Calculation of disease index (DI)
DI severity was classified into nine different levels according to the
percentage of the leaf area affected by the disease in individual leaves
(James, 1971). Levels 0 to 9 respectively were 0, 0~5,
6~10, 11~20, 21~30,
31~40, 41~60, 61~80, and
81~100 %, respectively. DI was calculated using the
following formula:
\begin{equation}
DI=\frac{\sum\left(x*t\right)}{s*\sum t}\times 100\nonumber \\
\end{equation}where x is the degree of disease severity, t is the total number of
leaves showing each degree of disease severity, and s is the highest
degree of disease severity observed.
Statisticalanalysis
The plant DI, phytohormones concentration and colony diameter, were
analyzed with the SPSS software (Version22.0, IBM, Chicago, USA).
Statistically significant differences were determined by ANOVA followed
by Duncan’s post hoc tests. A value of P < 0.05 was
considered to be statistically significant.