Age, rate of growth, carbohydrate and amino acid contents of spring barley plants in relation to their resistance to powdery mildew (Erysiphe graminis f.sp. hordei)

1983 ◽  
Vol 22 (1) ◽  
pp. 1-14 ◽  
Author(s):  
B.K. Hwang ◽  
W.-D. Ibenthal ◽  
R. Heitefuss
Keyword(s):  
Amino Acid ◽  
Powdery Mildew ◽  
Spring Barley ◽  
Erysiphe Graminis ◽  
Rate Of Growth ◽  
Amino Acid Contents

Effects of inoculum sources on the accuracy and precision of experiments testing different times of applying fungicides to control powdery mildew (Erysiphe graminis f.sp hordei on spring barley

1996 ◽  
Vol 126 (3) ◽  
pp. 259-275 ◽  
Author(s):  
J. F. Jenkyn ◽  
A. D. Todd ◽  
A. Bainbridge ◽  
G. V. Dyke
Keyword(s):  
Powdery Mildew ◽  
Treatment Effects ◽  
Spring Barley ◽  
Conclusive Evidence ◽  
Erysiphe Graminis ◽  
Regression Analyses ◽  
Yield Losses ◽  
Inoculum Sources ◽  
Accuracy And Precision ◽  
Inoculum Pressure

SUMMARYExperiments on spring barley at Rothamsted over the years 1974–81 were used to study how sources of powdery mildew inoculum affected responses to fungicide sprays applied at different times. Reinfection of early-sprayed plots was generally faster where they were close to a potent source of inoculum than where they were not. Conversely, effects of sources on yield, although not always significant, occurred mainly in the later-sprayed plots. Sources thus had their most important effects before these later sprays were applied, and probably during the very early stages of the epidemic. This implies that if experiments are to approximate to fields, they should, initially, be part of a large, uniformly-susceptible area of crop.Regression analyses showed that delaying the application of fungicide sprays after the optimum date caused smaller yield losses in plots near minimal sources of inoculum than in plots near more potent sources. There was no conclusive evidence for effects of inoculum sources on the optimum date to apply a fungicide spray but the tendency was for the optimum to become later as inoculum pressure increased.Separating fungicide-treated plots with mildew-resistant barley resulted in larger treatment effects and smaller residual mean squares than where there was no separation. Judged by residual mean squares alone, precision was approximately doubled by separation.

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