Plant extracts containing caffeic acid and rosmarinic acid inhibit zoospore germination of Phytophthora spp. pathogenic to Theobroma cacao

Abstract

The three most important species of Phytophthora worldwide causing black pod disease of cacao are P. palmivora, P. megakarya, and P. capsici. Chemicals are effective in controlling this disease but more natural methods would be preferred. One alternative is to use natural plant extracts. Rosemary and lavender leaf extracts were found to be effective in reducing germination of P. capsici, P. megakarya, and P. palmivora zoospores when supplemented to agar plates at different dilutions. The extracts displayed the biggest impact on P. megakarya zoospores where it completely inhibited germination at a 25% dilution of the prepared extract. When applied to cacao leaf disks, rosemary extract reduced necrosis caused by P. megakarya zoospores. In a bioassay, pears first treated with lavender extract showed no symptoms of P. megakarya infection compared with the non-treated controls. Based upon HPLC analyses, the active compound in these extracts was determined to be caffeic acid, rosmarinic acid or some simple derivative thereof. When added to agar plates, synthetic caffeic acid and rosmarinic acid completely inhibited germination of P. capsici, P. megakarya, and P. palmivora zoospores at concentrations of 3 and 6 g l )1 , respectively. In addition, sage and rice bran extracts, which both contain caffeic acid, were also effective in reducing zoospore germination. In contrast, inhibition of Botrytis cinerea or Trichoderma asperellum conidia germination did not occur, displaying some level of specificity. These extracts could provide an economically safe method for reducing damage caused by black pod disease on cacao until resistant varieties are developed and released.

Antimicrobial Activity of Syzygium aromaticum and Zanthoxylum xanthoxyloides Essential Oils Against Phytophthora megakarya

“…The latter being a mean of reducing the inoculum spread in the farm. By suppressing the infection or slowing down the appearance of symptoms on artificially infected CPHP, our results corroborate the findings of Widmer and Laurent () who reported that Rosemary and Lavender leaves extracts can inhibit the germination of the zoospores of Phytophthora capsici , Phytophthora palmivora and Phytophthora megakarya on the surface of cocoa pods in the field. Recently in 2010, Sirirat and Kittipot showed that clove oil can prevent the postharvest rot of tomato and related its effectiveness with the inhibition of fungal conidia germination.…”

The effect of burdock leaf fraction on adhesion, biofilm formation, quorum sensing and virulence factors ofPseudomonas aeruginosa

“…Studies have showed that caffeic acid, chlorogenic acid, rutin, p ‐coumaric acid, luteolin and quercetin exhibited high antibacterial activity (Widmer and Laurent ; Lou et al . , ; Fratianni et al .…”

Secondary Metabolite Profiling in Various Parts of Tomato Plants

“…Young leaves of strawberry plants also included greater content of phenolic compounds than old leaves (Kim et al, 2013). Antimicrobial activity of caffeic acid has been tested against various fungi and bacteria (Harrison et al, 2003;Kim et al, 2012;Rauha et al, 2000;Widmer and Laurent, 2006). The results show that leaves of tomato include more antimicrobial and antihervibore phenolic compounds than other parts.…”