Modélisation de cinétiques de la maladie de la tache de la carotte provoquée par un complexe d'agents pathogènes du genre Pythium dominé par le Pythium violae

• Published in: Canadian journal of plant pathology Vol. 29; no. 1; pp. 41 - 55
• Main Author: Suffert, F.
• Format: Journal Article
• Language: English; French
• Published: Ottawa, ON Taylor & Francis Group 01-03-2007; Canadian Phytopathological Society; Taylor & Francis
• Subjects: alloinfection; autoinfection; bilogistic model; carrot cavity spot; Champignons phytopathogènes; Life Sciences; Phythium violae; Phytopathologie. Zoologie agricole. Protection des cultures et des forets; Sciences biologiques et medicales; Sciences biologiques fondamentales et appliquees. Psychologie; seconday infection; Cavité; Daucus carota; Phycomycetes; Modèle bilogistique; Fungi; Appareil végétatif; allo-infection; Maladie; Cinétique; Dicotyledones; Angiospermae; Complexe espèces; Pythium violae; Racine; Thallophyta; Carotte (légume); Phytopathologie; Modèle mathématique; Lésion; maladie de la tache de la carotte; Modélisation; Infection; infection secondaire; Phytopathogène; Mycose; auto-infection; Spermatophyta; Umbelliferae; Plante légumière; CARROT CAVITY SPOT; MALADIE DE LA TACHE DE LA CAROTTE; AUTO-INFECTION; MODELE BILOGISTIQUE; SECONDARY INFECTION; BILOGISTIC MODEL; ALLO-INFECTION; INFECTION SECONDAIRE; PYTHIUM VIOLAE; ALLOINFECTION
• ISSN: 0706-0661; 1715-2992
• DOI: 10.1080/07060660709507436

Carrot cavity spot is caused by a complex of pathogens belonging to the genus Pythium, including Pythium violae. The disease is characterized by the appearance of sunken elliptical lesions on the taproot. The objective of the present study is to identify, understand, and prioritize the processes that induce the spatio-temporal kinetics of epidemics of cavity spot. We favoured the hypothesis that considers primary infection (from soilborne inoculum) and secondary infection (root-to-root contaminations from existing lesions, i.e., auto- and allo-infections). Epidemics were obtained during a 3-year field experiment after artificial soil infestation of plots with P. violae at increasing inoculum doses. Different kinetics of cavity spot were described using standardized disease measurements. The analysis of the incidence curves showed the early appearance of a plateau, with differences in the disease level that are positively correlated with the inoculum doses. These differences disappeared at the end of the cropping season. Three simulation models, integrating or not the concomitance of the primary and secondary infections, were fitted to the disease incidence to test if progress curves were compatible with the hypothesis of the occurrence of both infection processes: the logistic model, the bilogistic model of Hau and Amorim, and the model of Brassett and Gilligan without temporal decline of the soil inoculum potential. The quality of the fitting was correct in the three cases, and the hypothesis of the occurrence of secondary infections was not refuted. This result is an important argument to demonstrate the polycyclic nature of the disease.