1,721,142 research outputs found
Biological control with a fungus called Beauveria bassiana
No full textSeveral commercial biological products are based on fungal microorganisms that are antagonistic of insects and fungal pathogens causing severe damage of agricultural plants.
Beauveria bassiana is the most wide-spread entomopathogenic fungus, component of several commercial products. This fungus parasitizes a wide range of noxious pests for agricultural plants such as the greenhouse whitefly (T. vaporariorum), different aphid species (Aphis fabae, Macrosiphum euphorbiae, Chaetosiphon fragaefolii), thrips (Frankliniella occidentalis and Thrips tabaci) and spider mites (Tetranychus urticae). When spores of B. bassiana come in contact with the skin of a susceptible insect, they penetrate its body, grow inside and kill the insect within few days. Finally, a white mould comes out from the cadaver and produces new spores that can colonize others hosts.
Beauveria bassiana based products have not a preharvest interval (PHI), any harmful effects on human or animal health, on groundwater or they have not any unacceptable influence on the environment. Furthermore, no effects of B. bassiana on bees (Apis mellifera) or other pollinators have been observed and the fact that bee vectoring is used to apply this strain would indicate a low risk to bees and other pollinators, making B. bassiana a useful tool in pests management strategies
Biocontrol ability of Trichoderma harzianum strain T22 against Fusarium wilt disease on water-stressed lettuce plants
No full textThe control ability of Trichoderma harzianum strain T22 against Fusarium wilt of lettuce caused by Fusarium oxysporum f.sp. lactucae strain 365.07 was studied through mesocosm assays under extreme soil water content available for plants (-0.5 and -0.03 MPa).T22 was applied to nursery substrate at seeding, and to mesocosm soil at transplant of seedlings artficially infected by the pathogen. T22 decreased disease severity in comparison to infected controls by 57 and 78% in dry and wet conditions, respectively. Plant biomass was increased by T22 under both moisture levels. T22 colony growth, spore germination and antagonism to the pathogen were investigated under different water potential ( -0.03, -0.1, -0.5, -1.0, -2.0, -7.0 and -14.0 MPa) on minimal agar medium. All these parameters were influenced by water potential. However, they were similar at the same MPa values tested in the mesocosm assays.Our results provide evidence that T. harzianum strain T22 could be effective to control wilt disease caused by F. oxysporum f.sp. lactucae strain 365.07 under extreme soil moisture regimes already present in Italy, and susceptible to become more frequent in the near future
Potential for biocontrol of Pleurotus ostreatus green mould disease by Aureobasidium pullulans De Bary (Arnaud)
Full text linkPleurotus ostreatus, commonly known as “oyster mushroom”, is an edible fungus economically important worldwide. The green mould, caused by Trichoderma pleuroti and T. pleuroticola, is a very important fungal disease, and it is commonly controlled by the use of fungicides. The yeast-like fungus Aureobasidium pullulans is a biocontrol agent naturally found throughout a wide range of habitats. The effect of A. pullulans L1 and L8 strains on P. ostreatus, T. pleuroti and T. pleuroticola was studied in in vitro assays. Both yeast strains resulted compatible with P. ostreatus growth, and effective in reducing the T. pleuroticola and T. pleuroti colony growth. The inhibitory effect of L1 and L8 was similar in the majority of the Trichoderma-A. pullulans combinations on agar plates. Both strains were more efficient than Trichoderma in substrate colonization, and produced volatile and nonvolatile metabolites which reduced Trichoderma growth. When the activity of L1 and L8 was tested against the green mould disease of P. ostreatus under controlled conditions similar to those of a mushroom farm, only L8 was effective in controlling the disease. It showed an effect similar to that of the fungicide prochloraz against T. pleuroticola, the less aggressive pathogen, and lower than that of the fungicide against T. pleuroti, the most aggressive. The antagonism was the result of mechanisms like antibiosis and competition for space and nutrients, whereas the direct attachment of A. pullulans with hyphae of the pathogens did not play a role
Defense response against postharvest pathogens in hot water treated apples
Full text linkHot water treatment (HWT) has been demonstrated to be a safe and effective method to control postharvest diseases. In the present study, the effect of HWT (45 °C for 10 min) was investigated on the response of apple fruit against Botrytis cinerea, Colletotrichum acutatum and Neofabraea vagabunda infections. In vivo experiments were conducted with apples treated with HW and then inoculated with pathogen spore suspensions 0, 3, 6 and 24 h after the treatment. In vitro experiments were carried out in order to investigate the HWT effect on the pathogenesis enzyme activities of the three pathogens. These assays were conducted with the crude protein extracts (CPEs) derived from the hot water treated apples. A significant reduction of rot incidence was observed in fruit inoculated at 6 h (B. cinerea 22.7% and C. acutatum 11.0%) and 3 h (N. vagabunda 68.8%) after HWT with respect to the controls (22.0, 18.5 and 19.67 mm, respectively). CPEs extracted from hot water treated fruit inoculated at 6 h and 3 h showed the highest conidia germination inhibition (B. cinerea 85.6%; C. acutatum 52.7% and N. vagabunda 83.1%) with respect to the controls (74.0, 71.0 and 90.3% of conidia germination, respectively). A significant reduction of pathogenesis enzyme activities of the three pathogens was detected when pathogens were exposed to CPEs derived from hot water treated apples. The results showed that HWT can stimulate a defense response on apple against some postharvest pathogens
Effect of fungicides and herbicides on in vitro sensitivity of Clonostachys rosea and different strains of Trichoderma
No full textBiocontrol of Rhizoctonia solani disease and biostimulant effect by microbial products on bean plants
Full text linkMicrobial products containing a mixture of fungi and bacteria (EM Bokashi® 2-fi and EM-5 Sutociu® characterised by plant biostimulant activity), Trichoderma harzianum T22 (biofungicide) and the antagonist fungus Trichoderma sp. TJ40 were tested for efficacy against R. solani disease and for their biostimulant effects on bean plants, in growth chamber experiments, and for their direct effect on the pathogen growth, through in vitro experiments. In growth chamber experiments, EM-5 Sutociu was applied to seed (Sut/Se), substrate (Sut/S) and leaf (Sut/L) many times, EM Bokashi 2-fi to substrare (Bok/S) once and combined with Sut, T22 and TJ40 were applied once to substrate. The pathogen was inoculated to substrate at seeding time (first experiment) or at seedling phase (second experiment). Under our experimental conditions, Bok/S+Sut/S+Sut/L, Sut/S+Sut/L, Sut/Se+Sut/S+Sut/L and T22, in the first experiment, and all treatments, with the exception of Bok/S applied alone in the second experiment, gave significantly disease severity reduction and increase of dry weight and leaf area with respect to the infected control. The TJ40 treatment reduced both disease incidence and disease severity only in the second experiment. In the experiment on the biostimulant effect, T22, Bok/S+Sut/S+Sut/L, Sut/S+Sut/L and Sut/Se+Sut/S+Sut/L showed significantly increases of both dry weight and leaf area. The direct effect of the treatment with T22, TJ40, Bok and Sut on R. solani growth in vitro was studied with two methods, submerged colony (SC) and well diffusion (WD) assays. The pathogen growth was completely inhibited by Trichoderma T22 in both assays, by Trichoderma TJ40 in a range of 80-50 % in SD assay, and 50-30 % in WD assay and slightly inhibited or not inhibited by Bok and Sut
Activity of seaweed and cyanobacteria water extracts against Podosphaera xanthii on zucchini
Full text linkThe purpose of this research was to study the effects of water extracts of algae belonging to the phylum Rodophyta, Heterokontophya, Chlorophyta and of Cyanobacteria against Podosphaera xanthii on zucchini (Cucurbita pepo) cotyledons. Each extract was sprayed on the upper surface of cotyledons at the concentration of 0.5 %, then cotyledons were inoculated with six 10-µl drops of a spore suspension of the pathogen (1×106 spores/ml), and incubated on water agar in Petri dishes. Depending on the species, the extracts showed inhibition, stimulation or no effect on the disease severity caused by P. xanthii and on the pathogen sporulation density. Extracts of Corallina sp., Halopithys sp., Sargassum sp. and Anabaena sp. showed significant inhibitory effect on both parameters. This study suggests that seaweed and cyanobacteria water extracts applied on zucchini cotyledons may be considered in further experiments on plants as a useful preventative tool for the disease management in sustainable agriculture
Compatibility of Beauveria bassiana with fungicides in vitro and on zucchini plants infested with Trialeurodes vaporariorum
No full textThe effect of fungicides on the entomopathogenic fungus Beauveria bassiana strain ATCC 74040 (Naturalis®) was evaluated in vitro and in vivo. The formulated fungicides Cantus® (boscalid), Frupica (mepanipyrim), Galben (benalaxyl), Melody® Compact (iprovalicarb + Cu oxychloride), Oracle⢠(fenamidone + Cu), Prosper® 300 CS (spiroxamine), Signum® (boscalid + pyraclostrobin), Switch® (cyprodinil + fludioxonil) and Talendo® (proquinazid) were tested on fungal colony growth from 10 field dose (10FD) to 10â4 FD. Each product mixed with Naturalis at FD was also tested against Trialeurodes vaporariorum on zucchini plants. Fungal colony growth was not affected by Cantus, Galben, Melody Compact, Oracle and Talendo at FD, while Frupica and Prosper 300 CS reduced colony growth by 9.7% and 6.9%, respectively. All these products did not inhibit the activity of B. bassiana on whiteflies at FD. On the contrary, Signum and Switch significantly inhibited colony growth at all doses and reduced the entomopathogenic activity on whiteflies when applied in mixture with B. bassiana. The toxic effect of both fungicides on B. bassiana persisted for 10 days after treatments, with a 91.2% reduction in nymph mortality in comparison to control for Signum and 87.4% for Switch. The mode of action of their active ingredients, boscalid, pyraclostrobin, cyprodinil and fludioxonil, individually and in mixture (boscalid + pyraclostrobin and cyprodinil + fludioxonil), was studied on fungal colony growth, spore germination, germ tube elongation and spore survival from 10FD to 10â2 FD. All these parameters were reduced by the four active ingredients at all doses, pyraclostrobin and fludioxonil completely inhibited spore germination, fludioxonil alone and in mixture with cyprodinil also inhibited completely spore survival
A preliminary investigation into Aureobasidium pullulans as a potential biocontrol agent against Phytophthora infestans of tomato
No full textTwo biological control agents (BCAs), Aureobasidium pullulans L1 and L8 strains, were evaluated for their efficacy against Phytophthora infestans, the casual agent of tomato late blight. Yeast strains were applied (108 CFU/mL) on tomato plants, grown under greenhouse conditions, 24 h before or 16 h after inoculation with P. infestans (1 Ã 104 sporangia/mL). The BCAs applied 24 h before the pathogen inoculation were significantly more effective (43.9%) than those applied after pathogen inoculation. L8 reduced AUDPC more (60%) than L1 (37%), while both strains reduced the disease in a similar way (average 32.2%) in the post-inoculation treatment. Dynamic population assay revealed that L1 and L8 were able to survive and colonize the tomato leaf surface during the ten days of experiments. In vitro experiments showed that both strains enhanced plant defence response by increasing leaf Î2-1,3-glucanase activity (>30% than the control). BCAs also produced bioactive volatile and non-volatile metabolites able to inhibit pathogen colony growth and to cause morphological alterations of hyphae. Overall, volatile metabolites were more effective than non-volatiles in reducing pathogen growth. In addition, 2-phenyl, 1-butanol-3-methyl, 1-butanol-2-methyl and 1-propanol-2-methyl synthetic volatile compounds produced by both strains showed EC50 values for pathogen mycelial growth of 3.9 ÂμL Lâ1 on average. This study showed that L1 and L8 strains could be considered part of a control strategy against P. infestans on tomato
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