What is the aggressiveness index and how is it calculated for Phytophthora infestans? I have calculated different epidemiological components such as infection frequency (IF), latent infection period (LIP), lesion size (LS), lesion growth rate (LGR) and RAULEC for different isolates of Phytophthora infestans on potato leaves. My objective is to determine which isolate is more aggressive. How can I transform these five epidemiological components (IF, LIP, LS, LGR and RAULEC) into a single value which could be used as an aggressiveness determinant?
You can find some idea in the following paper, in spite that it was done with Erwinia amylovora, a bacterium which causes fireblight in rosaceous plants. we used a combined index, based on the rate of infection/disease progression, and the median infective dose (similar to LD50). You can download the paper in my Researchgate area.
Cabrefiga, J.; Montesinos, E. 2005. Analysis of aggressiveness of Erwinia amylovora using disease-dose and time relationships. Phytopathology. 95: 1430-1437.
Thanks Dr. Emilio,
I downloaded you paper and it is very helpful. I can apply the method for aggressiveness described in your article with slight modifications. thanks
Thank George, your provided link solved my problem. according to the method described in the article, composite aggressiveness index can be calculated by the formula
CAI = IF x LS x SC/ LP
where, IF= infection frequency, LS= lesion size (mm2), SC= sporulation capacity; LP= Latent infection period.
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