  
Annual Medicago

Asurvey of 30 medic pastures for root-rots was undertaken in Western Australia and pathogenicity tests of representative fungal isolates from roots sampled were conducted to determine the main factors contributing to medic decline and the association between those factors. In particular, the contribution of pathogenic fungi and nematodes to medic root-rot in Western Australia was studied. From a total of 30 000 pieces of root plated, 3836 fungal isolates were obtained and identified at least to genus level. Four hundred and seventy-two representative isolates were tested for in vitro pathogenicity in Medicago sphaerocarpos cv. Orion. Of these, 32 were further tested in the glasshouse. The pathogenicity tests indicated that 56% of isolates were capable of causing significant damage to the root system and it is likely that pathogenic fungi are largely responsible for medic root-rot in the field. In contrast, the number of Pratylenchus spp. in the roots was not found to relate to disease symptoms. It is concluded that soil-borne pathogenic fungi such as species of Pythium, Fusarium, and Phoma contribute significantly to medic pasture decline in Western Australia.

scholarly journals Characterization of Pyrenophora Species Causing Brown Leaf Spot on Italian Ryegrass (Lolium multiflorum) in Southwestern China

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 1900-1907
Author(s):  
Longhai Xue ◽  
Yong Liu ◽  
Su Zhou ◽  
James F. White ◽  
Chunjie Li
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Lolium Multiflorum ◽  
Morphological Characteristics ◽  
Italian Ryegrass ◽  
Large Area ◽  
Internal Transcribed Spacer Region ◽  
Brown Leaf Spot ◽  
Brown Leaf ◽  
Pathogenicity Tests

Drechslera leaf spot (DLS) caused by Pyrenophora (Drechslera) species is one of the most serious diseases affecting Italian ryegrass (Lolium multiflorum) in China. Between 2015 and 2018, this disease was observed in three Italian ryegrass fields in the province of Sichuan, China. Average leaf disease incidence was approximately 1 to 12% but could range up to 100%. Symptoms appeared as brown or tan spots surrounded by a yellow halo, or brown to dark brown net blotch; subsequently, spots increased in number and size, and they later covered a large area of leaf, eventually causing leaf death. In this study, 86 strains of Pyrenophora fungi were isolated from leaf lesions of Italian ryegrass. Coupled with phylogenetic analysis of the internal transcribed spacer region, partial 28S ribosomal RNA gene, and glyceraldehyde-3-phosphate dehydrogenase gene, morphological characteristics showed that Pyrenophora dictyoides and P. nobleae are associated with Italian ryegrass in southwest China. Pathogenicity tests confirmed that both species can infect Italian ryegrass, causing leaf spot, whereas the virulence of the two species differed; P. nobleae showed lower pathogenicity to Italian ryegrass. This is the first time that these two Pyrenophora species were formally reported on Italian ryegrass based on both morphological and molecular characters. Overall, this study improves knowledge of the Pyrenophora species associated with Italian ryegrass and provides a foundation for control of this disease in the future.

scholarly journals Characterization and fungicides sensitivity of Phytophthora cinnamomi isolates causing avocado root rot in Zitácuaro, Michoacán

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Alejandra Mondragón-Flores ◽  
Patricia Manosalva ◽  
Salvador Ochoa-Ascencio ◽  
Marlene Díaz-Celaya ◽  
Gerardo Rodríguez-Alvarado ◽  
...  
Keyword(s):  
Growth Rate ◽  
Mating Type ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Potassium Phosphite ◽  
Pathogenicity Tests

<em>Phytophthora cinnamomi</em> is the pathogen most frequently associated with avocado root rot. In Zitácuaro, Michoacán, production has increased by 19.8%; however, there are no studies of root rot in this area. The objective of the study was to characterize the isolates obtained from avocado roots and assess the sensitivity to fungicides. Samples from 5 avocado orchards were collected, sampling 5 trees per orchard (a total of 25 samples). The samples isolated were characterized morphological and molecularly. Mating type was analyzed using reference isolates of<em> P. cinnamomi</em> A1 (isolate from camelia) and A2 (isolate from avocado). To confirm the pathogenicity, tests were performed on avocado fruits with the isolates. The sensitivity of 15 isolates to potassium phosphite and to metalaxyl-M at different concentrations was evaluated<em> in vitro</em>. In a subgroup of six isolates, it was evaluated whether there was a relationship between growth rate and potassium phosphite sensitivity. Fifteen isolates were obtained with coenocytic coraloid mycelium, chlamydospores, sporangia without papilla, ovoid to ellipsoid, with internal proliferation, heterothallic with mating type A2, with amphigynous antheridia and plerotic oospores, characteristics consistent with <em>P. cinnamomi</em>. The inoculated isolates were pathogenic on avocado fruits. The isolates were more sensitive to potassium phosphite than to metalaxyl-M, with mean EC50 values of 24.62 and 0.215 ?g mL-1 of i.a., respectively. No relationship was observed between growth rate and potassium phosphite sensitivity. It is necessary to obtain a greater number of<em> P. cinnamomi</em> isolates for virulence studies.

scholarly journals Species of Botryosphaeriaceae associated with citrus branch diseases in China

2021 ◽  
Author(s):  
X.E. Xiao ◽  
W. Wang ◽  
P.W. Crous ◽  
H.K. Wang ◽  
C. Jiao ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Dna Sequences ◽  
Fungal Pathogens ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Botryosphaeria Dothidea ◽  
Internal Transcribed Spacer Region

Citrus is an important and widely cultivated fruit crop in South China. Although the species of fungal diseases of leaves and fruits have been extensively studied, the causal organisms of branch diseases remain poorly known in China. Species of Botryosphaeriaceae are known as important fungal pathogens causing branch diseases on citrus in the USA and Europe. To determine the diversity of Botryosphaeriaceae species associated with citrus branch diseases in China, surveys were conducted in the major citrus-producing areas from 2017 to 2020. Diseased tissues were collected from twigs, branches and trunks with a range of symptoms including cankers, cracking, dieback and gummosis. Based on morphological characteristics and phylogenetic comparison of the DNA sequences of the internal transcribed spacer region (ITS), the translation elongation factor 1-alpha gene (tef1), the β-tubulin gene (tub2) and the DNA-directed RNA polymerase II second largest subunit (rpb2), 111 isolates from nine provinces were identified as 18 species of Botryosphaeriaceae, including Botryosphaeria dothidea, B. fabicerciana, Diplodia seriata, Dothiorella alpina, Do. plurivora, Lasiodiplodia citricola, L. iraniensis, L. microconidia, L. pseudotheobromae, L. theobromae, Neodeightonia subglobosa, Neofusicoccum parvum, and six previously undescribed species, namely Do. citrimurcotticola, L. guilinensis, L. huangyanensis, L. linhaiensis, L. ponkanicola and Sphaeropsis linhaiensis spp. nov. Botryosphaeria dothidea (28.8 %) was the most abundant species, followed by L. pseudotheobromae (23.4 %), which was the most widely distributed species on citrus, occurring in six of the nine provinces sampled. Pathogenicity tests indicated that all 18 species of Botryosphaeriaceae obtained from diseased citrus tissues in this study were pathogenic to the tested Citrus reticulata shoots in vitro, while not all species are pathogenic to the tested Cocktail grapefruit (C. paradisi × C. reticulata) shoots in vivo. In addition, Lasiodiplodia was the most aggressive genus both in vitro and in vivo. This is the first study to identify Botryosphaeriaceae species related to citrus branch diseases in China and the results provide a theoretical basis for the implementation of prevention and control measures.

scholarly journals Neocosmospora spp. associated with dry root rot of citrus in South Africa

2021 ◽  
Vol 60 (1) ◽  
pp. 79-100
Author(s):  
Vladimiro GUARNACCIA ◽  
Jan VAN NIEKERK ◽  
Pedro CROUS ◽  
Marcelo SANDOVAL-DENIS
Keyword(s):  
South Africa ◽  
Rna Polymerase ◽  
Root Rot ◽  
Large Subunit ◽  
Elongation Factor ◽  
Common Disease ◽  
Atp Citrate Lyase ◽  
Internal Transcribed Spacer Region ◽  
Citrus Production ◽  
Citrus Trees

Citrus is one of the most important fruit crops cultivated in South Africa. Internationally, citrus dry root rot is a common disease in major citrus production areas. Several abiotic and biotic factors are involved in disease development, in which Neocosmospora species are important biotic agents. The diversity of Neocosmospora species associated with dry root rot symptoms of Citrus trees cultivated in South Africa was evaluated using morphological and molecular analyses. Multi-locus analysis was conducted, based on fragments of seven loci including: ATP citrate lyase (acl1), calmodulin (cal), internal transcribed spacer region of the rRNA (ITS), large subunit of the rRNA (LSU), RNA polymerase largest subunit (rpb1), RNA polymerase second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1). A total of 62 strains representing 11 Neocosmospora species were isolated from crowns, trunks and roots of citrus trees affected by dry root rot, as well as from soils sampled in affected citrus orchards. The most commonly isolated taxa were N. citricola, N. ferruginea and N. solani, while rarely encountered taxa included N. brevis, N. crassa, N. hypothenemi and N. noneumartii. Furthermore, four Neocosmospora species are also newly described, namely N. addoensis, N. citricola, N. gamtoosensis and N. lerouxii.

scholarly journals A Survey of Trunk Disease Pathogens within Citrus Trees in Iran

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 754
Author(s):  
Nahid Espargham ◽  
Hamid Mohammadi ◽  
David Gramaje
Keyword(s):  
Sequence Data ◽  
Fusarium Species ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Nuclear Ribosomal Dna ◽  
Internal Transcribed Spacer Region ◽  
Lasiodiplodia Theobromae ◽  
Dna Sequence Data ◽  
Pathogenicity Tests ◽  
Citrus Trees

Citrus trees with cankers and dieback symptoms were observed in Bushehr (Bushehr province, Iran). Isolations were made from diseased cankers and branches. Recovered fungal isolates were identified using cultural and morphological characteristics, as well as comparisons of DNA sequence data of the nuclear ribosomal DNA-internal transcribed spacer region, translation elongation factor 1α, β-tubulin, and actin gene regions. Dothiorella viticola, Lasiodiplodia theobromae, Neoscytalidium hyalinum, Phaeoacremonium (P.) parasiticum, P. italicum, P. iranianum, P. rubrigenum, P. minimum, P. croatiense, P. fraxinopensylvanicum, Phaeoacremonium sp., Cadophora luteo-olivacea, Biscogniauxia (B.) mediterranea, Colletotrichum gloeosporioides, C. boninense, Peyronellaea (Pa.) pinodella, Stilbocrea (S.) walteri, and several isolates of Phoma, Pestalotiopsis, and Fusarium species were obtained from diseased trees. The pathogenicity tests were conducted by artificial inoculation of excised shoots of healthy acid lime trees (Citrus aurantifolia) under controlled conditions. Lasiodiplodia theobromae was the most virulent and caused the longest lesions within 40 days of inoculation. According to literature reviews, this is the first report of L. theobromae and N. hyalinum on citrus in Iran. Additionally, we report several Phaeoacremonium species, S. walteri, Pa. pinodella and C. luteo-olivacea on citrus trees for the first time in the world.

Fusarium spp. associated with root rot of pulse crops and their cross pathogenicity to cereal crops in Montana

Plant Disease ◽  
2020 ◽  
Author(s):  
Swarnalatha Moparthi ◽  
Mary Eileen Burrows ◽  
Josephine Mgbechi-Ezeri ◽  
Bright Agindotan
Keyword(s):  
Root Rot ◽  
Fusarium Species ◽  
Elongation Factor ◽  
Abundant Species ◽  
Cereal Crops ◽  
Fusarium Spp ◽  
Internal Transcribed Spacer Region ◽  
Translation Elongation ◽  
Pulse Crops ◽  
Disease Management Strategy

Root rot caused by Fusarium species is a major problem in the pulse growing regions of Montana. Fusarium isolates (n=112) were obtained from seeds and/or roots of chickpea, dry pea, and lentil. Isolates were identified by comparing the sequences of the internal transcribed spacer region and the translation elongation factor 1-α in Fusarium-ID database. Fusarium avenaceum was the most abundant species (28%), followed by F. acuminatum (21%), F. poae (13%), F. oxysporum (8%), F. culmorum (6%), F. redolens (6%), F. sporotrichioides (6%), F. solani (4%), F. graminearum (2%), F. torulosum (2%) and F. tricinctum (0.9%). The aggressiveness of a subset of 50 isolates that represent various sources of isolation was tested on three pulse crops and two cereal crops. Nonparametric analysis of variance conducted on ranks of disease severity indicated that F. avenaceum and F. solani isolates were highly aggressive on pea and chickpea. In lentil, F. avenaceum and F. culmorum were highly aggressive. In barley, F. avenaceum, F. solani, F. culmorum, and F. graminearum were highly aggressive. In wheat, F. avenaceum, F. graminearum, and F. culmorum were highly aggressive. Two F. avenaceum isolates were highly aggressive across all the crops tested and found to be cross pathogenic. One isolate of F. culmorum and an isolate of F. graminearum obtained from chickpea and lentil seed were highly aggressive on barley and wheat. The results indicate that multiple Fusarium spp. from seeds and roots can cause root rot on both pulse and cereal crops. Rotating these crops may still lead to an increase in inoculum levels, making crop rotation limited in efficacy as a disease management strategy.

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