During the harvest of 2020 and 2021, sweet cherry (Prunus avium) fruit showed a firm rot with irregular pale to dark brown lesions on the fruit surface, with green to light brown fungal growth resembling Alternaria-like infection (Simmons, 2007). Diseased cherries (n= 80 fruit) were collected at harvest in mature (over 10-year-old) commercial orchards of cherry tree varieties Lapins, Regina, Santina, Skeena, and Sweetheart planted in four localities of the regions O´Higgins (33°59´ S, 70°42´W; San Francisco de Mostazal and Graneros) and Maule (35°00'S, 71°23´W; Curicó and Sagrada Familia), Central Chile. The incidence of black rot was 1.9 and 3.2% in O´Higgins and Maule region, respectively, and it was increased to up to 5% during cold storage. The fruit collected previously, were transported to the lab, and surface disinfected in 75% ethanol for 15 s, and rinsed in sterile water. Internal pieces from the junction of diseased and healthy tissues of fruits were placed on potato dextrose agar (PDA, 2%) for 7 days at 20°C. Forty-two isolates of Alternaria-like (Simmons, 2007) were recovered consistently from pure cultures taking hyphal tips from 7 days old cultures. On PDA, 28 isolates (group A) were characterized by cottony, white-gray to green colonies and conidial chains (4 to 10 conidia) with secondary chains (1 to 5 conidia) branching on the conidiophore. Conidia were ovate to obclavate (mean 22.8 ± 5.1 x 8.8 ± 1.5 μm; n=40) with 3 to 7 transepta and 1 longisepta. The remaining 14 isolates (group B) were characterized by cottony, olive-green to olive-brown colonies following a ring pattern of growth and white margins, with conidial chains (4 to 14 conidia) and uncommon secondary chains (1 to 4 conidia). Conidia were obpyriform to ovate, light brown to brown with a cylindrical short beak at the tip (mean 24.7 ± 5.9 × 11.2 ± 1.3 μm; n=40) with 2 to 4 transepta, and 0 to 2 longisepta. Two representative isolates of group A (Sant-02-2020 and Bing-03-2020) and group B (Sant-26-2021 and Skeen-43-2021) were amplified for the Alternaria major allergen (Alt a1), plasma membrane ATPase (ATP), and calmodulin (Cal) loci following the protocols described by Hong et al. (2005) and Lawrence et al. (2013). A MegaBlast search of sequences of group A (GenBank nos. OR267293- OR267294, OR258001- OR258002, and OR267297- OR267298, for Alt a1, ATP, and Cal, respectively) showed 100% similarity to strains UCD10529 and UCD10539 of A. alternata, and group B (GenBank nos. OR267295- OR267296, OR258003- OR258004, and OR258005- OR258006, for Alt a1, ATP, and Cal, respectively) showed 100% similarity to strains EGS 34-015 and A30 of A. tenuissima. Combined phylogenetic analysis using MEGA X clustered isolates Sant-02-2020 and Bing-03-2020, and Sant-26-2021 and Skeen-43-2021 with ex-type of A. alternata and A. tenuissima, respectively. Pathogenicity tests were conducted using isolates of A. alternata (Sant-02-2020; Bing-03-2020) and A. tenuissima (Sant-26-2021; Skeen-43-2021). Detached ripe cherry fruit var. Sweetheart (n=40 fruits/isolate) and Regina (n=40 fruits/isolate) were surfaces disinfested (75% ethanol, 30 s), wounded in the middle with a sterile needle (2 mm in depth), and inoculated with 20 μL of conidial suspension (106 conidia/mL). An equal number of healthy cherries (n=40 fruits) treated with sterile water were used as controls. The experiment was repeated once. All inoculated fruit incubated for 7 days at 22°C, developed between 13 ± 2.7 to 23 ± 2.5 mm and 14.1 ± 1.1 to 19 ± 3.6 mm in lesion diameter for A. alternata and A. tenuissima isolates, respectively. Koch´s postulates were fulfilled by 100% reisolation of the causal pathogen from inoculated fruit, and molecular identification of A. alternata and A. tenuissima isolates. Previously, A. alternata has been described as causing rots on cherries in Chile (Acuña 2010), and China (Zhao and Liu, 2012; Ahmad et al., 2020). To our knowledge, this is the first occurrence of cherry black rot caused by A. alternata and A. tenuissima in Central Chile. Epidemiological studies are necessary to develop integrated management of cherry black rot in Central Chile.

English walnut (Juglans regia), cv. Chandler is the most cultivated tree nut in Chile, with 43,734 ha. In Maule Region, central Chile, English walnut plantings have expanded over an additional 7,00...

Botryosphaeria dieback disease is a significant grapevine trunk disease (GTD) caused by species of Botryosphaeriaceae in Chile and worldwide. Moreover, Botryosphaeriaceae have been described attacking fruit and nut crops in Chile. However, it remains unknown whether fungal isolates from tree hosts have the potential to infect grapevines in Chile. The aggressiveness and potential cross infection of species of Botryosphaeriaceae collected from crops (grapevines, apples, blueberries, and walnuts), was assessed on grapevines. Plant materials, including nursery cuttings, lignified canes, and green shoots of grapevine cultivars (Cabernet Sauvignon, Syrah, Sauvignon Blanc, Malbec, Aspirant Bouschet, and Merlot), were inoculated with Diplodia mutila, D. seriata, Dothiorella sarmentorum, Lasiodiplodia theobromae, Neofusicoccum arbuti, and N. parvum, under greenhouse and vineyard conditions. Regardless of the origin of the isolates, most species of Botryosphaeriaceae were pathogenic on plant materials, causing necrotic lesions of mean lengths from 11.9 to 86.2 mm using mycelial suspension and from 24.8 to 253.7 mm with mycelial plugs. Notably, Neofusicoccum species were the most aggressive, regardless of host origin. Other less aggressive species included L. theobromae, D. mutila, and D. seriata isolated from apple and walnut. This study highlights the potential of species of Botryosphaeriaceae from alternative fruit hosts as inoculum sources for grapevines in Chile.

Botryosphaeria dieback, caused by species in the Botryosphaeriaceae family, is a major grapevine trunk disease worldwide. Symptoms include vine decline, spurs and cordons dieback, and wedge-shaped wood necrosis. Infection occurs through pruning wounds, which remain susceptible for weeks. Therefore, wound protection is key to integrated management. This study evaluated efficacy and persistence of registered fungicides and a biological protectant against host-jumping Botryosphaeriaceae isolates. Field trials were conducted in 2024 on Vitis vinifera cultivar Cabernet Sauvignon in the Maule, Chile. Results showed that infection levels ranged from 6.7 to 26.7% for treatments applied 1 day after pruning and from 33.3 to 53.3% for treatments applied 15 days postpruning, highlighting the importance of timely application for optimal disease control. These findings provide evidence to guide grower decisions on pruning wound protection to reduce dieback risk.

Highbush blueberry (Vaccinium corymbosum L.) is an important economic fruit crop in Chile, with an approximate total area of 17,000 ha, i.e., 5,626 ha in the Maule region (35°26'S, 71°40'W), Central Chile (www.odepa.cl, 2025). Botryosphaeria stem blight is a threat to blueberry production in Chile, with incidence between 15 and 45%, attributed to Botryosphaeriaceae spp., including Neofusicoccum arbuti, N. australe, N. nonquaesitum, and N. parvum (Espinosa et al. 2009; Perez et al. 2014; Millas et al. 2023). In January 2023, five bushes of 12-year-old blueberry cv. Brigitta, from a commercial plantation, with and incidence of 8% was assessed across the 5 ha, in Longaví, Maule region, were submitted to the Fruit Pathology Lab at the University of Talca. Symptoms included decline, basal canker, stem and cane blight (red flagging) (Polashok et al. 2017). In cross-section, lignified stems have brown U or V-shaped necrotic or discolored hard tissues. Diseased stems were disinfected according to Díaz and Latorre (2014), and internal tissues were cut into small pieces (3 x 3 mm) and placed on potato dextrose agar (PDA) and 0.1% Igepal CO-630. After 5 days incubation at 20°C in darkness, 10 pure cultures were transferred to PDA. Four isolates developed white to white-grey fast-growing colonies with abundant aerial mycelium, and abundant aggregated black pycnidia after 28 days at 20°C. Conidia were one-cell, hyaline, thick-walled, ellipsoidal to cylindrical with a size of (27.7-) 25.1 ±1.5 (-22.4) x (14.7-) 13.2 ± 1.3 (-11.4) µm with a ratio 1.9 length/width. To determine the species level, three isolates were amplified and sequenced using ITS1/ITS4, Bt2a/Bt2b and EF1-728F/EF1-986R pair-primers of the internal transcribed spacer (ITS1-5.8S-ITS2) region, a beta-tubulin (tub), and the translation elongation factor 1-α (TEF) DNA regions, respectively (Alves et al., 2004; Dissanayake et al. 2015). The sequences showed a 99% similarity with sequences of D. mutila CBS 112553 ex-type. The sequences of D. mutila isolates Bot-ara-1 to Bot-ara 3 were deposited in GenBank (ITS: PV032958 to PV032960; BT: PV037028 to PV037030; TEF: PV037031 to PV037033). A phylogenetic tree, constructed using the maximum parsimony method using the concatenated sequences of the three regions, grouped the three isolates in the same clade with CBS 112553 ex-type. Pathogenicity tests were conducted in the field (Longaví, Maule region) using D. mutila isolates (Bot-ara-1 to Bot-ara-3) on blueberry of five-year-old cv. Brigitta in July. Twenty dormant stems (five per bush) were pruned (tip) with shears, and 80 µL of conidial suspension (105 conidia/mL) was placed on each fresh pruning using a micropipette. Additionally, 20 dormant stems (40 cm long) were wounded with a sterile cork borer and inoculated with mycelial plugs of D. mutila (5 days old). An equal number of stems inoculated with sterile water or sterile PDA media were used as controls. Necrotic lesions of 61 to 90 mm in length and dieback symptoms were observed after five months in stems inoculated with conidial suspension. Necrotic lesions of 53 to 67 mm in length were measured after three months on stems inoculated with mycelial plugs. D. mutila was reisolated from all samples (100%) and reidentified using morphological characteristics and sequencing of ITS region. Control stems remained symptomless. To our knowledge, this is the first report of D. mutila causing Botryosphaeria stem blight in Chile and worldwide.

Botryosphaeria dieback, caused by species of Botryosphaeriaceae, causes significant economic losses by infecting pruning wounds in vineyards and fruit trees. Previous studies have shown that pruning wounds constitute the main entry point for Botryosphaeriaceae and that isolates from different fruit hosts can infect these tissues regardless of origin. This study assessed the temporal susceptibility of Vitis vinifera pruning wounds in four cultivars (Cabernet Sauvignon, Malbec, Merlot, and Sauvignon Blanc) to six Botryosphaeriaceae isolates from different fruit hosts (grapevine, apple, blueberry, and walnut) under greenhouse and field conditions in central Chile. Pruning wounds were inoculated at 1, 15, 30, 45, and 60 d after pruning, and lesion length and wound infection (%) were evaluated. Both variables decreased with increasing wound age in greenhouse and field trials. Wounds were most susceptible during the first 15 d after pruning, with a marked reduction thereafter, although susceptibility persisted up to 60 d. Neofusicoccum parvum and N. arbuti showed the highest aggressiveness. All isolates were able to infect pruning wounds regardless of host of origin. These results indicate that pruning wounds remain susceptible for an extended period and highlight the importance of considering both wound age and cross-host inoculum sources in disease management strategies.