Guy Meilleur
Addicted to ArboristSite
Called so many times to sick trees: mal-grown, misplanted and overmulched miseable trees. Paid to write a treatment protocol so here it is; any thoughts?
September 8th 2004 I inspected declining maples. Root excavation revealed a varying degree of root girdling (wrapping around the stem), and stem decay. Primary cause was nursery defect, where soil was heaped over the original root zone. Aggravating cause was improper installation, when trunk flare was not exposed and roots were not straightened or cut if too severe to straighten. (see New Tree Planting info sheet)
An ongoing aggravating factor on these maples and all other trees on the campus has been the practice of repeatedly placing mulch on the trunk, which is incompatible with any industry standards. (see Proper Mulching Techniques info sheet) Secondary girdling roots growing through decomposed mulch were found, and the decaying organic matter placed on the trunk caused or at least accelerated the Phytophthora trunk infection. Curing these infections is uncertain and costly, so cultural practices must be geared to avoid them.
Every tree on the campus should have its trunk flare visible. If it is not, it is necessary to excavate around the root collar until it can be seen. Some of the maples have formed adventitious roots above the trunk flare. If these are vigorous, they should not be removed. Root excavation shall only be done by trained personnel. Cherry and zelkova trees near the entrance exhibit the same syndrome. The cherries are in decline due to these defects, and poor drainage. Surrounded on three sides by a wall, their prognosis is poor unless a drainage system is installed.
Campus-wide, a further aggravating condition has been the practice of limiting the area of earth dedicated to tree root function, even as the growing trees demand more resources. Mulch areas should be just beyond the line beneath the branch tips. This is called the “drip line”, because it is where the water drips off the tree. This water is needed by the tree, so turf should not be cultured inside that line. Turfgrass also takes away nutrients needed by the tree, and exudes allelopathic chemicals that retard the growth of tree roots. Also, any weedkiller applied to the lawn retards the growth of trees, the biggest “broadleaf weeds” in the lawn. (see Turf and Trees info sheet)
Expanding the mulched area around the individual trees will improve their health and performance. It will also reduce maintenance needs and the appearance of the plants, since less pruning of lower branches will be required. Following are general recommendations for managing the trees to avoid any more losses, and to increase their value and contribution over time.
TREE CARE RECOMMENDATIONS
1. Excavate around all new plantings to expose trunk flare. Excavation is most quickly and thoroughly done with compressed air. Remove any girdling or adventitious roots that the tree does not need to survive. Excavate any decayed areas in the trunk—all this shall be done by experienced personnel only. The black lesions are caused by Phytophthora fungus or another decay-causing organism. Lesions should be excavated of dead material and may be disinfected with hydrogen peroxide, properly diluted. Any tree with lesions should be treated with a basal drench of Subdue or Alliette fungicide, following label directions. Applying Cambistat (paclobutrazol) tree growth regulator at the same time may retard fungal activity and shunt tree resources toward fine root production.
2. Remove pinestraw mulch beyond dripline. Broadcast time-release fertilizer according to soil test results. Apply 4-6”, deeper where roots are exposed, of aged mulch between the raised ring of earth that was formed at the time of planting and the dripline. In areas where aesthetics are a major consideration, the pinestraw can be reapplied over the top of the aged mulch. Overall, pinestraw use should be curtailed, since it is more acidic and less insulating than other mulch. It is also poorer in nutrients and poorer in microbial activity, which is highly beneficial to the tree’s health and growth rate. All the above work is best done early in the dormant season, October-December.
3. When the leaves are off, assess branch architecture and prune dead, dying, diseased, damaged and interfering branches, not to exceed 25% of the total crown. Do not remove lower branches unless absolutely necessary, as this can cause bark death by sunscald. (see Mature Tree Care info sheet). Late in the winter, a second broadcasting of fertilizer at the approved rate may be beneficial. At that time, a restorative pruning on the ice-damaged landmark water oak, Quercus nigra, at the entrance would greatly improve its health and appearance
This concludes my preliminary recommendations. I am free to clarify anything above, and recommend contractors for the air excavation or other work that will not be done in-house.
September 8th 2004 I inspected declining maples. Root excavation revealed a varying degree of root girdling (wrapping around the stem), and stem decay. Primary cause was nursery defect, where soil was heaped over the original root zone. Aggravating cause was improper installation, when trunk flare was not exposed and roots were not straightened or cut if too severe to straighten. (see New Tree Planting info sheet)
An ongoing aggravating factor on these maples and all other trees on the campus has been the practice of repeatedly placing mulch on the trunk, which is incompatible with any industry standards. (see Proper Mulching Techniques info sheet) Secondary girdling roots growing through decomposed mulch were found, and the decaying organic matter placed on the trunk caused or at least accelerated the Phytophthora trunk infection. Curing these infections is uncertain and costly, so cultural practices must be geared to avoid them.
Every tree on the campus should have its trunk flare visible. If it is not, it is necessary to excavate around the root collar until it can be seen. Some of the maples have formed adventitious roots above the trunk flare. If these are vigorous, they should not be removed. Root excavation shall only be done by trained personnel. Cherry and zelkova trees near the entrance exhibit the same syndrome. The cherries are in decline due to these defects, and poor drainage. Surrounded on three sides by a wall, their prognosis is poor unless a drainage system is installed.
Campus-wide, a further aggravating condition has been the practice of limiting the area of earth dedicated to tree root function, even as the growing trees demand more resources. Mulch areas should be just beyond the line beneath the branch tips. This is called the “drip line”, because it is where the water drips off the tree. This water is needed by the tree, so turf should not be cultured inside that line. Turfgrass also takes away nutrients needed by the tree, and exudes allelopathic chemicals that retard the growth of tree roots. Also, any weedkiller applied to the lawn retards the growth of trees, the biggest “broadleaf weeds” in the lawn. (see Turf and Trees info sheet)
Expanding the mulched area around the individual trees will improve their health and performance. It will also reduce maintenance needs and the appearance of the plants, since less pruning of lower branches will be required. Following are general recommendations for managing the trees to avoid any more losses, and to increase their value and contribution over time.
TREE CARE RECOMMENDATIONS
1. Excavate around all new plantings to expose trunk flare. Excavation is most quickly and thoroughly done with compressed air. Remove any girdling or adventitious roots that the tree does not need to survive. Excavate any decayed areas in the trunk—all this shall be done by experienced personnel only. The black lesions are caused by Phytophthora fungus or another decay-causing organism. Lesions should be excavated of dead material and may be disinfected with hydrogen peroxide, properly diluted. Any tree with lesions should be treated with a basal drench of Subdue or Alliette fungicide, following label directions. Applying Cambistat (paclobutrazol) tree growth regulator at the same time may retard fungal activity and shunt tree resources toward fine root production.
2. Remove pinestraw mulch beyond dripline. Broadcast time-release fertilizer according to soil test results. Apply 4-6”, deeper where roots are exposed, of aged mulch between the raised ring of earth that was formed at the time of planting and the dripline. In areas where aesthetics are a major consideration, the pinestraw can be reapplied over the top of the aged mulch. Overall, pinestraw use should be curtailed, since it is more acidic and less insulating than other mulch. It is also poorer in nutrients and poorer in microbial activity, which is highly beneficial to the tree’s health and growth rate. All the above work is best done early in the dormant season, October-December.
3. When the leaves are off, assess branch architecture and prune dead, dying, diseased, damaged and interfering branches, not to exceed 25% of the total crown. Do not remove lower branches unless absolutely necessary, as this can cause bark death by sunscald. (see Mature Tree Care info sheet). Late in the winter, a second broadcasting of fertilizer at the approved rate may be beneficial. At that time, a restorative pruning on the ice-damaged landmark water oak, Quercus nigra, at the entrance would greatly improve its health and appearance
This concludes my preliminary recommendations. I am free to clarify anything above, and recommend contractors for the air excavation or other work that will not be done in-house.
