scholarly journals Rice Blast in Puerto Rico

1969 ◽  
Vol 62 (3) ◽  
pp. 290-300
Author(s):  
Lii-Jang Liu
Keyword(s):  
Puerto Rico ◽  
Rice Straw ◽  
Rice Blast ◽  
Mycelial Growth ◽  
Potato Dextrose Agar ◽  
Pyricularia Oryzae ◽  
In Vitro Tests ◽  
Optimum Temperature ◽  
Pathogenicity Tests

Rice blast, which had not been observed during the last six decades in Puerto Rico, reappeared recently in Manatí and in the Gurabo Substation, affecting Brazos, a cultivar introduced from Texas. Pathogenicity tests, as well as studies on the conidial morphology, showed that the fungus isolated from typical blast lesions is Pyricularia oryzae Cav. The physiology of the fungus and its sporulation on various media also were studied. The optimum temperature range, both for mycelial growth and for germination of conidia, was found to be between 24 to 28° C. Sporulation occurred satisfactorily on potato-dextrose agar enriched with coconut milk, and on steamed corn and barley, and rice-straw-decoction agars. In vitro tests with fungicides benomyl, pentachloronitrobenzene, mancozeb, chloroneb, and captan indicated that the first two compounds are the most effective in inhibiting mycelial growth of P. oryzae.

In vitro evaluation of bio-agents against Pyricularia oryzae (Cav.) causing rice blast disease

2017 ◽  
Vol 37 (03) ◽  
Author(s):  
Akhilesh Kumar Kulmitra ◽  
Neha Sahu ◽  
V.B. Sanath Kumar ◽  
Thejesha A. G. ◽  
Amlan Ghosh ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Fluorescens ◽  
Rice Blast ◽  
Mycelial Growth ◽  
Trichoderma Viride ◽  
Culture Technique ◽  
Pyricularia Oryzae ◽  
Blast Disease ◽  
Dual Culture

The five different bio-agents viz., Trichoderma viride, T. harzianum, T. virens, Pseudomonas fluorescens and Bacillus subtilis were evaluated against Pyricularia oryzae at four and eight days after incubation through dual culture technique. Among the five different bio-agents, highest per cent inhibition of mycelial growth of fungus was recorded in T. virens i.e. 67 per cent and 70 percent after four and eight days after incubation respectively with mean of 68.5 per cent followed by Trichoderma viride with the inhibition of 61 and 63 per cent respectively with mean of 62 per cent. The Pseudomonas fluorescens did not show any inhibition of mycelial growth of P. oryzae as the pathogen over grew the bio-agents.

scholarly journals Fungi pathogenic to the corm of arracacha (Arracada xanthorrhiza) in Puerto Rico

1969 ◽  
Vol 84 (1-2) ◽  
pp. 53-64
Author(s):  
Evelyn Rosa-Márquez ◽  
Lydia I. Rivera ◽  
Carlos E. Ortiz ◽  
Arcángel Rodríguez
Keyword(s):  
Puerto Rico ◽  
Phytophthora Palmivora ◽  
In Vitro Tests ◽  
Fusarium Spp ◽  
Thiophanate Methyl ◽  
Pathogenicity Tests

Phytophthora palmivora, Rhizoctonia sp. and two isolates of Fusarium spp. were identified and associated with the arracacha (Arracada xanthorrhiza) corm rot in pathogenicity tests conducted in vitro and in vivo. In vitro tests revealed that these fungi were pathogenic to the corm. Fungi caused lesions to the corm under greenhouse conditions. Three major symptoms were observed: necrotized roots; necrotized roots with a dry, brown, hard injury to the internal corm tissue; and wet lesions with brown shades. The highest incidence of affected corms occurred with P. palmivora in combination with Rhizoctonia sp., and the lowest was observed in corms inoculated with Rhizoctonia sp. alone. The most severe symptoms were caused by P. palmivora alone and in combination with Rhizoctonia sp. In vitro tests were conducted to evaluate the efficacy of metalaxyl, etridiazofe thiophanate-methyl, and fosetyl-al against the isolated fungi at doses of 5 to 200 mg ai/kg. Among the fungicides tested, etridiazole thiophanate-methyl was effective against all fungi associated with corm rot. Micelial growth of P. palmivora was completely inhibited with metataxyl at all doses and by etridiazole thiophanate-methyl with doses of 20 or more mg ai/kg.

scholarly journals Neofusicoccum mediterraneum Is Involved in a Twig and Branch Dieback of Olive Trees Observed in Salento (Apulia, Italy)

Pathogens ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 53
Author(s):  
Angela Brunetti ◽  
Antonio Matere ◽  
Valentina Lumia ◽  
Vittorio Pasciuta ◽  
Valeria Fusco ◽  
...  
Keyword(s):  
Prolonged Exposure ◽  
Fungal Species ◽  
In Vitro Tests ◽  
Wood Discoloration ◽  
Olive Groves ◽  
Pathogenicity Tests ◽  
Olive Quick Decline Syndrome ◽  
Olive Trees ◽  
Branch Dieback

Olive trees are infected and damaged by Botryosphaeriaceae fungi in various countries. The botryosphaeriaceous fungus Neofusicoccum mediterraneum is highly aggressive and is a major concern for olive groves in Spain and California (USA), where it causes ‘branch and twig dieback’ characterized by wood discoloration, bark canker, and canopy blight. During surveys of olive groves in Apulia (southern Italy), we noticed that—in some areas—trees were heavily affected by severe branch and twig dieback. In addition, chlorosis and the appearance of red-bronze patches on the leaf preceded the wilting of the foliage, with necrotic leaves persisting on the twigs. Given the severity of the manifestation in zones also subject to olive quick decline syndrome (OQDS) caused by Xylella fastidiosa subsp. pauca, we investigated the etiology and provide indications for differentiating the symptoms from OQDS. Isolation from diseased wood samples revealed a mycete, which was morphologically and molecularly identified as N. mediterraneum. The pathogenicity tests clearly showed that this fungus is able to cause the natural symptoms. Therefore, also considering the low number of tested samples, N. mediterraneum is a potential causal agent of the observed disease. Specifically, inoculation of the twigs caused complete wilting in two to three weeks, while inoculation at the base of the stem caused severe girdling wedge-shaped cankers. The growth rate of the fungus in in vitro tests was progressively higher from 10 to 30 °C, failing to grow at higher temperatures, but keeping its viability even after prolonged exposure at 50 °C. The capacity of the isolate to produce catenulate chlamydospores, which is novel for the species, highlights the possibility of a new morphological strain within N. mediterraneum. Further investigations are ongoing to verify whether additional fungal species are involved in this symptomatology.

scholarly journals Acid Rain Increases Impact of Rice Blast on Crop Health via Inhibition of Resistance Enzymes

Plants ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 881
Author(s):  
Hong-Ru Li ◽  
Hui-Min Xiang ◽  
Jia-Wen Zhong ◽  
Xiao-Qiao Ren ◽  
Hui Wei ◽  
...  
Keyword(s):  
Acid Rain ◽  
Rice Blast ◽  
Crop Yields ◽  
Pyricularia Oryzae ◽  
Plant Pathogen Interaction ◽  
Rice Leaves ◽  
Decreasing Ph ◽  
Crop Health ◽  
Cultivation Experiment

Worldwide, rice blast (Pyricularia oryzae) causes more rice crop loss than other diseases. Acid rain has reduced crop yields globally for nearly a century. However, the effects of acid rain on rice-Pyricularia oryzae systems are still far from fully understood. In this study, we conducted a lab cultivation experiment of P. oryzae under a series of acidity conditions as well as a glasshouse cultivation experiment of rice that was inoculated with P. oryzae either before (P. + SAR) or after (SAR + P.) simulated acid rain (SAR) at pH 5.0, 4.0, 3.0 and 2.0. Our results showed that the growth and pathogenicity of P. oryzae was significantly inhibited with decreasing pH treatments in vitro culture. The SAR + P. treatment with a pH of 4.0 was associated with the highest inhibition of P. oryzae expansion. However, regardless of the inoculation time, higher-acidity rain treatments showed a decreased inhibition of P. oryzae via disease-resistance related enzymes and metabolites in rice leaves, thus increasing disease index. The combined effects of high acidity and fungal inoculation were more serious than that of either alone. This study provides novel insights into the effects of acid rain on the plant–pathogen interaction and may also serve as a guide for evaluating disease control and crop health in the context of acid rain.

scholarly journals Effect of Agrochemicals Used in the Cultivation of Soybean and Irrigated Rice on Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok

2019 ◽  
Vol 11 (17) ◽  
pp. 167
Author(s):  
Vanessa P. Gonçalves ◽  
Cândida R. J. de Farias ◽  
Victoria Moreira-Nunêz ◽  
Renata Moccellin ◽  
Viviana Gaviria-Hernández ◽  
...  
Keyword(s):  
Beauveria Bassiana ◽  
Entomopathogenic Fungi ◽  
Spore Germination ◽  
Metarhizium Anisopliae ◽  
Mycelial Growth ◽  
Potato Dextrose Agar ◽  
Irrigated Rice ◽  
Spray Method ◽  
Fungitoxic Effect

The objective of this work was to evaluate the fungitoxic effect of the agrochemicals used in the cultivation of soybean and irrigated rice on entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae by means of the mycelial growth, sporulation and spore germination. The isolates were inoculated in potato-dextrose-agar (PDA) medium containing the pesticides and exposed to spraying with the products. It was observed that chlorantraniliprole produced the best results regarding and was compatible with the two methods of contact of the product with the fungi. Flubendiamide it’s very toxic to fungi, producing 100% inhibition when incorporated into the medium, when by spraying, the fungus M. anisopliae got mycelial growth. Etofenprox and thiamethoxam changed their toxity classification according to the method of contact with product, was moderately compatible to B. bassiana and compatible to M. anisopliae and spinosad showed more compatibility with M. anisopliae than B. bassiana and was classified as compatible. Among fungicides the tricyclazole was the only compatible with the fungus by the spray method. The results showed that in vitro agrochemicals such as tricyclazole, thiamethoxam, flubendiamide and etofenprox are harmful to fungi. It was found that environmental interference could minimize the effects on organisms, especially when the chemicals are applied by spraying.

scholarly journals Variations In Different Isolates Of Rhizoctonia Solani Based On Temperature And pH

1970 ◽  
Vol 36 (3) ◽  
pp. 389-396 ◽  
Author(s):  
BK Goswami ◽  
MM Rahaman ◽  
AKMA Hoque ◽  
K Bhuiyan ◽  
IH Mian
Keyword(s):  
Growth Factors ◽  
Rhizoctonia Solani ◽  
Radial Growth ◽  
Mycelial Growth ◽  
Potato Dextrose Agar ◽  
Optimum Temperature ◽  
Optimum Ph ◽  
Sclerotial Formation ◽  
Rates Of Growth ◽  
Different Levels

An experiment was conducted to find out variation in isolated Rhizoctonia solani based on radial mycelial growth and sclerotial production. Five isolates of Rhizoctonia solani representing five clusters group were selected and were grown at different levels of temperature and pH on potato dextrose agar (PDA). It was observed that optimum temperature and pH for growth and scierotial production varied among the isolates. The rates of growth and sclerotial formation were not uniform at the same levels of the two growth factors. The maximum mycelial growth of all isolates was found at 30°C. At 35°C, only GAZ-9 and GAZ-18 showed initiation of growth, but the rate was very slow. The optimum temperature for sclerotial production of the isolates GAZ-9, JES- 16, GAZ-18 SYL-26 was 30°C and for the isolate DIN-8 was 25°C. The optimum pH for maximum radial growth was 6 for DIN-8 and 7 for other four isolates. The maximum number of sclerotia was produced by DIN-8, GAZ-9, and SYL-30 at pH 8, 4, and 7, respectively. The optimum pH for sclerotia formation in JES-16 and GAZ-18 was pH 6. Keywords: Rhizoctonia solani; variations; temperature; pH. DOI: http://dx.doi.org/10.3329/bjar.v36i3.9267 BJAR 2011; 36(3): 389-396

In vitro growth of some species of Ascochyta Lib.

2012 ◽  
Vol 7 (6) ◽  
pp. 1076-1083
Author(s):  
Tomasz Kosiada
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Mycelial Growth ◽  
Potato Dextrose Agar ◽  
In Vitro Growth ◽  
Light Conditions ◽  
Oatmeal Agar ◽  
The Family ◽  
Effects Of Temperature

AbstractFungi from the genus Ascochyta are generally facultative saprotrophs, which cause diseases in both monocots and dicots. Over 1 000 species belonging to this genus have been identified, 18 of which infect monocot plants from the family Poaceae. This study analyses the effects of temperature and light on the growth of selected fungi which infect monocots (A. agrostidis, A. avenae, A. brachypodii, A. desmazieri, A. digraphidis, A. ducis-aprutii, A. festucae, A. graminea, A. hordei, A. hordei var. americana, A. hordei var. europea, A. hordei var. hordei, A. melicae, A. phleina, A. skagwayensis, A. sorghi, A. stipae, A. zeicola), grown on three types of media; Potato Dextrose Agar (PDA), Coon’s agar (CN) and oatmeal agar (OMA). The fastest growth among the analyzed fungi at low temperatures was found in Ascochyta melicae, while at high temperatures it was A. zeicola. The fastest in vitro growth (average of all fungi) was observed on CN medium at 20°C (3.4 mm/day), while the lowest on OM medium at 5°C (1.0 mm/day). Radial mycelial growth in dark and the light conditions varied. On average, all isolates grew faster in the dark (3.1 mm/day) than in the light (1.9 mm/day). The greatest effect on the production of pycnidia was found for the isolates. Variation in growth and production of pycnidia depended on temperature, medium and lighting for fungi from the genus Ascochyta infecting monocots. Such variation indicates a potential occurrence of these fungi in different environments.

scholarly journals Diversity of Pestalotiopsis-Like Species Causing Gray Blight Disease of Tea Plants (Camellia sinensis) in China, Including two Novel Pestalotiopsis Species, and Analysis of Their Pathogenicity

Plant Disease ◽  
2019 ◽  
Vol 103 (10) ◽  
pp. 2548-2558 ◽  
Author(s):  
Yuchun Wang ◽  
Fei Xiong ◽  
Qinhua Lu ◽  
Xinyuan Hao ◽  
Mengxia Zheng ◽  
...  
Keyword(s):  
Geographical Distribution ◽  
Mycelial Growth ◽  
Elongation Factor ◽  
Tea Plant ◽  
Translation Elongation ◽  
Pathogenicity Tests ◽  
Tea Production ◽  
Tea Plants ◽  
Blight Disease

Several Pestalotiopsis-like species cause gray blight disease in tea plants, resulting in severe tea production losses. However, systematic and comprehensive research on the diversity, geographical distribution, and pathogenicity of pathogenic species associated with tea plants in China is limited. In this study, 168 Pestalotiopsis-like isolates were obtained from diseased tea plant leaves from 13 primary tea-producing provinces and cities in China. Based on a multilocus (internal transcribed spacer, translation elongation factor 1-α, and β-tubulin gene region) phylogenetic analysis coupled with an assessment of conidial characteristics, 20 Neopestalotiopsis unclassified isolates, seven Pestalotiopsis species, including two novel (Pestalotiopsis menhaiensis and Pestalotiopsis sichuanensis), four known (Pestalotiopsis camelliae, Pestalotiopsis chamaeropis, Pestalotiopsis kenyana, and Pestalotiopsis rhodomyrtus) and one indistinguishable species, and three Pseudopestalotiopsis species, including two known (Pseudopestalotiopsis camelliae-sinensis and Pseudopestalotiopsis chinensis) and one indistinguishable species, were identified. This study is the first to evaluate Pestalotiopsis chamaeropis on tea plants in China. The geographical distribution and pathogenicity tests showed Pseudopestalotiopsis camelliae-sinensis to be the dominant cause of gray blight of tea plants in China. In vitro antifungal assays demonstrated that theobromine not only derepressed mycelial growth of the 29 representative isolates but also increased their growth. Correlation analysis revealed a linear positive relationship between the mycelial growth rate and pathogenicity (P = 0.0148).

scholarly journals Corynespora Leaf Spot of Papaya (Carica papaya L.) in Puerto Rico

1969 ◽  
Vol 55 (4) ◽  
pp. 411-425
Author(s):  
Pedro Luis Meléndez ◽  
Julio Bird Piñero
Keyword(s):  
Puerto Rico ◽  
Puerto Rican ◽  
Carica Papaya ◽  
Corynespora Cassiicola ◽  
Optimum Temperature ◽  
Santa Cruz ◽  
Highly Pathogenic ◽  
Optimum Ph ◽  
Pathogenicity Tests ◽  
Main Station

The fungus Corynespora cassiicola (Berk. & Curt.) Wei, causal agent of "greasy spot" or "papaya decline" in St. Croix, was found invading papaya plants of both Solo and Puerto Rican varieties in the Gurabo and Isabela Substations and in the Solis field in the Main Station. Plants of both varieties in the field appeared severely affected by the fungus as evidenced by heavy spotting on the foliage and the stems and by premature defoliation of the trees. Pathogenicity tests conducted with three isolates of the fungus isolated from Gurabo (Gurabo isolate), from Isabela (Isabela isolate), and from diseased-papaya plants from St. Croix (Santa Cruz isolate), proved that it is highly pathogenic to both Solo and Puerto Rican papayas. Optimum temperature and optimum pH for growth of the fungus, as well as the best medium for growth and sporulation, were determined. Cultural characteristics, response to varying temperatures, morphology, and symptoms expressed by inoculated plants of both papaya varieties were similar for all three isolates studied.

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