ITEMS FROM ITALY

INSTITUTE OF PHYTOPATHOLOGY, COLLEGE OF AGRICULTURE

Via Filippo Re 8, 40126 Bologna, Italy.

Reactions of cultivars of common wheat to wheat soilborne mosaic virus.

C. Rubies-Autonell, V. Vallega, M. Turina, C. Ratti, and S. Contoli.

In Italy, WSBMV is widespread, especially in the northern and central regions of the country. Grain yield losses of nearly 50 % have been recorded on susceptible common wheat cultivars. The only economically viable means of controlling this virus is growing WSBMV-resistant genotypes, yet little is known about the reactions of the common wheat cultivars presently grown in Italy. During 1996-97, we grew 36 such cultivars in a severely WSBMV-infested field near Bologna. Each of the cultivars was grown in a 10-m2 plot placed in the field according to a randomized block design with three replicates. Resistance to WSBMV was evaluated on the basis of DAS ELISA readings, symptom severity (on a 0-4 scale), and agronomic performance. Symptom severity (mean score = 0.6; range 0.0-2.6) and ELISA values (mean = 0.750) were relatively low, especially when compared to those observed on the 33 durum wheats grown in an adjacent field. The 12 common wheat cultivars analyzed remained asymptomatic throughout the entire season, and nine were devoid of the causal agent, at least according to the ELISA tests performed. Simple correlation coefficients between agronomic data, ELISA values, and symptom scores (Table 1) were significant in most cases. Regression analysis indicated that the common wheat cultivars presenting disease scores higher than 1.1 suffered grain losses attributable to WSBMV of about 30 %. Mean kernel weight and plant height were reduced by about 15 %.

Reactions of cultivars of durum wheat to wheat soilborne mosaic virus.

C. Rubies-Autonell, V. Vallega, M. Turina, C. Ratti, and L. Concari.

WSBMV causes severe economic losses on both common and durum wheat crops. In Italy, susceptible durum wheat cultivars can have yield losses of nearly 70 %. During 1996-97, we assayed the reactions to WSBMV of 33 durum wheat cultivars in a severely WSBMV-infested field situated near Bologna. Each cultivar was grown in a 10-m^2^ plot distributed in the field according to a randomized block design with three replicates. Resistance to WSBMV was evaluated on the basis of DAS-ELISA readings, symptom severity (on a 0-4 scale), and agronomic performance. Symptom severity (mean score = 1.5; range 0.1-3.6) and ELISA values (mean = 0.789) were moderately high. The highest grain yields were recorded for the cultivars Ceedur, Louxor, Duilio, Ares, Neodur, and Parsifal. These cultivars also had mild symptoms and relatively low ELISA values. Simple correlation coefficients between agronomic data, ELISA values, and symptom scores (Table 2) were relatively high and statistically significant. Regression analysis indicated that the cultivars presenting disease scores above 2.1 (i.e., Grazia, Cirillo, Bronte, Balsamo, Platani, Giemme, Creso, and Simeto) suffered grain losses attributable to WSBMV of about 55 %. In these cultivars, test weight was reduced by about 3 kg/hl, mean kernel weight by about 17 %, and plant height by about 10 cm.