Russian Olive Control with HBT

Herbicide Ballistic Technology (HBT) is a new approach of delivering herbicide using an encapsulated gel (ball) with a compressed air gun. Research conducted in Hawaii found that HBT was useful to control invasive weeds in remote locations or areas unreachable with conventional weed control equipment. An experiment was established near the Sheyenne National Grassland in southeastern North Dakota to evaluate the efficacy of triclopyr and imazapyr applied with HBT for Russian olive control. Herbicide application was made using gel capsules (balls) filled with a single herbicide concentration of imazapyr at 19 mg ae/capsule or triclopyr at 400 mg ae/capsule. Herbicide rate was controlled by the number of capsules that hit each tree and included 6, 12, 18 or 24 capsules/tree equal to imazapyr at 114, 228, 342, and 456 mg, respectively, or triclopyr at 2400, 4800, 7200, and 9600 mg, respectively. Treatment evaluation was based on percent visual injury, which ranged from 0% (no injury) to 100% (complete leaf drop and no new growth) compared to an untreated control. The experiment was a randomized complete block design with four replicates. A plot consisted of one tree and the replicates were grouped according to tree size based on measurements of trunk circumference. The trees ranged from an average of 31 cm in diameter in replicate one to 90 cm diameter in replicate four. Initial injury was 39 and 62% with imazapyr and triclopyr, respectively, 1 month after treatment (MAT) averaged over all application rates. In general, injury increased as application rate (capsules/tree) increased. For instance, injury averaged 57% with 2400 mg of triclopyr (6 capsules/tree) to 92% when 9600 mg (24 capsules/tree) 9 MAT. In general, triclopyr provided better control than imazapyr, but many larger trees began to regrow 13 MAT regardless of herbicide or application rate. Although all trees were severely injured, less than 50% were completely killed. HBT could be used to control established trees in areas unreachable with traditional field equipment but likely would require retreatment to control regrowth and kill larger trees. 

 

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