Changes in agronomic practices and incidence and severity of diseases in winter wheat in England and Wales between 1999 and 2019

2021 ◽  
Author(s):  
JA Turner ◽  
T Chantry ◽  
MC Taylor ◽  
MC Kennedy
2003 ◽  
Vol 1 (1) ◽  
pp. 43-57 ◽  
Author(s):  
C. S. Srinivasan ◽  
Colin Thirtle ◽  
Paolo Palladino

AbstractGenealogical data have been used very widely to construct indices with which to examine the contribution of plant breeding programmes to the maintenance and enhancement of genetic resources. In this paper we use such indices to examine changes in the genetic diversity of the winter wheat crop in England and Wales between 1923 and 1995. We find that, except for one period characterized by the dominance of imported varieties, the genetic diversity of the winter wheat crop has been remarkably stable. This agrees with many studies of plant breeding programmes elsewhere. However, underlying the stability of the winter wheat crop is accelerating varietal turnover without any significant diversification of the genetic resources used. Moreover, the changes we observe are more directly attributable to changes in the varietal shares of the area under winter wheat than to the genealogical relationship between the varieties sown. We argue, therefore, that while genealogical indices reflect how well plant breeders have retained and exploited the resources with which they started, these indices suffer from a critical limitation. They do not reflect the proportion of the available range of genetic resources which has been effectively utilized in the breeding programme: complex crosses of a given set of varieties can yield high indices, and yet disguise the loss (or non-utilization) of a large proportion of the available genetic diversity.


1992 ◽  
Vol 72 (3) ◽  
pp. 965-972 ◽  
Author(s):  
D. K. Tompkins ◽  
D. B. Fowler ◽  
A. T. Wright

Agronomic practices must be modified to maximize winter wheat (Triticum aestivum L.) yield in different environments. Changes in crop management may modify the microclimate within the crop canopy thereby influencing the development of foliar pathogens. This study was initiated to determine the effect of cultivar, nitrogen (N) fertility, seed rate (SR) and row spacing (RS) on the severity of powdery mildew (Erysiphe graminis DC f.sp. tritici E. Marchal) on the upper leaves of no-till winter wheat grown in the Saskatchewan Parkland region. Average powdery mildew (PM) severity was greater on the upper leaves of the semi-dwarf cultivar Norwin than on the tall cultivar Norstar and increased under conditions of high N fertility. The use of 36 cm RS and 140 kg ha−1 SR compared to 9 cm RS and 35 kg ha−1 SR also resulted in increased PM severity. In general, wide RS enhanced spore dispersal and disease progress up the plant while high SR created a more favourable crop canopy microclimate for PM development once the pathogen was established on a leaf.Key words: Wheat (winter). Triticum aestivum L., no-till, powdery mildew, Erysiphe graminis, row spacing, seed rate, nitrogen fertilizer


1980 ◽  
Vol 29 (1) ◽  
pp. 9-20 ◽  
Author(s):  
J. B. TYLDESLEY ◽  
N. THOMPSON

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