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CORESTA Meeting, Agronomy/Phytopathology, Bucharest, 2003, PPOST 13

Studies concerning the control of blue mold (Peronospora tabacina Adam) in Virginia tobacco fields in Romania

STANESCU V.; PAUNESCU A.D.; CIUPERCA A.; DUMITRASCU P.
Central Research Station for Tobacco Culture and Industrialization, Bucharest, Romania.

Blue mold caused by Peronospora tabacina Adam acts in the field by the emergence of yellow spots on the tobacco leaves, the attacked tissues dry, the leaves are penetrated and become deformed. In Romania, this dangerous pathogen causes damage when the air temperature is between 17 and 24 °C and the humidity of the air around 80%, in all the areas where tobacco is grown. In the period 1997 - 2002 studies were conducted concerning the chemical control of the species Peronospora tabacina in the field with Virginia tobacco. The following fungicides were used for the tests: Ridomil MZ Gold 68 WP (metalaxyl 4% + mancozeb 64%) - 2.5 kg/ha; Ridomil Plus Gold (metalaxyl 2.5% + Copper 40%) - 2.5 kg/ha; Shavith F 71.5 WP (triadimenol 1.5% + folpet 70%) - 2 kg/ha and Champion 50 WP (Copper hydroxide with 50% metallic copper) - 2 kg/ha. The experiment was arranged in randomized blocks, in four replications, the treatments being made when the first characteristic spots for blue mold appeared. The observations and notes were recorded at 7 and 14 days after the treatment, according to the CORESTA scale, the intensity of the attack was noted with marks from 1 to 5, and the frequency of the attack represented the percent of plants affected. After determination of the rate of attack, all the treated variants recorded sub-unit values while the untreated control values exceeded 2 - these values were statistically assured. The yields of tobacco in the treated plots are higher compared with the untreated control, the differences obtained being very significant versus the untreated controls.