Detection of the parasitic plant, Orobanche cumana on sunflower (Helianthus annuus L.) in Tunisia
Orobanche cumana broomrape is a parasitic plant described as an agricultural problem for sunflower production in many countries. In Tunisia, this pathogen was found parasitizing sunflower cultivars in some fields in the Béja region, for the first time during the 2009-2010 agricultural season. Clear O. cumana attachments were observed in some sunflower fields and the infestation rates ranged from low to very high with an average of 39.4 ± 33.1, 211.8 ± 164.7 g and 54.9 ± 48.3 g for the total Orobanche number (TON/P), the total Orobanche fresh weight (TOFW/P) and the total Orobanche dry weight per host plant (TODW/P), respectively. Pathogenicity test on several host species (faba bean, rapeseed, sunflower, lentil, pea, tomato, pepper and potatoes) showed that attachments were observed only on sunflower root system. In some fields, O. cumana seed bank in the soil was high enough to decrease sunflower yield and to allow fast expansion of the infestation and therefore reduce the sunflower cropping area and production. The early detection of this new parasite in Tunisia and application of quarantine and control measures can be helpful in reducing the speed of its spread.
Key words: Broomrape, Orobanche cumana, sunflower, Tunisia.