While most of us may just associate mistletoe with Christmas parties, the fact is that it can be a nuisance in the wild. It's a parasitic plant (a group of plants, actually) that grows in trees or shrubs, penetrating their branches to absorb water and nutrients. In sufficient numbers, mistletoe plants can actually kill their host. That's why scientists are taking the offensive, with a system that shoots herbicide up into trees' high branches.
The setup was developed by a team from Mexico's INECOL institute led by researcher Mayra del Ángel, and working with colleagues at the Advanced Technology Center in Queretaro (CIATEQ).
It consists of a paintball-like gun, along with capsules containing a bio-herbicide that kills mistletoe while not harming the host plant. Using compressed air, the gun can shoot those capsules to a height of up to 25 m (82 ft), allowing them to hit mistletoe clusters that would otherwise be difficult to reach.
Each capsule has two layers, made up of a blend of three biodegradable polymers. This formulation allows it to remain intact even upon rapid acceleration (such as when it's being shot out of the gun), yet still split open upon contact with its leafy target.
In field tests, the technology has been found to be effective at eradicating mistletoe infestations. According to Ángel, the capsules could also be adapted to deliver substances such as fertilizer or insecticide.