Between late 2022 and early 2023, Aloe vera plants in three cultivated sites in the Achchuveli region of Jaffna, Sri Lanka, showed widespread tip necrosis, with a disease incidence of 80%. Symptoms included necrotic lesions at leaf tips, bordered by a chlorotic zone separating healthy tissue. The lesions extended downwards, causing leaf yellowing, reduced succulence and eventual leaf loss (Figure 1). Affected plants also exhibited stunted growth compared to healthy ones. Pure cultures were obtained by isolating fungi from 18 diseased leaves on potato dextrose agar and subculturing on the same medium. Isolates produced slow-growing, cottony colonies with aerial mycelium, creamy yellow undersides with grey concentric rings and developed black pycnidial conidiomata (Figure 2). Conidia were fusiform to ellipsoidal (24.53 ± 1.18 µm × 7.69 ± 0.00 µm, n = 30), 4-septate, with thick-walled, cylindrical, yellow-brown median cells; triangular apical cells with 2–3 appendages; and hyaline, truncate basal cells (Figure 3). Based on these morphological features, the isolates were identified as Pestalotiopsis sp., consistent with descriptions by Maharachchikumbura et al. (2011). Total DNA was extracted from representative isolates ATN1, ATN3 and ATN4. The ITS region and partial regions of translation elongation factor 1-α (TEF1) and β-tubulin (TUB2) genes were PCR-amplified and sequenced, and sequences were submitted to GenBank (Accession Nos. for ITS: PP464154, PV799931, PV799932; TEF1: PX692865, PX692866, PX692867; and TUB2: PX692862, PX692863, PX692864, for ATN1, ATN3 and ATN4, respectively). Multi-locus phylogenetic analysis using Maximum Likelihood and Bayesian Inference methods grouped all three isolates in a single clade with P. biciliata strain CBS 124463, supported by 87% bootstrap value and a posterior probability of 0.97, confirming their identification as the P. biciliata (Figure 4). To confirm pathogenicity, six surface-disinfected leaf tips were sprayed with 1 mL of conidial suspension (1 × 105 conidia/mL), while controls received sterile distilled water. Leaves were incubated at 27°C ± 2°C with a 16-h photoperiod. The test was repeated three times. Symptoms appeared within 4 days as brown necrotic patches at leaf tips, later expanding, merging and causing chlorosis, leaf margin rolling and reduced succulence. Fungi re-isolated from symptomatic leaves matched the original isolates, while controls showed no symptoms (Figure 5). P. biciliata has been reported on Eucalyptus spp. (Morales-Rodríguez et al. 2019) and Pinus pinea (Hlaiem et al. 2022), while Pseudopestalotiopsis theae was linked to A. vera leaf spot in Bangladesh (Ahmmed et al. 2022). In Sri Lanka, Lasiodiplodia species and Nigrospora sphaerica have been reported to cause diseases in A. vera (Thangarajah and Emmanuel 2024; Kathurjan and Emmanuel 2025). However, this is the first report of P. biciliata causing tip necrosis in A. vera and its first record in Sri Lanka. The work was supported by funds obtained from the University Research Grant (URG/2019/SEIT/24), University of Jaffna, Sri Lanka.
Kathurjan et al. (Thu,) studied this question.