J.H. Miller; Manning, S.T; and S.F. Enloe. 2010. A Management Guide for Invasive Plants of Southern Forests. Southern Research Station. Forest Health Protetion. Asheville, NC. 123 p.
Biological control, or biocontrol, of plants uses living organisms to weaken, kill, or stop seed production of a targeted invasive plant. The most common agents in biocontrol programs are insects and pathogens, and uses of nematodes and mites are under study.
Classical biocontrol involves finding agents in the home range or similar habitat of the invasive plant, followed by intensive research on feeding habits and reproduction, and a planned introduction of plant-specific agents into invaded areas. The goal is to identify predators that are host specific to the target invasives, i.e., they will not attack native plants, and will increase and spread in the new range to permanently suppress the invasive species. Classical biocontrol has an initially high public cost due to an often lengthy search for the right agent, extensive feeding tests in special quarantine facilities, coordinated releases, and long-term monitoring. There are specific requirements through a series of scheduled oversights by a Federal Government interagency committee requiring documented studies to strictly control biocontrol agent releases. Following release, nontarget damage is very rare but has occurred with the classic example of the musk thistle head weevil (Rhinocyllus conicus Frölich, 1792) attacking native thistles. In general, scientific evaluations of past releases have shown that the benefits from biocontrol over a region outweigh the detriments.
Classical biocontrol programs in the southern region are under development for tallowtree [Triadica sebifera (L.) Roxb.], Chinese privet, and tropical soda apple (Solanum viarum Dunal), and in Florida for Old World climbing fern also known as small-leaf climbing fern [Lygodium microphyllum (Cav.) R. Br.]. Successful projects underway target purple loosestrife (Lythrum salicaria L.), melaleuca [Melaleuca quinquenervia (Cav.) S.F. Blake], and alligatorweed.
Augmentative and inundative biocontrol identifies native insects, pathogens, nematodes, and mites that feed upon nonnative invasive plants in this country. When the appropriate agents are discovered and researched, there is an attempt to release large numbers of them into high infestation areas of the invasive plant. A program under development for kudzu uses this method. This program and other prior efforts have used pathogens and have been formulated into sprays, often referred to as bioherbicides. The challenge has been to maintain the viability of the pathogen or spores during packaging, shipment, application, and residence on the target foliage.
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