ABSTRACT
Downy mildew is a disease with high destructive potential for onion crops. Onion producers have increased the density of their crops with the aim of rising productivity, which can provide even more favorable conditions for the disease. The aim of this study was to investigate the effect of nitrogen fertilization and plant density on the severity of downy mildew and bulb biomass production under super-dense cultivation for the conditions at Alto Vale do Itajaí – Santa Catarina State, Brazil. Treatments consisted of four plant densities (400, 600, 800 thousand and 1.0 million plants ha-1) receiving two nitrogen levels (150 and 200 kg N ha-1). Nitrogen levels of 150 and 200 kg ha-1 do not influence the severity of downy mildew and the biomass of bulbs. The increase in plant density from 600 thousand plants ha-1 increases the severity of downy mildew and reduces the biomass of bulbs.
Keywords
Allium cepa
;
Peronospora destructor
; nitrogen; plant density; biomass
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