SEED PRODUCTION AND GROWTH OF WATERCHESTNUT AS INFLUENCED BY CUTTING

A major infestation of waterchestnut (Trapa natans L.) in a reservoir in New York State was studied to evaluate the efficacy of air boat cut ting as a possible control measure. A measure of the status of the see d bank through sediment core analysis showed that deposition of new se eds in a treatment site was reduced to no net gain of seeds versus an average of 170 seeds/m(2) added to the seed bank in an untreated site. Results from seed-fall collection baskets placed in two untreated sit es revealed new deposition of 180 seeds/m(2) and 143 2 seeds/m(2), res pectively, which corroborated the results from Sediment core data. Cut rosette fragments, produced by the cuffing operation, were compared t o undisturbed whole plants for vigor and seed production. Both vigor a nd seed production rates were less than those of intact plants.