Domestic Geese: Biological Weed Control in an Agricultural Setting

Abstract

Vertebrate herbivores can be effective agents of biological weed control in certain applications. I compared the use of domestic geese for weed control in an agricultural field with the herbicide hexazinone and with hand control. Newly planted spruce seedlings acted as a prototype crop that would be unpalatable to the geese. Trampling by geese led to as much as 47% tree seedling mortality during the 1st yr; this was reduced significantly by either limiting the amount of time the geese spent in the plots or surrounding seedlings with small wire fences. When compared with plots with no weed control, weed control by geese improved the diameter growth of the surviving seedlings by over 100% during the 1st yr of the study, but had no effect in the 2nd yr. The geese controlled a variety of weed species, but were most effective against quackgrass (Agropyron repens). However, grazing effectively selected for unpalatable weed species (including pineapple weed, Matricaria matricarioides, prostrate knotweed, Polygonum aviculare, and wild chamomile, Tripleurospermum phaeocephalum) so that by the end of the 2nd yr plots weeded only by geese had 25 times as much cover of unpalatable species as plots with no weed control. In contrast, the herbicide was ineffective against grass and effective against the unpalatable weed species. A successful integrated weed management strategy would thus require combining geese with another method of weed control, and would include measures to prevent crop trampling.