This fine feathery leaved plant is Scentless Mayweed. A commonly occurring weed on a range of soil types and always troublesome what ever the crop.
Why troublesome? In part, direct competition for light and then the contamination of the harvested crop. What is less well appreciated is that (like many plants) it exhibits allelopathic (inhibitory) effects upon other plant species such as some species of legumes and interestingly Italian Ryegrass especially during their establishment phase.
This effect can be demonstrated in trials as a significant reduction in the germination of wheat and barley seed. This further results in a depressive effect on root and shoot growth and final fresh weight. Winter wheat shows a greater sensitivity than winter barley. So what about Oil Seed Rape?
This can be achieved with the use of a herbicide that is either residual in nature or has contact action. However in this day and age we are all supposed to think about “alternative methods of control. With this in mind what options do you have? Well you can always graze off the offending problem (see grazing earlier blog!)
Initially it becomes critical to prevent the production and spread of seed. Sowing clean seed, cleaning equipment whenever it is moved from infested to uninfected areas are also advocated. After that small infestations can be eliminated by hand pulling and digging. (I can see this will be popular!)
Cultivation may be employed when plants are in the seedling stage, prior to seed set and don’t forget several cultural operations maybe necessary to get them all. There are currently no biological control methods available.
Alternatively you can use a herbicide. Actives such as bromoxynil and dicamba may be used. The Sulphonyl ureas work well as do many others. Remember to get the Agronomist to recommend the correct rate and instruct on the correct timing so as to get the best results.