This week Nigel Chaffey finds a gentler way to kill a plant.
Our ‘Shock, horror!’ moment this month comes from a story that some sensationalist news sources might promote as ‘Absence of light kills plants’. Well, it would, wouldn’t it? After all, plants are photosynthetic organisms, so if deprived of light – their ultimate energy source – they can’t make food and will die. Yes, but we often need to dig below the surface and get beyond the ‘obvious’ for the real story.
This item concerns an environmentally-sensitive way of dealing with an invasive plant problem. Common Buckthorn (Rhamnus cathartica) is a particularly unwelcome plant visitor in the United States of America because these ‘exotic buckthorns tend to form dense, even-aged thickets, crowding and shading out native shrubs and herbs, often completely obliterating them’. ‘Control’ (a euphemism for removal and destruction of the plant) of the plant in the USA is desirable because, amongst other problems, the buckthorn degrades wildlife habitats, threatens the future of forests, wetlands, prairies, and other natural habitats and serves as host to other pests, such as crown rust fungus and soybean aphid, etc. Whilst a range of control methods have been proposed, one of the most successful also appears to be the least environmentally-damaging, mainly because it doesn’t involve use of potentially harmful chemicals.
Instead, the offending plants are cut down to near ground level and the stump is enclosed in a light-blocking, thick, black plastic bag. Over time – and it needs several months  to be effective – this ‘cut-and-cover’ approach prevents the stump from resprouting and the plant dies. The straightforwardly named ‘Buckthorn Baggie’ procedure was invented by Matthew Hamilton (currently studying engineering at the University of Wisconsin–Madison, USA). Furthermore, the Buckthorn Baggie is also an effective way to get rid of Frangula alnus (alder buckthorn or glossy buckthorn in the USA), and ‘almost every other tree that does not use root sucker to promulgate’.
Plants – knowing them better so we may kill them more effectively: Discuss…