First report of Nalanthamala vermoesenii causing pink rot of Phoenix canariensis in Mexico

In Mexico City, the Canary Island date palm ( Chabaud) is an important plant forming part of its landscape identity. In February 2022, pink rot disease symptoms were observed on 16 plants in Mexico City (19°25'43.98"N, 99° 9'49.41"W). The incidence was 27%, while the severity 12%. External symptoms included necrotic lesions that advanced from the petiole towards the rachis. Internal symptoms were rotted, dark brown discoloration in bud, petiole, and rachis. Abundant conidial masses were developed on the infected tissues. Pieces of diseased tissues (5-mm cubes) were surface sterilized for 2 min in 3% sodium hypochlorite, rinsed with sterilized distilled water, plated onto potato dextrose agar (PDA), and incubated at 24°C and 12-h photoperiod, 20 pink fungal colonies were developed with sparse aerial mycelia on PDA. Conidiophores were hyaline, dimorphic, penicillate, and -like. Conidia were dimorphic, typically with somewhat truncated ends, 4.5 to 5.7 × 1.9 to 2.3 μm (mean 4.99 × 2.15, n = 100), borne in long chains on penicillate conidiophores; on -like conidiophores conidia were cylindrical, straight, and slightly curved, 4.55 to 10.1 × 1.2 to 2.35 μm (mean 8.2 × 1.7, n = 100). These morphological characteristics resembled those of (Biourge) Schroers (Schroers . 2005). Genomic DNA was extracted from the mycelia of a representative isolate CP-SP53. The internal transcribed spacer (ITS) region and the large subunit of ribosomal ribonucleic acid (LSU) were amplified and sequenced. The sequences were deposited in GenBank with accession numbers OQ581472 (ITS) and OQ581465 (LSU). Phylogenetic trees based on ITS and LSU sequences of species were reconstructed using maximum likelihood and Bayesian inference methods. Isolate CP-SP53 was placed in the clade of . The pathogenicity test was carried out twice with isolate CP-SP53 on five 3-year-old plants. Four petioles per plant were surface disinfected with 75% ethanol, and wounded with a sterilized scalpel (shallow cuts 0.5 cm wide). A mycelial plug (5 mm in diam.) of a 1-week-old PDA culture was placed on each wounded site. Sterile PDA plugs were used for five non-inoculated control plants. All plants were maintained at 22 ± 2°C and a 12-h photoperiod. Twenty-five days after inoculation (dai), wounded petioles showed the same symptoms observed in the field, whereas control plants remained healthy. Forty-five dai, all inoculated plants died. Pink conidial masses developed on symptomatic tissues. To fulfill Koch's po