Evaluation of full-season programs for the management of Fusarium wilt of blackberry caused by a new lineage of the Fusarium oxysporum species complex

Abstract

Wilt is currently the most critical disease affecting blackberry crops in Mexico, and more than 2,500 ha have been lost to the disease to date. Thus, the objectives of this research were: a) to determine the etiology of blackberry crop wilt in Mexico and b) to evaluate strategies for season-long integrated disease management. From 2013 to 2015, fungal isolates were recovered from the vascular tissue of symptomatic blackberry plants cv ‘Tupy.’ Morphological features were determined, and phylogenetic identification of the fungal isolates was performed by amplifying and sequencing the partial translation elongation factor (TEF-1 alpha) gene. Pathogenicity tests were completed in the greenhouse on 6-month-old blackberry plants from the same cultivar. Thirteen disease management programs consisting of fungicides, biocontrol agents, and plant resistance inducers were evaluated during the 2014–2015 and 2015–2016 growing seasons in a commercial plot with 30% disease incidence. The results of this study suggest that blackberry wilt in Mexico is caused by a new lineage in the F. oxysporum species complex. In the two crop seasons, the programs with the most consistent effect on the reduction of disease intensity were based on sequential applications of the microbial soil inoculant Maya Magic®. Also, those that started with 2 or 3 applications of prochloraz or difenoconazole followed with biweekly applications of the biostimulant Kendal Nem®. These results indicate the feasibility of using soil microbial inoculants and the integration of technologies for the season-long management of epidemics caused by F. oxysporum in infected commercial blackberry crops.