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Chamorro M.,Centro IFAPA Las Torres Tomejil CAPDR JA | Aguado A.,Centro IFAPA Las Torres Tomejil CAPDR JA | de los Santos B.,Centro IFAPA Las Torres Tomejil CAPDR JA
Plant Disease | Year: 2016

Strawberry (Fragaria x ananassa Duch.) is one of the most important crops in Huelva (southwestern Spain) with 7,300 ha cultivated in 2012 yielding 275,300 tonnes (98% of the total Spanish production). At the beginning of the 2013-2014 season, a low incidence of mortality (~1%) in strawberry plants cultivated at Huelva Province was observed. Symptoms consisted of discoloration or brown necrotic areas in crown and root. To isolate the causal agent, crowns and roots were surface disinfected for 2 min in 1% sodium hypochlorite, rinsed twice in sterile distilled water, air dried in a laminar-flow cabinet, and plated on potato dextrose agar (PDA). Pure cultures of the fungus were grown on PDA at 25°C with a 12-h photoperiod for 7 to 10 days. Fungal colonies were white and cottony, edge undulate, circular (upper side), and pale luteous (reverse side). The acervuli (avg. 280 μm) were black, concentric, and appeared throughout the entire plate after 10 days. Conidia were fusiform to ellipsoid and five-celled (average 22.7 × 7.7 μm) (n = 100). Apical and basal cells were hyaline, whereas the third and fourth cells from the base were darker (brown) than the second cell from base (pale brown). Conidia had one basal appendage (average 9.5 μm) and two to four apical appendages (avg. 25.9 μm). On the basis of colony and conidia morphology, isolates were identified as Pestalotiopsis clavispora(G.F. Atk.) Steyaert, recently renamed as Neopestalotiopsis clavispora (Maharachchikumbura et al. 2014). The identification as P. clavispora was confirmed by amplifying and sequencing of three genetic regions: ITS [(ITS1, 5.8S, ITS2) (GenBank Accession No. KU096879), β-tubulin (KU096880), andtef1 gene (KU096881) from three isolates (Maharachchikumbura et al. 2012). BLAST analysis showed in all cases 98 to 99% identity with P. clavispora [KM402033.1 (ITS); KC537822.1 (β-tubulin); and KM402034.1, JX399044, and KC537815.1 (tef1)]. Pathogenicity assays were carried out in a randomized complete block design with three blocks of 12 plants each, divided among three isolates and a control. Three isolates were compared with noninoculated controls on three strawberry cultivars: ‘Florida Radiance,’ ‘Sabrina,’ and ‘Splendor.’ The roots of three strawberry transplants per isolate were dipped for 4 min in a conidial suspension (1•105 conidia/ml) from 10-day-old PDA cultures and planted in pots (14-cm diameter) filled with sterilized soil. Control plants were dipped in sterilized 0.01% Tween-20. Plants were held at 25°C and 40/70% relative humidity (day/night) in a growth chamber with a 16-h photoperiod. After 3 months of incubation, the mortality of the inoculated plants was: 7.4, 7.4, and 11.1% for Florida Radiance, Splendor, and Sabrina, respectively. No mortality was observed in the control plants. About 23.4% and 25.9% of the inoculated plants showed more than 75% of root rot and crown rot, respectively. The experiment was repeated twice. All isolates showed similar pathogenicity. P. clavispora was consistently reisolated from symptomatic plants. P. clavisporahas been reported causing canker and dieback on blueberry in Chile (Espinoza et al. 2008) and Uruguay (González et al. 2012). P. longisetula has been reported as the cause of strawberry fruit rot in Egypt (Embaby 2007), but to our knowledge, this is the first report of P. clavispora causing crown and root rot of strawberry worldwide. © 2016 The American Phytopathological Society. Source


Chamorro M.,Centro IFAPA Las Torres Tomejil CAPDR JA | Dominguez P.,Centro IFAPA Las Torres Tomejil CAPDR JA | Medina J.J.,Centro IFAPA Las Torres Tomejil CAPDR JA | Miranda L.,Centro IFAPA Las Torres Tomejil CAPDR JA | And 6 more authors.
Scientia Horticulturae | Year: 2015

The phase-out of methyl bromide (MB) in strawberry has increased the difficulty of controlling Macrophomina phaseolina, a soil-borne pathogen and causal agent of charcoal rot disease. In this study, several chemicals and one biosolarization treatment were compared for the control M. phaseolina in three successive seasons between 2009 and 2011. Trials were conducted in two fields with different history of chemical soil treatments in the south-western coast of Spain (Huelva). At Fres-Gómez S.L. farm (Palos de la Frontera), the soil was fumigated with 1,3-dichloropropene:chloropicrin from 2005 to 2008, whereas the soil of Occifresa S.C.A. farm (Moguer), was fumigated with MB until 2001. We determined treatment effects on plant mortality, M. phaseolina population in soil over time, and fruit yield. Five treatments were applied during the 2009-10 season: biosolarization with chicken manure, dazomet + 1,3-dichloropropene, 1,3-dichloropropene:chloropicrin, chloropicrin, and dimethyl disulfide + chloropicrin by shank. During the 2010-11 and 2011-12 seasons, two additional treatments were added: dimethyl disulfide + chloropicrin through drip irrigation and dazomet. An untreated control was also included in all tests. Strawberry cv. 'Camarosa' was grown following Spanish standard production practices in high plastic tunnels. Over each season, most treatments reduced M. phaseolina populations in soil 20-100%. However, populations were not significantly reduced by the dimethyl disulfide + chloropicrin applied through drip irrigation. In both farms, treatments reduced plant mortality caused by charcoal rot 35-100% and increased yields 5-56% relative to the untreated control during all three seasons. Economic analyses showed that the cost of treatments was easily offset by increases in yield. © 2015 Published by Elsevier B.V. Source


Chamorro M.,Centro IFAPA Las Torres Tomejil CAPDR JA | Miranda L.,Centro IFAPA Las Torres Tomejil CAPDR JA | Dominguez P.,Centro IFAPA Las Torres Tomejil CAPDR JA | Medina J.J.,Centro IFAPA Las Torres Tomejil CAPDR JA | And 4 more authors.
Crop Protection | Year: 2015

Macrophomina phaseolina, the causal agent of charcoal rot, is a primarily soil-borne pathogen. Charcoal rot has become increasingly troublesome in strawberry (Fragaria×ananassa Duch.) in Spain, where it was reported for the first time in 2006, and worldwide. After the phase out of methyl bromide, some authors have associated the changes in the fumigation products used and methods of applying them prior to planting strawberries with the establishment of M.phaseolina. Moreover, in developed countries, the majority of useful chemical alternatives are futureless, because of regulatory restrictions. Among the non-chemical alternatives for strawberry fruit production is soil biosolarization, a new technique that combines soil biofumigation and soil solarization. In this study, we compared the efficacy of several biosolarization treatments to control M.phaseolina for three successive seasons in a non-chemical treated field near Moguer, Huelva (southwestern Spain). The influence of these treatments on M.phaseolina soil population, charcoal rot development, and strawberry yield was assessed each year. Soil was biofumigated by amendment of fresh chicken manure at 12,500kg/ha with or without Trichoderma spp (TUSAL®) at 3.5kg/ha; fresh chicken manure at 25,000kg/ha; Brassica spp. pellets (BIOFENCE®) at 2000kg/ha and 15,000kg/ha; dried olive pomace at 12,500kg/ha or sugar beet vinasse at 15,000kg/ha. Soil was then solarized for 30 days by covering with a clear plastic mulch. A control that received fermented manure remained uncovered. The treatments reduced or stabilized M.phaseolina sclerotia populations in soil compared to the untreated control. Treatments which combined biosolarization with chicken manure at 25,000kg/ha or sugar beet vinasse at 15,000kg/ha significantly reduced the incidence of charcoal rot compared to the untreated control. Furthermore, yields obtained by amendment with fresh chicken manure (59,319-89,421kg/ha) were also similar to the yields previously reported for the standard chemical fumigation with 1,3-dichloropropene:chloropicrin. Therefore, biosolarization with fresh chicken manure could be a promising and sustainable option for strawberry crops grown in warm temperate climate areas. © 2014 Elsevier Ltd. Source

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