According to the public relations office of the Iranian Research Institute of Plant Protection, due to the restrictions in sustainable Rapeseed production in the fields infected with the parasitic plant Orobanche nana, Dr. Mehdi Minbashi and Dr. Nooshin Nezamabadi, the faculty members of the Weed Research Department of the Institute by implementing several research projects have proposed chemical, non-chemical, and integrated control methods for Orobanche, use of rapeseed tolerant cultivars, and trap plants to reduce seed bank of this weed in rapeseed fields.
Dr. Minbashi, Deputy Director of research, technology and research findings transfer of the Institute regarding the use of non-chemical control methods of Orobanche nana, recommended to cultivate Bersim clover as a trap crop to reduce the Orobanche seed bank in the soil. This plant stimulates the germination of Orobanche seeds, but the weed is not able to attach and grow on the roots of Bersim clover. Cultivation of a mixture of 4 kg of clover with 5 kg of rapeseed seeds per hectare reduces the damage of Orobanche at least by 80% in rapeseed fields.
He mentioned rotation in cultivation as one of the effective methods of managing this important weed in rapeseed fields and added: avoiding continuous planting of rapeseed and crops on which Orobanche have the ability to grow and reproduce on them, such as broad beans, red clover, Mung bean and visia are also effective methods in managing this weed. If plants that do not host Orobanche, such as cotton, garlic, flax and cowpea are planted in areas where the soil is contaminated with Orobanche then this weed will not be able to attach to the roots of these plants. These plants can also be cultivated alternately with rapeseed.
For chemical control of Orobanche, Dr. Nezamabadi, the head of Weed Research Department recommended the use of glyphosate herbicide at a rate of 80 ml per hectare along with 1% ammonium sulfate. She emphasized that the above combination should be used for autumn rapeseed cultivars in three stages (early regrowth of rapeseed from rosette, 20 and 40 days later and for spring rapeseed cultivars such as Hayola 50, in the 5-leaf stage of rapeseed, 20 and 40 days later.
She specified: for spraying the second and third stages, if it is not possible to enter the farm, sprayers with a long boom (for example, 30 meters) could be used by observing the farm traffic. It should be noted that the occurrence of rain 6 to 24 hours after spraying reduces the effectiveness of the herbicide. It is not recommended to spray on rapeseed under dry stress and temperature less than 10 ° C.
The head of weed research department, while pointing to integrated control as one of the useful methods in Orobanche management in rapeseed fields, said: "When planting in fields infected with this weed, a mixture of 4 kg of Bersim clover with 5 kg of canola seeds per hectare (recommended seed rate per hectare for rapeseed) with glyphosate herbicide at a rate of 80 ml per hectare with 1% ammonium sulfate according to chemical control instructions can be used.
Dr. Nezamabadi added: In the areas with long periods of winter with temperature below -5 degrees Celsius, it is not possible to grow Bersim clover.