Integrated control of cercospora leaf spot in sugar beet
2001
Stevanato, P. | Biaggi, M. de | Colombo, M. | Biancardi, E. (Istituto sperimentale per le Colture Industriali, Rovigo (Italy)) | Ghedini, R.
The effects of chemical protection and genetic resistance in sugar beet under cercospora leaf spot (CLS) attack were studied in a three-year and two-location trials conducted in Northern Italy. Different intensities of CLS were obtained with three levels of fungicide protection on six commercial varieties that were rated from very susceptible to resistant. The applied treatments were the following: TO = untreated; T1 = treated every 20 days beginning at the first appearance of spots on the leaves; T2 = as T1 but repeated every 10 days. The yield and the processing quality were checked in each of three dates of harvest (early, middle, late). The effect of the integrated control (resistance and fungicides) improved significantly over harvest time. Compared to the mean of the six varieties in the untreated plots, the normal treatment (T1) increased sugar production by 2 t/ha at the last harvest. The effects of fungicide treatment on sugar yield were always greater then the effects of varieties. The difference between resistant and susceptible varieties increased with the length of the season and was greater than 1,5 t/ha at the third harvest. The relative difference in sugar yield of the susceptible varieties decreases with the time and remains at the same level under the T1 protection. The resistant varieties gradually increase the sugar yield even without chemical protection. The T1 protection produced gain of more than 2 t/ha at the last harvest. This increase suggested that a positive interaction occurred between resistance and fungicide treatments.
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