Effect of kind and time of welsh onion (Allium fistulosum) leaves harvest on Alternaría spp fungus incidence

Abstract

Welsh onion crops are affected by several diseases mainly those caused by fungus. In this group, leaf diseases have caused more losses because they damage the commercial product. The work objective was to study the influence of kind and time of welsh onion leaves harvest on Alternaría spp incidence, in field conditions. The experiment was conducted at experimental area of the Agronomy Department - CCA/UEL, in April to June 1994. It was utilised plants with 3 bulbs each, and the treatments were: control (no harvest); total harvest (100% of the leaves) 20 days after planting (dap); total harvest 42 dap; total harvest 58 dap; partial harvest (50% of the leaves) 20 dap; partial harvest 42 dap; and partial harvest 58 dap. Although the diseases incidence had been low due to the small lesions number, they were well developed, and injured considerable part of the leaf tissues. More lesions number were observed in the treatments with older leaves (control) and partial harvest ones, when compared to total harvest's for the same period. The results show a possible inocule transferring from old to young leaves. Due to the results, we conclude that for a good sanitation and quality of welsh onion leaves, the best system is total harvest without delay.