Isolation trials of pathogens causing root rot disease of pepper plants collected from El Behera and El-Dakahlia
Governorates revealed the presence of two isolates of Rhizoctonia solani, one of each of Fusarium solani, F. oxysporum,
Alternaria alternate, Sclerotium bataticola and Phytophthora capsaci. Isolation from seeds of 2 pepper cvs. Sweet
(California wonder) and hot (Cayenne) exhibited the presence of A. alternate, F. solani and S. bataticola. F. solani was
more present on sweet pepper (41.5%) than hot pepper (38.2%).
The reaction of the pepper cultivars to the isolated fungi showed that the mixed infection; with all tested fungi, was
severe pathogenic, the sweet cultivar was more susceptible (Total mortality 73%) than the hot cultivar (47%), both pepper
cvs, showed significant decrease in shoot and root fresh and dry weight compared with the control.
In vitro studies; 2 isolates of each T. harzianum, T. viride and one of Bacillus subtilis were used. The results showed
that B. subtilis significantly decreased the growth diameter of the tested pathogens. T. viride isolate 2 and T. harzianum
isolate 1 were more effective. Tazolien fungicide at 0.19 g/ li was superior followed by Rhizolix-T at 0.45g/l. Hot pepper
oil and camphor oil completely inhibited the growth of F. solani, S. bataticola and R.solani at 500 mg/l.
Green house experiments showed that T. harzianum significantly decreased infection percentages (less than 7%) in
both cultivars with mixed inoculation infection. Rhizolix-T. at 0.45 g./l. was next, where it decreased the infection up to 3-
10% (53-83% untreated control). The use of hot pepper oil and camphor oil significantly decreased infection up to 20% in
hot pepper and 30-37% in sweet pepper.
Seed treatment increased significantly the chlorophyll content of leaves. Estimation of total phenols in leaves of
pepper cultivar showed increase of phenol content after infection, the increase was more in hot pepper than the sweet
cultivar.