Broad-leaved dock (Rumex obtusifolius), a widely-distributed member of the Polygonaceae, occurs in the grasslands and The Wilderness area of campus. Alternative names include bitter dock, due to the leaf taste, and butter dock, as it was formerly used to wrap butter. A more unusual common name is Cushy-cows. Classified as an injurious weed under The Weeds Act of 1959, it out-competes grass and forage species and damages agricultural pasture. Farmers usually control it with herbicide however, organic farming requires labour-intensive, manual clearance. An innovative technological response to this problem was made by a Dutch research team who have developed and field-tested a prototype robot to detect and destroy individual weeds with a cutting device (van Evert et al 2011). Using GPS and a camera the robot achieved a weed detection rate of 93% and effective control in 73% of cases. The authors conclude the robot is effective for broad-leaved dock control on commercial farms.
Broad-leaved dock has positive attributes; the seeds are important winter food for birds such as Dunnocks (Prunella modularis) (Bishton 1986), whilst leaves are eaten by insects, including green dock beetles (Gastrophysa viridula). There is little scientific evidence to support the well-known British practice of rubbing leaves on nettle stings to reduce pain, but you may be one of the many who swear it works.
Image: Author: James Lindsey http://en.wikipedia.org/wiki/File:Gastrophysa.viridula.jpg
Bishton G. (1986), The diet and foraging behaviour of the Dunnock Prunella modularis in a hedgerow habitat. Ibis, 128: 526–539.
Van Evert, F.K. et al (2011) A robot to detect and control broad-leaved dock (Rumex obtusifolius L.) in grassland. Journal of Field Robotics. Volume 28: 264-277.
I’m a long term user of Dock to alleviate nettle stings however I’m willing to accept that it might just be the cooling effect of such moist leaves and the gentle rubbing with the leaf that do the good.
Is the dock destroying robot cost effective or just a novelty?
I don’t know about cost-effective (yet), but I have seen it in action in the Netherlands and it is very impressive. One of the problems in controlling Rumex is that they start very patchily distributed in a field and thus are not worth controlling. But each add many thousands of seeds a year to the long-lived seed bank and then when the field is cultivated, dock monoculture results. A robotic spot herbicide treatment of the patchily occuring plants could be very important.
I have heard via agriculture that on severe infestations of dock on organic farms, these beetles and larvae are used to good affect to control docks. Others in the Chrysomelidae are also very impressive at eating through foliage, i have witnessed how quickly the Watercress Leaf Beetle (Phaedon aeruginosa) divours vegetation when surveying for southerndamselfy.
Indeed, the beetles can be very effective in at least reducing the size of R. obtusifolius plants and their seed production. After a number of years they can even kill the plants, but it is not quick. I’ve been researching them for many years now, and introduced some onto campus last century. They still seem to survive.