This is an open invitation for noxious weeds to come into an area. If land is not managed correctly, then the most aggressive, non-native plants that are established nearby may take over an area, choking out native grasses and forbs. The knapweed infestation in Montana is contributing to the death of over 200 elk per year and several cattle ranches have been abandoned due to the overwhelming invasion of Leafy spurge and knapweed.
It is important to keep in mind that biological control is a slow process and will not eradicate noxious weeds. However, they do have their place in an integrated pest management plan. When used in conjunction with mechanical, cultural and/or chemical control methods, bio control can improve the overall efforts.