(Some biological characteristics of Spilocaea oleaginea, the causal agent of olive leaf spot)
1994
Guechi, A. | Walid, A.
The appearance of peacock leaf spot disease caused by Cycloconium oleaginum in the Setif region (east of Algeria) was found to be severe in spring and late autumn until early winter and very mild from early July until the middle of November. Infection on the lower parts was more severe than on the upper part of the trees. Damage on the leaves facing north was much more than on the ones facing south. Production of conidia in the leaf spots was found to be high in spring and late autumn but very limited in summer and early autumn. Temperature ranging from 15 to 18 deg C were found optimal for the growth of the fungus. A reduction in growth was noticed at 3 deg C, 5 deg C and 25 deg C with complete growth inhibition at 30 deg C. Results obtained suggest that the dead leaves do not play a role in new infections and the role of the remaining spots on the tree during summer is of little importance. Four periods of infection of new growth was noticed in the Setif region. The first, during late spring, where new leaves of young shoots were found infected. During this period inoculum remains hidden until late autumn. The second infection period occurs in autumn following rainfall. The third, in late autumn-early winter and is characterized by the occurrence of new leaf spots which are usually concentrated on the lowest pair of newly grown leaves. The fourth period of infection occurs during early spring and is the most important. The infected leaves of this period represent the source of inoculum for all above mentioned three infection periods
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