Effect of sowing date on Orobanche foetida infection and seed yield of resistant and susceptible faba bean cultivars

Orobanche foetida is an important new agricultural problem in Tunisia. It has been recently observed on vetch in Morocco showing increased risk of spread. In order to control this new parasite, field trials were conducted during two crop seasons to examine the effect of sowing date on O. foetida infection by using resistant and susceptible faba bean cultivars. The results demonstrated that late sowing reduced significantly the number and the dry weight of emerged O. foetida shoots for the resistant Najeh cultivar but not for the susceptible Badi cultivar. Late sowing (December) also reduced the number of underground tubercles for both cultivars. With December sowing, some attachments reached emergence stage for Badi but not for Najeh showing a delay in the growth of O. foetida on the resistant cultivar. Seed yield increased significantly on late sowing especially for the resistant Najeh cultivar which produces a much higher seed yield than the susceptible Badi cultivar. This can be explained by the reduced number and dry weight of O. foetida attachments and a slight decrease in shoot dry weight of the resistant cultivar. Combining both resistant cultivar with late sowing could be a useful tool as part of an integrated strategy to control O. foetida in Tunisia