Mowing selected, low-g rowing vegetation within the tree row is being considered using adapted equipment that fits under tree limbs. Flails are a series of rotating knives on a shaft that cut vegetation very near the soil surface. Moisture loss from weeds is diminshed until regrowth occurs. Flailing also can hasten early season dormancy of some sods, thus reducing water use on som e sites. Prostrate weeds such as spotted catsear or false dandelion, prostrate knotweed, and others often become established when competition from the grass sod is reduced due to flailing.
Herbicides selectively control unwanted vegetation within the crop.
Agricultural chemicals require considerable testing to assess potential hazards and to minimize possible crop injury before they can be registered and sold for use in specified or labelled crops. Registrations are based on specific use patterns and instructions summarized on product labels. Herbicides are applied either to the soil before weeds emerge or to the foliage of unwanted vegetation. Most soil-applied herbicides are applied preemergence to weed growth during winter. Rains during this season or irrigation are required to activat e the chemical within the top soil layer.