Effect of various fungicides in the control of Alternaria leaf blight in carrot crops

Abstract

Effect of various fungicides in the control of Alternaria leaf blight in carrot crops Alternaria leaf blight, caused by the fungus Alternaria dauci, is considered to be the most common and destructive disease in carrot crops in Brazil and worldwide. To evaluate the effectiveness of different fungicides in controlling Alternaria leaf blight, we conducted an experiment using the cultivar ‘Verano’ in Andradas, Minas Gerais, from February to April 2017. A randomized complete block design was used with seven treatment and four replicate plots of 4 m2 each. Six applications of 400 L/ha were applied at 7-day intervals. The severity of the disease was determined based on the percentage of leaf area affected by the disease (0 to 100%). The results of four evaluations were used to calculate the area under the disease-progress curve. All fungicides significantly reduced the severity and progression of the disease compared to the control. Fluxapyroxad + pyraclostrobin (0.3 L c.p./ha) was more effective than boscalid + kresoxim-methyl (0.5 L c.p./ha), copper hydroxide (1.5 kg c.p./ha), and azoxystrobin (0.12 kg c.p./ha), but similar in effectiveness to pyraclostrobin + metiram (2.0 kg c.p./ha) and boscalid (0.15 kg c.p./ha). Azoxystrobin (0.12 kg c.p./ha) was the least effective fungicide. None of the tested fungicides were phytotoxic to the carrot crop.