In Chile, the planted area of European hazelnut (Corylus avellana L.) reaches around 30,000 hectares, mainly concentrated in the central and southern area of the country where climate and soil prov...

Boeremia exigua var. exigua is a recurrent pathogen causing root rot in industrial chicory. Currently, there is no chemical or varietal control for this disease, and thus, management strategies need to be developed. This study determined the biocontrol effect of strains of Pseudomonas protegens bacteria with antimicrobial compounds on the fungus B. exigua var. exigua under in vitro, in vivo, and field conditions. In addition, root colonization by these bacteria was estimated by the phlD-specific PCR-based dilution end point assay. Eighteen isolates of Pseudomonas spp were evaluated, and the strains that showed the greatest in vitro inhibition of fungal mycelial growth (mm), Ca10A and ChB7, were selected. Inoculation with the strain ChB7 showed less severity (necrotic area) under in vivo conditions (root trials) compared with the control inoculated with the pathogen (p ≤ 0.05). The molecular analysis revealed that the root colonization of plants grown in pots was equal to or greater than 70%. Similar levels were observed in the field trials conducted at the Selva Negra and Canteras experimental stations (2015–2016 season), with values ranging from 85.7 to 70.5% and from 75.0 to 79.5%, respectively. Regarding yield (ton ha⁻¹), values were higher in the treatments inoculated with strains Ca10A and ChB7 (p ≤ 0.05) at both experimental sites, while a lower incidence and severity of root rot were observed at Selva Negra. These results suggest that the Chilean strains of P. protegens are a promising tool for the control of root diseases in industrial chicory.

Grapevine (Vitis vinifera L.) is an economically important fruit crop cultivated worldwide. However, its production and fruit quality are severely constrained by powdery mildew (Erysiphe necator) and Botrytis bunch rot (Botrytis cinerea) diseases. Increasing concerns regarding chemical fungicide resistance and environmental sustainability highlight the urgent need to develop alternative and more sustainable disease management strategies. This study assessed the field efficacy of Pseudomonas protegens-based formulations (TANIRI^® WP at 1 g·L⁻¹ and MaxGrowth at 1 mL·L⁻¹) within an integrated disease management program in cv. Chardonnay. Defense-related gene expression analysis revealed that biological treatments predominantly up-regulated pr1, pr2, and pr10 in both leaves and berries. In contrast, the chemical inducer acibenzolar-S-methyl (ASM) triggered earlier but less consistent induction of pr1 and pr2, alongside transient activation of pal and lox9. Repeated field applications of P. protegens formulations moderately reduced the severity of Botrytis bunch rot (20.89%) and powdery mildew (6.14%), though control levels remained below conventional sulfur/Bacillus subtilis-based treatments (30.04% and 13.56%, respectively). Overall, these findings suggest that biological inducers could complement conventional management practices for grapevine health. In particular, P. protegens may act mainly by systemically inducing host defense responses and partially suppressing pathogen development under field conditions.

Orange trees (Citrus × sinensis (L.) Osbeck) are the third-most cultivated citrus fruit species in Chile. In recent years, several trees in three orange orchards of ‘Lane late’ and ‘Fukumoto’ cultivars grafted on ‘Robidoux’ trifoliate orange (Poncirus trifoliata (L.) Raf.) have shown chlorosis, canopy reduction, wilting, root necrosis, defoliation, and plant death symptoms. This study aims to characterize the morphological symptoms observed in diseased orange trees in central Chile and identify the fungal pathogens that are involved. Isolation and morphological characterization of the pathogens were conducted by using different culture media. A total of 53 isolates were obtained, morphologically characterized and 12 isolates were selected for molecular identification. The isolates were identified using ITS, TEF-1α, and RPB2 regions. Two Fusarium species complexes were identified, Neocosmospora (Fusarium) solani (FSSC) and F. oxysporum (FOSC), based on >99% identity. Pathogenicity tests were conducted on young orange seedlings under greenhouse conditions. Results indicated that two months post inoculation, trifoliate orange seedlings displayed root rot symptoms such as necrosis, vascular discoloration, and wilting. FSSC and FOSC were re-isolated from necrotic seedling roots and identified through a combination of morphological traits and molecular techniques. This is the first detailed report of this disease, attributed to FSSC and FOSC, in orange orchards in Chile. These diagnostic results represent the first step in developing adequate phytosanitary programs for managing this disease.

Fungal trunk disease (FTD) poses a significant threat to hazelnut (Corylus avellana L.) production worldwide. In Chile, the fungus Diplodia mutila, from the Botryosphaeriaceae family, has been frequently identified causing this disease in the Maule and Ñuble Regions. However, control measures for D. mutila remain limited. This research aimed to evaluate the effectiveness of chemical and biological fungicides against D. mutila under in vitro, controlled pot experiment, and field conditions. An in vitro screening of 30 fungicides was conducted. The effectiveness was assessed by measuring the length of vascular lesions in hazelnut branches inoculated with D. mutila mycelium disks under controlled and field conditions. Field trials were conducted in a hazelnut orchard in Ñiquén, Ñuble Region, Chile. The results showed that three biological and five chemical fungicides were selected in vitro with >31% inhibition after 14 days. In pot experiments, all fungicides reduced necrotic lesions on branches by 32% to 61%. In field experiments, the most effective systemic fungicides were fluopyram/tebuconazole, fluxapyroxad/pyraclostrobin, and tebuconazole, while the effectiveness of antagonists Pseudomonas protegens ChC7 and Bacillus subtilis QST713 varied with seasonal temperatures. Effective conventional and biological fungicides against D. mutila could be integrated into disease management programs to protect hazelnut wounds from infections.

Fungal trunk disease (FTD) poses a significant threat to hazelnut (Corylus avellana L.) production worldwide. In Chile, the fungus Diplodia mutila, from the Botryosphaeriaceae family, has been frequently identified causing this disease in the Maule and Ñuble Regions. However, control measures for D. mutila remain limited. This research aimed to evaluate the effectiveness of chemical and biological fungicides against D. mutila under in vitro, controlled pot experiment, and field conditions. An in vitro screening of 30 fungicides was conducted. The effectiveness was assessed by measuring the length of vascular lesions in hazelnut branches inoculated with D. mutila mycelium disks under controlled and field conditions. Field trials were conducted in a hazelnut orchard in Ñiquén, Ñuble Region, Chile. Results showed that three biological and five chemical fungicides were selected in vitro with > 31% inhibition after 14 days. In pot experiments, all fungicides reduced necrotic lesions on branches by 32 to 61%. In field experiments, the most effective systemic fungicides were fluopyram/tebuconazole, fluxapyroxad/pyraclostrobin, and tebuconazole, while the effectiveness of antagonists Pseudomonas protegens ChC7 and Bacillus subtilis QST713 varied with seasonal temperatures. Effective conventional and biological fungicides against D. mutila could be integrated into disease management programs to protect hazelnut wounds from infections.