Environmental data of 1998 and 2003, reflecting two
contrasting yet representative seasons of vine growth
(Fig. 6), were used to examine the sensitivity of a leaf
epidemic to the date and stage of initial inoculation and to
explain differences in epidemic development according to
interactions between the development of the host and the
pathogen. The year 2003 was characterized by early
budbreak, quicker development and high production of
secondary shoots because of high temperatures. Simulated epidemics were initiated by considering the infection of
the first expanded leaf (the closest to the bark) at different
phenological stages (from stage-1 to stage-7 expanded
leaves; L1–L7) of vine development. For these simulations,
the day of flowering, when grape bunches were at their
most susceptible to the disease, was achieved when the
accumulated sum of the mean daily temperature above
10°C reached 380 starting from day 1 (1 January). Shoot
topping was simulated 10 days after flowering. Parameters
used for simulation are summarized in Table 1. In these
simulations, for two contrasting growing seasons, 1998
and 2003, (i) the sensitivity of epidemic development to
the time of first infection was examined with particular
emphasis on disease severity at time of flowering, (ii) a
direct comparison of epidemic behaviour was made for
the two contrasting growing seasons from the same
day of initial infection, (iii) differences in epidemic
development were examined according to changes in
susceptibility classes of the leaf population and (iv) the
relationship between rate of disease development and
relative volumes of sporulating and susceptible leaf tissue
was investigated
Environmental data of 1998 and 2003, reflecting twocontrasting yet representative seasons of vine growth(Fig. 6), were used to examine the sensitivity of a leafepidemic to the date and stage of initial inoculation and toexplain differences in epidemic development according tointeractions between the development of the host and thepathogen. The year 2003 was characterized by earlybudbreak, quicker development and high production ofsecondary shoots because of high temperatures. Simulated epidemics were initiated by considering the infection ofthe first expanded leaf (the closest to the bark) at differentphenological stages (from stage-1 to stage-7 expandedleaves; L1–L7) of vine development. For these simulations,the day of flowering, when grape bunches were at theirmost susceptible to the disease, was achieved when theaccumulated sum of the mean daily temperature above10°C reached 380 starting from day 1 (1 January). Shoottopping was simulated 10 days after flowering. Parametersused for simulation are summarized in Table 1. In thesesimulations, for two contrasting growing seasons, 1998and 2003, (i) the sensitivity of epidemic development tothe time of first infection was examined with particularemphasis on disease severity at time of flowering, (ii) adirect comparison of epidemic behaviour was made forthe two contrasting growing seasons from the sameday of initial infection, (iii) differences in epidemicdevelopment were examined according to changes in
susceptibility classes of the leaf population and (iv) the
relationship between rate of disease development and
relative volumes of sporulating and susceptible leaf tissue
was investigated
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