Ivy is an attractive plant that can become a menace and cause damage to buildings and monuments, although it does provide cover and food for wildlife, so its removal needs to be considered carefully.
It is difficult to control with herbicide, but woody growth can be effectively tackled during the winter months, says Monsanto's Manda Sansom
Identify the enemy
Ivy is a creeping/climbing, evergreen plant which has distinctive arrow-shaped leaves arising direct from the woody stem in its juvenile form, and larger, more rounded leaves once it reaches maturity. Only the mature stems produce flowers in October and November, giving way to clusters of round, green-black berries at the top of the stems.
It thrives in shady conditions and will act as a ground creeper, putting down adventitious roots as it spreads, or very often as a climber. Ivy can reach 30m high with stems up to 25cm diameter in the right conditions. The hair-like roots enable the plant to cling to hard surfaces, and it can be found climbing up trees, fences, walls, and brickwork.
Many ornamental varieties have been bred, which make useful garden plants, and berries provide an excellent source of bird food as well as shelter for many insects during barren winter months, so it is welcome in the right place. Yet the wild, green form can cause damage to buildings as it takes root-hold in mortar and loosens brickwork. Manual removal from ancient or sensitive heritage sites can cause irreparable damage to masonry.
Going into battle
Due to the exceptionally thick waxy cuticle, fairly small leaf area and creeping nature, this weed is usually classed as resistant to glyphosate.
However, it can be tackled with carefully timed foliar applications, by treating cut stumps after mechanical control or via chemical thinning.
To maximise control in areas where an alternative residual weed control is not possible, or where recropping of the area is planned, it may be necessary to use a non-residual, environmentally acceptable herbicide, Roundup ProBiactive 450 or Roundup ProBio may be successfully used.
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 Roundup ProBiactive 450 or Roundup ProBio recommended - i.e. 8l/ha in 100-200l /10l/ha in 100-200l water with a droplet size on the finer side of medium. In a knapsack, this rate is 40ml/ 50ml per litre of water sprayed to just before run-off.
Add up to 2 percent Mixture B NF or other approved wetter to increase penetration of the cuticle.
A weedwiper, with one part Roundup ProBiactive 450 to three parts water or one part Roundup ProBio to two parts water, could also be used where decorative plants are growing intimately with the ivy.
Monitor and retreat the sites as necessary over a period of three years.
Seeing the wood from the trees
Where ivy is mature and growing up masonry or trees, there may be a woody trunk which can be treated in the same way as trees in the dormant season. This method is very effective.
Ivy must be dormant, which 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
1) Rate: 16 per cent solution of Roundup ProBiactive 450/20 per cent solution of Roundup ProBio
2) Method: Application 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 ten minutes. Application to a cut that has partially sealed means absorption is slow, and rain within six hours could wash some of the product off.
1) Rate: 1.6ml of neat Roundup ProBiactive 450/ 2mls of neat Roundup ProBio for each 10cm diameter of the stem.
2) Method: Neat Roundup ProBiactive 450/Roundup ProBio is introduced straight into the phloem through a hatchet 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. a trunk of up to 10cm diameter requires just one cut, 20cm diameter requires two cuts etc Alternatively, where the ivy stem is sufficiently broad, the concentrate can be introduced through an 8mm drill hole, about 40mm long, aimed slightly downwards and radially towards the centre of the stem.
Ivy is often associated with holly as one of the evergreens still used to decorate houses and churches at Christmas - a custom deriving from pre-Christian times and once banned by the church because of these pagan associations.
Ivy was thought to counter the effects of alcohol, hence its appearance as an accoutrement of Bacchus, Greek god of wine, and on inn signs
In the USA, Ivy is classified as an invasive species in more than twenty-eight states and a 'noxious species' in several others, including Oregon, for one of the very reasons that it was introduced - its ability to rapidly spread. An internet search yields a multitude of American websites offering advice on 'how to combat English Ivy'!
For more information visit www.monsanto-ag.co.uk or telephone the Monsanto Hotline on 01954 717575
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