- Check for ISA arborist certification. ISA Certified Arborists are experienced professionals who have passed an extensive examination covering all aspects of tree care.
- Ask for proof of insurance and then phone the insurance company if you are not satisfied. A reputable arborist carries personal and property damage insurance as well as workers’ compensation insurance.
- Check for necessary permits and licenses. Some governmental agencies require contractors to apply for permits and/or to apply for a license before they are able to work.
- Ask for references to find out where the company has done work similar to what you are requesting. Don’t hesitate to check references or visit other work sites where the company or individual has done tree work.
- Get more than one estimate, unless you know and are comfortable with the arborist. You may have to pay for the estimates, and it will take more time, but it will be worth the investment.
- Don’t always accept the low bid. You should examine the credentials and the written specifications of the firms that submitted bids and determine the best combination of price, work to be done, skill, and professionalism to protect your substantial investment.
- Be wary of individuals who go door-to-door and offer bargains for performing tree work. Most reputable companies are too busy to solicit work in this manner.
- Keep in mind that good arborists will perform only industry accepted practices. For example, practices such as topping a tree, removing an excessive amount of live wood, using climbing spikes on trees that are not being removed, and removing or disfiguring living trees without just cause are improper practices and violate industry standards.
- Get it in writing. Most reputable arborists have their clients sign a contract. Be sure to read the contract carefully. Don’t be afraid to ask questions, such as:
- When will the work be started and completed?
- Who will be responsible for clean-up?
- Is this the total price?
- What are the terms of payment?
- If I would like more to be done, what is your hourly rate?
- Pruning. An arborist can determine the type of pruning necessary to maintain or improve the health, appearance, and safety of trees.
- Tree Removal. Although tree removal is a last resort, there are circumstances when it is necessary. An arborist can help decide whether a tree should be removed.
- Emergency Tree Care. An arborist can assist in performing emergency tree care in a safe manner, while reducing further risk of damage to property.
- Planting. Some arborists plant trees, and most can recommend species that are appropriate for a particular location.
- Plant Health Care. Preventive maintenance helps keep trees in good health while reducing any insect, disease, or site problems.
- Many other services. Consulting services, tree risk assessment, cabling and bracing trees, etc.
An arborist by definition is an individual who is trained in the art and science of planting, caring for, and maintaining individual trees. ISA arborist certification is a nongovernmental, voluntary process by which individuals can document their base of knowledge. Certified Arborists are individuals who have achieved a level of knowledge in the art and science of tree care through experience and by passing a comprehensive examination developed by some of the nation’s leading experts on tree care.
Arborists specialize in the care of individual trees. They are knowledgeable about the needs of trees, and are trained and equipped to provide proper care. Hiring an arborist is a decision that should not be taken lightly. Proper tree care is an investment that can lead to substantial returns. Well cared-for trees are attractive and can add considerable value to your property. Poorly maintained trees can be a significant liability. Pruning or removing trees, especially large trees, can be dangerous work. Tree work should be done only by those trained and equipped to work safely in trees.
Since BRR disease causes root rot at the lower trunk above grade level (e.g. it could be observed up to 2 m in some tree species) and/or root collar and/or roots at the sub-soil level, it is essential to evaluate the thickness of sound wood of the tree at horizontal plane at critical levels (i.e. area showing decay and/or specific signs/symptoms of BRR disease) of the lower trunk, as well as at the trunk base, through the use of tomography and/or resistography. For sub-soil level evaluation, the trunk base or even at lower levels (e.g. after soil excavation using spade and/or air spade without affecting tree stability) could be assessed using resistography drilling at an angle (45 degree) downwards which could provide some indication on the relative soundness of tree roots.
Yes, early diagnostic symptoms of BRR disease are often difficult to detect, despite the fact that the disease can cause a rapid decline in tree growth conditions within a short time. More often than not, obvious symptoms will only be visible at a late stage of infection. Once symptoms such as abnormal crown symptoms (e.g. sparse foliage density, abnormal foliage colour (chlorosis), abnormal leaf size, dieback twigs are discernible in the above ground portion of the tree, the majority of its roots are likely to have been infected and the tree basically cannot be cured
Yes, root excavation with appropriate tools (e.g. handheld adze, digger, air spade, etc.) may be required to expose the root collar and roots. The exposed root collar and roots could subsequently be examined for the typical signs of BRR disease. Scraping off of bark tissue should only be conducted on decayed, damaged or dead wood/roots. Mallets may be used to differentiate healthy wood/roots from decayed, damaged or dead wood/roots. Damage to healthy wood/roots should be avoided as this may cause unnecessary damage to the tree, which may also create open wound for fungal invasion
The typical signs of BRR disease are a) fruiting bodies of Phellinus noxius, b) mycelial encrustation, c) soil aggregates and d) mycelial nets. (a) The appearance, on lower trunk or roots, of brownish-black/dark greyish-brown colored imbricate or resupinate fruiting bodies of Phellinus noxius with their characteristic porous hymenium surface up-facing is an obvious sign of BRR infection. The sizes of fruiting bodies vary greatly ranging from 3-10 cm in length to 8-20 cm in width. The fruiting bodies of Phellinus noxius are the sexual stage of the fungal lifecycle and their development, under the right conditions, begin with the formation of the primordial stage. The developing fruiting bodies would continue to grow in size, reach a stage of maturity in bracket and/or resupinate forms from which basidospores are formed for dissemination, and end at senescence. There are occasions where the developing fruiting bodies become abortive and reach premature senescence without forming basidopsores.
If the mycelia of Phellinus noxius are spreading under the bark, or under the outer layer of roots, these parts can peel off easily. The diseased parts look rough with flaky appearance on their surfaces covered by a brownish-black mycelial encrustation. Normally, the mycelial encrustation can extend from the root collar to 1 m high on the tree trunk. There are also reported cases from the literature that mycelial encrustation can reach 2-3 m in height.
If fruiting bodies of Phellinus noxius and mycelial encrustation cannot be found, the bark of the entire lower trunk/root collar and the outer layer of all the roots of the suspected diseased tree should be examined. If necessary, cut open with appropriate tools (e.g. handheld adze, knife, etc.) upon soil excavation to check for soil aggregates and yellow, dark brown or brownish-black mycelial netting on the inner surface between the bark and the wood tissues
Symptoms of the disease are of two types, namely slow decline and rapid decline. For trees experiencing slow decline, the most noticeable symptoms may include crown thinning out gradually and turning yellowish and their leaves reduced in size or even dropped as a result of early senescence. The trees could be dead in months or one to two years and structurally become unstable. Trees suffering from quick decline will wilt rapidly. Their leaves become brownish in color and the trees will die within weeks. The leaves of the dead trees will not fall immediately but remain attached on the branches for months.
Field diagnosis through visual tree assessment is based on observable symptoms and signs of BRR. There are two steps. Step 1: Identify abnormal crown symptoms (e.g. sparse foliage density, abnormal foliage colour (chlorosis), abnormal leaf size, dieback twigs) as these are exhibited in infected trees. Step 2: examine the entire lower trunk, root collar and individual roots of the trees to look for typical signs of BRR disease, i.e. a) fruiting bodies of Phellinus noxius, b) mycelial encrustation, c) soil aggregates and d) mycelial nets. If a tree with a crown abnormality contains one or more of the typical signs of BRR disease under step 2 examination, the tree is considered infected with BRR disease.
The disease mainly spreads through root-to-root contact or through infested wood debris in soil, though there may be the possibility of spreading of the disease through the dissemination of basidiospores from fruiting bodies. According to literature, mature fruiting bodies of Phellinus noxius seldom form in nature, though their basidiospores may assist in the long range dissemination of the fungus. In Hong Kong, there were observations that fruiting bodies of Phellinus noxius produced massive basidiospores on infected trees. The prevalence of the fruiting bodies in this region remains unknown.
It has been reported that over 200 plant species in 59 families are hosts to Phellinus noxius. In Hong Kong, we know that trees species such as Aleurities moluccana, Bombax ceiba, Celtis sinensis, Delonix regia, Ficus microcarpa, Ficus benjamina, Gleditsia fera, Lophostemon confertus, and Mangifera indica are host to BRR disease.
Phellinus noxius is a fungus that causes BRR disease on trees. Belonging to the genus Phellinus, P. noxius is placed under the family of Hymenochaetaceae within the Phylum Basidiomycota. Most of the species within the genus Phellinus act as saprotrophs in nature or as weak pathogens on trees. Only very few species are pathogenic with strong virulence, and P. noxius is one of the strongest among them. It prefers acidic, hot and humid conditions. It is characterised by its brownish black fruiting bodies (which will turn black with a drop of 3-5%KOH) with no clamp connections in its vegetative hyphae. The species within Phellinus are the typical white rotters, which can release enzymes through the action of microhyphae and decompose lignin and polysaccharides such as cellulose, hemicellulose and pectic substance, resulting in wood decay. Phellinus noxius causes white simultaneous rot in which the major components of wood (i.e. cellulose, hemicellulose and lignin) degrade at approximately the same rate.
Regardless of whether the lease contains any clause requiring the owner of a private lot to properly maintain the trees within his/her lot, it is the responsibility of the owner to properly manage his/her property including the trees planted on the lot. Private lot owners may be held liable for any casualty or property loss arising from their failure to properly maintain the trees within their properties.
In addition, if the lease contains clauses requiring the owner to properly maintain the trees and the owner fails to comply with the lease conditions, Lands D will, upon detection, take lease enforcement action in the capacity of the grantor of a government lease. Such action includes issuing warning letters to the owner concerned.
For the sake of public safety, tree pruning or removal can first be carried out by the owner of a private lot if the tree within the lot is considered to pose an immediate danger to the public after assessment by a professional employed by the lot owner meeting the requirements of the Practice Note Issue No. 7/2007 even though the lease of the lot contains a tree preservation clause (see Q.23). But the lot owner or his/her representative has to submit a detailed report prepared by the professional to Lands D within 21 days after the pruning or removal of the tree. The report should contain the justifications and evidence for tree pruning or removal, photos taken before and after the pruning or removal works, and the required compensatory planting proposal. For details, please refer to Appendix II of the Practice Note Issue No. 7/2007 of Lands D.
Where the lease of a private lot contains a tree preservation clause, if the lot owner carries out tree removal or pruning within the lot without DLO’s written consent, appropriate action will be taken by DLO upon detection. Such action includes issuing warning letters to the owner, requiring the owner to carry out compensatory planting or pay a premium if retrospective approval is given.
In granting a plot of land, the Lands Department (“Lands D”) executes a lease with the grantee who is required to comply with the lease conditions after becoming the owner of the land. Leases executed at different times contain varying conditions. Private lot owners have to check and comply with the lease conditions. Where there is no tree preservation clause in the lease of a private lot, the lot owner can employ qualified professionals to attend to the trees within the lot. Regarding the employment of qualified professionals, private lot owners can refer to the tree website of the Development Bureau for the list of contractors or professional bodies providing tree management services. Generally speaking, where the lease of a private lot contains a tree preservation clause, the lot owner has to, except in an emergency situation, make a prior application to the District Lands Office (DLO) of Lands D and obtain a written consent before removing or pruning trees within the lot. To apply for tree removal or pruning, the private lot owner is required to submit a report prepared by a professional meeting the requirements specified in the Practice Note Issue No. 7/2007 available at Lands D’s website, providing sufficient justifications and evidence for consideration. In granting a written consent, DLO may impose conditions on transplanting, compensatory landscaping or replanting as deemed appropriate. For application procedures for tree removal or pruning and guidelines on report preparation, please refer to the Practice Note Issue No. 7/2007 of Lands D. Further enquiries can be made to DLOs, the contact details of which can be found at the website of Lands D.
If the tree concerned is located on leased land with tree preservation clause(s), removal (inclusive of tree transplanting and/or tree felling) of such tree is controlled by the relevant lease clauses.
Prior to any tree removal, the lot owner or his/her representative shall submit a tree removal application to the respective District Lands Office of the Lands Department for approval. The application shall include tree information, reasons of tree removal and compensatory planting proposals. No tree removal is allowed until written approval is obtained from the Lands Department.
For details and enquiries regarding tree removal applications, please refer to Lands Administration Office”s Practice Note Issue No. 7/2007 or contact the respective District Lands Office of the Lands Department.
The publicly accessible Tree Register was established in July 2010. It contains such information as the distribution and conditions of and risk mitigation measures for important trees (Old and Valuable Trees (OVTs) and stonewall trees) and problematic trees that require close monitoring. The Tree Register is updated regularly. Departmental inspection officers assess the health and structural conditions of the trees on the Register and work out remedial actions and inspection timeframes (from several days to several months); while the TMO reviews the relevant risk assessment reports and conducts site inspections. Public can access the Tree Register website.
Currently (February 2016), the TMO has a total of 17 posts responsible for tree management. Most of these post-holders possess international professional qualifications in arboriculture, such as the International Society of Arboriculture (ISA) Certified Municipal Specialist, ISA Certified Tree Risk Assessor, ISA Certified Arborist, holder of Certificate in Professional Tree Inspection (LANTRA Awards UK) or honorary bachelor degree in arboriculture, etc. One of the post-holders has a doctoral degree in arboriculture.
The Government adopts an “integrated approach” for the management of trees. Under this approach, the different departments responsible for the maintenance of an area or a facility are also responsible for the maintenance of trees there, so as to optimise the use of resources. The duties of the TMO are to co-ordinate the tree management work of different departments, enhance public education and community involvement, provide regular training, promulgate best practices, conduct relevant researches and resolve complex cases, etc., so as to facilitate the departments to manage the trees under their care in a more effective and professional manner.