The effect of Verticillium and Fusarium wilts on the growth of four melon (Cucumis melo L.) cultivars

Abstract

The susceptibility of the Greek melon cv. Kokkini banana, Thraki, Peplos and Amynteou to Verticillium dahliae and Fusarium oxysporum f. sp. melonis was tested. Seedlings of the four cv. were inoculated by root immersion in a Verticillium and a Fusarium inoculum suspension of 106 spores ml-1 for 1 h. Disease incidence was determinated after 35 days with a disease index, calculated as the product of the ‘leaf symptom index’ and the ‘vascular discoloration index’ of each plant. In addition, certain growth characteristics: plant height, main stem diameter, above-ground fresh and dry weight and root fresh and dry weight were measured, to have a basis for determining the effect of wilt upon plant growth. The adverse effect of the Verticillium and Fusarium wilts on the plants was estimated by the regression line slope coefficient (b) between the disease index and those growth characteristics. Both fungi had a significant negative effect on all the measured characteristics irrespective of the cultivar. Cultivars Kokkini banana and Peplos were the most susceptible, cv. Amynteou and Thraki the least susceptible to both fungi. The four melon cultivars exhibited a different susceptibility to Verticillium and to Fusarium indicating that selective breeding for resistance is a practical possibility.