Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

First report of benzimidazole, DMI and QoI-insensitive Cercospora beticola in sugar beet in Morocco.

Abstract

Cercospora leaf spot, caused by Cercospora beticola, is of the major foliar diseases of sugarbeet (Beta vulgaris) in Morocco. During the 2016-17 growing season, symptomatic sugarbeet leaves were collected from the 4 major sugarbeet producing regions (Berkane, Doukala, Ghareb and Tadla) to evaluate the sensitivity of C. beticola to thiophanate-methyl, difenoconazole, epoxiconazole, tetraconazole, azoxystrobin and trifloxystrobin fungicides. The results showed that all isolates were resistant to thiophanate-methyl. For difenoconazole 41% of isolates were sensitive and 59% were resistant while for tetraconazole and epoxiconazole 27.3% of isolates were resistant, 66.7% with medium resistance and 6% were sensitive. Furthermore, the mycelial growth inhibition with QoI was less effective with azoxystrobin compared to that obtained with trifloxystrobin. There were at least 54.54% of isolates which demonstrated resistance to azoxystrobin. This is the first report of benzimidazole-DMI and QoI-insensitive C. beticola isolates in Morocco.