Comparison of Different Sources of Vector Resistance for Controlling Wheat Streak Mosaic in Winter Wheat
- J. B. Thomas *a,
- R. L. Connerb and
- R. J. Grafc
- a Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB, R3T 2M9, Canada
b Morden Research Station, Agriculture and Agri-Food Canada, Unit 100-101, Route 100, Morden, MB, R6M 1Y5, Canada
c Lethbridge Research Centre, Agriculture and Agri-Food Canada, P.O. Box 3000, Lethbridge, AB, T1J 4B1, Canada
Wheat streak mosaic (WSM) is a serious viral disease of wheat (Triticum aestivum L.) that is vectored by the wheat curl mite (Aceria tosichella Keifer). Deployment of wheat cultivars with vector resistance is a possible method for WSM control. This 3-yr (1996–1997/1998–1999) field study compared by means of a split-plot design the effect of different sources of mite-resistance backcrossed into a common winter wheat genetic background on both the spread of WSM and on the resulting yield losses. The various lines were first seeded early (in July) in blocks of spaced plots to provide different disease source or spreader treatments as main plots. The same winter wheat lines were then seeded in mid-September into the spaces between the spreaders as subplot treatments to mimic the crop. Main-plot (spreader) treatments included the mite-susceptible winter wheat cultivars CDC Kestrel or Norstar, two mite-resistant backcross lines of Norstar with resistance from Thinopyrum ponticum (Podpera) Liu & Wang (Nst*5/Cmc2) and Triticum tauschii (Coss.) Schmal. (Nst*5/Cmc1) plus oat (Avena sativa L.) as a nonhost. The two mite-resistant winter wheat lines, plus another mite-resistant backcross line with resistance from rye (Secale cereale L.) (Nst*5/1RS-1BL) and Norstar were also used as subplot treatments. The presence of vector resistance in the spreader treatments reduced the intensity of disease symptoms in the spreader rows themselves and increased their grain yield. In 2 of 3 yr, these yield differences were dramatic. Resistance in the spreader also reduced the secondary spread of WSM into the adjacent winter wheat subplots with conventional planting dates. During severe outbreaks of WSM, (1996-1997 and 1997-1998), Nst*5/Cmc2 was more effective with a lower frequency of severely infected plants and smaller yield losses than Nst*5/Cmc1 or Nst*5/1RS-1BL. In conclusion, control of WSM through vector resistance requires an effective resistance gene in both the spreader and the crop.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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