Spatio‐temporal dynamics of brown rot (Monilinia fructigena) on apple and pear

Abstract

Spatio-temporal development of brown rot (Monilinia fructigena) on apple and pear was monitored in an apple (cv. Cox) orchard and a pear orchard of several cultivars over several years. Disease on individual trees was recorded weekly from July to harvest, individual fruits with brown rot were tagged but not removed and rot-origin identified. On apple cv. Cox and pear (cvs Conference and Comice), all primary rot arose from infection via wounds caused by insects, birds and growth cracks. Birds were the most important wounding agents on pear in the field. Secondary (fruit-to-fruit contact) rot was considerably less than primary rot, especially for pear. Incidence of disease (percentage of fruits with brown rot) increased gradually from late July up to harvest; the final disease incidence varied with seasons and cultivars, ranging from 1 to 11%. For pear, Comice had greater incidence than Conference. Significant aggregation of diseased fruits among trees was detected for assessment dates when the overall incidence of disease was greater than 0´5%. On Cox and Conference, significant correlation of disease incidence between adjacent trees or trees separated by one or more trees (i.e. spatial lag measured as units of distance between adjacent trees) was detected, but there was no clear relationship between the correlation, the distance or time. For Comice, there was consistent and significant positive correlation of brown rot incidence over 3 years. It is speculated that behavioural characteristics of wounding agents may have played an important role in influencing the spatio-temporal dynamics of brown rot on apple and pear.

Monitoring conidial density of Monilinia fructigena in the air in relation to brown rot development in integrated and organic apple orchards

“…another (Croxall et al 1951;Lack 1989) and they were the major wounding agents in pome fruit orchards acting as prerequisite factors for infection (Xu et al 2001b). Only a few studies have monitored aerial spore density of M. fructigena conidia.…”

“…Airborne conidia have been trapped on exposed dishes and vaseline slides (Horne 1933;Bucksteeg 1939) but the authors did not quantify the aerial spore density in M. fructigena-infected orchards. Recently two studies reported a low aerial density of M. fructigena conidia in integrated apple orchards (Van Leeuwen 2000;Xu et al 2001b). Xu et al (2001b) in the UK recorded the presence but not the number of M. fructigena conidia.…”

“…Recently two studies reported a low aerial density of M. fructigena conidia in integrated apple orchards (Van Leeuwen 2000;Xu et al 2001b). Xu et al (2001b) in the UK recorded the presence but not the number of M. fructigena conidia. Van Leeuwen (2000) in The Netherlands did quantify aerial spore density of M. fructigena, but it was assessed only in a low-inoculum apple orchard and only from mid-July (appearance of first infected fruit) until mid-September (harvest date).…”

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

“…However, it is known that disease aggregation characteristics tend to vary with changes in means (Madden and Hughes, 1995;Xu and Ridout, 1998;Ridout and Xu, 2000;Xu et al, 2001). Here we took into account this varying aggregation characteristic by assuming a common variance-to-mean relationship of Equation (1) for heterogeneity across all data sets as well as a negative binomial distribution for the data, so…”

Spatial Patterns of Brown Rot Epidemics and Development of Microsatellite Markers for Analyzing Fine-Scale Genetic Structure of Monilinia fructicola Populations Within Peach Tree Canopies

“…Analysis of spatial patterns of plant disease in orchard crops can help shed light on the relative importance of different inoculum sources and potential mechanisms of dissemination within and among trees (6,30,33). Most studies have focused on quantifying two-dimensional patterns of disease among trees (i.e., on an x-y plane), whereas the number of studies explicitly considering three-dimensional disease patterns within canopies (i.e., in an x-y-z cube) has been limited (2,16,28).…”