Preliminary Investigation of Effect of Neem-Derived Pesticides on Plasmopara halstedii Pathotype 704 in Sunflower under In Vitro and In Vivo Conditions

Abstract

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.

Efficacy of some plant resistance inducers against several sunflower downy mildew (Plasmopara halstedii (Farl.) Berl. et de Toni) isolates

“…Neem extracts and products have demonstrated multimodal activity against phytopathogens, beginning with direct growth suppression, inhibiting pathogen establishment and subsequent development on the host plant, and inducing SAR in the pathogens (Goel et al 2016). Our findings are comparable with those of Doshi et al (2020). that the maximal concentration of Neem Azal was more effective than the aqueous solution of neem leaf extract in decreasing the infection rate in P. halstedii race 704-infected sunflowers.…”

“…There is a growing body of research on the use of plant activators, such as chemical inducers (e.g., benzothiadiazole), botanical pesticides (e.g., azadirachtin), and biocontrol agents (e.g., Trichoderma spp.) for disease control (Bán et al 2023;Doshi et al 2020;Tarigan et al 2022). One of the underlying processes is induced resistance, whereby a prior treatment with resistance inducers or inoculation with a non-aggressive, or avirulent pathogen can cause the susceptible plant to respond relatively quickly to a subsequent attack (Vallad and Goodman (2004); Walters et al 2013;Kamle et al 2020;Yassin et al 2021).…”

“…such as azadirone, azadirachtin, flavonoids etc., with AZA the most efficient active ingredient, is effective against several plant diseases (Kumar et al 2020; Adusei and Azupio 2022). Preliminary studies showed that neem leaf extract and AZA performed well against an aggressive isolate of P. halstedii (Doshi et al 2020).…”

Identification of Potential Phytochemical/Antimicrobial Agents against Pseudoperonospora cubensis Causing Downy Mildew in Cucumber through In-Silico Docking

“…The active compounds or chemical constituents of the botanicals act against pathogens. The botanicals used in this study, i.e., neem, tulsi, pudina, clove, and garlic are good sources of anti-microbial compounds and are used against many fungal pathogens, especially the oomycetes of fungi [13][14][15][16][17]. Binding interactions between two proteins of P. cubensis and ligands derived from C. sativus (L.), Syzygium aromaticum (L.) Merr.…”

The situation in the population of the sunflower downy mildew pathogen in some regions of the Russian Federation

“…Основные защитные мероприятия от ложной мучнистой росы подсолнечника -это севооборот, предпосевное протравливание семян и возделывание устойчивых генотипов. Разрабатываются и биологические методы контроля болезни; они могут иметь хорошие перспективы, но пока не нашли широкого применения в промышленном производстве [1,2]. Из-за высокой рентабельности этой сельскохозяйственной культуры резко сократились севообороты в последние десятилетия не только в РФ, но и во многих странах мира: вместо ротации 7-10 лет, подсолнечник возвращают на прежнее поле через 1-4 года.…”