Storm Spotlighted Long-Standing Problem in Stream Corridor

April 15, 2007 storm flooded basements with no previous history of problems and was followed by 2 months of water-logged properties Cause of blockage identified to be 50-foot debris deposit in stream bed + Japanese Knotweed invasion of stream’s flood plain Obropta’s team at Rutgers advised remediation plan of Knotweed eradication

 

Rutgers Eradication Plan

All stems cut and removed in July-August New growth sprayed with 8 % Rodeo + surfactant in September Overall results were close to 100% control for one full year following previous year treatment Downside is procedure is very labor intensive

Stem Injection

Initial project employed re-usable plastic syringeswith 5 cc of Rodeo/stem Rate of treatment was 125 stems/hour Hole drilled into stem using rotary saw Program extended from well before first frost, to after a mild frost, and beyond hard frost

Stem Injection + Stream Bank Cleaning

All areas treated had a mono-culture of Knotweed directly abutting stream edge Mixture of rose bushes and Knotweed in one area Extensive trash trapped in Knotweed stems was removed to dumpster Two weeks after injection, stems were cut and stacked in large piles

Records of Stems Treated in All Areas Were Documented

Stem injection from October to mid-December using syringes with drilled holes After mid-December JK injector gun was employed until first week of January Rate of stem injection with JK gun was 350 stems/hour of 5 cc Rodeo/stem Stem injection continued even with soil temperature at 35 oF in January Details of foliar treatment and stem injection available at www.stopknotweednj.com

Stem Injection Results: Fall/Winter

Results in Spring showed treatment before-frost and after-frost were identical: 80-95% eradication Stems injected after hard frost required drilling of stem when syringes were used Stems injected after hard frost with JK gun required no pre-drilling of holes Very rapid injection possible from date of hard frost into January in New Jersey due to stems being soft

Summary -- Stem Injection Results Spring ‘08

Stem injection in March/April very rapid due to stems being soft and easy to inject All stems reduced to liquid-like puddle in 2 weeks – no stem removal necessary Speed of stem injection improved by penetration anywhere from 1-5 feet from ground Combination of Fall and Spring injection leads to 100% eradication as defined as lasting for one full year after treatment

Summary -- Stem Injection Results Summer ‘08

Stems in full sun best drilled prior to injection Best technique is light-weight drill in one handand JK gun in other hand Drilling allows stems of all sizes to be injected and avoids splitting of thin stems Stems in shade require only JK gun Stems after rain are soft requiring only JK gun Pre-cutting of dried stems in March speeds stem injection of newly emerging stems

Summary -- Stem Injection Results Summer ‘08

Knotweed stem injection in NJ can be done for 10 months of the year Stem injection in Fall/Spring leads to 100% eradication(re-population of “eradicated” areas by small and medium size stems has been subsequently observed in treated areas) Stem injection after hard frost produces soft stems that are easy to stem inject with JK Injection Tool Two-handed drilling and injection proven for all stem sizes Pre-cutting of dried stems improves injection step by speeding process

Summary/Future Directions

Stem injection improved after rain - softer stems Stems in shade are intrinsically softer and only require use of JK gun Large clusters in March and April can be encased in plastic drum liners preventing large bio-mass development Battery-powered equipment speeds injection in cases of tough stems and/or when small stems are encountered Large areas can be treated in systematic way using Blazon dye added to herbicide Dr. Ron Crockett advises strategy of – “TREAT IT AND LEAVE IT” (re-planting may not be necessary/required)