ABSTRACT
A field trial was conducted in 2017 and 2018 to quantify the fluctuation of conidia of Botrytis squamosa and its relationship with the severity of botrytis leaf blight on onions. Onion seeds of cultivar ‘Bola Precoce’ were sown as four replicates of 600 plants. Conidia were collected with a “vane”-type spore collector containing a microscope slide, which was smeared with Vaseline and was weekly quantified under a microscope. Disease severity was analyzed through the percentage of the affected leaf area. The number of sporangia and the severity of botrytis leaf blight on onions were subjected to Pearson correlation coefficient calculator (r). In 2017, conidial collection occurred after the disease detection, probably because there was low inoculum concentration in the air. In 2018, conidial collection was concomitant to the disease occurrence, but continuously and at greater quantities, indicating that the conidia captured by the collector were already present in the air. Correlation between the variables conidial fluctuation and disease severity was significant, showing r=0.678 and r=0.767 for 2017 and 2018, respectively. The severity of botrytis leaf blight on onions is influenced by the presence of conidia collected from the air.
Keywords
Allium cepa
; aerobiology; Botrytis leaf blight