Surveys of diseases of winter wheat in England and Wales, 1976–1988

Abstract

SummarySamples from 300 – 400 randomly selected winter wheat crops were taken annually at growth stage 73 – 75 from 1976 to 1988 with the exception of 1983 and 1984. The number of samples from each region was proportional to the area of wheat grown in each region. The percentage of the area of the top two leaves affected by diseases, the severity of ear and stem base diseases and, in 6 years, the severity of take‐all were recorded. Septoria tritici and Septoria nodorum were, on average, the most severe of the foliar diseases and eyespot (Pseudocercosporella herpotrichoides) was the most severe of the stem base diseases. Regional differences in levels of S. tritici, brown rust, sharp eyespot and nodal fusarium were significant. Cultivar resistance affected disease severity, and previous cropping patterns particularly affected take‐all and eyespot. Eyespot and sharp eyespot were less severe in late‐ than in early‐sown crops. The percentage of crops treated with a fungicidal spray increased from 14% in 1976 to over 90% between 1983 and 1985. Use of benzimidazole fungicides applied at growth stage 31 declined, while use of morpholines from flag leaf emergence onwards increased between 1985 and 1988.

Effects of sharp eyespot (Rhizoctonia cerealis) on yield and grain quality of winter wheat

“…The relatively severe disease in 2007 was associated with the relatively warm and wet autumn and winter followed by warmer and wet spring and colder and wet summer. Warmer winters and moist springs, which favour infection and colonization by R. cerealis, usually increase incidence and severity of disease (Clarkson and Cook 1983;Wiese 1987;Polley and Thomas 1991;Colbach et al 1997;Cromey et al 2002). Regional differences in incidence of sharp eyespot, which occurs most often in cooler regions, were also reported from the United Kingdom (Polley and Thomas 1991) and Canada (Hall and Sutton 1998).…”

Perte de rendement due aux maladies cryptogamiques sur blé tendre d'hiver. Construction et validation d'un modèle de l'effet du système de culture

“…Le changement de politique agricole se traduit par une forte baisse du prix du blé qui impose la conception de nouveaux itinéraires techniques à niveaux d'intrants plus faibles. Cet ajustement de la conduite de la culture à de nouveaux rapports de prix ne pourra être réalisé que si l'on dispose de modèles prédictifs de l'effet des techniques culturales sur le rendement (Meynard, 1991 (Meynard, 1991 (Rapilly, 1991) (Lechapt, 1983 ;Meynard, 1985 ;Stoop, 1992 Scott, 1980 ;Rapilly, 1982 ;Steinbrenner et Hoflich, 1984 ;Huet, 1986a ;Schultz et al, 1990) et, dans une moindre mesure, les maladies du feuillage (Palti, 1981 ;Caron, 1988 ;Polley et Thomas, 1991). La majorité des contaminations hivernales en souches normales de Pseudocercosporella herpotrichoïdes est réalisée au 31 janvier (Rapilly et al, 1979 (Caron, 1988) et le piétin-verse (Steinbrenner et Höflich, 1984), par l'effet de la densité et de la turgescence de la population végétale, de même que sur le niveau de sensibilité de la plante aux maladies (Palti, 1981 ;Chaboussou, 1985 1980, 1981, 1983, 1987, 1988, 1989 et 1991 sont fortes, correspondant, en effet, à de fortes attaques de rouille jaune (1983, 1988 et 1989), de fusariose de l'épi (1987 et 1991), et de septorioses (1980, 1981, 1983, 1987 et 1988).…”

A test method based on microscopic assessments to determine curative and protectant fungicide properties against Septoria tritici

“…In recent years, leaf blotch caused by Septoria tritici, the anamorph of Mycosphaerella graminicola, has been reported as increasing in severity in major wheat growing areas (Polley & Thomas, 1991;Meien-Vogeler et al, 1994). A range of decision models has been developed in the past to optimize fungicide input for the control of this pathogen.…”