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

Abstract

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.

Evaluation of disease management approaches for powdery mildew onCannabis sativaL. (marijuana) plants

“…When neem oil fractions were purified and single triterpenoids were tested against a range of common plant pathogens, such as Fusarium oxysporum and Alternaria tenuis, there was a loss of effect (Govindachari et al 1998). When applied to whole plants, neem products had a significant effect on reducing powdery mildew disease development on rose (Pasini et al 1997), pea (Patil et al 2017;Vivek et al 2017;Deshmukh et al 2018), okra (Moharam and Obiadalla Ali 2012), and other crops. Our results are consistent with previously published reports that show that neem oil or neem extracts are effective at reducing powdery mildew development.…”

Preventive and curative control of sclerotium rot disease of cocoyam cormel (Colocasia esculenta [L., Scott]) using plant extracts and Trichoderma koningii

“…Its local names include Dogon Yaro (Nigeria), Azad Dirkht (Persian), and Neeb (Arabic). Several authors have reported the medicinal uses and phytotoxicity of A. indica, where extracts from the seed have been reported to greatly reduce conidial germination in several fungi [13]. Chromolaena odorata (family Asteraceae) is a perennial weed shrub of crops and pastures found mainly in West Africa and South Asia [14].…”

Suppression of Powdery Mildew on Flax by Foliar Application of Essential Oils

“…). In addition, Moharam and Obiadalla Ali () reported that 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 Erysiphe cichoracearum completely, the causal pathogen of okra PM.…”