Abstract: Phytophthora infestans (P. infestans) is a pathogenic fungus known for its destructive characteristic against tomato and potato.
The pathogen is notorious for its mutative ability against very effective antifungal drugs. This research, therefore, focused on the possible effects
of methanol leaf extract of Eucalyptus globulus (E. globulus) against P. infestans of tomato. Crude extract of E. globulus was obtained through
percolation eucalyptus leaf sample with methanol. Tomato seeds were planted in a nursery bed and later transplanted into pots. The plants were
inoculated with P. infestans pathogen then treated with different concentrations of E. globulus extract. There are 6 experimental treatments
consisting of T0 (negative control without pathogen inoculation), T1 (inoculated with P. infestans without treatment), T2, T3 and T4 were inoculated
with pathogen and treated with 0.2, 0.4 and 0.6 mg/ ml E. globulus extract respectively, while, T5 was inoculated with pathogen and treated with
0.2 mg/100 ml Mancozeb solution. Data were collected on plant height, leaf count, leaf area, stem girth, number of flowers, fruit count and yield
weight. The phytochemical analysis showed the presence of alkaloids, flavonoids, tannins, saponins, phenols and cardiac glycosides, while
phlobatanins, terpenoids and amino acids were absent. The effects of the E. globulus extract showed significant increase (p < 0.05) on all growth
parameters with the highest mean leaf count (218.53), leaf area (29.11 cm2) and stem girth (8.45 cm) occurring in T0, while the highest mean plant
height (39.43 cm) occurred in T5. The yield parameter showed significant increase (p < 0.05) in flower count, fruit count and yield weight of T0
compared to T1, with mean values of 67.56, 24.32 and 2.50 kg respectively. Methanol leaf extract of E. globulus expressed promising effect against
P. infestans of tomato, especially at 0.4 mg/ml application rate and therefore, 0.4 mg/ml could be a promising application rate for the management
of this disease.
Keywords: Antifungal, Eucalyptus globulus, Late blight, Lycopersicon esculentum, Phytochemical, Phytophthora infestans, Tomato.
jaerem NEW Obidola, Shakirdeen Mayowa 2
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