Epidemiology of brown rot (Monilinia fructigena) on apple: infection of fruits by conidia

Abstract

Effects of fruit maturity, wound age, temperature and the duration of wetness periods on infection of apple fruits by conidia of the brown rot fungus, Monilinia fructigena, were studied. Inoculation of fruits on potted apple trees and harvested mature fruits showed that wounding was essential for infection by M. fructigena. On potted trees, there was a significant difference between the susceptibility of cvs Cox and Gala and this difference depended on wound age. The incidence of brown rot was affected greatly by fruit maturity and wound age. Wounds on younger fruits were more resistant to infection than those on older fruits, whilst the older the wound, the more resistant it was to infection. Furthermore, the degree of wound age-related resistance was greater on younger fruits than on older fruits. These relationships were well described by regression models. The effect of the duration of wetness periods was very small: increasing the duration of wetness periods reduced the incidence of brown rot on older wounds. For detached fruits, all those wounded were rotted after inoculation, except for those in two treatments under 20ЊC on fruits with wounds which were 8 days old. The incubation period of the fungus was generally very short. Wound age was the single most important factor influencing the length of the incubation period; the incubation period increased as wound age increased.

The Crop Load Affects Brown Rot Progression in Fruit Orchards: High Fruit Densities Facilitate Fruit Exposure to Spores but Reduce the Infection Rate by Decreasing Fruit Growth and Cuticle Cracking

“…We assumed a fruit to be susceptible to infection from the time t i at which P(FD) = 0.1, with FD assumed to be a linear function of time, until the time of fruit harvest t H . We assumed as favorable those days when precipitations occurred and mean temperature was comprehended between 22 and 26 • C in accordance to previous studies indicating that conidia reproduction preferably occurs in wet conditions (Tamm and Flückiger, 1993;Xu and Robinson, 2000;Gell et al, 2008;Holb, 2008) and that it is impaired at "extreme" temperatures that are likely to be met in those days with mean daily temperature <22 or >26 • C (Tamm and Flückiger, 1993;Holb, 2008). Eventually we computed how many favorable days for brown rot spreading occurred in 2014 and 2015, (i.e., number of rainy days with mean temperature between 22 and 26 • C in the time period t i -t h ).…”

“…The spores that successfully infect a fruit reproduce and generate secondary inoculum (Biggs and Northover, 1985) that will cause new infections (Corbin, 1963;Byrde and Willetts, 1977). Infection occurs when the fungus succeeds in passing through the fruit cuticular surface via stomata, lenticels, wounds or cuticle cracks (Byrde and Willetts, 1977;Xu and Robinson, 2000;Gibert et al, 2009) and reaches the fruit pulp. Cuticle cracks can represent more than 10% of the fruit surface area at ripeness (Gibert et al, 2007) and provide straightforward ways for fungal infection (Nguyen-the, 1991;Fourie and Holz, 2003).…”

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

“…In addition, uninjured fruit is hardly infected by M. fructigena in contrast with M. fructicola (Byrde and Willetts 1977;Xu and Robinson 2000), indicating a great injury-dependence of M. fructigena infection on pome fruits. This difference in the epidemiology of the two fungi may also influence the amount of aerially dispersed conidia of M. fructigena compared with M. fructicola.…”

Peach Brown Rot: Still in Search of an Ideal Management Option

“…Epiphytologically, the knowledge of the ecological requirements of Monilinia species is essential in the development of a predictive model to comprehend the epidemiology of brown rot and provide adequate disease management strategies [75,76]. Important abiotic factors determining the potential for conidia germination and the growth of Monilinia propagules on the host exterior include temperature (T), water availability (water activity a w ), and wetting period (W) [77,78].…”