Relationship between the incidences of ear and spikelet infection of Fusarium ear blight in wheat

Abstract

There is a urgent need to develop a rational strategy for managing Fusarium ear blight in order to reduce current reliance on routine fungicide applications, based on an objective assessment of disease risks. One of important components for such a management strategy is a fast, easy, accurate and reliable method for disease assessment. The relationship between incidence of Fusarium ear blight ear infection and number of spikelets infected on an ear (or incidence of spikelet infection) were investigated during three seasons and in four countries in order to derive a simple relationship for predicting disease at the spikelet level using ear incidence. More than half of the data sets of the number of infected spikelets on an ear could not be fitted satisfactorily by a Poisson distribution. Three two-parameter discrete distributions (negative binominal, Neyman type A and Polya-Aeppli) provided a significantly better fit than the Poisson distribution, indicating a degree of aggregation of number of infected spikelets on an ear. Taylor's power-law satisfactorily described the observed variance-mean relationship for the number of infected spikelets on an ear; this relationship was generally consistent over years and countries. A robust relationship between incidence of ear infection and average number of infected spikelets per ear was obtained assuming a fixed variancemean relationship and a negative binomial distribution for the number of infected spikelets. A relationship between incidences of spikelet and ear infection was also obtained based on the complementary log-log or logit transformation of ear and spikelet infection incidence. These models appeared to be consistent over years and countries and thus may be used in making practical disease management decisions involving fungicide applications.

Fusarium head blight (FHB) in Flanders: population diversity, inter-species associations and DON contamination in commercial winter wheat varieties

“…Results show a clear and consistent differential resistance response of the different varieties to natural FHB infection. It is known that wheat varieties differ in their susceptibility to FHB Lemmens et al 2004;Mesterhazy et al 1999;Xu et al 2004). These studies were mainly conducted using artificial infections to eliminate side effects such as differences in ).…”

“…Consequently, it is difficult to implement Fusarium resistance into breeding programmes and only few studies address FHB resistance since it is not easy to accurately measure (Brennan et al 2007;Mesterhazy et al 1999;Xu et al 2004). Differences in geographic regions, environmental conditions and periods of anthesis often hamper the interpretation of infection data with regard to varietal resistance (Brennan et al 2007;Doohan et al 2003).…”

Effects of genotype, environment and fungicide treatment on development of Fusarium head blight and accumulation of DON in winter wheat grain

“…Using important weather variables, a weather-based model to predict the concentration of DON in grain at heading was developed by Hooker et al (2002). A quantitative assessment model to predict the risk of FHB and the associated production of mycotoxins (Xu et al 2004) appeared to be useful for making practical disease management decisions involving fungicide applications. Cultivar resistance is another important factor that may significantly contribute to the efficient control of the disease.…”

Predominance and association of pathogenic fungi causing Fusarium ear blightin wheat in four European countries

“…FEB incidence and severity (as number of spikelets infected per ear), and their relationship within each sampling site have already been separately dealt with (Xu et al, 2004). In logistic regression analysis, the presence of each FEB pathogen at each site was assumed to be distributed binomially.…”

“…20 ng ll )1 , for use in PCR. The species-specific PCR primer pairs used to detect each pathogen were those described in Nicholson et al (2004). PCR reactions were carried out in volumes of 50 ll PCR buffer containing 200 ng DNA sample, 100 lM each of dATP, dGTP, dCTP and dTTP, 5 pmol of each specific forward and reverse primer, and 0.8 units of Taq polymerase (Boehringer Mannheim).…”