EFFECT OF PLASTIC COVERING METHOD ON THE INFECTION OF SOME CULTIVAR OF TOMATO ( Lycopersicon esculentum Mill ) TO EARLY BLIGHT DISEASE CAUSED BY Alternaria solani AT DESERT AREA OF BASRAH CITY

Abstract

This study was conducted under desert conditions at Al-Basrah city/Iraq during the winter season of 2005/2006. The aim of the experiment was to study the influence of cultivars and plastic covering method on infection of tomatoes plant in early blight disease. Experiment included 9 treatments resulting from the interaction between three cultivars ( "Douna"," Hatouf" and "Saria") and three methods of plastic covering ( Double layers air space between them, Double layers without air space and Single layer ).. Randomized Complete Block Design was used with three replicates. R.L.S.D. test was used at probability of 5% to compare mean variations. Results can be summarized as follows:- Results showed that highest decreasing percentage of productivity was 20.11% due to the incidence of early blight disease was at planting "Hatouf" cultivar plant under double layers of plastic covering without air space, whereas the least was 6.37% from "Saria" cultivar under single layer, which gave the highest damage factor 93.6% and least economic loses percentage about 5.99%, whereas the expected will gave the least yield (3279.8 g. plant-1) in the absence of the disease and therefore it gave the lowest economic loses in its yield about 196.5 g. plant-1 regarding with "Douna" cultivar planting under the double layers covering without air space which gave the lowest damage factor 76.2% and the highest economic loses percentage 18.14% and the expected yield (3457.1 g. plant-1) in the absence of the disease, whereas it gave 2830.0 g. plant and therefore it gave the highest economic loses in its yield 627.1 g. plant-1.