Although Ben Franklin’s quote, “An ounce of prevention is worth a pound of cure” was made in reference to fire prevention it can certainly be applied to grassland managers dealing with sericea lespedeza and blackberries. Due to their rapid spread and persistence controlling them only gets more difficult and expensive as they become more established in your pastures.
Good growing conditions in most areas coupled with the biology of these plants make this an ideal time to apply control measures. The fact that most control measures that are effective in the fall are more economical than those used earlier in the growing season is a huge bonus as well.
Sericea Lespedeza is in the process of setting flowers, which is a prime time to apply herbicides and get effective control. After sericea has flowered and up until the first freeze, metsulfuron (marketed under Escort, Ally, Cimarron, and other trade names) is the herbicide of choice for control. Metsulfuron can control sericea even through seed fill, unless the plants are under drought stress. However, to avoid the formation of viable seed timing of spray is ideal toward the end of full flower.
Some recent K-State research has also studied burning native grass pastures around the first of September as a method to greatly reduce seed production and keep this noxious weed in check. Results from these studies are very promising and I would strongly suggest you use this tool to battle this plant.
It is also a good idea not to graze of hay sericea after it has gone to seed. This can prevent spread of seed by cattle to other areas. Controlling sericea is a mulit-year process and any control measures will need followup to maintain effectiveness . Spraying remaining plants after a late summer burn or herbicide application next June when the plants are in a vegetative growth stage with Remedy or PastureGard according to label directions can further reduce stands of sericea.
Blackberry plants are utilizing the current good growing conditions to re-build the carbohydrate reserves of it’s underground rhizomes, which occurs after fruiting. Herbicides containing metsulfuron have been shown to be effective in controlling blackberries if applied during this time of year. Metsulfuron is a slow acting herbicide so be sure to apply controls about 45 days or more prior to a killing freeze.
Herbicide treatments on blackberries that have been mowed within the past four months aren’t recommended due to the reduced leaf area to absorb the herbicide.
Regardless of which herbicide you choose be sure to read and follow all label directions and play particular attention to details on recommended rates, surfactants and managing herbicide drift.
Ben Franklin’s axiom certainly applies to controlling blackberries and sericea, if left unchecked these pests continue to reduce the carrying capacity of your grassland and become increasingly more costly to control.