L. Mol et al., THEORETICAL APPROACH TO THE DYNAMICS OF THE INOCULUM DENSITY OF VERTICILLIUM-DAHLIAE IN THE SOIL - FIRST TEST OF A SIMPLE-MODEL, Plant Pathology, 45(2), 1996, pp. 192-204
A mathematical equation was developed that describes the inoculum dens
ities of microsclerotia of Verticillium dahliae in the soil over a lon
g time span. The equation was based on measurable parameters and ecolo
gically meaningful principles. In the model, the number of systemic in
fections of plant roots during crop growth was related to soil inoculu
m density. In turn, formation of microsclerotia in debris and reductio
n of the amount of crop growth were related to the number of systemic
infections. Finally, a gradual release and mortality of microsclerotia
in the soil were included to calculate subsequent inoculum densities
in the soil. Fitting the function to experimental data of potato cvs E
lement, Ostara, Mirka and Astarte, flax, pea, barley, sugar beet, onio
n and faba bean gave a very high correlation between observed and pred
icted soil inoculum densities. The clear differences in inoculum produ
ction among potato cultivars and other crops were expressed in quantit
ative terms. The highest inoculum density after incorporation of the d
ebris of a susceptible crop was estimated to occur at 2.3 thermal time
units of 3600 degree days (base 0 degrees C). Ten per cent of the ini
tial input of inoculum was still present after 4.5 thermal time units.
The model was used to predict the dynamics of soil inoculum densities
for V. dahliae under various cropping frequency schemes and performed
satisfactorily.