In vivo anti-mildew activity of essential oils against downy mildew of sunflower caused by PLASMOPARA HALSTEDII

Two neem-derived pesticides were examined under in vitro and in vivo conditions to test their efficacy in controlling Plasmopara halstedii pathotype 704, a causal agent of downy mildew in sunflower. All the tested concentrations of neem leaf extract and the highest concentration of commercial neem product significantly reduced the sporangial germination under in vitro conditions. In in vivo experiment, 3-days old pre-treated seedlings with both concentrations of neem leaf extract and the highest concentration of commercial product showed a significant reduction in the infection indicating possible systemic effect of neem. When the seedlings were treated following the infection with P. halstedii (i.e., post-treatment), only the highest concentrations of neem leaf extract and the commercial product showed a significant reduction in the infection indicating curative effect of neem. Possibilities for the control of P. halstedii with neem-derived pesticides are discussed.

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Determination of anti-mildew activity of essential oils against downy mildew of sunflower caused by Plasmopara halstedii

Journal of Plant Diseases and Protection ◽

10.1007/s41348-020-00310-4 ◽

2020 ◽

Vol 127 (5) ◽

pp. 709-713

Author(s):

Yesim Er ◽

Nuray Özer ◽

Yakup Zekai Katırcıoğlu

Keyword(s):

Essential Oils ◽

Downy Mildew ◽

Plasmopara Halstedii

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Symptoms Development as Tools to Differentiate Dorizontal Resistance in Sunflower

Agrotek ◽

10.30862/agt.v2i6.529 ◽

2018 ◽

Vol 2 (6) ◽

Author(s):

Cipta Meliala ◽

Felicity Fear ◽

Denis Tourvieille de Labrouhe

Keyword(s):

Downy Mildew ◽

Natural Infection ◽

Resistance Mechanism ◽

Good Method ◽

Vegetative Stage ◽

Horizontal Resistance ◽

Symptom Development ◽

Plasmopara Halstedii ◽

Controlled Conditions ◽

Symptom Progression

Downy mildew symptoms caused by Plasmopara halstedii encountered in sunflower plantation are varied. This variation may be related to the resistance mechanism presented by plant to the invasion of the fungus. Our objectives were firstly is to evaluate symptom development after fungus race 710 inoculation on some vegetative stage of susceptible hybrid. Second objective is to evaluate the reaction some sunflower genotypes after fungus inoculation. The study was conducted under controlled conditions or under netting cages in the field. The development of downy mildew symptoms were affected by all factors studied. Shoot inoculation may present a good method to produce downy mildew symptom similar to the natural infection. Downy mildew symptom progression may be used to screen a genotype with a horizontal resistance.

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Evaluation of Seven Essential Oils as Seed Treatments against Seedborne Fungal Pathogens of Cucurbita maxima

Molecules ◽

10.3390/molecules26082354 ◽

2021 ◽

Vol 26 (8) ◽

pp. 2354

Author(s):

Marwa Moumni ◽

Mohamed Bechir Allagui ◽

Kaies Mezrioui ◽

Hajer Ben Amara ◽

Gianfranco Romanazzi

Keyword(s):

Essential Oil ◽

Essential Oils ◽

Fungal Pathogens ◽

Seedling Emergence ◽

Cucurbita Maxima ◽

Melaleuca Alternifolia ◽

Seedborne Pathogens ◽

Origanum Majorana ◽

Potential Use

Essential oils are gaining interest as environmentally friendly alternatives to synthetic fungicides for management of seedborne pathogens. Here, seven essential oils were initially tested in vivo for disinfection of squash seeds (Cucurbita maxima) naturally contaminated by Stagonosporopsis cucurbitacearum, Alternaria alternata, Fusarium fujikuro, Fusarium solani, Paramyrothecium roridum, Albifimbria verrucaria, Curvularia spicifera, and Rhizopus stolonifer. The seeds were treated with essential oils from Cymbopogon citratus, Lavandula dentata, Lavandula hybrida, Melaleuca alternifolia, Laurus nobilis, and Origanum majorana (#1 and #2). Incidence of S. cucurbitacearum was reduced, representing a range between 67.0% in L. nobilis to 84.4% in O. majorana #2. Treatments at 0.5 mg/mL essential oils did not affect seed germination, although radicles were shorter than controls, except with C. citratus and O. majorana #1 essential oils. Four days after seeding, seedling emergence was 20%, 30%, and 10% for control seeds and seeds treated with C. citratus essential oil (0.5 mg/mL) and fungicides (25 g/L difenoconazole plus 25 g/L fludioxonil). S. cucurbitacearum incidence was reduced by ~40% for plantlets from seeds treated with C. citratus essential oil. These data show the effectiveness of this essential oil to control the transmission of S. cucurbitacearum from seeds to plantlets, and thus define their potential use for seed decontamination in integrated pest management and organic agriculture.

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Updated Characterization of Races of Plasmopara halstedii and Entomopathogenic Fungi as Endophytes of Sunflower Plants in Axenic Culture

Agronomy ◽

10.3390/agronomy11020268 ◽

2021 ◽

Vol 11 (2) ◽

pp. 268

Author(s):

Pedro Miranda-Fuentes ◽

Ana B. García-Carneros ◽

Leire Molinero-Ruiz

Keyword(s):

Plant Growth ◽

Downy Mildew ◽

Entomopathogenic Fungi ◽

Genetic Resistance ◽

Axenic Culture ◽

Plasmopara Halstedii ◽

Successful Establishment ◽

Axenic Conditions ◽

Highly Virulent

The management of downy mildew (Plasmopara halstedii) in sunflower, is heavily dependent on genetic resistance, whilst entomopathogenic fungi (EF) can reduce other sunflower diseases. In this work, we characterized P. halstedii from Spain and other countries collected in the past few years. Twenty-three races were identified (the most frequent in Spain being 310, 304, 705 and 715), with an increasing proportion of highly virulent races. Five isolates from countries other than Spain overcame the resistance in RHA-340. In addition, we assessed the efficacy of five EF against downy mildew and their effects on sunflower growth in axenic conditions. None of the entomopathogens reduced disease severity, nor did they have any effect on plant growth when applied together with P. halstedii. In contrast, three EF reduced some of the plant growth variables in the absence of the pathogen. Microbiological and molecular diagnostics suggest that the axenic system and the short experimental time used in this study did not favor the successful establishment of EF in the plants or their potential biocontrol effect. Our results show a shift in P. halstedii racial patterns and suggest that soil as a growth substrate and long infection times are needed for EF effectiveness against downy mildew.

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DISTRIBUTION AND RACE COMPOSITION OF DOWNY MILDEW (Plasmopara halstedii (Farl.) Berl. and de Toni) IN BULGARIA / EXTENSION Y RAZAS DEL MILDIU (Plasmopara halstedii (Farl.) Berl. y de Toni) EN BULGARIA / ÉTENDUE ET RACES DE LA ROUILLE (Plasmopara halstedii (Farl.) Berl. and de Toni) EN BULGARIE

Helia ◽

10.1515/helia.2000.23.33.25 ◽

2000 ◽

Vol 23 (33) ◽

pp. 25-32

Author(s):

P.S. Shindrova

Keyword(s):

Downy Mildew ◽

Resistance Gene ◽

The Other ◽

Plasmopara Halstedii ◽

North West ◽

North East ◽

Race 1 ◽

Race 2 ◽

Production Areas ◽

Number Of Authors

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.

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67 Current Status and Future Prospective of the Use of Plant Bioactive Compounds in Dairy and Beef Cattle

Journal of Animal Science ◽

10.1093/jas/skab054.222 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 132-132

Author(s):

Sergio Calsamiglia ◽

Maria Rodriguez-Prado ◽

Gonzalo Fernandez-Turren ◽

Lorena Castillejos

Keyword(s):

Beef Cattle ◽

Essential Oils ◽

Average Daily Gain ◽

Rumen Fermentation ◽

Production Performance ◽

In Vivo Studies ◽

Current Status ◽

The Impact

Abstract In the last 20 years there has been extensive in vitro research on the effects of plant extracts and essential oils on rumen microbial fermentation. The main objectives have been to improve energy metabolism through a reduction in methane emissions and an increase in propionate production; and to improve protein metabolism by reducing proteolysis and deamination. While the positive results from in vitro studies has stimulated the release of commercial products based on blends of essential oils, there is limited in vivo evidence on the rumen fermentation and production performance effects. A literature search was conducted to select in vivo studies where information on rumen fermentation and animal performance was reported. For dairy cattle, we identified 37 studies of which 21 were adequate to test production performance. Ten studies reported increases and 3 decreases in milk yield. For beef cattle, we identified 20 studies with rumen fermentation profile and 22 with performance data. Average daily gain improved in 7 and decreased in 1 study. Only 1 out of 16 studies reported an improvement in feed efficiency. Data indicate that out of more than 500 products tested in vitro, only around 20 have been tested in vivo in different mixtures and doses. The use of statistical approaches will allow to describe the conditions, doses and responses in dairy and beef cattle performance. The search for postruminal effects offers another alternative use. Evidence for effects on the intestinal and systemic effects on the immune system and antioxidant status (i.e., capsicum, garlic, eugenol, cinnamaldehyde curcuma, catechins, anethol or pinene), and in the modulation of metabolic regulation (capsicum, cinnamaldehyde, curcuma or garlic) may open the opportunity for future applications. However, stability of the product in the GI tract, description of the mechanisms of action and the impact of these changes on performance needs to be further demonstrated.

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