Bill Pramuk, Trees and People: Ivy and trees – not a good combination | Bill Pramuk

0
27
Bill Pramuk, Trees and People: Ivy and trees – not a good combination | Bill Pramuk


BILL PRAMUK

Acres of ivy are a common sight in and around Napa on older residential properties and wooden creek banks. On the one hand, ivies — English and Algerian — are easy-to-grow broadleaf evergreen ground covers. Once they are established in partly shaded areas, they are fairly drought-tolerant, low-maintenance, and they have a pleasant, glossy green look.

On the other hand, they run wild, displacing beneficial native plants and covering trees. Ivy aerial roots serve only as hold-fasts without actually rooting into the living tissue inside the tree. The foremost problem, from an arborist’s point of view, is that it covers things that need to be seen when we evaluate tree health and structural condition.

Support local news coverage and the people who report it by subscribing to the Napa Valley Register.

Tree assessment needs to be methodical. It’s like when you go to the doctor. They always take your temperature, weight and blood pressure — important factors that are simple to assess.

With trees, we start with a visual examination from ground level, nothing invasive or technical. The root collar, the base of the tree where the trunk flares outward into the buttress roots, is a critical juncture. In my experience, many, many tree-health questions have been answered by a quick examination of the root collar. But how can you examine it when it is tightly covered with ivy?

People are also reading…

Then there is the matter of tree risk assessment. The initial exam is called a Level 2 Basic Assessment. Big trouble can often be spotted with a simple close look: cavities, fungal fruiting bodies, grade changes, and soil or root problems. Again, these need to be visible to be assessed.




Submitted photo

In some instances, ivy gets way out of hand, climbing high into the canopy. When that happens, it can shade and suppress leaves, leading to a loss of lower inner foliage, which trees need for good health and structure.

Concerning fire safety, ivies seem to be somewhere in the middle ground. A quick check turned up one city (Oakland) listing Algerian ivy as a pyrophyte, or fire hazard plant.

With respect to oak woodland ecology, ivies occupy space that could be better used by native plants that interact beneficially with trees and wildlife. Think pollen, nectar, seeds, berries and the network of beneficial fungi in the soil.

Along with many other plants, English and Algerian ivies (Hedera helix and H. canariensis) are on the California Invasive Plant Council list of invasive plants. It ranges from grasses to woody stemmed plants and ground covers, up to large trees. Some of the ground covers on that list are still sold in retail nurseries: Cape weed, certain ice plants, periwinkle (Vinca major) and these two ivies.

For details, see www.cal-ipc.org/plants/profiles/.

Getting ivy off trees can be a daunting chore. If it is just getting started up a tree, peel it off and clear it back at least 2 feet from the trunk. And keep it on the list of annual chores! Where it has gotten way out of hand, get estimates from tree services to remove it. As a halfway measure, just cut the ivy stems near ground level. The leaves and stems will die and remain unsightly, but it’s better that letting the stuff run wild.

Photos: Callery pear invasion is ‘a real menace’

Stinky Pear Invasion

Daniel Patterson, a sophomore at John Handley High School, walks home from school below blooming Bradford pear trees on March 30, 2016, in Winchester, Va. Their beauty and supposed sterility made Bradford pears a widely popular ornamental, but they wound up being pollinated by other ornamental varieties of Callery pears and turning highly invasive. (Jeff Taylor/The Winchester Star via AP)


jeff taylor

Stinky Pear Invasion

Snow covers blossoms on a Bradford pear tree in Roanoke, Va., on March 21, 2018. (Erica Yoon/The Roanoke Times via AP)


Erica Yoon

Stinky Pear Invasion

A Bradford pear tree, damaged by ice following an overnight winter storm, is seen in Wichita, Kan., on April 10, 2013. Their beauty and supposed sterility made Bradford pears a widely popular ornamental, but the deep Vs formed by some branches turned out to make them prone to breaking after 20 to 30 years. They also wound up pollinated by other ornamental varieties of Callery pears and turning highly invasive. (Mike Hutmacher/The Wichita Eagle via AP)


Mike Hatter

Stinky Pear Invasion

A Callery pear tree is seen in Auburn, Ga., on Sunday, March 13, 2021. A stinky but handsome and widely popular landscape tree has become an aggressive invader, creating dense thickets that overwhelm native plants and bear four-inch spikes that can Flatten tractor tires. (AP Photo/Alex Sanz)


Alex Sanz

Stinky Pear Invasion

This photo provided by David R. Coyle shows spiky invasive Callery pear saplings in a horse pasture near Woodruff, SC, on Jan. 20, 2020. Those only a few months old can bear spurs that endanger tractor tires, says Coyle, an assistant professor in Clemson University’s Department of Forestry and Environmental Conservation. (David R. Coyle via AP)


David R Coyle

Stinky Pear Invasion

This photo provided by David R. Coyle shows invasive Callery pear trees blooming along Georgia Higway 441 near Nicholson, Ga., on Feb. 21, 2019. Georgia is among more than 30 states where the trees have been reported as invasive. (David R. Coyle via AP)


David R Coyle

Stinky Pear Invasion

In this drone photo provided by Jerrod Carlisle, invasive Callery pear trees bloom white among 29,000 still leafless native trees on his land in Otwell, Ind., on March 26, 2020. In the area where there are only native trees, he has eliminated the invaders by cutting them one by one and applying herbicide foam around the edge of each stump top. He believes the invasive trees sprouted from seeds produced by five trees — three ornamentals and two that were supposed to bear edible pears. Indiana is among more than 30 states where Callery pears have been reported as invasive. (Jerrod Carlisle via AP)


Jerrod Carlisle

Stinky Pear Invasion

This photo made available by the US Department of Agriculture National Agricultural Library, Special Collections, shows an unidentified man looking toward dwarf Callery pears growing in arid soil on a 2,000-foot-high mountaintop in China on March 31, 1917. The location, described as “near Nan chang yen, Hupeh, China,” may have been in Nanzhang county, Hubei. Now, ornamental varieties have crossbred and become invasive in at least 33 US states. (Courtesy of USDA via AP)

Stinky Pear Invasion

This photo made available by the US Department of Agriculture National Agricultural Library, Special Collections, shows USDA plant explorer Frank N. Meyer on Mount Wutai, Shanxi, China, on Feb. 25, 1908. Meyer, who died in 1918, sent an estimated 2,500 species of plants, including his namesake Meyer lemon and Callery pears, to the United States. (Courtesy of USDA via AP)

Stinky Pear Invasion

This photo made available by the US Department of Agriculture National Agricultural Library, Special Collections, shows an unidentified man holding a spur of a large Callery pear tree next to a pine tree during an expedition to collect plants in China for the USDA, on March 31 , 1917. The location, described as “near Nan chang yen, Hupeh, China,” may have been in Nanzhang county in Hubei. “Very few trees find pine trees congenial mates, but this remarkable Calleryana pear occurs at times quite plentiful in open pine forests, on sterile mountain slopes,” USDA plant explorer Frank N. Meyer wrote to his supervisor. Invasive varieties of Callery pear have been reported in at least 33 US states. (Courtesy of USDA via AP)

Bill Pramuk is an ASCA registered consulting arborist and an ISA certified arborist. Visit his website, www.billpramuk.com. Email questions to info@billpramuk.com, or call him at 707-363-0114.



Source link

2022-07-01 20:45:00

napavalleyregister.com