Commercial extract from the brown seaweed Ascophyllum nodosum reduces fungal diseases in greenhouse cucumber

Abstract

This study examined the effects of Stimplex™, a marine plant extract formulation from Ascophyllum nodosum, on some common cucumber fungal pathogens. Greenhouse cucumber plants were sprayed and/or root drenched using Stimplex™ at 0.5% or 1% concentration twice at 10-day intervals. Treatments also included application of fungicide (chlorothalonil, 2 g L −1 ) alternating with Stimplex™ application. Treated plants were inoculated with four cucumber fungal pathogens including Alternaria cucumerinum, Didymella applanata, Fusarium oxysporum, and Botrytis cinerea. Stimplex™ application resulted in a significant reduction in disease incidence of all the pathogens tested. The disease control effect was greater for Alternaria and Fusarium infection, followed by Didymella and Botrytis. Combined spray and root drenching with Stimplex™ was more effective than either spray or root drenching alone. The alternation of one fungicide application, alternated with Stimplex™ application, was highly effective and found to be the best treatment in reducing the disease ratings. Plants treated with Stimplex™ showed enhanced activities of various defenserelated enzymes including chitinase, β-1,3-glucanase, peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, and lipoxygenase. Altered transcript levels of various defense genes, including chitinase, lipoxygenase, glucanase, peroxidase, and phenylalanine ammonia lyase were observed in treated plants. Cucumber plants treated with Stimplex™ also accumulated higher level of phenolics compared to water controls. These results suggest that seaweed extracts enhance disease resistance in cucumber probably through induction of defense genes or enzymes.

Effect on yield, total phenolic, total flavonoid and total isothiocyanate content of two broccoli cultivars (Brassica oleraceae var italica) following the application of a commercial brown seaweed extract (Ascophyllum nodosum)

“…In our study the application of a cold process seaweed extract increased the phytochemical levels in broccoli plants. The enhanced accumulation of phenolic compounds may be related to an increased activity of phenylalanine ammonia lyase (PAL) and peroxidases (PO) enzymes which cause an increase in the available phenolic free pool (Jayaraman et al 2011). It is well documented that increase in phytochemical compounds can be affected by many factors such as light, water, CO 2 , methyl jasmonate, abiotic stress factors such as water deprivation (Guo et al 2011).…”

“…More research is needed to elucidate the action mechanisms of seaweed extracts and the elicited physiological responses on plants as well as the interactions between plant/pathogen attack in plants with increased levels of phytochemicals. The advantage of using seaweed extracts is that it may help the plants respond to biotic and abiotic stress better, besides promoting plant growth (Jayaraman et al 2011). The prolonged application of seaweed extract can significantly increase the amount of total phenolics, flavonoids and isothiocyanates.…”

Control of Fusarium Dry Rot Incited by Fusarium oxysporum f. sp. tuberosi Using Sargassum vulgare Aqueous and Organic Extracts

“…Furthermore, cucumber plants grown under greenhouse condition and sprayed and/or drenched with 0.5 and 1% (v/v) of Ascophyllum nodosum extracts showed decreased incidence of Fusarium wilt caused by F. oxysporum f. sp. cucumerinum [40]. In a recent study, Guesmi [27] found that S. vulgare methanolic extract, tested at 0.5 and 1 g/L, suppressed leaf damage index (96%) and the vascular discoloration extent (100%) caused by Verticillium dahliae infection on tomato and eggplant plants, compared to the untreated controls.…”

Impact of marine extracts applications on cv. Syrah grape (Vitis vinifera L.) yield components, harvest juice quality parameters, and nutrient uptake

“…Three foliar applications of 0.2% SWE reduced Alternaria radicina and Botrytis cinerea infections in carrots by 57% and 53.5%, respectively [130]. Greenhouse cucumbers treated with foliar or root drench applications of 0.15 or 0.3 ml of SWE at 3 10-day intervals had reductions in the severity of the fungal diseases Alternaria cucumerinum, Didymella applanata, Fusarium oxysporum, and Botrytis cinerea [146]. However, the SWE Marinure applied at the m anufacturer's recom m ended rates had no im pact on soil -borne diseases of tomatoes [94].…”

“…Olive trees treated with two wintertime applications of 17.5 ml SWE/tree developed color sooner than untreated trees [117]. Foliar SWE applications resulted in greater total phenolics in carrots [130] and cucumbers [131]. SWE typically does not influence TSS, pH, or TA of strawberries [127], watermelons [128], oranges [132], or mandarins [124].…”