Erysiphe Cichoracearum DC Research Articles

Assessment of Okra Powdery Mildew (Erysiphe Cichoracearum DC) by Using Bio-agents and Chemical Fungicides

The present study aimed to assess okra powdery mildew (Erysiphe Cichoracearum DC) by using bio-agents and chemical fungicides. Okra (Abelmoschus esculentus (L.) Moench occupies a prominent place in the horticultural wealth and economy of the country. Powdery mildew disease on okra (Abelmoschus esculentus (L.) Moench incited by fungus, Erysiphe cichoracearum is a limiting factor in the successful cultivation in Bundelkhand region of Uttar Pradesh. Studies were carried out to find out disease management strategies against okra powdery mildew using bioagents and chemical fungicides. Disease incidence declined after first, second and third sprays. The fungicide Hexaconazole (Contaf 5% EC) @ 0.1%, showed significantly lowest disease incidence (19.53 %) with maximum (68.40 %) disease control. On the basis of effectiveness in controlling the powdery mildew disease of okra the most effective fungicides recorded in the order of merit were Carbendazim (Bavistin 50WP) @0.1%, Propiconazole (Tilt 25EC) @0.1%, Trichoderma viride (3 %), Sulphur (Sulfex 80% WP) @ 0.3%, Pseudomonas flouresens (4 %) and Trichoderma harizum (4 %).

Studies on Symptomatology, Morphological and Molecular Characterisiation of Erysiphe cichoracearum Causing Powdery Mildew of Okra

Okra (Abelmoschus esculentus (L.) Moench) is a globally important annual vegetable belongs to family malvaceae, it is most broadly distributed vegetable all over the world. Among the fungal diseases affecting okra crop, powdery mildew caused by Erysiphe cichoracearum DC. is the most important disease causing considerable yield losses. The disease was characterized by the appearance of small white powdery specks on upper surface of the lower leaves which enlarged and coalesced forming bigger patches. Later on the disease spread to the upper leaves, coalescing of the white powdery specks and enlargement in their size ultimately resulted in complete coating of white fungal mass on the leaves. The morphological studies of the pathogen in the laboratory revealed, that the mycelium is septate, ectophytic, hyaline and adjacent to the mycelium, basal septum of the conidiophores was seen. The conidiophores were erect, on which conidia were produced either singly or in short chains. The conidia were found cylindrical or barrel in shape, hyaline, non-septate and measured 75.23 µm x 40.65 µm. Molecular characterisation of the native isolate resulted in the DNA amplicon at the region 531 bp. Further, DNA sequence was obtained for ITS Rdna and was deposited in NCBI gene bank. Accession number ‘MW774352’ was obtained and it was confirmed that the causal pathogen of okra powdery mildew of Raichur region is Erysiphe cichoracearum.

Screening of Okra Genotypes against Powdery Mildew under Natural Epiphytotic Conditions

Okra (Abelmoschus esculentus (L.) Moench) is a globally crucialannual vegetable belonging to family malvaceae, it is the most broadly distributed vegetable all over the world. Among the fungal diseases affecting okra crops, powdery mildew caused by Erysiphecichoracearum DC. is the most crucial disease-causing considerable yield losses. Host plant resistance is one of the most practical, economical and feasible methods of management of plant diseases. An attempt was made to identify sources of resistance which could be used in developing resistant variety to mitigate loss in farmer’s field.Fifty okra genotypes were screened for their response to powdery mildew under natural epiphytotic conditions during Rabi, 2020-21Results revealed that, out of fifty genotypes screened, none of them showed immune and resistant reactions to powdery mildew. However, one genotype i.e., EC329404 showed a moderately resistance reaction. Twenty genotypes showed a moderately susceptible reaction. While twenty-two genotypes showed susceptible reaction, and one genotype viz., IC42531 showed a highly susceptible reaction. The average ‘r’ value ranged from 0.070 to 0.123. The highest average ‘r-value (0.123) was observed in genotypes IC42524 and EC329405, with the least average ‘r’ value in genotype EC329415 (0.070). For yield, It was found that most of the genotypes screened were potential yielders and recorded good yield despite the pathogen attack. Thus these high-yielding genotypes can be utilised in back cross-breeding along with disease resistant parent (EC 329404) to obtain resistant variety with high-yielding potential.

Вміст біохімічних речовин у рослин Phlox paniculata L. в умовах Лісостепу України

Досліджено питання стійкості декоративних рослин Phlox paniculata L. до біотичного стресу. За результатами дослідження листків рослин 11 сортів Phlox paniculata з різним ступенем ураження збудником борошнистої роси (Erysiphe cichoracearum DC. f. phlogis Jacz.) визначено кількісний вміст біохімічних речовин (проліну, катехінів, флавонолів та антоціанів) в умовах Лісостепу України. Виявлено, що рослини, уражені збудником борошнистої роси, характеризувалися нижчим рівнем флавонолів (сорти 'Poliarnyi' – 0,268 мг/г, 'Mohuchii' – 0,354 мг/г), неуражені – вищим вмістом (сорти 'Mohuchii' – 0,729 мг/г та 'Fiosin' – 0,719 мг/г). Окрім цього, встановлено тенденцію до істотного збільшення вмісту катехінів у цілому на 8˗21 % в уражених борошнистою росою рослин, порівняно із неураженими. Відзначено певну закономірність щодо вмісту антоціанів: в уражених рослин він був на 18˗48 % вищим, ніж у неуражених. Зроблено висновок, що вторинні метаболіти є маркерами відповідної реакції та стійкості рослинного організму до стресу різного походження, оскільки під дією стресу, спричиненого збудником борошнистої роси, збільшується вміст флавонолів, катехінів та антоціанів. На відміну від інших показників, рівень проліну істотно не залежить від ступеня ураженості рослин Phlox paniculata збудником борошнистої роси, оскільки в цьому механізмі захисту рослин від стресу, спричиненого збудником борошнистої роси, діє інший механізм із залученням вторинних метаболітів.

Characterization of Ampelomyces and its Potentiality as an Effective Biocontrol Agent against Erysiphe cichoracearum DC Causing Powdery Mildew disease in Bhendi (Abelmoschus esculentus (L.)

Characterization of Ampelomyces and its Potentiality as an Effective Biocontrol Agent against Erysiphe cichoracearum DC Causing Powdery Mildew disease in Bhendi (Abelmoschus esculentus (L.)

Induction of Defense-Related Physiological and Antioxidant Enzyme Response against Powdery Mildew Disease in Okra (Abelmoschus esculentus L.) Plant by Using Chitosan and Potassium Salts

Foliar sprays of three plant resistance inducers, including chitosan (CH), potassium sorbate (PS) (C6H7kO2), and potassium bicarbonates (PB) (KHCO3), were used for resistance inducing against Erysiphe cichoracearum DC (powdery mildew) infecting okra plants. Experiments under green house and field conditions showed that, the powdery mildew disease severity was significantly reduced with all tested treatments of CH, PS, and PB in comparison with untreated control. CH at 0.5% and 0.75% (w/v) plus PS at 1.0% and 2.0% and/or PB at 2.0% or 3.0% recorded as the most effective treatments. Moreover, the highest values of vegetative studies and yield were observed with such treatments. CH and potassium salts treatments reflected many compounds of defense singles which leading to the activation power defense system in okra plant. The highest records of reduction in powdery mildew were accompanied with increasing in total phenolic, protein content and increased the activity of polyphenol oxidase, peroxidase, chitinase, and β-1,3-glucanase in okra plants. Meanwhile, single treatments of CH, PS, and PB at high concentration (0.75%, 2.0%, and/or 3.0%) caused considerable effects. Therefore, application of CH and potassium salts as natural and chemical inducers by foliar methods can be used to control of powdery mildew disease at early stages of growth and led to a maximum fruit yield in okra plants.

Fungicidal management of okra powdery mildew, caused by Erysiphe cichoracearum DC.

Fungicidal management of okra powdery mildew, caused by Erysiphe cichoracearum DC.

Management of sunflower powdery mildew caused by Erysiphe cichoracearum DC. with botanicals and natural products

Sunflower is reported to suffer heavy losses because of fungal, viral and bacterial diseases and one of the prominent diseases among them is powdery mildew caused by E. cichoracearum. Recently Powdery mildew is most important limiting factors for production of sunflower in Karnataka. Management of powdery mildew in sunflower was studied in both in vitro and in vivo conditions. Azadirachtin, NSKE, Turmeric (leaf extract), Lantana camara (leaf extract) and Ipomoea carnea (leaf extract) were effective in inhibiting spore germination of pathogen both under in vitro condition at 5 per cent concentration. Similar trend was observed in field condition also with Azadirachtin and NSKE at 5 per cent concentration with least disease incidence of 25.78 and 27.56 per cent disease index, respectively in contrast to 83.33 per cent disease index in control.

Preventative and Curative Effects of Several Plant Derived Agents Against Powdery Mildew Disease of Okra

The preventative and curative effects of some plant derived agents based on plant extracts or essential oils were studied at different concentrations against Erysiphe cichoracearum DC. ex Merat, the causal pathogen of okra powdery mildew by the detached leaf-disk and potted plants bioassays. Through detached leaf-disk assay, the highest mean preventative effect (97.74%) was recorded by neem seed oil followed by jojoba oil (89.82%) and extract of Rynoutria sachalinensis (82.77%). Neem seed oil at 1% was the most effective agent followed by jojoba oil and extract of R. sachalinensis at 1.5% and 2%, respectively, where they suppressed E. cichoracearum completely. Potted plants assay revealed that neem seed oil, jojoba oil and extract of R. sachalinensis as well as the fungicide (active ingredient dinocap) showed higher preventative efficacy at all leaf olds treated after 7 and 14 days of inoculation as compared with extracts of henna and garlic. Moreover, the preventative efficacy partly remained apparent after 14 days of inoculation at all leaf olds tested. In field trials through 2010 and 2011 growing seasons, when the first symptoms of powdery mildew appeared naturally, 1.5% jojoba oil, 2% extract of R. sachalinensis and 1% neem seed oil were sprayed individually twice on grown plants to evaluate their efficacy on controlling powdery mildew, growth and yield of okra. Resulted showed that neem seed oil was the most effective agent and highly decreased the disease severity to 29.92%, recorded the highly curative effect (68.15%) and also improved plant growth and pods yield.

Resistance to Powdery Mildew (Erysiphe cichoracearum DC.) in Oriental and Semi-Oriental Tobacco Germplasm under Field Conditions

Powdery mildew (Erysiphe cichoracearum DC.) is an important disease of tobacco (Nicotiana tabacum L.) in many countries. Losses in yield and quality have been reported to be around 30% to 80% in severe cases. Northwestern Iran is a hotspot for tobacco powdery mildew. To identify resistant genotypes, tobacco germplasm, including recombinant inbred lines (RILs) derived from the cross Basma S.31 × Dubec566, some Iranian landraces, and cultivars from different countries were evaluated under field conditions using a simple lattice design (10×10) with two replications. Each plot comprised 3 rows, 5 meters long. Spacing between rows was 65 cm and between plants within rows 20 cm. Susceptible line (Basma S.31) was planted throughout the experiment to guarantee homogeneous inoculation. The most resistant genotypes were 12 RILs (PD205, PD209, PD379, PD324, PD328, PD329, PD336, PD345, PD364, PD365, PD371, and PD381), three Iranian landraces (SPT413, Jahrom15, and Jahrom12), and cultivars (Basma104-1 and Pobeda1). Three cultivars (Kuklen6, Nevrokop261, and L17), two mutants (Mutant 2 and Mutant 3), and Matianus were included in the resistant group. The more resistant RILs (PD205 and PD209) were evaluated across three years and showed consistent behavior across years. Most genotypes studied were susceptible or highly susceptible to the disease. This information should be helpful in tobacco breeding programs.

INDUCED RESISTANCE IN BHENDI AGAINST POWDERY MILDEW BY FOLIAR APPLICATION OF SALICYLIC ACID

ABSTRACT The effect of salicylic acid in inducing systemic resistance in bhendi against powdery mildew caused by Erysiphe cichoracearum DC was investigated by the application of salicylic acid (1mM) to induce production of defense related enzymes and chemicals in plants when it was applied as pre-inoculation, post-inoculation, salicylic acid alone, pathogen alone and water control. The results revealed that earlier and increased activities of phenyl alanine ammonia lyase, was observed in salicylic acid pretreated bhendi plants challenge inoculated with E.cichoracearum. Higher accumulation of phenolics was also noticed in plants pretreated with salicylic acid and able to enhance the resistance against invasion of E. cichoracearum in bhendi.

INFLUENCE OF ANTAGONISTIC AGENT, PLANT PRODUCTS AND CHEMICAL AGENTS ON THE POWDERY MILDEW DISEASE OF BHENDI AND ITS PRODUCTION

Field investigations were made to study the influence of integrated disease management involving plant products and biological control agents of powdery mildew of Bhendi (Erysiphe cichoracearum DC) with ten treatments viz.,Pseudomonas fluorescens I18 (0.2%), P.fluorescens 1(0.2%), Ocimum sanctum 10%, Neem Seed Kernel Extract 5%, K2 HPO4 50 mM, Salicylic acid 1mM, O. sanctum 5% + P. fluorescens I18 (0.2%),Neem Seed Kernel Extract 5 % + P.fluorescens I18 (0.2%), Carbendazim 0.1% and Control. Two sprays were given; first one on 30 days after sowing and the second one on 60 days after sowing. Powdery mildew disease severity was recorded at weekly interval after the second spray on randomly selected plants based on 0-5 grade scale and PDI was calculated. At the end of the season, yield was recorded in each plot. The minimum disease incidence of 8.83% was recorded with Neem Seed Kernel Extract 5%+ Pseudomonas fluorescens I18 0.2% followed by 9.49% with Pseudomonas fluorescens I18 0.2%,10.36% with carbendazim and 11.9% with Pseudomonas fluorescens -1.The yield was also increased to the tune of 43.43% over control in NSKE 5%+Pseudomonas fluorescens I18 followed by 42.44% in Pseudomonas fluorescens I18 ,41.84% with 0.1% carbendazim and 39.73% with Pseudomonas fluorescens -1.

Screening cultivated okra, related species and their interspecific hybrid derivatives for resistance to powdery mildew (Erysiphe cichoracearum DC)

Screening cultivated okra, related species and their interspecific hybrid derivatives for resistance to powdery mildew (Erysiphe cichoracearum DC)

Outbreak of Powdery Mildew on Common Sage in Argentina.

Common sage, Salvia officinalis L., is produced primarily in greenhouses for the culinary herb market in Argentina. Since 2003 during autumn and winter, powdery mildew symptoms have been repeatedly observed on potted common sage plants in commercial greenhouses located on the outskirts of Buenos Aires. The average disease incidence during this period was 85 to 90%. Circular, white, powdery patches developed on leaf surfaces and stems. Heavily infected leaves turned brown and died. Hyaline mycelium and nonlobed appressoria were observed. Conidiophores were simple with straight foot cells measuring 53.0 to 80.0 × 10.0 to 12.3 μm. Conidia were aseptate, hyaline, cylindrical to ovoid, measured 33.0 to 40.5 × 15.0 to 18.5 μm, did not contain fibrosine bodies, and were produced in chains. Cleistothecia were not observed. The pathogen was identified as Erysiphe cichoracearum DC (1). Pathogenicity was confirmed by gently pressing leaves displaying abundant sporulation onto the adaxial surface of healthy leaves. After 10 to 12 days, typical signs and symptoms of powdery mildew appeared on all inoculated plants. Pathogenicity tests were conducted in a greenhouse at 20 to 23°C and included 10 sage plants (five inoculated and five noninoculated). The experiment was performed twice, each time with the same result. Control plants did not show any signs or symptoms. E. cichoracearum DC was previously reported in the United States on Salvia sp. (2).To our knowledge, this is the first report of an outbreak of powdery mildew caused by E. cichoracearun on potted common sage plants produced in greenhouses in Argentina.

Antisense expression of a ω-3 fatty acid desaturase gene in tobacco plants enhances susceptibility against pathogens

Membrane lipids in higher plants contain a high proportion of trienoic fatty acids. ω-3 Fatty acid desaturases act on membrane lipids to catalyze the formation of trienoic acids. We isolated a wound-inducible Arabidopsis plastid ω-3 fatty acid desaturase (fad7) gene, and generated transgenic tobacco plants constitutively expressing the antisense fad7 RNA. Selected transgenic lines showed significant reductions in the content of trienoic fatty acids compared with control plants. The transgenic lines showed enhanced susceptibility against Tobacco mosaic virus infection, where necrotic lesions with brown halos developed much earlier and were larger in the transgenic lines than in control plants. After Tobacco mosaic virus infection, expression and protein accumulations of the wound-inducible protein kinase WIPK, as well as defense-response gene expressions such as lipoxygenase (lox) and defensin (pdf1.2), were retarded in the transgenic lines compared with control plants. Increased susceptibility of the transgenic lines was also demonstrated by infections with Pseudomonas syringae pv. tabaci (van Hall) Ash et al., which caused wildfire disease, and with a powdery mildew fungus (Erysiphe cichoracearum DC). These findings support the concept that trienoic fatty acids are involved in plant defense signaling.Key words: ω-3 fatty acid desaturase, linolenic acid, Nicotiana tabacum 'Xanthi', Pseudomonas syringae pv. tabaci, powdery mildew fungus, Tobacco mosaic virus.

Influence of phytohormones on development of conidial inoculum of causative agents of the phlox and barley powdery mildew

We studied the role of phytohormones: zeatin, kinetin, and abscisic acid, in the regulation of development of the conidial inoculum of Erysiphe cichoracearum DC. f. phlogis Jacz. and E. graminis DC. f. hordei Marchal. When the pathogen conidia were in direct contact with phytohormones, the intensity of their germination significantly increased. In the presence of cytokinins, the amount of normal appressoria decreased and that of abnormal growth tubes increased. On the phlox leaves treated with cytokinins, the intensity of germination of the conidia increased, as compared to the control, while abscisic acid exerted the opposite effect. The treatment of barley leaves with cytokinins did not affect markedly the development of conidial inoculum, as compared to the control, while abscisic acid significantly decreased the intensity of germination of the conidia. On the leaves of different Phlox species, the degree of germination of the conidial negative correlated with their resistance against the powdery mildew. The role of cytokinins in pathogenesis of biotrophic fungi is discussed.

Evaluation of Disease Resistance among 57 Cultivars of Zinnia

Fifty-seven cultivars of zinnia (Zinnia elegans Jacq.) were studied for 17 weeks to determine their resistance to alternaria blight (Alternaria zinniae Pape), powdery mildew (Erysiphe cichoracearum DC ex Merat) and bacterial leaf & flower spot [Xanthomonas campestris pv. zinniae (syn. X. nigromaculans f. sp. zinniae Hopkins & Dowson)]. A disease severity scale was used to determine acceptability for landscape use. At week 4, all cultivars were acceptable. At week 10, eleven cultivars were acceptable. At week 17, all cultivars were unacceptable. Ten cultivars had been killed by one or more pathogens by week 17. Only two cultivars showed any tolerance to any disease (powdery mildew) at week 17.

First Report of Powdery Mildew on Heath Aster Caused by Erysiphe cichoracearum in Argentina.

In 1995, powdery mildew was observed on commercial greenhousegrown Aster ericoides L. from La Plata, Buenos Aires Province. The disease affected about 95% of the growers. Mildew first appeared as white circular patches on the adaxial surface of leaves. As disease progressed, the abaxial surface of leaves, petioles, stems, and calyces were covered by cottony masses of mycelium and conidia, and basal leaves later wilted and died. Young plants (4 to 5 leaves) through flowering plants were affected. Conidia were ovoid-cylindrical, often slightly constricted at the ends, and were produced in chains on unbranched conidiophores. Conidia lacked fibrosin bodies and ranged from 30 to 41 μm × 10 to 19 μm. Long unbranched germ tubes were formed from the ends of conidia. The morphological characteristics of the fungus fit those described for Erysiphe cichoracearum DC (1). In addition, the perfect stage was found on older tissues. Subglobose, dark brown cleistothecia (105 to 210 μm in diameter) with a basal ring of myceloid appendages were observed. Cleistothecia contained multiple ellipsoid asci (48 to 69 μm × 30 to 37 μm) with two hyaline, one-celled, ellipsoid ascospores (22 to 26 μm × 11 to 15 μm). Pathogenicity was tested by pressing diseased leaves onto healthy leaves of aster cv. Sunset and incubating plants in humidity chambers for 48 h. The powdery mildew that developed was morphologically identical to the original isolate. This is the first report of E. cichoracearum on heath aster in Argentina. Reference: (1) H. J. Boesewinkel. Bot. Rev. 46:167, 1980.

First Report of Powdery Mildew, Caused by Erysiphe cichoracearum, on Coneflowers.

Purple coneflowers (Echinacea purpurea) are grown in North America and Europe for their medicinal properties and as ornamental plants. In September 1997 and again in 1998, a previously undescribed disease was noticed on fully grown coneflower plants in Summerland and Oliver, British Columbia. Mycelia were observed on stems, foliage, and flowers, and distinct dark red to black, round (approximately 5 mm in diameter) lesions were observed on the flower petals. The disease appeared similar to powdery mildews that have been reported on numerous genera of the Asteraceae. Samples of the diseased tissue were examined and the salient features of the fungus on two specimens were determined: cleistothecia infrequent, subglobose or flattened on the side next to the leaf surface, 121 to 209 μm in diameter; epidermal (surface) cells 20 μm in diameter; appendages hyphoid, 5 μm in diameter, up to 200 μm long; asci, 10 to 19 in each cleistothecium, broadly ellipsoid, 47 to 85 × 28 to 37 μm with a short stalk, about 8 to 13 μm long and 8 μm in diameter; ascospores, immature, two per ascus, ellipsoid to broadly ellipsoid, 17 to 25 × 11 to 13 μm, thin walled, hyaline, and smooth; conidia oblong with sides slightly convex and apices truncate, 27 to 40 × 14 to 20 μm, walls hyaline, thin, smooth. Based on the occurrence of asci that contained two ascospores and the hyphoid appendages on the cleistothecia we concluded that the fungus was Erysiphe cichoracearum DC. Damage due to this disease was minimal in 1997 and 1998 because it developed very late in the growing season and occurred sporadically within the plantings. In order to complete Koch's postulates, Echinacea purpurea plants grown in the greenhouse were inoculated with a conidial suspension (105 to 106 conidia per ml) from field-infected plants. Powdery mildew first appeared 3 months later, eventually infecting leaves and stems of 12 of 49 inoculated plants. It was distinctly white and in discrete patches on leaves, compared with coalescing dark brown areas on the stems. Microscopic examination of the conidia confirmed that they were E. cichoracearum. Although powdery mildew caused by E. cichoracearum has been widely reported on lettuce, safflower, and other cultivated and wild Compositae, we found no reference to it on Echinacea spp. in Canada (1,2), the U.S. (3), or elsewhere in the world (4). The specimens have been deposited in the National Mycological Herbarium of Canada (DAOM) with accession numbers 225933 and 225934 for Oliver and Summerland, B.C., respectively.

First Report of Erysiphe cichoracearum Infecting Hedera canariensis var. azorica in Italy.

A powdery mildew disease of variegated ivy (Hedera canariensis L. var. azorica) was observed on the Tyrrhenian coast in Tuscany (Italy) in spring 1998. Symptoms began as small, nearly circular reddish spots that later enlarged and coalesced. The hyaline mycelium produced abundant, ellipsoid conidia in long chains that ranged from 20 to 40 μm in length and from 12 to 25 μm in width. Cleistothecia were globose (100 to 120 μm diameter), dark brown (when mature) with a basal ring of mycelioid appendages, and contained several (up to 20) ovate asci, each generally containing two ascospores. Ascospores were hyaline, one-celled, ellipsoid (20 to 35 μm in length and 10 to 20 μm in width). The morphological characteristics of this fungus were those given for Erysiphe cichoracearum DC. Infection also was found on English ivy (Hedera helix L.). It is reported that this species is, occasionally, subject to powdery mildew caused by E. cichoracearum (1). Conidia from infected leaves were shaken onto leaves of melon (Cucumis melo L.), cucumber (Cucumis sativus L.), watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai), lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.) and variegated and English ivy. After 7 days, the disease was observed on cucumber, melon, watermelon, tobacco, and variegated ivy. Examination confirmed that test plants were infected with E. cichoracearum. This is the first report of E. cichoracearum on variegated ivy in Italy. Reference: (1) P. P. Pirone. 1970. Diseases and Pests of Ornamental Plants. The Ronald Press, New York.