Efficiency of ethanolic extract of eucalyptus (Eucalyptus globulus) in the control of Alternaria sp. in cabbage and potato crops

The inhibitory effect of ethanolic extracts against Alternaria sp. in greenhouse cabbage cultivation (Oleracea brassica) and in-situ potato growing (Solanum tuberosum) was tested. Ethanolic extracts were prepared from Eucalyptus leaves (Eucalyptus globulus) with a Soxhlet extractor. Phytochemical analysis revealed the presence of considerable amounts of quinones, lactones and coumaranes, and small amounts of triterpenes and steroids. The experimental layout in the greenhouse cabbage cultivation consisted of three ethanol levels, one classical chemical treatment (Trizimand) and one control, ten cabbages per treatment, three repetitions, arranged in a randomized complete block design. The effect of three concentration levels of ethanol, one time sprayed on the leaves of the potato crop, was tested. The treatment plots, including a control plot, were randomized, each block 4 times repeated. In the greenhouse trial, the treatments with the effective dose increased by 50 and 25% displayed a comparable activity with the chemical treatment. Those treatments showed an increased effectiveness, compared with the effective dose at lab conditions. In the potato field essay, based on the incidence of pustules measured in the period of 65 to 85 days after planting, all treatments had an equal effect. It is believed that the observed overall minor and equal impact of the ethanol treatments on the potato crop is due to the high plot-to-plot variability and the more than normal wet conditions during the growing season.