Sporulation ( Figure 9 ) may occur on the surface of infected tubers in storage or on discarded cull piles. Infected tuber tissues ( Figures 7,8 ) are copper brown, reddish or purplish in color. Infections generally begin in tuber cracks, eyes or lenticels. Potato tubers can become infected in the field when sporangia are washed from lesions on the foliage and enter into the soil. As many lesions accumulate, the entire plant can be destroyed in a matter of days after the first lesions are observed if the appropriate fungicide applications are not used ( Figure 6 ).įigure 3. infestans produces sporangia and sporangiophores on the surface of infected tissue and the resulting white sporulation can be seen at the margins of lesions on abaxial (lower) surfaces of leaves ( Figures 5 ). Late blight of potato is identified by blackish/brown lesions on leaves and stems ( Figures 3,4 ) that may be small at first and appear water-soaked or have chlorotic borders but expand rapidly and the entire leaf becomes become necrotic. Symptoms and Signs Potato stems and leaves These early studies also contributed to Louis Pasteur's germ theory which was proposed 15 years later.įigure 2. Thus, late blight signifies the official beginning of the science of plant pathology. infestans on infected potato plants was the causal agent of the disease and not the result of spontaneous generation from the decaying vegetation or the wrath of God. de Bary's ( Figure 2B ) (the "father of plant pathology") conclusive studies convinced the scientific community that the white sporulation of P. Berkeley (Figure 2A) and subsequently named Phytophthora infestans by Anton de Bary (Figure 2B) in the 1870’s (Berkeley, 1846 de Bary, 1876). Late blight is the disease that caused the Irish potato famine of the 1840s (Figure 1). A potato field in eastern NC with late blight. Schumann, University of Massachusetts, Amherstįigure 1. HOSTS: Potato, tomato (economically important hosts) Updated 2018.ĭISEASE: Late blight of potato and tomato In the free exposition system the highest values of these parameters with 77%, 0.15 and 1,573, respectively, were obtained however, the introductions LA1480 and LA2075 showed the lowest values under this production system.Ĭhromista phylogenetic resources severity solanaceae rate of disease development area under the disease progress curve.Schumann, G.L. According to the analysis, under the semi cover system the lowest numerical values for final severity, r and AUDPC, with 47%, 0.09 and 1,133, was obtained, respectively standing out the introductions LA1480, IAC1686, LA2131 and LA2692. Finally, an analysis of variance and Duncan's tests was conducted. In addition, the regression coefficients of the evaluated variables was calculated. The evaluated variables were: severity (%), rate of disease development (r) and area under the disease progress curve (AUDPC) of late blight. Split plots was the experimental design used, being the main plots the production systems, and the subplots, the tomato introductions, with four replications. The study was conducted with fifteen wild tomato introductions at the Montelindo's farm of the Universidad de Caldas, in two production systems: free exposition and semi cover. To reach this purpose, it is necessary to carry out epidemiological studies and evaluate wild introductions against tomato late blight caused by Phytophthora infestans, the most devastating disease worldwide. Hence, it is necessary to evaluate and identify promising wild genotypes to observe their reaction to the main pathological problems of cultivated species, in order to be considered in future programs of tomato production improvement. Most of the genes responsible of resistance of tomato to fungi, bacteria, virus and nematodes, has been derivate from wild species of tomato. EPIDEMIOLOGY OF LATE BLIGHT ( Phytophthora infestans(MONT.) DE BARY) IN FIFTEEN INTRODUCTIOS OF WILD TOMATO. CARDONA-PIEDRAHITA, Luisa Fernanda CASTANO-ZAPATA, Jairo and CEBALLOS-AGUIRRE, Nelson.
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