This is extreme dormant pruning. Pollard and coppice pruning involve complete removal of all new growth. They typically involve growth from a previous season annually. A two-year cycle involves growth from two previous seasons, and so on. This repetitive pruning to the same origins stimulates distended callus growth there. It is as brutal as it sounds.
This is why pollard and coppice pruning are vilified in America. The techniques evolved through centuries of horticulture and several cultures. Both are still practical for various reasons everywhere else. However, American arboriculture classifies them as topping or disfigurement. Consequently, very few arborists here know how or want to do it properly.
Like other dormant pruning, pollard and coppice pruning must happen during winter. It is too severe for active vegetation. Also, pollard pruning exposes bark of trunks and limbs. Such bark would scald during sunnier summer weather. Growth from distended callus growth, or knuckles, shades lower stems by summer. It is very vigorous through spring.
That is why pollard and coppice pruning is still useful for within other cultures. Vigorous foliage is useful for fodder for livestock, including silkworms. Vigorous stems are useful for kindling and basketry. Some species bloom more vigorously on vigorous new growth. Others can not bloom to produce unwanted pollen or messy fruit within the same year.
Colorful or variegated foliage is more colorful in response to pollard or coppice pruning. Some eucalypti generate juvenile foliage for floral design. Such foliage is more aromatic than adult foliage. Improved foliar vigor enhances resistance to some diseases, such as mildew and rust. Coppicing can renovate some types of overgrown or shabby shrubbery.
The difference between pollard and coppice pruning is that pollard pruning retains limbs. Coppice pruning retains only a stump near grade. It is less reliant on repetition, and may never need it again. Pollard pruning compromises structural integrity, which necessitates repetition. Otherwise, pruning to restore structure will eventually become necessary. Not many species are receptive to such extreme pruning techniques.
Highlight: California sycamore
The tallest, largest and oldest trees of the world are all native to California. So are the rarest pine, rarest fir and largest oak. California sycamore, Platanus racemosa, is loyal to this tradition of distinction. Although not the tallest sycamore, it might be the grandest. It develops gnarly and sculpturally irregular form. Some develop multiple massive trunks.
Because of its scale, California sycamore is uncommonly available from nurseries. It is simply not proportionate to home gardens or even big landscapes. Most old specimens are older than the landscapes around them. They are somewhat adaptable to landscape irrigation. However, increased moisture increases potential for spontaneous limb failure.
California sycamore can grow a hundred feet tall with bulky trunks and limbs. Old trees may exhibit scars from shedding limbs throughout their long lifespans. Their mottled bark is gray and tan, and roughens only slowly with age. The deciduous foliage of such large trees is very copious through a long defoliation. Foliar tomentum (fuzz) is quite irritating.
Tony Tomeo can be contacted at tonytomeo.com.
