Studies on the control of broomrape (Orobancheramosa L.) in Virginia tobacco (Nicotianatabacum L.)

During 1997 and 1998, in the province of Perugia (Umbria, central Italy), four field experimental trials were carried out to study the control of broomrape (OrobancheramosaL.) in Virginia tobacco. In 1997, maleic hydrazide (2040 mL ha-1), flumetralin (1200 mL ha-1), n-decanol (10720 mL ha-1), glyphosate (180-324 mL ha-1) and rimsulfuron (12.5-25 g ha-1) were tested on the variety K 394. In the second year, maleic hydrazide (2040 mL ha-1), n-decanol (10720 mL ha-1) and butralin (2160 mL ha-1) were utilised in the same variety. Furthermore, a field experiment was performed to assess the susceptibility of different untopped Virginia tobacco varieties to broomrape. The presence of the weed was recorded as the number of the aboveground broomrape plants per m2 and after harvest dry weight was determined. Maleic hydrazide proved to be highly effective against the parasitic weed when used at the early flowering stage of the crop, reducing by 95% and 73%, on average, the number of broomrape plants with respect to the untreated control, respectively in 1997 and 1998. Rimsulfuron, used 55 days after transplanting, had a satisfactory activity against broomrape (reduction of 50-70%). A double treatment with glyphosate caused a reduction of 100% of broomrape but it significantly depressed tobacco yield. Flumetralin, n-decanol and butralin did not show any control of broomrape. The variety BC 60 FB was found to be highly resistant to the weed with an average of 85% reduction in broomrape plants compared to the other varieties in the experiment