Farm Ireland

Sunday 18 March 2018

Pay attention to young plantations now to maximise your future crop

William Merivale

With the planting season coming to an end, owners of young plantations should crack on with some general maintenance and spring cleaning. The first four years -- the establishment phase -- of a new forest are crucial and some attention to detail now will pay dividends in ensuring a well-stocked and healthy crop for the future.

Areas that should be looked at include:

• Stocking density: Dead trees must be replaced, known as 'beating up'. Payment of the second phase of the grant is conditional on a minimum 90pc survival rate -- 2,250 (conifers) or 2,970 (broadleaves) live, healthy trees per hectare.

A few plots chosen at random throughout the plantation should be sampled. To check the numbers is simplicity itself: all you need is two bamboos and a tape measure (or length of baler twine exactly 8m long, plus enough to tie a knot).

A circle with a radius of 8m has an area of exactly 1/50th of a hectare, so place one bamboo in the middle of the plot, attach to it the end of the tape measure (or string), pace out 8m and mark your starting point with the second bamboo. Now, holding the tape taut, walk in a circle counting the live trees within the circle as you go. Don't cheat; if any tree lies just beyond the end of the string ignore it. A fully stocked circle will contain at least 50 conifers or 66 broadleaves, so at year four the minimum requirement will be 45 and 60 trees respectively.

In the intervening years, near to full stocking should be maintained. Averaging the numbers in the plots will give a good indication of the overall failure rate and consequently the amount of beating up required.

• Spring cleaning: Competing vegetation poses a significant threat to young trees and is the commonest cause of poor performance, even failure. As well as stealing light, moisture and nutrients, weeds suppress small trees and cause physical damage. Broadleaves are particularly susceptible to nutrient and moisture competition, and on the more fertile sites vegetation is likely to be more lush and pose a still greater threat.

Some weed competition, especially in young conifers, can be trampled or cut back with a hook, particularly so where physical damage is the main threat, rather than competition for nutrients and moisture. By and large, once a healthy conifer has a head start over surrounding vegetation it will outgrow it, but there will be instances where there is a need to resort to chemical treatment.

Also Read

More often than not, broadleaves will need at least one careful application of herbicide and frequently more. It is essential to use a cowl on the head of the sprayer to protect the trees from as much spray drift as possible. Avoid spraying in windy conditions.

It's a good idea to add some dye to the mix to highlight any areas that might have been missed, and if the trees are in leaf, any spray drift can be quickly spotted and the leaf torn off before the herbicide is absorbed. The aim should be to kill the vegetation in a one-metre circle around each tree.


The principal herbicides still available and in general use are glyphosate (eg, Roundup) for grasses and broadleaved weeds, and triclopyr (eg, Garlon) for woody weeds and brushwood.

• Fencing: Walk the entire boundary to check the fence is stockproof. Even young calves, let alone store cattle and suckler cows, can cause immense damage to trees and the drainage network in a plantation in a very short space of time and must be excluded.

Get to know your plantation as well as possible in these early years. Watch out for the areas of good, indifferent and poor growth, and any wet spots that might need more drainage.

Areas of poor growth may need additional fertiliser and it is usually more cost effective to wait until foliar analysis can be carried out.

For this, samples of foliage must be taken at the right time and sent for testing. Take the samples during the summer for broadleaves when the trees are in full leaf, and late November onwards for conifers when the trees are completely dormant.

The Coillte laboratory in Newtownmountkennedy offers this service for a small fee and will identify the deficiencies and recommend the type and amount of compound fertiliser required to rectify the problem.

William Merivale is national secretary of PEFC Ireland and a forestry consultant based in Cork. Email:

Indo Farming