Common Ivy
Introduction
Hedera helix, L.
Ivy is an evergreen climbing member of the Araliaceae family. Ivy is an important element in European and Asian woodlands, comprising a large portion of woodland understory, especially in the British Isles. There are several ornamental varieties that are grown for gardeners and it is prized by naturalists for the flowers and fruits it produces late in the autumn; a useful foodstuff and refuge for invertebrates and birds.
Ivy has aerial roots that have matted pads that enable the plant to cling to the substrate and climb to heights of up to 30 metres to the canopy. It uses trees and buildings to climb to a great height enabling it to benefit from being in the top of the canopy without the structural investment that other canopy species make. If Ivy is unable to climb it will creep along the ground and not exceed more than 20 cm in height.
Ivy is not directly harmful to trees however the "sail effect" created by an enlarged canopy particularly during the winter when most broadleaved species lose their leaves can make older, veteran trees susceptible to damage. Ivy is unlikely to be a problem in the UK where a suite of natural pests and diseases keep it in check; and its benefits to wildlife far outweigh any damage it may do to the tree that it uses for support. It can however be a problem on structures where it can dry the mortar out and cause physical damage to walls.
Identification
Ivy is an evergreen climber that will scale up to 30 metres using its adventitious root system. Where no vertical surface exists it creeps along the ground. The leaves are alternately arranged on the stem, 50–100 mm long, with a 15–20 mm stem. Ivy has two types of leaves, five-lobed juvenile leaves on creeping and climbing stems, and unlobed adult leaves on fertile flowering stems exposed to full sun, usually high in the canopy of trees or at the top of structures. The flowers are produced from late summer until late autumn, individually small, in 3–5 cm diameter heads, greenish-yellow, and very rich in nectar, an important late autumn food source for bees and other insects. The fruit are purple-black berries 6–8 mm in diameter, ripening in late winter, and are an important food for many birds, though somewhat poisonous to humans.
Cultural Methods Of Control
Ivy does not tolerate being cut back therefore if it is surrounded by an area that is regularly mowed it can be constrained however because of its aerial roots it quite happily grows over and around barriers. It can also be controlled by placing it in a pot suspended away from the floor this will prevent is spreading however placing it into a deep open pot, a method used by gardeners to control certain invasive species from spreading, is not effective with Ivy simply because it will grow over the pot.
Chemical Methods Of Control
Professional Herbicides
Ivy has an exceptionally thick waxy cuticle, which prevents many foliar applied herbicides being very effective. Glyphosate, the active ingredient in Roundup ProVantage and Roundup ProActive can be used and the following notes will aid its efficacy;
To maximise control in areas where an alternative residual weed control is not possible or where re-cropping of the area is planned, the following will optimise control with Roundup herbicides.
Foliar Application
- Wait until the shoots have some new, soft leaf growth in the spring, usually May at the earliest. Over-wintered leaves have tough, thickened wax layers as they are hardened in the cold weather, which are more difficult to penetrate.
- Apply the highest rate of glyphosate recommended
- Add up to 2% Mixture B to increase penetration of the cuticle.
- A weedwiper could also be used where decorative plants are growing intimately with the ivy.
- Monitor and re-treat the sites as necessary over a period of three years.
- Cut Stump / Stem Injection Treatment
Where ivy is mature and growing up masonry or trees there may be a woody trunk which can be treated as trees in the dormant season. This method is very effective on ivy.
Application To Mature Ivy
Ivy must be dormant, this usually occurs between November and February, although in some seasons and in the most northern parts of the country this could extend until the end of March.
Cut Stump Method
Application of glyphosate must be made to a fresh cut so that uptake into the phloem is maximised.
Use a paintbrush and apply immediately after cutting. (Uptake is almost immediate from a fresh cut and will be rainfast within 10 minutes. Application to a cut that has partially sealed means absorption is slow and rain within 6 hours will wash some of the product off.)
Chemical Thinning
Neat glyphosate is introduced straight into the phloem through a axe cut into the bark of the ivy leaving the plant intact. A Spot gun with a solid stream nozzle is recommended and it is advisable to make a second cut under the first to catch any surplus herbicide. Work out how many hatchet cuts are needed according to the diameter of the trunk and space them round the girth. e.g. trunk of 20cm diameter requires 2 cuts. Alternatively, the concentrate can be introduced through an 8mm drill hole, about 40mm long, aimed slightly downwards and radially towards the centre of the stem.
Rates And Water Volumes
| Method | Dose Rate of Roundup ProVantage | Dose Rate of Roundup ProActive | Application Advice |
|---|---|---|---|
| Foliar Spray | 3.75l/ha in 80-250l water | 5l/ha in 150-250l water | Add 2% Mixture B NF, use droplets on the finer side of medium, spray to just before run-off |
| Weed Wiper | 1 part Roundup ProVantage to 3 parts water for ropewick applicators | 1 part Roundup ProActive to 2.25 parts water for ropewick applicators | Useful where decorative plants are growing nearby |
| Cut Stump | 7.5% solution of Roundup ProVantage and water | 20% solution of Roundup ProActive and water | Use a paintbrush and apply immediately after cutting |
| Chemical Thinning | 1.5ml of neat Roundup ProVantage per 10cm diameter (or less) of stem | 2ml of Roundup ProActive per 10cm diameter (or less) of stem | Evenly space the correct number of cuts required around the girth |
Domestic Weed Killer
Ivy has an exceptionally thick waxy cuticle, which prevents many foliar applied herbicides being very effective. Glyphosate, the active ingredient in Barclay Gallup Home & Garden can be used and the following notes will aid its efficacy. Barclay Gallup Home & Garden is a very effective herbicide that starts to degrade almost as soon as it is applied however it is not selective and will kill any plant it comes into contact with.
The following will optimise control with Barclay Gallup Home & Garden.
Foliar Application
- Wait until the shoots have some new, soft leaf growth in the spring, usually May at the earliest. Over-wintered leaves have tough, thickened wax layers as they are hardened in the cold weather, which are more difficult to penetrate.
- Monitor and re-treat the sites as necessary over a period of three years.