Control of Cercospora leaf spot on sugar beet in the Czech Republic

Ram Kumar

Doctoral thesis

Abstract:

Sugar beet (Beta vulgaris L.) is one of the most economical crops grown in the Czech Republic and Europe’s contribution is 45-50 of total world production. In the Czech Republic, in 2018 sugar beet harvested area was 64,70 thousand hectares and production was 3.72 million tonnes (world data atlas, 2018). The total crops losses reported due to plant disease are up to 25% of worldwide crop production per annum (Lugtenberg et al., 2016). The diseases of sugar beet are one of the foremost constraints in the profitability in the cultivation of sugar beet around the world. Cercospora leaf spot (CLS) is one of the most economical important foliar disease of sugar beet, it can reduce yield and sugar quality up to 50% if unmanaged (Shane & Teng, 1992; Rossi et al., 2000) . Cercospora beticola was first report by Saccardo in 1886, and after a short period, the CLS disease was reported as a severe issue in Europe and the United States. Cercospora spp. resistance was developed in the United States and Italy in the early 19th century(Stevanato et al., 2014). CLS disease primarily infects sugar beet in warm and humid growing region. CLS symptoms usually appear after close crop canopy, especially on older leaves close to the soil. Cercospora leaf spots are visible and circular, about 3-4 mm in diameter with dark brown to reddish-purple. As the disease progresses, leaf lesions merge, and whole leaves die, which remain attached to the plant and later buried in soil, infecting sugar beet plant in the next cropping season. Currently, fungicide applications with biological and resistant cultivars are using CLS management strategy to manage under field conditions. As of now, most sugar beet; cultivars are susceptible to the pathogen. CLS disease is primarily managed by several groups of fungicides recommended by Fungicide Resistance Action Committee (FRAC). However, the last decade’s research revealed fungicide resistance from every group of fungicides, e.g. Quinone outside Inhibitors (QoIs), DeMethylation Inhibitors (DMIs) and Succinate dehydrogenase inhibitors (SDHIs) (Robbertse et al., 2001; Bolton et al., 2011; Rosenzweig et al., 2019).

Keywords

Cercospora beticola, DMI fungicide, Sugar Beet

Language used: English

Date on which the thesis was submitted / produced: 6. 3. 2023

Thesis defence

• Supervisor: doc. Ing. Miloslav Zouhar, Ph.D.
• Reader: Pavel Matušinský, externi, Vladislav Čurn, externi

Czech University of Life Sciences Prague

Faculty of Agrobiology, Food and Natural Resources

Doctoral programme / field:
Agricultural Specialization / Agricultural and Forestry Phytopathology and Plant Protection