Summer chatter included conversations about Mink, Otters, Crayfish, Cormorants and Gosandada. Are birds plundering fish stocks? Are Otters chasing salmon upstream? We could have added local poachers to the list. However, we failed to mention something equally problematic, equally irritating and equally invasive, Himalayan Balsam!
There are places along the river Nidd no longer fishable because of this plant. On the river Laver, a significant tributary of the Ure, Yorkshire Dales River Trust has a three-year conservation project funded by the Environment Agency. A key objective of which is to survey and control Himalayan Balsam. There are many other examples!
Why is Himalayan Halsam such a problem?
Impatiens glandulifera has rapidly
become one of the UK’s most widespread and invasive weeds, colonising river banks,
wasteland, damp woodland, roadsides and railway embankments. HB can reach well above
head-height. It grows and spreading rapidly. The plant competes successfully with native
plant species for space, light, nutrients, pollinators, and prevents other plant growth
through shading and smothering. In winter it leaves river banks bare of vegetation and
open to erosion. Dead plant material entering streams increases the risk of flooding. The
plant has attracted as much environmental debate and research as crayfish, dutch elm and
killer bees.
For fly fishermen, HB quickly becomes an obstacle to casting and will snare more flies and leaders than overhanging trees! National databases and mapping projects are monitoring the problem. In truth, HB has already invaded nearly all of England and Wales. The issue now is more a question of control than prevention. The plant was first introduced as a greenhouse curiosity around 1839. I gets it name Himalayan from its natural habitat and because i's a culinary plant much used in North Indian cuisine.
Fortunately, for now, the upper Tees riverbanks seems relatively HB free compared to many UK rivers.
What do we need to do:
Make sure we can identify the plant.
Understand seed dispersion.
Report locations.
Plan which areas need to be managed.
Identifying the species.
In summer it is a succulent plant with pointed leaves on a red stem. In winter it leaves
tangle of pale woody canes over bare soil. HB can grow up to six feet high, or taller.
You can Google the plant for further information and photographs.
Understand seed dispersion for HB.
HB has pods which explode with some force. Seeds being further dispersed by wind, cattle,
birds and people. Squeezing the pods sets off the explosive action to disperse the seeds.
This is quite spectacular and people are not averse to demonstrating the effect to
children for its entertainment value. Taller plants can project seeds up to three meters.
Seeds are able to survive two or three years if conditions for germination are not right.
The diagram shows the reproductive time scale.
Reporting location of HB plant.
If we know where there are clusters of the plant causing access or casting problems it
might be possible to clear key areas.
Deciding which areas need to be cleared.
If HB becomes established it will not be possible to clear vast areas of the river bank.
The goal would be to clear paths and casting areas on our most popular pools and swims.
Dealing with Himalayan Balsam at the right time is essential. Clearing needs to be done
early in the plant's reproductive cycle before seed pods form. Fortunately, that should
coincide with Spring Working Weekend(s).
