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Búsquedas previas al 2023, Núm. 3. En la sección Volúmenes 30 - 41 (2012 - 2023).
Characterization and fungicide sensitivity of fungi causing postharvest deterioration in Allium sativum, Nuevo León, Mexico
By Germán Ramírez Jiménez, Omar G. Alvarado Gómez, Magdiel Torres de la Cruz*, Miguel Ángel Mayo Hernández, Ángel F. Huamán Pilco, Jorge R. Díaz Valderrama
* Corresponding Author. Email: / Institution:
Received: 07/June/2024 – Published: 21/February/2025 – DOI: https://doi.org/10.18781/R.MEX.FIT.2406-2
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Abstract Background/Objective. Garlic (Allium sativum) is a crop of economic relevance in Mexico. Nuevo León stands out in production; however, in the municipality of Aramberri, post-harvest losses have been reported due to diseases of unknown etiology. The objective of this work was to identify the fungi associated with the postharvest deterioration of A. sativum bulbs in Aramberri, Nuevo León, Mexico and to evaluate their in vitro sensitivity to fungicides.
Materials and Methods. From bulbs with evidence of deterioration and necrosis, fungi were isolated in PDA medium. Four isolates were identified by morphological analysis and one isolate from each morphological species was identified by molecular analysis. The pathogenicity of the four isolates on symptom-free bulbil was evaluated. In addition, in vitro susceptibility tests of the isolates to protective and systemic fungicides were performed. Fungicides were evaluated at three concentrations and mycelial growth reduction (MGR) and conidial germination inhibition (CGI) was estimated.
Results. The fungi Alternaria embellisia and Penicillium allii were identified in association with A. sativum bulbs with postharvest deterioration. P. allii showed the ability to develop internal infections from wounds; A. embellisia only showed growth on wounds. There were significant differences (p <0.0001) in the effectiveness of fungicides on the two species. Propiconazole and copper hydroxide inhibited 100% MGR and CGI in both fungi, at all doses evaluated.
Conclusion. P. allii is first reported as a causative agent of green garlic rot in Mexico. This study will serve as a basis for choosing control strategies and will contribute significantly to reducing economic losses in garlic production in this region.
Keywords: Carbendazim, mycelial inhibition, germination inhibition, propiconazole, tebuconazole.
Table 1. Systemic and protectant fungicides evaluated against Alternaria embellisia and Penicillium allii.
Table 2. Effectiveness of systemic and protectant fungicides on mycelial growth and spore germination of Alternaria embellisia and Penicillium allii in vitro.
Figure 1. A. Allium sativum bulbs of the “Don Fermín“ variety showing postharvest deterioration. B. A. sativum bulbils with cankers and green mold.
Figure 2. Alternaria embellisia (syn. Embellisia allii), isolates AL1D2B and AL1D3B. A. Seven-day-old colony growing on PDA medium at 25 °C. B, C. Simple conidiophore and solitary conidium. D, E. Branched conidiophore. F. Septate conidia. G, H. Chlamydospores.
Figure 3. Penicillium allii, isolates AL1D4B and AL1D5B. A. Seven-day-old colony growing on PDA medium at 25 °C. B. Conidiophore showing stipe and metula with rough walls. C. Conidiophore. D. Conidiophore with phialides and conidiation forming chains. E. Conidia. F, G. Terminal and intercalary chlamydospores.
Figure 4. A. Maximum likelihood phylogenetic tree constructed from partial sequences of the internal transcribed spacer 1 and 2 regions within the 5.8S rDNA subunit for the isolation of Alternaria embellisia (GenBank accession number: PP869831). B. Maximum likelihood phylogenetic tree constructed from partial sequences of the β-tubulin gene for the isolation of Penicillium allii (GenBank accession number: PP920512); both obtained from garlic bulb samples with postharvest rot in Aramberri, Nuevo León. Data for other Alternaria strains and species were obtained from Pryor and Bigelow (2003), while data for other Penicillium strains and species were sourced from Samson et al. (2004). The numbers next to the nodes indicate bootstrap support values in percentage.
Figure 5. Pathogenicity test of (A) Penicillium allii (AL1D4B) and (B) Alternaria embellisia (AL1D2B) on Allium sativum bulbils, 14 days after inoculation. (C) Control. Each bulbil in the same column represents repetitions of the isolate.
