Response of field pea cultivars to chlorothalonil in the control of mycosphaerella blight
2003
Xue, A.G. | Charest, J. | Davidson, C.G. | McAndrew, D.W. | Bing, D.J. | Warkentin, T.D.
The efficacy of chlorothalonil in controlling mycosphaerella blight in field pea was evaluated from 1998 to 2000 using 10 cultivars representing different leaf types, market classes, seed sizes, plant heights, and maturities. Significant differences ( P < 0.05) were observed among cultivars in disease severity, yield, 1000-seed weight (TSW), and seed infection each year. Cultivar × fungicide treatment interactions for these parameters were not significant in any of the 3 yr. Under both chlorothalonil treated and untreated conditions, Radley was the most resistant, while Carrera and Keoma were equally the most susceptible cultivars. A higher efficacy of chlorothalonil treatments was observed in 1999 when disease severity was greater than in 1998 or 2000. On average, chlorothalonil treatments reduced disease severity significantly in 1999 and 2000, but not in 1998. Overall, the fungicide increased yield by 6.4%, and TSW by 0.9-5.1%, which were significant in 1998 and 1999, but not in 2000. Based on 2-yr assessments of seed infection by Mycosphaerella pinodes, chlorothalonil reduced seed infection by 19.2%, which was significant in 1999, but not in 2000. Chlorothalonil treatments provide a greater benefit in years when disease pressure and yield potential are high.
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