Fungicidal Activity of Plant Volatile Compounds for Controlling Monilinia laxa in Stone Fruit

Nine plant-volatile compounds were tested for their activity against Monilinia laxa, the cause of brown rot in stone fruit. In vitro trials on conidial germination and mycelial growth showed a consistent fungicidal activity of trans-2-hexenal, carvacrol, and citral, whereas trans-cinnamaldehyde, hexanal, (-)-carvone, eugenol, 2-nonanone, and p-anisaldehyde exhibited a progressively lower inhibition. The best inhibitor of conidial germination was trans-2-hexenal (effective dose for 50 and 90% inhibition [ED50 and ED95] = 7.53 and 9.4 μl/liter, respectively; minimal inhibitory concentration [MIC] = 12.3 μl/liter], whereas carvacrol was the best inhibitor of mycelial growth (ED50 and ED95 = 2 and 3.4 μl/liter, respectively; MIC = 6.1 μl/liter). The three most active compounds in in vitro studies also were tested in vivo as postharvest biofumigants. The best control of brown rot was with trans-2-hexenal (efficacy ranging from 46.2 to 80.3%, depending on cultivar), whereas citral and carvacrol resulted in a lower efficacy of 40 and 32.9%, respectively. Fumigation with trans-2-hexenal at concentrations that stopped decay did not cause any visible disorders to plum, whereas it was phytotoxic to apricot, peach, and nectarine and produced off-odors or off-flavors in all species of stone fruit tested.

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Reduced Sensitivity in Monilinia fructicola Field Isolates from South Carolina and Georgia to Respiration Inhibitor Fungicides

Plant Disease ◽

10.1094/pdis-94-6-0737 ◽

2010 ◽

Vol 94 (6) ◽

pp. 737-743 ◽

Cited By ~ 44

Author(s):

A. Amiri ◽

P. M. Brannen ◽

G. Schnabel

Keyword(s):

South Carolina ◽

Mycelial Growth ◽

Disease Incidence ◽

Brown Rot ◽

Conidial Germination ◽

Cross Resistance ◽

Monilinia Fructicola ◽

Significant Difference

Quinone outside inhibitor (QoI) and succinate dehydrogenase inhibitor (SdhI) fungicides are respiration inhibitors (RIs) used for preharvest control of brown rot of stone fruit. Both chemical classes are site-specific and, thus, prone to resistance development. Between 2006 and 2008, 157 isolates of Monilinia fructicola collected from multiple peach and nectarine orchards with or without RI spray history in South Carolina and Georgia were characterized based upon conidial germination and mycelial growth inhibition for their sensitivity to QoI fungicides azoxystrobin and pyraclostrobin, SdhI fungicide boscalid, and a mixture of pyraclostrobin + boscalid. There was no significant difference (P = 0.05) between EC50 values for inhibition of conidial germination versus mycelial growth. The mean EC50 values based upon mycelial growth tests for 25 isolates from an orchard without RI-spray history were 0.15, 0.06, 2.23, and 0.09 μg/ml for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively. The respective mean EC50 values for 76 isolates from RI-sprayed orchards in South Carolina were 0.9, 0.1, 10.7, and 0.13 μg/ml and for 56 isolates from RI-sprayed orchards in Georgia were 1.2, 0.1, 8.91, and 0.17 μg/ml. Overall, mean EC50 values of populations from RI-sprayed orchards increased three-, two-, five-, and twofold between 2006 and 2008 for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively. A subset of 10 M. fructicola isolates representing low and high EC50 values for azoxystrobin, boscalid, and boscalid + pyraclostrobin was selected for a detached fruit assay to determine disease incidence and severity following protective treatments of formulated RI fungicides at label rates. Brown rot incidence was greater than 50% when fruit were inoculated with isolates having EC50 values of 2, 4, and 0.6 μg/ml for azoxystrobin, boscalid, and pyraclostrobin + boscalid, respectively. Pyraclostrobin failed to control any of the isolates tested in detached fruit assays. Based on minimum inhibitory concentration and brown rot incidence data, we recommend using 3 and 0.75 μg/ml as discriminatory doses to distinguish between sensitive isolates and those with reduced sensitivity to azoxystrobin and pyraclostrobin + boscalid, respectively. Results from our in vitro and in vivo assays indicate a shift toward reduced sensitivity in M. fructicola from the southeastern United States. No cross-resistance was observed between the QoI and the SdhI fungicides, which implies that rotation or tank mixtures of these two chemical classes can be used as a resistance management strategy.

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Anti-biofilm potential of some plant volatile compounds against Proteus mirabilis

Planta Medica ◽

10.1055/s-0036-1596215 ◽

2016 ◽

Vol 81 (S 01) ◽

pp. S1-S381

Author(s):

JAA do Nascimento Júnior ◽

BS dos Santos ◽

LCA de Araújo ◽

AVA Lima ◽

TD da Silva ◽

...

Keyword(s):

Volatile Compounds ◽

Proteus Mirabilis ◽

Plant Volatile ◽

Plant Volatile Compounds

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Improving the Biocontrol Potential of Bacterial Antagonists with Salicylic Acid against Brown Rot Disease and Impact on Nectarine Fruits Quality

Agronomy ◽

10.3390/agronomy11020209 ◽

2021 ◽

Vol 11 (2) ◽

pp. 209

Author(s):

Nadia Lyousfi ◽

Rachid Lahlali ◽

Chaimaa Letrib ◽

Zineb Belabess ◽

Rachida Ouaabou ◽

...

Keyword(s):

Salicylic Acid ◽

Disease Severity ◽

Mycelial Growth ◽

Brown Rot ◽

Antagonistic Bacteria ◽

Biological Treatments ◽

Rot Disease ◽

The Impact

The main objective of this study was to evaluate the ability of both antagonistic bacteria Bacillus amyloliquefaciens (SF14) and Alcaligenes faecalis (ACBC1) used in combination with salicylic acid (SA) to effectively control brown rot disease caused by Monilinia fructigena. Four concentrations of salicylic acid (0.5%, 2%, 3.5%, and 5%) were tested under in vitro and in vivo conditions. Furthermore, the impact of biological treatments on nectarine fruit parameters’ quality, in particular, weight loss, titratable acidity, and soluble solids content, was evaluated. Regardless of the bacterium, the results indicated that all combined treatments displayed a strong inhibitory effect on the mycelial growth of M. fructigena and disease severity. Interestingly, all SA concentrations significantly improved the biocontrol activity of each antagonist. The mycelial growth inhibition rate ranged from 9.79% to 88.02% with the highest reduction rate recorded for bacterial antagonists in combination with SA at both concentrations of 0.5% and 3.5%. The in vivo results confirmed the in vitro results with a disease severity varying from 0.00% to 51.91%. A significant biocontrol improvement was obtained with both antagonistic bacteria when used in combination with SA at concentrations of 0.5% and 2%. The lowest disease severity observed with ACBC1 compared with SF14 is likely due to a rapid adaptation and increase of antagonistic bacteria population in wounded sites. The impact of all biological treatments revealed moderate significant changes in the fruit quality parameters with weight loss for several treatments. These results suggest that the improved disease control of both antagonistic bacteria was more likely directly linked to both the inhibitory effects of SA on pathogen growth and induced fruit resistance.

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Saprophytic microorganisms with potential for biological control of Botrytis cinerea on Geraldton waxflower flowers

Australian Journal of Experimental Agriculture ◽

10.1071/ea00112 ◽

2001 ◽

Vol 41 (5) ◽

pp. 697 ◽

Cited By ~ 8

Author(s):

D. R. Beasley ◽

D. C. Joyce ◽

L. M. Coates ◽

A. H. Wearing

Keyword(s):

Botrytis Cinerea ◽

Mycelial Growth ◽

Germ Tube ◽

Conidial Germination ◽

Pseudomonas Sp ◽

Trichoderma Spp ◽

Fusarium Sp ◽

Flower Abscission ◽

Germ Tube Elongation

Saprophytic bacteria, yeasts and filamentous fungi were isolated from Geraldton waxflower flowers and screened to identify potential antagonism towards Botrytis cinerea. Isolates from other sources (e.g. avocado) were also tested. Isolates were initially screened in vitro for inhibition of B. cinerea conidial germination, germ tube elongation and mycelial growth. The most antagonistic bacteria, yeasts and fungi were selected for further testing on detached waxflower flowers. Conidia of the pathogen were mixed with conidia or cells of the selected antagonists, co-inoculated onto waxflower flowers, and the flowers were sealed in glass jars and incubated at 20˚C. The number of days required for the pathogen to cause flower abscission was determined. The most antagonistic bacterial isolate, Pseudomonas sp. 677, significantly reduced conidial germination and retarded germ tube elongation of B. cinerea. None of the yeast or fungal isolates tested was found to significantly reduce conidial germination or retard germ tube elongation, but several significantly inhibited growth of B. cinerea. Fusarium sp., Epicoccum sp. and Trichoderma spp. were the most antagonistic of these isolates. Of the isolates tested on waxflower, Pseudomonas sp. 677 was highly antagonistic towards B. cinerea and delayed waxflower abscission by about 3 days. Trichoderma harzianum also significantly delayed flower abscission. However, as with most of the fungal antagonists used, inoculation of waxflower flowers with this isolate resulted in unsightly mycelial growth.

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Bacterial, Fungal, and Plant Volatile Compounds in Reducing Plant Pathogen Inoculums

Bacteria in Agrobiology: Plant Nutrient Management ◽

10.1007/978-3-642-21061-7_13 ◽

2011 ◽

pp. 301-319 ◽

Cited By ~ 1

Author(s):

W. G. Dilantha Fernando ◽

Vidarshani Nawalage

Keyword(s):

Volatile Compounds ◽

Plant Pathogen ◽

Plant Volatile ◽

Plant Volatile Compounds

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Control of Penicillium expansum by plant volatile compounds

Plant Pathology ◽

10.1111/j.1365-3059.2005.01312.x ◽

2006 ◽

Vol 55 (1) ◽

pp. 100-105 ◽

Cited By ~ 89

Author(s):

F. Neri ◽

M. Mari ◽

S. Brigati

Keyword(s):

Volatile Compounds ◽

Penicillium Expansum ◽

Plant Volatile ◽

Plant Volatile Compounds

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Control of Neofabraea alba by plant volatile compounds and hot water

Postharvest Biology and Technology ◽

10.1016/j.postharvbio.2008.08.006 ◽

2009 ◽

Vol 51 (3) ◽

pp. 425-430 ◽

Cited By ~ 34

Author(s):

Fiorella Neri ◽

Marta Mari ◽

Stefano Brigati ◽

Paolo Bertolini

Keyword(s):

Volatile Compounds ◽

Hot Water ◽

Plant Volatile ◽

Plant Volatile Compounds

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Control of Sphaeropsis Rot in Stored Apple Fruit Caused by Sphaeropsis pyriputrescens with Postharvest Fungicides

Plant Disease ◽

10.1094/pdis-04-11-0273 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1075-1079 ◽

Cited By ~ 5

Author(s):

C. L. Xiao ◽

Y. K. Kim ◽

R. J. Boal

Keyword(s):

Mycelial Growth ◽

Disease Incidence ◽

Apple Fruit ◽

Conidial Germination ◽

Fruit Rot ◽

Mitigation Measures ◽

The Mean ◽

Rot Disease ◽

Sphaeropsis Rot

Sphaeropsis rot caused by Sphaeropsis pyriputrescens is a recently reported postharvest fruit rot disease of apple grown in Washington State. The objective of this study was to develop chemical-based mitigation measures for Sphaeropsis rot in stored apple fruit. To determine in vitro sensitivity of S. pyriputrescens to the three registered postharvest fungicides thiabendazole, fludioxonil, and pyrimethanil, 30 isolates of S. pyriputrescens obtained from various sources were tested for mycelial growth and conidial germination on fungicide-amended media. Golden Delicious apple fruit were inoculated with the pathogen in the orchard at 2 or 5 weeks before harvest. After harvest, fruit were either nontreated or dipped in thiabendazole, fludioxonil, or pyrimethanil solutions, stored at 0°C, and monitored for decay development for up to 9 months after harvest. The mean effective concentration of a fungicide that inhibits mycelial growth or spore germination by 50% relative to the nonamended control (EC50) values of thiabendazole, fludioxonil, and pyrimethanil on mycelial growth were 0.791, 0.0005, and 2.829 μg/ml, respectively. Fludioxonil and pyrimethanil also were effective in inhibiting conidial germination of the fungus with EC50 values of 0.02 μg/ml for fludioxonil and 5.626 μg/ml for pyrimethanil. All three postharvest fungicides applied at label rates immediately after harvest were equally effective in controlling Sphaeropsis rot in stored apple fruit, reducing disease incidence by 92 to 100% compared with the nontreated control. The results indicated that Sphaeropsis rot may be effectively controlled by the currently registered postharvest fungicides thiabendazole, fludioxonil, and pyrimethanil.

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