Invasive species

Question 1

What legislation governs invasive plant species?

Answer 1

Wildlife and Countryside Act 1991

Question 2

What are the consequences of causing the growth of invasive plant species?

Answer 2

It’s a criminal offence. You can face up to 2 years in prison and/or unlimited fines for allowing the growth of invasive plant species
Land owners can also face civil action for allowing it to spread to neighbouring properties

Question 3

Why is Japanese Knotweed a problem?

Answer 3

Japanese Knotweed can grow through hard standing and foundation, causing instability and breaking up the concrete
It can be difficult to get a mortgage if there has been Japanese Knotweed present in the last 3 years

Question 4

How do you identify Japanese Knotweed?

Answer 4

Winter (Nov-Feb) - Dead with brittle stems
Spring (Mar-Apr) - Small purple shoots (spears and leaves)
Summer (May-Jun) - Green stems develop purple specs
Summer (Jul -Aug) - Fast dense growth
Autumn (Sept-Oct) - Small white flowers

It can grow up to 3m in height, spade shaped leaves, small white flowers, stems are like bamboo with green and red/purple speckles

Question 5

What are the treatment options for Japanese Knotweed?

Answer 5

• Spray treatment
• Injection treatment
• Excavation
• Burial
• Natural Predators

Question 6

What is involved in spray treatment of Japanese Knotweed?

Answer 6

• Spraying is an appropriate treatment for large areas
• Likely to require repeat treatment every two years
• Can only be done in the summer

Question 7

What is involved in injection treatment for Japanese Knotweed?

Answer 7

• Injection is required when they are close to a waterway or other plants (as spraying with contaminate)
• All stems must be injected, therefore labour and time intensive

Question 8

What is involved in excavation as a treatment for Japanese Knotweed?

Answer 8

• Dig and dump type system, where it is excavated and taken for safe disposal
• Can prevent need for re-treatment, but due to extensive rhizome (up to 3m deep) excavation must be extensive and disposal is expensive (controlled waste)

Question 9

What is involved in burial as a treatment for Japanese Knotweed?

Answer 9

• Soil/ plants are encapsulated and buried (at least 7m deep)
• High risk of recurrence

Question 10

What is involved in using a natural predator as a treatment for Japanese Knotweed?

Answer 10

There is a type of insect that exclusively eats Japanese Knotweed. It dies over the winter

Question 11

What is the issue with Giant Hogweed?

Answer 11

The sap reduces the skin’s ability to resist UV which results in burns and irritation with 24 hours. Can be very dangerous for children

Question 12

How would you identify Giant Hogweed?

Answer 12

Winter - dead stems
Summer (Jun-Jul) - white head of flowers
Summer (Aug-Sept) - releases seeds

Grow up to 3-5m high, with large leaves 1.5m wide, furry green/purple stems (ridged), large flower heads, look like giant cows parsley

Question 13

What treatments are available for Giant Hogweed?

Answer 13

Similar treatments as Japanese Knotweed - spray, injection, excavation, burial

Seeds can lie dormant for up to 15 years, so repetition of treatments are required if not caught after first year before seed release