Dealingwith black-grass in stubbles is the first step in a successful weed controlprogramme for the year ahead, Bayer CropScience is reminding growers.
Peoplehave several options at this stage of the season, but the biggest factors arecrop choice and soil moisture.
Itobviously depends on what crop is following what, says Ben Giles of Bayer,oilseed rape after wheat is usually pretty tight, whereas if youre latedrilling winter cereals then you might have eight weeks or more to tackle weedproblems.
Themain tactic is to promote a flush of weeds black-grass and anything elsethats lurking in the soil and kill them off. For this, soil moisture is keybut it can be in short supply in August so its a case of waiting for moisterconditions for weeds to start growing.
Ifyou are trying to encourage black-grass, do everything you can to createseedbed conditions which will retain moisture and promote germination. Remembersome brome species are different and need to be left alone and not moved ifthese are a problem.
Afterharvest, many people like to cultivate the soil with discs but this can justend up drying out any moisture left in the ground and so some form ofconsolidation is important to create the false seedbed and encourage a flush.
Iknow of some people who run the drill through this false seedbed to replicateexactly what happens when a crop goes in.
Overall,there are whole range of tricks and methods which are geared to particular soiland conditions its all about learning from what has or hasnt worked in thepast.
Oneadditional thing to consider is the new stewardship guidelines for glyphosateusage which recommend only two applications per crop. Ben Giles believes thatthe new guidelines shouldnt have a big effect on control programmes: It meansyou can get rid of two flushes of black-grass, the first will be whenever thestubble starts to green up after harvest the second just before drilling.
Youhave to remember that the potential size of the black-grass seedbank can beenormous so you cant expect to eliminate every seed.
Whatyou are trying to do is create the best conditions for pre-emergence productsby killing as many as possible and getting plant numbers low enough for pre-emsto clean up the field.