Integrated approach for control of foliar diseases in strawberry runner nurseries and management of chemical resistance (original) (raw)
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Crop Protection, 2008
Strawberry powdery mildew is a serious disease and its control is based on chemical fungicides. The efficacy of alternatives to chemical fungicides was evaluated and their integration into strategies against strawberry powdery mildew to reduce pesticide residues on fruits was also tested. Bicarbonates and mineral oils were poorly effective. Biocontrol agents (BCAs), like Ampelomyces quisqualis, Bacillus subtilis and Trichoderma harzianum T39, controlled the disease, but to a lesser extent than chemical fungicides. When BCAs were alternated with chemicals, a significant reduction of chemical fungicide residues was achieved while maintaining good powdery mildew control. None of the tested strategies increased populations of the pest Tetranychus urticae, nor had side effects on the beneficial predatory mite Amblyseius andersoni populations and, consequently, they can be regarded as safe for the ecological balance of arthropods in strawberry greenhouses. r
V International Strawberry Symposium, 2006
In Croatia, strawberry production has been increasing steadily in recent years. The assortment of cultivars changes from year to year due to the introduction of new cultivars. The most popular cultivars currently in production are 'Elsanta', 'Marmolada', 'Maya', 'Madeleine', 'Miranda', 'Miss' and 'Raurica'. The aim of our research was to determine the sensitivity of these cultivars to major fungal foliar diseases in Croatia, namely: common leaf spot (Mycosphaerella fragariae), leaf scorch (Diplocarpon earliana), leaf blotch (Gnomonia comari) and leaf blight (Phomopsis obscurans). In order to determine the possibilities of controlling these diseases, we conducted tests of fungicide efficacy on the most sensitive cultivars. The infection intensity of each disease was assessed according to the Townsend-Heuberg formula based on an analysis of 200 leaves and our own scale of 0-5, while the fungicide efficacy was determined by Abbott's formula. Among the cultivars tested for common leaf spot, the most sensitive cultivar was 'Madeleine', followed by 'Marmolada', 'Maya' and 'Miss'. The other cultivars were relatively resistant to this disease. The cultivars most sensitive to leaf scorch were 'Miranda' and 'Raurica', while 'Marmolada' was somewhat less sensitive. Among the fungicides Folicur M and Euparen M were the most efficacious for all tested diseases, while Kidan SC and Quadris KS also had good efficacy. Based on the results we created a programme for control of foliar diseases.
Investigating novel approaches for the integrated control of the soilborne strawberry pathogens Macrophomina phaseolina and Fusarium oxysporum f. sp. fragariae Mel Carter Macrophomina phaseolina (Mp) and Fusarium oxysporum f. sp. fragariae (Fof) are emerging soilborne pathogens causing crown rot and Fusarium wilt, respectively, in commercial strawberry production in California. Fungicides representing eight active ingredients from four different mode of action groups (FRAC groups 1, 3, 7 and 12) were evaluated for their efficacy against each pathogen in vitro and each disease in planta. Fungicide active ingredients were evaluated for their ability to inhibit mycelial growth of both pathogens in vitro. Half-strength potato dextrose agar was amended with six different concentrations (0.01, 0.1, 1.0, 5.0, 10, 50 µg a.i./ml) of seven fungicides in FRAC groups 3, 7 and 12. Concentrations that inhibited fungal growth by 75% (EC75) compared to unamended media were determined for two different isolates each of Mp and Fof and were used to determine fungicide rates for subsequent in planta studies. Tebuconazole strongly inhibited the mycelial growth of both pathogens (average EC75 for Mp was 2.4 ppm; average EC75 for Fof was 7.48 ppm), as did metconazole (average EC75 for Mp was2.53 ppm; average EC75 for Fof was 1.28 ppm). Fludioxonil strongly inhibited mycelial growth of Mp, but had no impact on the growth of Fof. Penthiopyrad, fluopyram, flutriafol, and flutolanil were less effective at inhibiting fungal growth of either fungus. Greenhouse in planta studies evaluated twenty-four fungicide treatments v (eight fungicides at low, med and high rates) that were drench applied to infested potting media two days prior to planting of pathogen susceptible strawberry cultivars (San Andreas for Mp and Monterey for Fof) and again at day 21. Controls were a noninoculated and an inoculated water-drench treatment. Buried inoculum was recovered at days 2 and 23 and plated on selective media for colony forming unit (CFU) quantification. Plant disease assessments were made each week for 11 weeks. An analysis of variance (ANOVA) of CFUs revealed no significant differences (p > 0.05) among treatments and when compared to the non-treated control for both Mp and Fof, but showed significant decreases (p < 0.05) in CFUs between weeks 1 and 3 for both Mp and Fof. An ANOVA for disease assessments in the form of area under the disease progress curve (AUDPC) showed significant decreases of disease severity in treatments with penthiopyrad only (low, medium and high rates) (p < 0.05). There were no significant differences (p > 0.05) in AUDPC among treatments and when compared to the noninoculated and no-fungicide controls for Fof. The data indicates that these fungicides used alone are not effective against these pathogens in planta. A strawberry plant extract (germination stimulant) was assessed for its ability to stimulate germination of Mp microsclerotia in vitro and in planta. The germination stimulant was applied as a drench at six different concentrations (0, 10, 100, 1,000, 10,000 and 30,000 ppm) to soil containing filter disk packets of microsclerotia of Mp at day 0 and 14. Filter disk packets were retrieved three days after the drench and microsclerotia were observed microscopically for germination. Results showed that the number of germinating microsclerotia was significantly higher after the application of the germination stimulant compared to non-drench and 0 ppm controls (p < 0.001). vi An integrated container trial was also conducted using the germination stimulant at 10,000 ppm applied three days prior to a fungicide drench with tebuconazole or thiophanate-methyl to determine the effect of fungicides on the germinated microscleotia. The use of the germination stimulant with label rates of the fungicides lowered the number of germinated intact microsclerotia significantly (p < 0.001) especially after two drench applications. The use of the germination stimulant with fungicides could be investigated further as one method for controlling soilborne diseases of strawberry.
Japanese Journal of Farm Work Research, 2021
Extensive use of sterol demethylation inhibitor (DMI) fungicides against strawberry powdery mildew has resulted in DMI-resistant genotype emergence. In this study, we examined the preventive effect of hot water spraying (HWS) on the occurrence of powdery mildew in everbearing strawberry, predominantly infected by DMI-resistant powdery mildew fungi from 2016 to 2018. Hot water of 54 1°C was sprayed on Natsuakari for 20 s to achieve the target leaf temperature of 50°C. Disease occurrence under the chemical fungicide (F) + HWS treatment was less severe than that under the F treatment until the end of the cultivation period in February 2018. However, the preventive effect of HWS was not observed in already infected leaves. The incidence of DMI-resistant genotype was 0% at the start, and it increased to 62% and 100% in the infected fruits and leaves (including F+HWS) in September and November 2016 until the end of cultivation, respectively. On the contrary, disease severity increased between August 2017 and February 2018 under the F treatment, whereas only a slight infection was detected under the F+HWS treatment. Thus, HWS could induce resistance in strawberry against powdery mildew fungi, including DMI-resistant fungi, and effectively control the occurrence of powdery mildew in long-term everbearing strawberry cultivation.
Crop Protection, 2013
Biological control of plant pathogens on strawberries may be improved by the simultaneous application of different biological control agents (BCAs). Therefore, the compatibility of various BCAs which had previously shown to be effective against powdery mildew (Podosphaera aphanis (Wallr.) U. Braun & S. Takam) under laboratory conditions was examined in vitro. Inhibitory effects between fungal and bacterial BCAs were demonstrated in dual culture tests on two solid nutrient media. Leaf disc assays with single and multiple strain treatments demonstrated either unaffected or significantly improved control of P. aphanis for many multiple strain treatments, even if antagonistic interactions previously occurred in dual culture tests. Highest inhibition of powdery mildew conidiation (80.7% reduction) was achieved with multiple strain treatments with Bacillus subtilis FZB24 and Metarhizium anisopliae (p < 0.001). In this combination, conidiation was 3.7 times lower than in single treatments with B. subtilis indicating synergistic interactions between these BCAs. Combinations of Trichoderma harzianum T58 and B. subtilis FZB24 showed antagonistic interactions in dual culture tests as well as in leaf disc assays. In this combination, powdery mildew conidiation on leaf discs was four times higher compared to single treatments with T. harzianum T58.
Integrated Management of Fungal Diseases in Strawberry
An experimental trial with eight treatments viz. carbendazim 50 WP (0.05%), hexaconazole 5 EC (0.03%), mancozeb 75 WP (0.3%) cultural control (removal of older leaves + weeding), aqueous extracts of datura leaves, extract of garlic cloves, mulching (polythene) and check (without treatment) in RBD manner was carried out in Research Farm of SKUAST-K. Treatments were replicated thrice. The data on individual effect of treatments revealed that five diseases viz. root rot (Pythium sp. Rhizoctonia solani), fruit rot (Botrytis cineria), Alternaria leaf blight (Alternaria alternata), leaf spot (Hainesia lythri) and foliage blight (Sclerotium rolfsii) were noticed in variable per cent disease index (PDI), whereas, fruit rot caused by Botrytis cineria did not appear in beds where three sprays of carbendazim, mancozeb and hexaconazole were given after 15 days interval but mulching with polyethylene in the month of June also gave excellent result and no fruit rot incidence was observed. Minimum root rot (0.23%) was recorded when carbendazim was sprayed than that of other treatments. Cultural practices comprised with removal of basal leaves and weeding had profound effect after the fungicidal sprays. In case of Alternaria leaf blight, spray of the crop with hexaconazole reduced its incidence and recorded minimum PDI (2.67) than other treatments but cultural practices and extract of garlic cloves exhibited almost at par effect against Alternaria leaf blight. Among the major diseases, leaf spot caused by Hainesia lythri was significantly checked by all the treatments and minimum leaf spot was recorded when crop was treated with carbendazim and hexaconazole followed by cultural practices (5.67) but effects of extracts and mulching had at par effect. Despite, foliage blight caused by Sclerotium rolfsii also occurred on vines, blossom and leaves of crop in variable PDI whereas minimum PDI (2.33) was noticed when crop was sprayed with hexaconazole but cultural practices and mulching showed at par effect (7.33). Similarly, maximum fruits weight was computed in carbendazim followed by hexaconazole while as other treatments also gave significant fruit yield over control.
Powdery mildew, caused by Podosphaera aphanis, is one of the major fungal diseases of cultivated strawberry (Fragaria × ananassa Duchense) world-wide. In the present research we report the efficacy of various control agents in induced resistance in strawberry plants against Powdery mildew. Inducers tested are Trichoderma harzianum T39, acibenzolar-S-methyl (Bion), a new protein hydrolysate inducer, an isolate of a bacterium and one of a yeast, and biochar. These agents induced systemic resistance when applied to the root zone, while the disease was found and measured on the leaves. In addition, we studied the effect of T39, Bion and biochar on plant defense related gene expression. We show that while Bion induced Systemic Acquired Resistance (SAR) only, as expected, T39 as well as biochar induced SAR and Induced Systemic Resistance (ISR).
BioTech
Grey mould, caused by Botrytis cinerea and other Botrytis spp., is a major cause of fruit rot in strawberries and other fruit crops worldwide. Repeated fungicide applications are essential in order to secure harvests. However, resistance to all currently registered single-site fungicides is widespread. The rising importance of strains with multiple resistance to most or all fungicides is of particular concern. These strains may be introduced into fields via contaminated nursery plants and/or by immigration from adjacent plots. On the basis of research conducted in northern German and Danish strawberry production, a concept to manage fungicide resistance under northern European conditions has been developed and put into regional strawberry production practice. This principally includes the testing of nursery plants for fungicide-resistant Botrytis strains prior to planting; the restricted and specific use of fungicides at flowering in the production fields, taking account of the resi...