IT'S a safe bet the strong winds that have been raging around the country recently will have left more than a few trees damaged and in need of repair.

But if you're tempted to take up the offer of the "professional arborist" knocking on your door and offering to "top and lop" for a tenner (or more likely £50 to £100), take heed.

According to the National Arborist Association (NAA), a trade association which represents commercial tree care firms, there is nothing like a few storms to bring the cowboy tree surgeons out of the woodwork. They will be more than happy to relieve you of your hard-earned cash - but they might not have a clue what they're doing, and could end up doing a lot of damage.

"Disreputable companies are renowned for ripping gutters off, breaking fences and bird baths, and even dropping trees on houses," a spokesman for the NAA said. "Then they typically fold up and leave, never to be seen again.

"They also have little understanding of tree species and species-specific pruning regimes, resulting in a beautiful tree being butchered, which may cause its death."

Neil Hale, of Wheldrake-based Lewis Tree Surgery, a local firm that is affiliated to the NAA, has seen the results of the cowboys' work. They can leave a "trail of devastation" in their wake, he says - as well as charging over the odds and doing work that can be downright dangerous.

He knows of cases locally where cowboys have charged £80 to do a job he would have asked a tenner for - and £800 for felling three conifers, a job he'd have done for £200.

As with most things, if you want to be sure the person you hire is up to the job, the golden rule is check them out first. It's too late, after the "professional arborist" you hired to remove a tree drops it on your house instead of your lawn, to then ask whether he or his company is insured. It's vital you check beforehand.

"With thousands of pounds at stake, not to mention the integrity and appearance of your property and your personal safety, make sure you investigate before deciding which tree company you should hire," warns the NAA.

The most important thing, Mr Hale says, is to always check a company is insured - and to insist on a written quote before authorising work to go ahead. If possible, ask for local references so you can check the quality of the work someone has done, and verify any qualifications or professional affiliations a company might have.

The people to avoid absolutely, he says, are those who knock on your door saying they are "in the area" and offering to do some work on trees cheaply.

"That's always a sure sign," he says. "The kind of people who say: 'We're in the area and we can trim your conifer for £50'. As likely as not, when they've done the job, they will say: 'It has taken us a bit longer than we expected, and it's going to be £80'."

The good news is, there are plenty of well-qualified tree surgeons around, who will do a decent job for a reasonable price. The trick is telling the professional from the cowboy.

Some local authorities list approved tree surgeons - but York does not.

Both the NAA and the Arboricultural Association, a registered UK charity which accredits tree surgeons after carefully scrutinising their work and checking their insurance status, keep lists of members and can give you details of accredited tree surgeons in your area.

Failing that, the best thing, according to the NAA, is to start with the arborists in the phone book. Don't place too much emphasis on the size of the Yellow Pages ad - some of the most reputable firms rely almost entirely on word-of-mouth advertising, the NAA says. Look instead for what the ad tells you about the company: the number of years it has been in business, professional affiliations, college diplomas, licences, certification and so on.

The Arboricultural Association suggests another good rule of thumb is to ask around your neighbourhood to see if any of your neighbours have used a tree surgeon who has done a good job. Word of mouth can often be better than relying on Yellow Pages, says spokesman Andrew Martins.

Here, with thanks to the NAA, is a list of simple do's and don'ts:

DO:

- Ask to see insurance certificates

- Ask for local references, so you can check on quality of work

- Check out professional affiliations the company might have

- Insist on a signed contract detailing cost, dates of work and exactly what is to be done

- Get a second opinion

DON'T

- Employ the man with a chainsaw knocking on your door saying he's "in the area"

- Pay in advance

- Employ someone without getting a written estimate first

- Employ companies that advertise "topping and lopping" - an "injurious and unacceptable practice", the NAA says.

- Details of local tree surgeons who are members of the National Arboricultural Association can be obtained by telephoning 01794 368717 or logging on to www.trees.org.uk. The NAA also has a list of members. Call 01794 512367 or visit www.natlarb.com to find out more.

Updated: 09:19 Thursday, March 14, 2002