Identification of the Causal Agent of Dieback in Blueberry (Vaccinium corymbosum) and Its In Vitro Control

Objetive:The objective of this study was to isolate, identify, and characterize the causal agent of blueberry (Vaccinium corymbosum) dieback and its in vitro control. Design/methodology/approach: Samples were collected from three municipalities in Michoacán with different edaphoclimatic conditions. Using the Agrios protocol, three strains identified as Pestalotiopsis sp. were isolated and labeled as CAZr01, CAZh02, and CATg03. The isolates’ morphological characteristics were determined. For in vitro sensitivity bioassays, the fungicides Robust R®, Tacora 25 Ew®, Cabrio® C, Programic® Mega, and Aliette® Wdg were tested at three doses (low, medium, and high) according to the manufacturer's recommendations, with sterile water serving as the control treatment. The virulence and severity of the isolates were determined through pathogenicity tests on healthy plants. The experimental design was completely randomized, and a Tukey mean comparison test was applied with a 5% probability of error. Results: The most effective fungicide for controlling mycelial growth was Tacora 25 Ew®, which showed significant inhibition at all tested doses. Of the isolated strains, CAZh02 was the most virulent, causing plant death in the shortest time. Limitations/implications:This study provides information on the pathogen affecting blueberry and proposes an effective method for its control. Findings/conclusions:It was found that blueberry dryer is caused by Pestalotiopsis sp., which is most efficiently controlled in vitro with Tacora 25 Ew®. Among the three isolated strains, CAZh02 was found to be the most virulent.