Examinando por Materia "Fusarium wilt"

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Biosecurity for small growers of local and organic export banana in Peru – seeking synergies with food safety and ecological intensification
(International Society for Horticultural Science, 2023-05-17) Staver, C.; Delgado, R.; Rojas Llanque, Juan Carlos; Rivas, J. C.
For decades, banana Fusarium wilt Race 1 (FWR1) has spread throughout banana growing areas of Peru. In response, small growers have changed cultivars and crops. The threat of FW to bananas countrywide has worsened with the detection of Fusarium wilt Tropical Race 4 (FWTR4) in organic export banana on the northern coast. Farm-level biosecurity measures to reduce the risks of FWTR4/R1 are directed toward physical barriers and control points to minimize vehicles and persons entering and leaving the farm and ensure their sanitation. We completed a diagnostic study of biosecurity practices in two smallholder banana-growing regions – organic export Cavendish on the north coast and cultivars for national markets often susceptible to FWR1 in the central Selva. Simultaneously we examined the potential to increase productivity through ecological intensification and to gain market acceptability through food safety measures. We hypothesized that among resource-scarce growers, biosecurity measures which contribute to productivity and food safety requirements will be more readily put into practice. Seven farms in central Selva and five marketing associations were profiled through site visits, drone views and structured interviews. Interviews were also conducted with research and regulatory agencies. The assessment showed that growers in both zones had received little training on banana disease symptoms and epidemiology and were not implementing biosecurity measures. In the central Selva, planting material appeared to be the major path for FWR1 spread and 6 of 7 farms visited already had infected fields. On the north coast, fields are contiguous joined by flood irrigation and served by over 75 mobile packing sheds and harvesting crews which move from farm to farm and sector to sector without biosecurity measures, both contributing to major risk of spread. Inspectors for certification in both regions and input sales representatives on the north coast arriving from abroad are not subject to biosecurity measures. Practical training on disease symptoms, characteristics and management of healthy planting material and epidemiology-based risk assessment and the promotion of multi-purpose living hedges as barriers could contribute to biosecurity, productivity and food safety, while control of international and local visitors addresses biosecurity and food safety.
First report of Fusarium oxysporum f. sp. cubense tropical race 4 causing Fusarium wilt in Cavendish bananas in Peru
(American Phytopathological Society, 2022-06-29) Acuña, R.; Rouard, M.; Leiva, A. M.; Marques, C.; Olortegui, J. A.; Ureta, C.; Cabrera Pintado, Rosa María; Rojas Llanque, Juan Carlos; Lopez Alvarez, Diana; Cenci, A.; Cuellar, W. J.; Dita, M.
Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), the causal agent of Fusarium wilt of banana (FWB), is currently the major threat to the banana industry worldwide (Dita et al. 2018). Restricted to South Asia for more than 20 years, Foc TR4 has spread in the last years to the Middle East, Mozambique, and Colombia (García-Bastidas et al. 2020; https://pestdisplace.org/embed/news/map/disease/11). The incursion of Foc TR4 in Colombia increased awareness and prevention efforts across Latin America and the Caribbean (LAC). However, new Foc TR4 outbreaks in LAC countries were considered inevitable. In April 2021, banana (Musa spp., Cavendish, AAA) plants (30% of incidence) showing typical symptoms of FWB, such as leaf yellowing, wilting, and vascular discoloration, were observed in one farm (about 1 ha) located in Querecotillo, Peru (4°43′54.84″ S, 80°33′45.00″ W). Mycological analyses of samples (pseudostem strands) collected from 10 symptomatic plants were performed as described by Dita et al. (2010). These analyses revealed a continuous presence of fungal colonies identified as F. oxysporum species complex. Molecular diagnostics targeting two different genome regions (Dita et al. 2010; Li et al. 2013) identified nine of these isolates as Foc TR4. These results were further confirmed by qPCR analyses using the commercial Clear Detections TR4 kit. The genomes of four single-spore isolates (PerS1, PerS2, PerS3, and PerS4) were sequenced using the Illumina platform (MiSeq Kit, 2x151 bp Paired-End). The strain PerS4 was also sequenced using Oxford Nanopore (FLOW-MIN111; R10.3 chemistry) as described by López-Alvarez et al. (2020). The generated draft assembly yielded 533 contigs for a size of 47 Mbp (BioProject: PRJNA755905), which is comparable with sizes of previously reported Foc TR4 strains (Asai et al. 2019; García-Bastidas et al. 2020; Maymon et al. 2020; Warmington et al. 2019; Zheng et al. 2018). The sequence assembly showed high contiguity (94.9%) and high similarity (95.48%) with the high-quality genome sequence of the Foc TR4 isolate ‘UK0001’ (Warmington et al. 2019). Further analyses to identify the presence/absence of full sequences for the putative effector genes (Secreted in Xylem - SIX) and their allelic copies also revealed that the SIX gene profiles of the strains isolated from Querecotillo matched with previously reported Foc TR4 isolates (Czislowski et al. 2017). Pathogenicity tests with three isolates and water controls were performed as described by Dita et al. (2010), using five Cavendish plantlets per treatment. Four weeks after the inoculation, typical external and internal symptoms of FWB were observed only in the inoculated plants. Fungal isolates recovered from inoculated plants tested positive for Foc TR4 when analyzed with PCR diagnostics as mentioned above. No fungal isolates were recovered from water-control plants, which did not show any symptoms. Altogether, our results confirm the first incursion of Foc TR4 in Peru. Currently, Foc TR4 has the phytosanitary status of a present pest with restricted distribution in Peru, and it is under official control of the National Plant Protection Organization – SENASA. Reinforced prevention and quarantine measures, disease monitoring, and capacity building to detect, contain and manage eventual new outbreaks of Foc TR4 are strongly encouraged across LAC banana-producing countries, especially those bordering Peru with larger banana plantations, such as Ecuador and Brazil.