Strawberry Fruit Rot Research Articles

First Report of Fusarium solani Causing Fruit Rot of Strawberry in Pakistan

First Report of <i>Fusarium solani</i> Causing Fruit Rot of Strawberry in Pakistan

First report of Curvularia inaequalis and C. spicifera causing leaf blight and fruit rot of strawberry in Iran

First report of Curvularia inaequalis and C. spicifera causing leaf blight and fruit rot of strawberry in Iran

Reveromycins A and B from Streptomyces sp. 3-10: Antifungal Activity against Plant Pathogenic Fungi In vitro and in a Strawberry Food Model System.

This study was conducted to determine the antifungal activity of the metabolites from Streptomyces sp. 3–10, and to purify and identify the metabolites. Meanwhile, the taxonomic status of strain 3–10 was re-evaluated. The cultural filtrates of strain 3–10 in potato dextrose broth were extracted with ethyl acetate. The resulting crude extract at 1 and 5 μg/ml inhibited growth of 22 species in 18 genera of plant pathogenic fungi and Oomycetes, accounting for 92% of the total 24 tested species, suggesting that it has a wide antifungal spectrum. Two compounds were purified from the crude extract and were identified as reveromycins A and B, which demonstrated high antifungal activity against Botrytis cinerea, Mucor hiemails, Rhizopus stolonifer, and Sclerotinia sclerotiorum under acidic pH conditions. Both the crude extract and reveromycin A from strain 3–10 at 10, 50, and 100 μg/ml showed high efficacy in suppression of strawberry fruit rot caused by the above-mentioned four pathogens. The efficacy was comparable to that of corresponding commercial fungicides (pyrimethanil, captan, dimetachlone) used in management of these pathogens. Morphological, physiological, and phylogenetic characterization showed that strain 3–10 is closely related to Streptomyces yanglinensis 1307T, representing a novel phylotype in that species. This study reported a new strain with reveromycins-producing capability. The finding is important for further exploitation of reveromycins for agricultural use.

First Worldwide Report of a Strawberry Fruit Rot Disease Caused by Phytophthora capsici Isolates

First Worldwide Report of a Strawberry Fruit Rot Disease Caused by <i>Phytophthora capsici</i> Isolates

Effect of Inoculum Concentration and Interrupted Wetness Duration on the Development of Anthracnose Fruit Rot of Strawberry.

Anthracnose fruit rot (AFR) of strawberry, caused by Colletotrichum acutatum, greatly affects production if not controlled. Application of fungicides in addition to the use of less susceptible cultivars are important tools for AFR control. The effects of interrupted wetness duration and inoculum concentration on the development of AFR were evaluated on strawberry cultivars with different levels of susceptibility. Fruit rot and flower blight incidence generally increased with increasing inoculum concentration. 'Camarosa' and 'Treasure' were more susceptible than 'Strawberry Festival' and flowers were more susceptible than immature fruit for most cultivars. Interruption in wetness periods had a significant effect on disease incidence when fruit where exposed to dry periods of 6 h or more compared with 24 h of continuous wetness. The results of this study will be used to refine a disease-warning system to predict AFR outbreaks in Florida strawberry production fields.

First Report of Fruit Rot of Strawberry Caused by Geotrichum candidum in Pakistan

First Report of Fruit Rot of Strawberry Caused by <i>Geotrichum candidum</i> in Pakistan

Resistance in Strawberry Isolates of Colletotrichum acutatum from Florida to Quinone-Outside Inhibitor Fungicides.

Anthracnose fruit rot of strawberry, caused by Colletotrichum acutatum, is a major disease in Florida and frequent quinone-outside inhibitor (QoI) fungicide applications are needed for disease control. From 1994 to 2014, 181 C. acutatum isolates were collected from multiple strawberry fields in Florida with or without QoI spray history. Sensitivity to azoxystrobin and pyraclostrobin was tested based upon mycelial growth and germ tube elongation inhibition. Mean effective concentration where growth was reduced by 50% (EC50) values for isolates collected prior to 2013 based upon mycelial growth were 0.22 and 0.013 μg/ml and upon germ tube elongation were 0.57 and 0.03 μg/ml for azoxystrobin and pyraclostrobin, respectively. Mycelial growth and germ tube elongation of 48 isolates collected in 2013 and 2014 were not inhibited with azoxystrobin at 3 μg/ml and pyraclostrobin at 0.110 μg/ml. A fungicide discriminatory dose assay indicated that 43 of the 48 isolates had EC50 values higher than 100 and 10 μg/ml for azoxystrobin and pyraclostrobin, respectively. Azoxystrobin and pyraclostrobin sprayed preventively on strawberry fruit inoculated with C. acutatum failed to control resistant isolates. Sequencing of the cytochrome b gene of sensitive and resistant isolates showed that QoI-resistant isolates contained either G143A or F129L amino acid substitutions.

Evaluation of epidemics and weather-based fungicide application programmes in controlling anthracnose fruit rot of day-neutral strawberry in outdoor field and protected cultivation systems

Anthracnose fruit rot caused by Colletotrichum acutatum is an economically important disease of strawberry in Ontario. Three years of experiments (2009–2011) were conducted at the University of Guelph’s Cedar Springs Research Station in Blenheim, ON to understand anthracnose fruit rot epidemics in outdoor field and protected production systems and to evaluate different fungicide spray programmes for disease control in day-neutral strawberry. Weather-based fungicide timing programmes were compared with calendar spray programmes in two day-neutral cultivars, ‘Seascape’ and ‘Albion’. Incidence of disease in high-tunnels was very low in all 3 years, even in fungicide non-sprayed plots, indicating that cultivation of day-neutral strawberry in high-tunnels could be an alternative strategy for controlling anthracnose fruit rot with minimal use of fungicides. In outdoor fields, disease incidence was greatly influenced by leaf wetness duration, rainfall and temperature. The use of a weather-based model to determine the timing of fungicide treatments reduced the number of sprays and was as effective as a calendar-based spray at 7-day intervals to reduce the disease and increase marketable fruit yield. Rotating fungicides with different modes of actions (pyraclostrobin, myclobutanil and boscalid + pyraclostrobin) was more effective in reducing disease than regular sprays of captan. The outcomes of this research will be useful to develop decision support tools and select proper fungicides and cultivation systems to manage anthracnose.

Anthracnose Fruit Rot of Strawberry

Anthracnose fruit rot is an important disease for strawberry worldwide. Lesions appear as dark, sunken spots on infected fruit. This revised 4-page fact sheet was written by James C. Mertely and Natalia A. Peres, and published by the UF Department of Plant Pathology, September 2012. PP-207/PP130: Anthracnose Fruit Rot of Strawberry (ufl.edu)

First Report of Anthracnose Fruit Rot of Strawberry Caused by Colletotrichum acutatum in Montenegro.

Strawberries (Fragaria × ananassa) in Montenegro have become an increasingly important economic crop in recent years. During May 2011, severe fruit damage in strawberry cv. Clery was observed in two fields in the Podgorica region. Fruit symptoms were typical for strawberry anthracnose: sunken, dark brown to black circular lesions appeared on maturing fruits. However, no stem, crown, or foliar symptoms were observed. Under wet conditions, orange masses of conidia were produced in acervuli in the center of lesions. Conidia were hyaline, aseptate, cylindrical, with pointed ends, measuring 9.8 to 17.2 (mean 14.3) × 2.5 to 6.1 (mean 4.4) μm. Colonies on potato dextrose agar (PDA) were initially white, then turned gray as conidia formed in orange to salmon pink masses around the center of the culture. Setae or an ascigerous stage were never observed in culture or on the host. Koch's postulates were fulfilled by inoculating ripe and unripe asymptomatic fruits (20 of each, removed from strawberry plants cv. Clery) with the isolated fungus. Fruits were sprayinoculated (106 conidia/ml). An equal number of noninoculated fruits were used as a control. After incubation time of 2 to 3 days at 25°C in a moist chamber, symptoms appeared on inoculated ripe fruits. On unripe fruits, the lesions developed only 3 to 4 days after the inoculation. No symptoms were found on control fruits. The fungus was reisolated from fruits, after which typical morphological characteristics developed in culture as described above. On the basis of the symptoms, the morphological and cultural characteristics of the fungus, and the pathogenicity test, the disease was identified as strawberry anthracnose caused by Colletotrichum acutatum, which is in accordance with previous reports (1,2,3,4). The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 131813). The internal transcribed spacer (ITS) region of the fungal DNA was amplified with ITS1F and ITS4 primers, sequenced, and submitted to NCBI GenBank (Accession No. JQ424934). BLASTn searches of GenBank using the ITS sequence revealed 99% similarity with database sequences of C. acutatum. Since the pathogen was found in the main Montenegrin strawberry production area, it poses a threat to strawberry production in Montenegro. To our knowledge, this is the first report of anthracnose fruit rot of strawberry in Montenegro.

Use of Leaf Wetness and Temperature to Time Fungicide Applications to Control Anthracnose Fruit Rot of Strawberry in Florida.

Anthracnose fruit rot (AFR), caused by Colletotrichum acutatum, is a major disease of strawberry in Florida and is generally controlled by weekly fungicide applications. More than 20 applications may be made during the growing season, most commonly using captan and the quinone-outside inhibitors. Field experiments were conducted for three seasons on a susceptible and a partially resistant cultivar to evaluate the effectiveness of timing fungicide applications for managing AFR based on a previously published model by Wilson and associates that uses leaf wetness duration and temperature to predict fruit infection by C. acutatum under controlled conditions. For most treatments, rules were established where captan was applied when the predicted proportion of fruit infected (INF) from the model exceeded 0.15 and pyraclostrobin was applied when INF exceeded 0.5. For one model-timed treatment where captan and pyraclostrobin were applied before symptoms first appeared in the field, disease control was as good as the treatment where calendar weekly applications were made and the model-timed treatment utilized 47% fewer sprays. In treatments where fungicide application began after symptom appearance, the number of applications was reduced further but disease control was 40% less effective. Model-timed fungicide treatments that included pyraclostrobin gave better control than the treatments using captan alone. The model relating leaf wetness and temperature to predict AFR infection can be used effectively in a disease-forecasting system to time fungicide treatments and greatly reduce the number of applications without loss of disease control or yield.

Use of Leaf Wetness and Temperature to Time Fungicide Applications to Control Botrytis Fruit Rot of Strawberry in Florida.

Botrytis fruit rot (BFR), caused by Botrytis cinerea, is a major disease of strawberry in Florida and is generally controlled by weekly fungicide applications. In this study, disease control programs using fungicides applied on a weekly basis were compared with applications based on three previously published models that correlated disease incidence with weather variables. Field trials were conducted for three seasons on two cultivars, 'Sweet Charlie' and 'Strawberry Festival'. Different thresholds for predicted BFR incidence were evaluated for triggering fungicide applications for the three models. BFR incidence in nontreated control plots of Sweet Charlie and Strawberry Festival was 12.4 and 3.5%, respectively, in 2006-07, 4.2 and 0.8% in 2007-08, and 1.3 and 0.5% in 2008-09. The model of Bulger and associates, with a threshold for disease flower incidence (INFBu) of 0.50, triggered half or fewer fungicide applications compared with a calendar-standard grower program, without significantly increasing BFR incidence or reducing yield. The model of Broome and associates, at a predicted fruit disease incidence threshold (INFBr) of 0.62, performed well but required more fungicide applications than the Bulger model (INFBu ≥ 0.50). The model of Xu and associates, based on field data to predict the incidence of diseased flowers, required more fungicide applications without improving disease control. Use of higher thresholds resulted in fewer applications but increased disease incidence in some cases. The Bulger model utilizing leaf wetness and temperature during the wetness period as input variables and a threshold of INFBu of 0.50 can be used effectively in a disease-forecasting system to time fungicide treatments, and greatly reduced the number of applications without loss of disease control or yield.

Control of Postharvest Botrytis Fruit Rot of Strawberry by Volatile Organic Compounds of Candida intermedia

A study was conducted to identify volatile organic compounds or volatiles produced by Candida intermedia strain C410 using gas chromatography-mass spectrometry, and to determine efficacy of the volatiles of C. intermedia in suppression of conidial germination and mycelial growth of Botrytis cinerea and control of Botrytis fruit rot of strawberry. Results showed that, among 49 volatiles (esters, alcohols, alkenes, alkanes, alkynes, organic acids, ketones, and aldehydes) identified from C. intermedia cultures on yeast extract peptone dextrose agar, two compounds, 1,3,5,7-cyclooctatetraene and 3-methyl-1-butanol, were the most abundant. Synthetic chemicals of 1,3,5,7-cyclooctatetraene; 3-methyl-1-butanol; 2-nonanone; pentanoic acid, 4-methyl-, ethyl ester; 3-methyl-1-butanol, acetate; acetic acid, pentyl ester; and hexanoic acid, ethyl ester were highly inhibitory to conidial germination and mycelial growth of B. cinerea. Inhibition of conidial germination and mycelial growth of B. cinerea by volatiles of C. intermedia was also observed. Meanwhile, results showed that incidence and severity of Botrytis fruit rot of strawberry was significantly (P < 0.01) reduced by exposure of the strawberry fruit to the volatiles from C. intermedia cultures or C. intermedia-infested strawberry fruit. These results suggest that the volatiles of C. intermedia C410 are promising biofumigants for control of Botrytis fruit rot of strawberry.

Pre- and post-inoculation activity of a protectant and a systemic fungicide for control of anthracnose fruit rot of strawberry under different wetness durations

A protectant fungicide (Captan, a.i. captan) and a systemic fungicide (Switch, a.i. fludioxonil + cyprodinil) were evaluated as pre- and post-inoculation applications for control of anthracnose fruit rot (AFR), caused by Colletotrichum acutatum, under a short (6 or 8 h) or long (18 or 24 h) wetting period. Evaluations were conducted for two seasons in Maryland and for two seasons in Florida. Both Captan and Switch were very effective for control of AFR when applied prior to inoculation, but control was more effective under the shorter wetting period. Switch was as effective when applied 4, 8, or 24 h post-inoculation as when applied before inoculation, but control was better under the short wetting period. Captan was effective when applied 4 or 8 h after inoculation under the short wetting period, but was ineffective at 24 h post-inoculation. Post-inoculation sprays of Captan were ineffective at any time under the long wetting period. The post-infection activity of Switch allows greater flexibility for managing AFR when fungicide applications are scheduled based on weather-based decision-support systems.

Preplant Fungicide Dips of Strawberry Transplants to Control Anthracnose Caused by Colletotrichum acutatum in California

Bare-root daughter plants of strawberry (Fragaria ×ananassa) were inoculated with Colletotrichum acutatum, the cause of crown rot, root rot, and fruit rot of strawberry in California. Plants were subsequently dipped in fungicide solutions or washed with running tap water immediately before planting in Summer and Fall 2002 and Fall 2004. Fungicide treatments reduced plant dieback by up to 92% in fruit production fields. Plants treated with azoxystrobin, the premixtures of boscalid + pyraclostrobin and cyprodinil + fludioxonil had 50% to 92% reduction in disease incidence, increased canopy size by more than 100%, and produced significantly higher marketable yields in all planting dates than the inoculated plants that were not treated with the fungicides. Chlorothalonil and captan also significantly reduced disease incidence but did not consistently increase marketable yield compared with the untreated, inoculated control. The effects of propiconazole and trifloxystrobin were inconsistent in reducing disease incidence. Water wash did not reduce root and crown disease incidence but significantly increased marketable yields by 13% over the untreated, inoculated controls in one of two plantings. No pretransplant treatments provided protection against fruit and foliar infection; thus, in-season fungicide applications would be necessary for disease control in commercial production fields if environmental conditions favored disease development.

Preplant Fungicide Dips of Strawberry Transplants to Control Anthracnose Caused by Colletotrichum acutatum in California

Bare-root daughter plants of strawberry (Fragaria ×ananassa) were inoculated with Colletotrichum acutatum, the cause of crown rot, root rot, and fruit rot of strawberry in California. Plants were subsequently dipped in fungicide solutions or washed with running tap water immediately before planting in Summer and Fall 2002 and Fall 2004. Fungicide treatments reduced plant dieback by up to 92% in fruit production fields. Plants treated with azoxystrobin, the premixtures of boscalid + pyraclostrobin and cyprodinil + fludioxonil had 50% to 92% reduction in disease incidence, increased canopy size by more than 100%, and produced significantly higher marketable yields in all planting dates than the inoculated plants that were not treated with the fungicides. Chlorothalonil and captan also significantly reduced disease incidence but did not consistently increase marketable yield compared with the untreated, inoculated control. The effects of propiconazole and trifloxystrobin were inconsistent in reducing disease incidence. Water wash did not reduce root and crown disease incidence but significantly increased marketable yields by 13% over the untreated, inoculated controls in one of two plantings. No pretransplant treatments provided protection against fruit and foliar infection; thus, in-season fungicide applications would be necessary for disease control in commercial production fields if environmental conditions favored disease development.

First Report of Fruit Rot of Strawberry Caused by an Alternaria sp. in Taiwan.

In March 2005, a fruit rot disease was found in several commercial strawberry (Fragaria × ananassa Duchesne) fields at Fongyuan, 24.25°N, 120.72°E, in Taichung County in central Taiwan. The disease was rare and was negligible in most cultivated areas. However, disease incidence has increased by 4 to 5% over the last 2 years and causes significant postharvest losses. In storage, symptoms on berries include light brown-to-black, sunken, irregularly shaped lesions. The lesions gradually enlarge and become firm with a dark green-to-black, velvety surface composed of mycelia, conidiophores, and conidia. Twelve single conidial isolates (AF-1 to AF-12) of a fungus were isolated by placing portions of symptomatic fruit from four locations onto acidified potato dextrose agar (PDA) and incubating at 24 ± 1°C. One isolate from each of the four locations, AF-2, 6, 9, and 12, was selected for identification and pathogenicity studies. The fungus was identified as an Alternaria sp. according to the morphological descriptions of A. tenuissima (2,3). Conidiophores were simple or branched, straight or flexuous, septate, pale to light brown, 3.0 to 5.0 μm in diameter, and bore two to six conidia in a chain. Conidia were dark brown, obclavate or oval, and multicellular with seven transverse (in most cases) and numerous longitudinal septa. Conidia were 15.5 to 56.5 μm (average 35.0 μm) long × 6.0 to 15.0 μm (average 11.0 μm) wide at the broadest point. The pathogen was consistently isolated from berries in the field or in storage. Pathogenicity tests were conducted by inoculating 12 surface-sterilized berries with each of the four isolates. Approximately 300 μl of a spore suspension (2 × 105 conidia per ml) was placed at two points on the uninjured surface of each fruit and allowed to dry for 5 min. Control fruits were treated with sterile water. The berries were then enclosed in a plastic bag and incubated at 24 ± 1°C for 2 days. Disease symptoms similar to those described above were observed on 95% of inoculated berries 3 days after inoculation, while no symptoms developed in control berries. Reisolation from the inoculated berries consistently yielded the Alternaria sp. described above. Pathogenicity tests were performed three times. Previously, strawberry fruit rot caused by A. tenuissima was reported from Florida (2) and Malaysia (1), however, to our knowledge, this is the first report of fruit rot of strawberry caused by a species of Alternaria in Taiwan.

Effect of volatile substances of Streptomycesplatensis F-1 on control of plant fungal diseases

Headspace volatile substances (VS) produced by Streptomyces platensis F-1 were preliminarily identified using GC–MS. The effects of VS released by S. platensis F-1 on the control of leaf blight/seedling blight of rice caused by Rhizoctonia solani, leaf blight of oilseed rape caused by Sclerotinia sclerotiorum and fruit rot of strawberry caused by Botrytis cinerea, as well as on the growth of these three pathogenic fungi, were investigated. Results showed that sixteen volatile compounds were tentatively identified in 1-week-old cultures of S. platensis F-1 grown on autoclaved wheat seeds. They could be chemically grouped into alcohols, esters, acids, alkanes, ketones and alkenes. The most abundant composition in volatiles of S. platensis F-1 is geosmin, an earthy-muddy–smelling compound. Two antifungal compounds, phenylethyl alcohol and (+)-epi-bicyclesesquiphellandrene, were detected in the volatile profile of S. platensis F-1. Consistent fumigation of healthy tissues of rice, oilseed rape and strawberry to VS of S. platensis effectively reduced the incidence and/or the severity of leaf blight/seedling blight of rice ( R. solani), leaf blight of oilseed rape ( S. sclerotiorum) and fruit rot of strawberry ( B. cinerea). A significant ( P < 0.05) suppression of the mycelial growth of R. solani, S. sclerotiorum and B. cinerea by the VS of S. platensis was observed. The potential of using VS of S. platensis F-1 as a biofumigant to control plant fungal diseases is discussed.

Detection of Colletotrichum acutatum latent infections in strawberry petioles and leaves

Colletotrichum acutatum is the most significant agent of anthracnose strawberry fruit rot. Besides being a necrotrophic pest, it can spend a part of its life cycle as an epiphyte, in a form of latent infection. The presence of the fungi on symptomless plant tissue is considered one of the main ways of distribution of this economically harmful pathogen in the world. Investigation of latent C. acutatum infection was carried out on artificially inoculated strawberries. The initiation of fungi sporulation on symptomless petioles and leaves was carried out by exposing them to the herbicide paraquat (0.25%) and low temperatures, which caused plant tissue decay in different ways. Surface sterilization with 0.5% NaOCl precedes the exposure of plant material to paraquat. The freezing procedure was carried out by exposure of plant material to the temperature of -20?C for 2h. After the freezing, one group was rinsed in Tween 20 (18 ?l/l), and another group underwent surface sterilization in 0.0525% NaOCl with an addition of Tween 20 (18 ?l/l). After 6 days of incubation, the appearance of acervuli and conidia was detected in 93.33 to 100% plant parts exposed to paraquat treatment and freezing procedure. In inoculated parts which were not exposed to herbicides or low temperatures, the presence of acervuli was detected in 3.33% tested petioles and 6.67% leaves.

Fruit rot of Strawberry pear (pitaya) caused by Bipolaris cactivora

Strawberry pear (pitahaya, pitaya) [Hylocereus undatus (Haw.) Britt. and Rose] postharvest fruit rot was found at an agricultural products store in Itoman city, Okinawa Prefecture in 2006. The symptoms included depressed, water-soaked lesions with olive to black powdery spots coalescing into a soft rot. The causal fungus was identified as Bipolaris cactivora (Petrak) Alcorn. This is the first report of strawberry pear fruit rot caused by B. cactivora.