Survey of Himalayan Balsam in the Clun Catchment report Part 1

SURVEY OF HIMALAYAN BALSAM (Impatiens glandulifera) IN THE CLUN

CATCHMENT

PART 1

0. Contents

1. Summary ..................................................................................................................................................................... 3

2. BACKGROUND INFORMATION ............................................................................................................................ 4

2.1 Project funding................................................................................................................................................ 5

2.2 Status of Himalayan Balsam in the Clun Catchment in April 2013 ............................................... 6

2.3 Identification and Biology of Himalayan Balsam ................................................................................ 9

2.4 Project Outline ............................................................................................................................................... 13

3. SURVEY....................................................................................................................................................................... 14

3.1. Target Area for Survey ................................................................................................................................ 15

3.2. Field Survey Approach ............................................................................................................................... 16

3.3. Reported Sightings Approach ................................................................................................................. 17

3.4. Summary of Field Survey Results - Clun ............................................................................................... 18

3.5. Summary of Field Survey Results - Unk ............................................................................................... 19

3.6. Summary of Field Survey Results - Kemp ........................................................................................... 20

3.7. Summary of Field Survey Results - Hopesay Brook ......................................................................... 21

3.8. Summary of Field Survey Results - Hopton Brook ............................................................................ 22

3.9. Summary of Field Survey Results - Redlake ....................................................................................... 23

3.10. Summary of Field Survey Results - Minor Watercourses in the Catchment ............................ 24

3.11. Practicalities of Field Surveying .............................................................................................................. 26

3.12. Presence of Japanese Knotweed (Fallopia japonica) ...................................................................... 27

3.13. Giant Hogweed (Heracleum mantegazzianum) ................................................................................ 29

3.14. Reported Sightings from the Public ...................................................................................................... 31

3.15. Overall Distribution ..................................................................................................................................... 32

4. Photographic Evidence of Himalayan Balsam ............................................................................................. 33

1. Summary

Himalayan Balsam is an issue in the Clun Catchment. It poses a risk to the Freshwater Pearl Mussel because it leaves banksides vulnerable to erosion during winter flooding and consequently leads to the sedimentation of gravels in which the mussels live.

During 2013, Natural England provided the Shropshire Hills AONB funding to survey the catchment for the presence of Himalayan Balsam and to undertake a limited amount of management in its upper locations. This is on account of the organisation’s responsibilities in promoting the conservation of the Special Area of Conservation located near Leintwardine, where the mussels occur.

Himalayan Balsam is a species of concern for the Environment Agency too. The organisation’s ‘Corporate Plan 2011-15’ points out its responsibilities in implementing the England Biodiversity Strategy and presents Aim 2.3, to ‘…help to reduce the impact of the most damaging water-related non-native species’ under its role to ‘Help to enhance the environment and biodiversity to improve quality of life’. The Environment Agency has supported the project by: helping to identify locations of Himalayan Balsam; providing authority to SHAONB staff to access riverside sites and underlining the responsibilities of farmers in controlling Himalayan Balsam on targeted site visits.

A better understanding of the spread and density of Himalayan Balsam has been derived through the project; it occurs along 41km of the River Clun and its tributaries, accounting for14.5% of the total catchment.

The complete eradication of Himalayan Balsam in the catchment is likely to be unattainable; however a concerted effort to control the species by landowners and targeted contractor effort would go a long way towards avoiding an escalation of the problem.

2. BACKGROUND INFORMATION

Himalayan Balsam growing at the field edge along the River Kemp

2.1 Project funding

‘The Invasive Non-Native Species Framework Strategy for Great Britain’ (NNSS 2008) places much emphasis on prevention measures for non-native species, stating ‘This will maximise the potential reduction in adverse impacts and the costs associated with tackling invasions once they achieve a foothold…It should therefore be given high priority’.

In the ‘River Clun SSSI/SAC Restoration Strategy’ (Atkins, March 2012) commissioned by Natural England, invasive species are considered one of the ‘key issues that are having an adverse impact on the characteristic habitats and species that are typical of the river.’

In early 2013, Natural England identified funding to be made available to SHAONB to undertake a comprehensive survey of the catchment for Himalayan Balsam. Funds were also set aside for the writing of a proposed control strategy. The outputs are presented in this document.

Within 50 miles of Craven Arms there appear to be only two other projects recorded by NNSS as specifically dealing with Himalayan Balsam - the Monnow Rivers Association and the Cannock Chase Streams of Life (Staffordshire Wildlife Trust).

2.2 Status of Himalayan Balsam in the Clun Catchment in April 2013

The NNSS (GB Non-Native Species Secretariat) describes the status of Himalayan Balsam in England as ‘Established….Well established and extremely invasive throughout most of lowland Great Britain… Impact is high in Great Britain. It is rapid-spreading on soft banks of waterbodies, dominant, forming extensive monoculture stands to the exclusion of most other plants’. It now occurs in at least 108 of the 112 vice-counties in over 2000 10km (hectad) squares. Figure 1a shows Himalayan Balsam’s presence in the area according to NBN Gateway. Planttracker (planttracker.naturelocator.org) does not (in April 2013) show a realistic extent of Himalayan Balsam in the area, with only two verified locations in the catchment marked (both being beside Clun Castle). A ‘Risk Assessment’ or ‘Invasive Species Action Plan’ for Himalayan Balsam has not yet been devised by the NNSS. Currently it is estimated that it would cost between £150-300 million to eradicate Himalayan Balsam from the UK (10).

Mike Kelly of the Shropshire Hills AONB has over the last decade noted the existence of Himalayan Balsam as part of site visits he has undertaken in the area. These have not been mapped or digitised and therefore records are difficult to interrogate. However, one piece of information that has been ascertained through this process is that Himalayan Balsam does not tend to occur above Clun Village. During 2012, The Environment Agency undertook a survey of Clun village vicinity and also considered its previous site visits and confirmed the SHAONB’s assessment. With the view that it is best to ascertain the uppermost location of Himalayan Balsam as the ‘parent source’ of seed in the catchment, a map of the location of the species around Clun was drawn up by the Environment Agency (Figure 1b). This showed Himalayan Balsam to occur at Leasowes and Bicton Farm.

The Jacobs Report ‘Clun Restoration Strategy 2013’ 6.7 states ‘Invasive species pose a problem within the Clun Catchment. In particular, Himalayan Balsam which was found along bank sides in various spots during January 2013, although it was difficult to identify the extent of its occurrence due to the midwinter timing of the survey… Himalayan Balsam poses problems in terms of biodiversity of the riparian habitat as a whole since it out-competes less vigorous native species, thus reducing their abundance, but also in terms of bank stability, where the shallow roots do not provide the stability that other trees and shrubs might afford’. Figure 1c indicates the findings of the winter survey.

Other methods of ascertaining distribution had not been pursued before April 2013. For example, farmers do not tend to advertise the fact that they have Himalayan Balsam because it is a requirement to control the species as part of Single Farm Payment conditions, and so it may have proved difficult to glean this information had questionnaires been undertaken.

No comprehensive information is available as to which landowners undertake management of Himalayan Balsam and whether this is timed correctly. The status of applications for permission to herbicide treat riverside Himalayan Balsam received by the Environment Agency over the last five years is unknown. At the ‘River Workshop’ organised by the SHAONB & Environment Agency at Purslow (February 2013) an insight into current management was gained; a number of attendees raised the issue that they were not prepared to control Himalayan Balsam on account of the fact that it was a ‘losing battle’ because the species was arriving from upstream.

(c) Crown Copyright and database rights 2013 Ordnance survey 100049049.

Figure 1a: Distribution of Himalayan Balsam in Locality According to NBN Gateway (30/4/2013)

Grey shaded areas show presence on Himalayan balsam

Figure 1b: Extent of Himalayan Balsam on the River Clun at Clun (Environment Agency, 2013)

Figure 1c

2.3 Identification and Biology of Himalayan Balsam

• Introduced into the UK in 1839 from Northern India (1, 2)

• Typically found on riverbanks and in damp areas (1, 3); moist and semi-shaded damp places, predominant on banksides by slow-moving watercourses (5).

• Tolerate low light levels (8)

• Has spread at an average rate of 645km2 per year in the UK (2, 7)

• The plant is annual (1, 5) It is the tallest annual plant in Britain (7)

• The species can grow into dense stands (1, 5).

• The leaves are dark green, lance-shaped, have a dark-red midrib, serrated edges and can grow up to 150mm long (1, 4) 5-18 cm long (5) They grow on the stem in whorls of three (4) or opposite (5).

• The stems are pinkish-red-translucent, sappy, succulent, brittle, stout and hollow with side branches originating from joints in the stem (1, 4, 5)

• It can grow up to 3m tall (1, 4, 7), 2m tall (3) 2.5m tall (5, 10) 2-3m (8)

• It has a shallow, fleshy root system (2)

• The flowers are slipper shaped, with helmeted upper petal and short spur (5), and they are purplish-pink or white in colour with a strong balsam smell (5). Flowers begin to appear in June (1, 4) June – August (3) June-October on long stalks (4, 7, 8) July-October (5)

• Dehiscent seed pods explode when touched or shaken (7).The ‘exploding’ seed pods mature in late July/August(1) From mid-July onwards (5) Seeds are set from August to October or until frost kills the plants(7) Onset of flowering can be delayed by 2-3 weeks in shaded sites (5).

• Each pod can contain up to 16 seeds. (1) 4-16 seeds (7) A plant can produce up to 800 seeds (2, 5, 7, 8) 2500 seeds per plant each year ((Invasive Weed Solutions Limited) 30,000 seeds per m2 (7)

• The white, brown and black seeds can be catapulted up to 7m. (1, 4, 5, 7, 8)

• They can be further spread by water movements (3)

• Seeds remain viable in the soil for: 1 year (1) 18 months (2, 3), 2 years (4, 8, 9) Most seeds overwinter for one season before germinating the following spring (they have a chilling requirement), however there is some evidence of a persistant seedbank lasting for at least 2 years (5, 7) Seed character suggests the seed should persist for less than 5 years (7).

• The seeds have a chilling requirement for germination to occur (7). Seeds can germinate underwater (Invasive Weed Solutions Limited). Germination occurs in February-March, followed by rapid shoot extension and leaf expansion from April (5). Seedlings begin to emerge as early as March (1); Seedlings can mature as late as November (1)

• One year of effective control (pre-seeding) can eradicate the problem (1); three years of control should sufficiently deplete the seed store (any plants remaining after a three year program will have germinated from either seed of plants surviving the control methods or new seed arriving from outside the control area) (2); two years of control should eradicate the plant if there is no further infestation from upstream (3)

Impact

• Invasive; dense stands shade out native species (1, 3, 5, 9). It may reduce species richness by 25% (7) It successfully competes with native plant species for space, light, nutrients and pollinators, and excludes other plant growth, thereby reducing native biodiversity (10).

• Bare areas are left following autumn dieback, so leaving areas liable to erosion (1, 3, 4, 9, 10) and destruction of bankside structure (5)

• Dense stands can impede water flow at times of high rainfall, thereby increasing the likelihood of flooding (5). Dead plant material can enter the waterbody thereby increasing risk of flooding (10).

• The copious sugary nectar (with extended flowering period) is attractive to native insects, luring species away from pollinating native flowers (1, 5, 9, 10). This form of indirect competition can reduce the genetic diversity of native species and lessen their fitness by reducing seed set (10).

• Seeds may be spread by human intervention on equipment and clothing (eg. fishermen) and by movement of contaminated soil; equipment should be checked, cleaned, washed and dried.

• Seeds in mud may be carried by animals.

• Stands restrict access to the river (10)

Most Relevant Legislation

• Under the Wildlife & Countryside Act 1981 it is an offence under section 14(2) of the Act to ‘plant or otherwise cause to grow in the wild’ any plant listed in Schedule 9, Part II. (The Countryside and Rights of Way Act 2000 include increased penalties available to the courts for offences committed under W&CA).

• Non-native plant weed material is considered a ‘controlled waste’ and must be disposed of in accordance with, and environmental permit issues under, the Environmental Permitting (England and Wales) Regulations 2007, unless one of the exemptions set out in Schedule 3 of these regulations applies (although exemptions also require registration with the Environment Agency).

• The Food and Environment Protection Act 1985 (Control of pesticides Regulations 1986, as amended) sets out the rules on using pesticides to control weeds growing in water or on land. Product labels of aquatic herbicides highlight the need to get permission from the Environment Agency to use herbicides on the banks of a watercourse.

Photo taken in September 2013 showing explosive seed pods

Photo showing serrated leaves in whorls

Mike Kelly, River Valleys Officer, demonstrating the tallness of the plant (at 2.5m) and the tight root system

2.4 Project Outline Action Detail Schedule CompletionFunding Funding sought by SHAONB for HB survey and works for period

2013-2014 Funding from Natural England confirmed SHAONB to seek further funding for 2014-15

February 2013 April 2013 January 2014

Completed Completed N/A 2014

Access Arrangements

Authorisation for land access to be sought from Environment Agency by SHAONB staff; this will permit access on site without needing to contact individual landowners (which is time-consuming).

Mid May 2013 Completed

Quotes for HB Treatment

Quotes to be sought from at least two contractors as a daily rateGauge of how much can be achieved in a set time, using choice of methods to be sought

Late April 2013 Late April 2013

Completed Completed

Survey of HB Identify target area for project (see below)Survey approach to be decided (see below) Survey of HB to be undertaken by SHAONB staff * EA application form AqHerb01 to be completed, if necessary, to secure approval for herbicide treatment.

Early May 2013 Early May 2013 Late May 2013 Late May 2013

CompletedCompleted Completed July 2013 Avoided; Bicton Farm undertaken by owner, remainder handpulled

Treatment of HB Risk assessment to be drawn up for contractor(s)Contractor or contractors to be appointed; to be issued with EA authority Contractors to commence treatments Contractors to complete works Payment to be made to contractors

Late May 2013 Late May 2013 Early June 2013 Late July 2013 Late July 2013

CompletedCompleted Started mid-June Completed August Paid August

Monitoring SHAONB staff to approve completion of treatments on a week by week basis ie. Site visits made SHAONB staff to revisit sites and pull up any emerging /flowering stems missed by previous treatments; where growth is significant, contractors to be re-employed subject to remaining funding.

Mid June 2013-Late July 2013 August 2013

Extended into August‘Clean-up days’ set aside by contractors

Publicity Seek HB sightings at Clun Green Man FestivalPublicise work and seek sightings through Press Release Seek HB sightings through School questionnaire Produce a flier to provide information to the public Publicise work and seek sightings through LLL Publicise work and seek sightings through NFU Publicise work and seek sightings through Shropshire HUB Record project on NNSS website Record sightings on Plant-tracker Publicise contractor work through Press Release Complete compilation of strategy, consult others and make available on SHAONB website

May 2013May 2013 May 2013 May 2013 May 2013 June 2013 May/June 2013 July 2013 August 2013 August 2013 December 2013

CompletedCompleted Analysis completed Leaflet uploaded to web Sept; draft poster not circulated during 2013 Completed NFU contacted; no progress Completed Completed August Completed August; also placed on Shropshire Botanical Society Database in October Completed August Draft form completed December

2014 Project Outline

Contact riverside owners regarding responsibilities for HB control; circulate guidance notes on control methods. If funding available, employ contractors to undertake treatments; if funding unavailable, organise volunteer groups to undertake hand-pulling treatment

Spring 2014 May 2014

2014 2014

*Surveys for Japanese knotweed and Giant Hogweed to be undertaken at the same time as for Himalayan Balsam.

3. SURVEY

Himalayan Balsam growing on the banks of the River Clun, on the upstream side of Jay Bridge.

3.1. Target Area for Survey

Based on existing information, during 2013 it was planned to focus survey effort on the River Clun, from approximately 3km upstream of Clun Village, all the way down to its junction with The Teme. Based on EA information, a survey was to be undertaken of the Unk up to Bicton Farm. As no information was available on the extent of Himalayan Balsam on the main tributaries of the Kemp, Hopesay Brook, Hopton Brook and Redlake, it was intended to survey the full lengths of these rivers. It was not proposed that all brooks associated with all the watercourses were also surveyed, though this was dependent on what was discovered during the main survey.

Surveying was delayed until the very end of May on account of the long winter and the lateness of the growth season. Even in the first week of June most plants were only around 8cm high and only visible when viewed at close proximity. A handful of Himalayan Balsam plants had started to flower in the second week of July, around a month late.

Figure 2: Survey Reaches

3.2. Field Survey Approach

• Each field along the water course was visited by SHAONB staff. Generally landowners were not contacted prior to gaining access; an authorisation letter from the Environment Agency was in hand.

• The existence and extent of Himalayan Balsam was marked for each field on the relevant map. The existence of Japanese knotweed and Giant Hogweed was also noted.

• Coverage of Himalayan Balsam were ‘judged’ as to whether it gave an impression of being ‘not observed’, ‘rare’, ‘occasional’, ‘frequent’ or ‘abundant’. These categories were marked on the relevant map. (The Plant-tracker scale of Low=<1m sq, Med= 1m-5m sq, High=>5m sq was not opted for).

• Photographs were taken at the time of survey or soon after to illustrate the presence of Himalayan Balsam.

• A summary sheet of reach conditions was devised and filled out on return to the office (see below). Raw mapped data was transferred to GIS and included as part of the summary sheet.

• As part of office-based work, grid references were sought for occurrences of Himalayan Balsam at regular intervals along the reaches from SCC iGIS; this information was sent to [email protected] using a proforma, so that it could be uploaded to Planttracker.naturelocator.org (see Appendix M).

3.3. Reported Sightings Approach

Reports of Himalayan Balsam from the Environment Agency were included as part of the main field survey information.

Press releases and questionnaires were issued (see Project Outline). Reports of Himalayan Balsam from farmers, the public and school children were noted.

3.4. Summary of Field Survey Results - Clun

The uppermost location of Himalayan Balsam on the Clun was found to be at 328977 281632 (junction of brook and River Clun at Leasowes Farm) just above Clun village. This was based on confirmed early sightings by the EA and absence of confirmations above this point, as well as the 2013 survey findings. Farmers contacted through the Land, Life and Livelihoods newsletter did not provide any information to dispute this. Himalayan Balsam was found along the whole of the Clun to the junction with the Teme however the width of plants was surprisingly narrow in the main (probably around 2-3m width). The density of Himalayan Balsam became most prolific from Hurst Mill downstream via Clunton to Purslow Farm and then again from Clunbury to Oaker Cottage. Here Himalayan Balsam was so abundant that it was found to be spreading into hedgerows, woodlands and roadside verges.

Though Himalayan Balsam was often located on beaches, it was also found on short to medium cliff faces and the top of banks, normally within the area which appeared to reach the usual strand line. It was noticeable that in locations grazed by stock, new plants still originated in disturbed soil such as mole hills and still occurred at the edges of fenced fields by the river. However, plants were most prominent in areas that were prevented from being grazed due to the presence of fence lines or existence of cliffs. Some plants also occurred along the edge of arable fields. (See ‘Survey of Himalayan Balsam in the Clun Catchment: Part 2’ for Survey Sheets)

3.5. Summary of Field Survey Results - Unk

The highest location of Himalayan Balsam on the Unk was found to be at Bicton Farm (328936 282733); this was based on confirmed early sightings by the EA and the absence of confirmations above this point. Bicton Farm was exceptional in having large numbers of Himalayan Balsam away from the river, and in having Giant Hogweed and Japanese Knotweed present there too. One gets the impression that the farm is a key source of seed along the river.

Reach HBUnk1 had a rather ‘bitty’ presence of Himalayan Balsam; the greatest concentrations being in the north within horse-grazed fields. The reach was quite well wooded; Himalayan Balsam was often found where there were gaps in the canopy where cattle couldn’t graze, but also along nettle-rich banks. At present, Himalayan Balsam seems to be a minor problem along the Unk.

(See ‘Survey of Himalayan Balsam in the Clun Catchment: Part 2’ for Survey Sheets)

3.6. Summary of Field Survey Results - Kemp

The highest location of Himalayan Balsam on the Kemp was found to be at SPARC centre at Bishops Castle 332452 287988. It appears that this is an isolated clump as spot checks immediately downstream do not record its presence.

The next observed sighting is at Little Brampton Farm at 328977 281632; this conclusion was based on walking the bottom section of the Kemp.

It appears that Himalayan Balsam occurs in the very meandering section of river nearest the River Clun. A concentration of Himalayan Balsam occurs close to an abandoned building and could have seeded from there, though one does get an impression that seed may have floated up-river when the nearby Clun has flooded and become deposited in the lower meanders of the Kemp.


3.7. Summary of Field Survey Results - Hopesay Brook

The highest location of Himalayan Balsam on the Hopesay Brook was found to be at Hesterworth at 339132 282856; this was based on the walking of the main branch of the watercourse and then undertaking spot checks on the minor branches. The presence of Himalayan Balsam was often as individual plants; the greatest concentration occurred in a newly-planted woodland, where grazing was absent, where the brook became particularly narrow. The area closest to Hesterworth was well-wooded with few sunlit gaps for Himalayan Balsam to establish. At present, Himalayan Balsam seems to be a minor problem along the brook.


3.8. Summary of Field Survey Results - Hopton Brook

The initial kilometre of the brook from its junction with the River Clun was walked and no Himalayan Balsam was found. A spot check was undertaken at the junction with the B road north of Heath House and no Himalayan Balsam was found there. It is therefore assumed that HB is not an issue along the brook. Perhaps the well-vegetated junction with the River Clun and the well-vegetated brook itself has prevented Himalayan Balsam from establishing with ease.


3.9. Summary of Field Survey Results - Redlake

The highest location of Himalayan Balsam on the Redlake was found to be at 335903 273886; this was based on the walking of the main branch of the watercourse to Bucknell village and then undertaking spot checks a few kilometres above Bucknell. Between Bucknell and Coxall Farm there were only handfuls of plants present. The greatest concentration of Himalayan Balsam on the Redlake was at Coxall Farm and Adley Moor. Clumps of Himalayan Balsam plants occurred downstream of Jay Barns to the junction with the River Clun. It appears that much of the source of the Himalayan Balsam seed is from the vicinity of Coxall Farm. In proportion to the length of the Redlake, the area affected is quite short, however along that stretch Himalayan Balsam is quite frequent.

Reaches 6-11 were not surveyed due to the absence of Himalayan Balsam immediately downstream.


3.10. Summary of Field Survey Results - Minor Watercourses in the Catchment

Himalayan balsam on minor watercourses in the lower catchment was generally restricted to flood zone areas adjoining the River Clun and usually does not extend more than a few tens of metres away from the main river. The following spot check investigations away from flood zone areas did not identify presence. Spot check on minor watercourses: 330824 281072 The Green, Clun 333569 281608 Clunton to Bury Ditches road 338597 281770 West of Oaker Cottage, Aston on Clun 340118 280101 Broome, south of Broome Farm 339473 288769 Near the Rectory, Clungunford 339402 277081 West of The Lynches (near Marlow) 339827 277666 Broome Road, The Gables

The status of Himalayan Balsam along minor watercourses was therefore assumed to be negligible. No other information came to light, such as from EA observations, to suggest otherwise.

3.11. Practicalities of Field Surveying

• Where tree cover was dense (eg. large trees closely spaced, field margin scrub tightly flailed) it proved difficult to assess Himalayan Balsam presence from the river bank eg. HBUnk1, HBClun9. In most cases there were some breaks in tree cover to allow observation of the river margin.

• Deep dingles occurred in HBLeasowes1 and made it extremely hazardous to survey for Himalayan Balsam. A gauge of presence was able to be assessed, however.

• Surveying early in the season (May-early June) required the surveyor to be ‘on top of’ the Himalayan Balsam in order to detect its presence. (Himalayan Balsam would have been easiest to survey from late July-August when plants were in flower). In later season visits, some Himalayan Balsam was observed, which hadn’t been identified in the earlier survey eg. HBClun3.

• By early July riverside vegetation could be very tall, whilst Himalayan Balsam plants were generally less than 60cm tall. The surveyor needed to part through vegetation in order to gain access to the river’s edge. Eg. HBRedlake1

• Binoculars were a useful tool in detecting Himalayan Balsam on the opposite side of the river.

• Barbed wire and netted fences or hedgerows and thickets prevented a smooth journey along the river bank, especially where there were changes in ownership.

• Bridges across the river were rare and therefore for any particular reach, plants were normally observed from one side of the river.

3.12. Presence of Japanese Knotweed (Fallopia japonica)

These species were only found at Bicton Farm.

Appendix B: Japanese knotweed, Fallopia japonica (from NNSS)

• Short description

Herbaceous perennial, with stems typically about 2m tall and an extensive system of rhizomes. It has large, roughly triangular leaves with truncate (not cordate (heart-shaped)) bases.Japanese knotweed is an invasive non-native weed, mainly in urban areas where it is considered a nuisance in property development, because plants regrowing from rhizomes can come up through gaps in flooring in conservatories and patios.

• Impacts summary

Possibly the most economically important invasive non-native species in GB, as eradication is required by law in property development sites and that can be expensive. It has only limited impact ecologically.

• Habitat summary

Urban areas, river banks and waste ground, usually in full sunshine. It is not shade tolerant and does not persist in woods. Long established stands by rivers tend to have a similar vernal ground flora to W6 Alnus glutinosa woods, with F. japonica providing the canopy layer during the summer months

• Dispersal Mechanisms

Dispersal is by deliberate or inadvertent human activity, except along rivers, where root pieces can be washed downstream during floods and subsequently become established elsewhere.

• Reproduction

Plants in GB are a male-sterile clone, so no seed is produced, although it can hybridise with other species of Fallopia.

• Known Predators/Herbivores

None known.

• Resistant Stages

All stages are viable; it does not produce seed in GB.

• Habitat Occupied in GB

Mostly urban areas and riverbanks. Sometimes it is found established on the edges of arable fields and other places where garden waste or topsoil has been dumped

• Environmental Impact

Its ecosystem impact is undocumented but seems likely to be low. Often-repeated claims of its impact on native species are not supported by evidence; it usually occurs in highly degraded urban situations where the native flora is already impoverished.

• Health and Social Impact

There are no documented health or social impacts. It has a considerable benefit to the environmental services industry, including waste disposal licensees.

• Economic Impact

The high economic impact is due to legislation that makes its eradication a legal requirement and the cost of its disposal expensive. Eradicating it from construction sites can cost well over £1,000 per square metre and, as a controlled waste, it can be expensive to dispose of the 'contaminated' topsoil. The total global cost of its control could be hundreds of millions of pounds per annum. Many sources claim that it can grow through solid concrete, but this claim is not supported by any published evidence and seems unlikely to be true.

• Risk Assessments

NNSS have devised a risk assessment for the species. It has not produced an Invasive Species Action Plan.

3.13. Giant Hogweed (Heracleum mantegazzianum)

Giant Hogweed, Heracleum mantegazzianum (from NNSS)

• Short description

Aptly named ‘giant’, this umbellifer (member of the cow-parsley family) has flowering stems typically 2-3 m high bearing umbels of flowers up to 80 cm in diameter. The basal leaves are often 1 m or more in size. First recorded in 1828. Giant hogweed is widespread in lowland GB, and is invasive by lowland rivers and on waste land.

• Impacts summary

The sap can sensitize human skin to ultra-violet light, leading to severe blisters. Affected skin may remain sensitive for several years. The plant is also a vigorous competitor, producing almost pure stands which exclude native vegetation and hinder anglers.

• Habitat summary

It is especially abundant by lowland streams and rivers, but also occurs widely on waste ground and in rough pastures. It grows on moist fertile soils, achieving its greatest stature in partial shade. In more open grassland, flowering may be delayed by repeated grazing

• Dispersal Mechanisms

The species reproduces entirely by seeds; fruits are oval-elliptical broadly winged mericarps. which are dispersed by wind, water and humans.

• Reproduction

The species is monocarpic, that is, it reproduces only once in its lifetime. Plants are able to self-fertilize. A single plant produces about 20,000 seeds which have to be stratified in the soil in cold and wet conditions during winter and then are highly germinable.

• Known Predators/Herbivores

Insect or pathogens have little effect. Grazing by livestock can significantly decrease the reproductive output but also prolong the lifespan before flowering.

• Resistant Stages

Seeds form a short-term persistent seed-bank; the majority of them germinate the following year after release and only about 1% of seeds are able to survive more than 3 years in the soil

• Environmental Impact

The species may form dense stands reducing species diversity.

• Health and Social Impact

The plant produces phytotoxic sap. The sap contains photosensitizing furanocoumarins, which in contact with human skin and combined with UV radiation cause skin burnings. The intensity of the reaction depends on individual sensitivity. The danger to human health complicates eradication efforts.

• Economic Impact

It has not been defined but it clearly lowers the recreational value of the landscape due to human health risk.

• Risk Assessments

NNSS have devised a risk assessment for the species. It has not produced an Invasive Species Action Plan.

3.14. Reported Sightings from the Public

The limited number of sightings received did not warrant the creation of a separate GIS map.

Green Man Festival

Though there was some interest from the public, no person highlighted Himalayan Balsam in the catchment other than from outside the catchment area. The show did not coincide with when the plants were in flower and this is likely to have limited the number of responses.

LLL Publicity

A request for sightings of Himalayan Balsam was made in the June’s ‘Land, Life and Livelihoods’ (LLL) newsletter. No reports were made of Himalayan Balsam in the upper reaches of the Clun by resident farmers. Though this method of ascertaining presence is not wholly reliable, it does seem to confirm the observations of SHAONB and EA.

Shropshire HUB E-letter

One phone call was received from a landowner outside the catchment requesting information on how Himalayan Balsam may be controlled. No sightings in the Clun catchment were reported.

NFU Publicity

NFU were contacted by SHAONB to ascertain whether they would be able to publicise the survey for the Himalayan Balsam. Sarah Faulkner of the NFU attended a Clun Steering Group meeting where the problems of Himalayan Balsam and the responsibilities of farmers were discussed. Subsequently Sarah Faulkner stated that she would be ‘willing to feed into the strategy and run it past members’. No sightings information was therefore obtained from the NFU.

Press Releases

This generated two phone calls from the public to state that Himalayan Balsam was present in the gardens close to Clun Bridge and the gardens below Clungunford Bridge.

The handful of other phone calls received related to Himalayan Balsam outside the Clun Catchment.

Isolated Sightings

During August, a report was made by Jeff Edwards (Natural England) of Himalayan Balsam at Sparc Leisure Centre in Bishops Castle. This appeared to be a self-contained area of Himalayan Balsam amongst dense wetland vegetation. Teme Leisure [email protected] were contacted to undertake control of the plants.

During August, Adam Shipp (Environment Agency) noted Himalayan Balsam on the Bishops Castle to Clunbury Road; a patch by the road at Bronte Cottage, Brockton (SO33130 86090); - now removed.

3.15. Overall Distribution

Overall distribution map taken from Plantracker following uploading of selected survey results. Affected catchment (41km) affects 14.5% of the Clun catchment (283km).

Clun

Aston on Clun

Leintwardine Bucknell

Bicton

4. Photographic Evidence of Himalayan Balsam

Himalayan Balsam growing along roadside verge

337929 281000

Himalayan Balsam growing at the base of hedge, some distance from the River Clun

337781 280936

Himalayan Balsam growing on steep bank well above the river

338083 281240

Himalayan Balsam growing amongst nettles beside the River Unk, highlighting the need for careful observation when surveying early on in the growing season.

Himalayan Balsam growing at base of brook channel at Leasowes Farm, amongst varied vegetation

Himalayan Balsam growing along cliff face within HBClun2

Himalayan Balsam at Hurst Barns

Point bar near Beambridge showing some Himalayan Balsam regrowth following a July strim by landowner

Himalayan Balsam growing in the buffer zone created by a new fenceline (river to rear)

Example of a Himalayan Balsam plant (Bicton Farm) only 4cm in height, yet still able to flower.

Area of Himalayan Balsam sprayed off with herbicide (Bicton Farm); isolated flowering seedlings apparent at the circumference.

Himalayan Balsam growing along the roadside amongst a heap of composted material and spoil (near Bicton Farm)

Area of Himalayan Balsam at roadside successfully controlled by strimming (Bicton Farm)

Isolated occurrence of Himalayan Balsam at SParc Leisure Centre (Bishops Castle) 332452 287988

Seedlings of Himalayan Balsam at Bicton Farm in late May/early June 2013

Clungunford Bridge

Purslow Farm

Hurst Mill

Clun SAC - Himalayan balsam at Mill Lane footbridge

4: REFERENCES

Himalayan Balsam along the River Kemp

References

1) Camel Valley Invasives Group HB Guidance and Control leaflet

2) A Report on Himalayan Balsam Control in the Wye Valley AONB 2009

3) Centre for Ecology & Hydrology Information Sheet 3: Himalayan Balsam 2004

4) Environment Agency Managing invasive non-native plants in or near fresh water 2010

5) Himalayan Balsam Overview NNSS 2011

6) Agreement to Use Herbicides in or near Water Guidance Notes, Environment Agency, January 2010

7) Himalayan Balsam Organic Weed Management, Garden Organic, 2007 including HDRA ‘The Biology and Non-chemical Control of Himalayan Balsam’ 2007

8) Himalayan Balsam Advice Search, Royal Horticultural Society, 2011

9) Himalayan Balsam RAFTS www.invasive Species Scotland.co.uk

10) Himalayan Balsam is a highly invasive annual weed www.cabi.org.

Appendix A

Appendix B

Appendix C

Appendix D:

APPENDIX L:

Appendix M: Survey Information for Uploading to PlantTracker

Date_Rec Taxon Amount lat long

dd/mm/yyyy e.g. Japanese Knotweed e.g. low, medium or high 51.768717,‐3.3564335

30/07/2013 Himalayan Balsam low 327838 280144



30/07/2013 Himalayan Balsam high 328007 280395







30/07/2013 Himalayan Balsam medium 328251 280821





































































































































































































































































30/07/2013 Japanese Knotweed low 328926 282809

30/07/2013 Giant Hogweed low 328877 282821



Appendix N:

Documents

Survey of Himalayan Balsam in the Clun Catchment report Part 1