I - --ii

40
0
50
45
40
35 Disease
30
S25
15
10 -No j
disease
5X
X
0 I I I I I I I
3 6 9 12 15 18 21 24 27 30
Temperature (oC)
Figure 4.Minimum periods of wetness duration and minimum temperatures for Ascochyta infection
on chickpea.
the rotation. The amount of debris mixed with seed is,on the other hand, not very
large, which again cuts down the probability for successful transmissions.
Role of Infected Seeds in Disease Initiation
Five microplots with 19 infected seeds each were prepared inside a macroplot of
susceptible chickpeas. The disease started on February 2, i.e., 3 weeks before the
first appearance in the debris-infested plots (Fig. 6). In all five microplots the
disease spread very rapidly. By March 26, 100% infection was reached. The
X