Inhibitory effects of aqueous and ethanolic extracts of pepper (<i>Capsicum annuum</i>) on the development of necrosis caused by <i>Phytophthora megakarya</i> in <i>Theobroma cacao</i>

Abstract

The cocoa tree (Theobroma cacao L.), also called "food of the gods", is a plant mainly cultivated for its beans. However, the cultivation of this plant is confronted with many parasitic attacks among which, attack due to Phytophthora megakarya which causes the most yield loss. The Control of this pathogen consisted in involving the use of aqueous and ethanolic extracts of pepper and two strains of Phytophthora megakarya in order to improve cocoa tolerance against the attack of this pathogen. These aqueous and ethanolic extracts were prepared in the laboratory and incorporated into Potato Dextrose Agar and Small Pea Agar culture media at concentrations (g / ml) of 10-1 , 10-2 , 10-3 and 10-4 , each containing a strain of Phytophthora megakarya. The results obtained revealed that all pepper treatments significantly inhibited the growth of Phytophthora megakarya with a 100% inhibition rate in the aqueous extract regardless of the strain used and inhibition rates of 89.33%. ; 63.35%; 54.39%; 42.86%; 100%; 70.22% and 57.54% for the ethanolic extract depending on the concentrations applied. In vivo treatment of leaf discs and pods detached prior to infection with Phytophthora megakarya resulted in significant inhibition, thereby reducing the incidence rate of disease severity. The values of this incidence vary from 0.1 to 1.2 for a percentage ranging from 0.5% to 20% of the severity of the disease depending on the nature of the extract of applied pepper. At concentrations (g / ml) 10-1 , 10-2 , 10-3 and 10-4 , the aqueous extract completely inhibited the growth of mycelium and the development of Phytophthora megakarya spores while the ethanolic extract of pepper showed its inhibitory power at the concentration 10-1 g/ml. The use of crude aqueous extracts or even diluted of pepper can therefore be considered in the fight against black pod desease in Cameroon.

Field Application of Ethanolic and Aqueous Chili Extracts to Control Diamondback Moth (Plutella Xylostella L.) in Cabbage (Brassica Oleracea Var. Capitata L.)

“…For defoliation, both the hot water and ethanolic extracts reported low values. Simo et al (2019) recommended aqueous extract rather than an ethanolic extract of pepper be used as a bio fungicide against the black pod disease (Phdeytophthora megakarya). Both aqueous and ethanolic extracts from chili pepper at a concentration of 50mg/L were toxic to two mosquito larvae, Anopheles and Culex (Ahmed, 2015).…”

Valorization of Capsicum annuum seed extract as an antifungal against Botrytis cinerea

“…Foliar treatments of tomatoes (leaves and fruits) with salicylic acid and aqueous extracts (from the seeds, roots, leaves, and bulbs of many botanical plants) represent a promising environmentally friendly alternative for achieving the total or partial reduction of mycelial growth and destruction of B. cinerea spores (Bahammou et al, 2017;Ullah et al, 2019). Several researchers have found Capsicum annuum extracts to be effective as a bio-fungicide against many phytopathogens, decreasing disease severity and stimulating plant defenses (Shayan et al, 2013;Silva et al, 2017;Simo et al, 2019). Chemical analysis of the aqueous extract of C. annuum seeds shows a pro le rich in avonoids, phenolic compounds, alkaloids, saponins, triterpenoids, terpenoids, phlobatannins, and tannins that have antifungal activity su cient to delay or suppress the action of many phytopathogens (Zimmer et al, 2012;Echave et al, 2020).…”

“…under laboratory conditions, andMaracahipes et al (2019) found that it inhibited the growth of the phytopathogens Fusarium lateritium, F. solani, F. oxysporum and Colletotrichum gloeosporioides. The latter researchers observed abnormal growth of the hyphae and clustering of cells in microscopic analysis Simo et al (2019). found that the aqueous extract of Capsicum spp.…”

Connaissances endogènes et perception du déficit hydrique liées à la culture du piment (<I>Capsicum spp.</I>) au Togo

“…Les oléorésines qui sont extraites des fruits secs sont utilisées dans la production de colorants de divers produits (Meghvansi et al, 2010). Il est aussi utilisé comme bio pesticide dans des programmes de lutte intégrée (Simo et al, 2019).…”