Advice from the Help Desk of the UC Master Gardener Program
for Contra Costa County
When to Remove Garden Monterey Pines
Client's Request:I live in El Sobrante near the San Pablo Reservoir. On August 8th PG&E had a tree crew come to prune trees away from the power lines. They did a rather drastic prune on our very large Monterey pine tree (which to this point has been very healthy with no signs of beetles or any other issues). The tree was large when we moved in ~30 years ago and was topped some time before that. It has been pruned by PG&E tree crews a number of times over the years but never to this extent.
About 2 weeks ago we started noticing a few small bits of what we think is dried pitch on the ground at the base of the tree. I didn't think too much of this as I assumed that it was falling from the cuts up high and I have not seen any sign of bugs. However, as you can see from the pictures taken on Sept 20th, there is quite a bit and now (starting about a week ago) some oozing of white/reddish pitch from the large roots. It does not look like there is anything coming from the trunk as high as I can see. The fresh cuts were dripping pitch, but it looks clear.
Is this in response to the prune or is there a problem that I cannot see? Your thoughts and suggestions would be greatly appreciated.
MGCC Help Desk Response: Thank you for contacting the UC Masters Gardener Program Help Desk with your question about the pitch oozing from the roots of your Monterey pine. And thank you very much for the photos. They are very helpful.
From the photos, I believe that the pitch you are seeing is the result of a bark beetle, most likely the red turpentine beetle, and not from the direct pruning cuts.
Bark beetles in general cause their damage when adults bore into the inner bark of trees where they lay their eggs. After the eggs hatch, the resulting larvae mine galleries that branch out from the egg-laying gallery. These larval mines are very narrow at first but increase in diameter as the larvae grow. All of this boring activity can start a flow of tree sap from pitch tubes. That flow may be accompanied by a sawdust-like frass. The sap and frass are the materials that you are seeing on the top of your roots.
Red turpentine beetles in particular are quite common in landscape Monterey pines. The pinkish to white pitch tubes on the lower trunk of standing trees are also characteristic of red turpentine beetles.
Healthy pines can generally tolerate a minor attack from a few beetles. Trees most likely to show signs of damage are those that are stressed by injuries or that may be declining due to old age. That means that you may be seeing signs of damage now due to a combination of the extensive pruning (or any other damage that may have occurred) and its age. Monterey pines generally live to only 45 to 50 years in inland climates.
Unfortunately, except for general cultural practices that improve tree vigor, little can be done to control most bark beetles once trees have been attacked. Because the beetles are under the bark, insecticides are rarely successful. You may want to monitor the tree for small entrance holes in the bark and increasing damage overall. If the main trunk is extensively attacked by bark beetles, the entire tree may have to be removed.
For more information on bark beetles, see http://ipm.ucanr.edu/PMG/PESTNOTES/pn7421.html
Please let us know if you have further questions or would like additional information.
Good luck with your tree!
HOrTCOCO Editor's add-on comments…Living in the same house and garden for the last 50 plus years, bought on a VA guaranteed loan, and coming new with bare dirt (mostly rock known as Martinez Massive Sandstone) and a tree (Fruitless Mulberry and an already dying lightly seeded front lawn and all the rest bare dirt and about 1/3 of it bare slopes (supposedly covered with erosion control plants), I soon planted on the slopes over 100 Monterey Pine seedlings at about 10 cents each irrigated with their own dripper. They grew fairly well but starting around 20 plus years the drippers each were at least half gone from squirrels and other problems including a few bark beetles. The neighborhood kids liked the jungle effect. By year 30 the bark beetles were having a steady impact every year, notably probably weakened from several drougths which basically set them up for bark beetle attacks. Meanwhile it should be noticed that many home owners in the subdivision had also planted Monterey Pines (inexpensive, but found to be too large, not being properly maintained or watered, etc.) and most were suffering the same problems mainly because of the beetles and not maintaining proper irrigation. One time during the later years I wasn't out in my garden much during the winter months because of weather was home and the largest Monterey (50ft) turned from green to brown in 30 days. My adjacent neighbor was not appreciative of the brown (large) Monterey adjacent to the fence and his house and managed to get the Fire District to send me a warning letter over the possible situation. Within the next 30 days I hired an “arborist” (and his family) who proceeded to cut and remove the 23 Monterey Pines remaining (ranging in size from 12” to 30” trunk diameter). One of the larger Pines completely broke off about head high during the “removal”, luckily the “arborists” weren't on site… I'm still thinking about that. I'm still here and I'm still looking at the back hill and the one lonely pine that survives, but that turns out to be a Japanese Black Pine a neighbor gave me when I also planted all the Montereys. |
Help Desk of the UC Master Gardener Program of Contra Costa County (ECS)
Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/. You can also subscribe to the Blog.
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- Author: Janet Hartin
Topping a tree is the process of giving a tree a virtual crewcut by making one or more horizontal cuts across the top of the tree (see photos below) to shorten it. Why is topping trees harmful? Topping trees results in unstable, unsafe, and unattractive trees. It also reduces the ability for trees to reduce high temperatures and provide adequate shade in urban heat islands, sequester (store) carbon produced by fossil fuels, and provide wildlife habitat.
In some cases, trees are topped because a tall tree that should not have been selected in the first place is growing into utility lines. In other cases, topping occurs due to a lack of knowledge about the dangers of topping and/or simply wanting to save money by going with the lowest bid. In all cases, topping should be avoided. The combination of improper balance and weak, poor-quality growth following topping creates a much higher likelihood of personal injury and property damage than occurs from properly pruned trees. (Top photo below: topped tree; Bottom photo below: untopped tree.)
Trees should be properly thinned and pruned rather than topped. Proper pruning involves maintaining the natural integrity and balance of the tree. Often this entails selecting a central leader and removing competing leaders, removing crossed branches, water sprouts, suckers and deadwood. In all cases proper pruning maintains the correct balance of weight and foliage in the upper, middle, and lower portion of the tree. (For more detailed information on proper pruning visit the International Society of Arboriculture's (ISA) consumer website: www.treesaregood.org). It may be useful to contact a Certified Arborist who is trained in tree health and care if you are in doubt about caring for your landscape trees. S/he will determine the proper pruning and thinning procedures and otherwise assess the overall health of your tree. Consult the ISA website for a Certified Arborist near you: https://www.isa-arbor.com/Credentials.
There are also several reliable and useful search engines to help you select the right tree for the right location. These user-friendly sites allow you to include several criteria in your search such as tree type (deciduous or evergreen), flower color, ultimate size, drought tolerance, pest resistance, and ability to attract pollinators among others. Grab a cub of java or tea and enjoy perusing such informative sites as: Urban Forest Ecosystems Institutes (https://selectree.calpoly.edu/); California Native Plant Society (https://calflora.org/); and UC's California Center for Urban Horticulture Water Use Classification of Landscape Species (WUCOLS) (https://ccuh.ucdavis.edu/wucols-iv).
Do you have a home garden or landscape question? Contact a trained UC Master Gardener volunteer serving your county using this link: http://mg.ucanr.edu/FindUs/. San Bernardino MGs may be reached at mgsanbern@ucanr.edu or (909)387-2182.
- Author: Gerry L Hernandez
One day I was in a nearby city and saw that the trees in the parking lot were topped and heavily thinned. I found out that the trees were topped and heavily thinned to get rid of the birds. You may notice in the picture that they even topped a Magnolia tree. Now, I know that this place has a terrible bird problem and with the drought the bird droppings are unbearable (p.s. the rain washes away the droppings).
Thinning and topping your trees will not get rid of the birds. The birds will return once the tree leafs out and grows new branches. What the tree trimmer did was create weak branches that will easily fall off in a wind.
The only reliable way to rid your trees of birds is to remove the tree. Someone sold this business waterfront property in Arizona!
Please do not top your trees for any reason. It is an unreliable way of pruning trees. If your tree trimmer wants to do this then you should find another tree trimmer.
Proper thinning of the tree's canopy increases light and air circulation, and reduces wind resistance and the occurrence of some diseases. A properly pruned tree is safer with strongly attached branches, more beautiful in form and its size is better controlled.
About 40 years ago I attended a lecture on best practices for tree pruning. Strybing Arboretum auditorium was filled because the speaker was a well-known arborist. When pruning side limbs, he said, the cut should be as flush with the trunk as possible. This allowed gravity to assist the tree in quickly closing the wound. I still recall the arborist’s name, but as subsequent research proved his advice incorrect, I won’t mention it.
Experiments by a university professor, whose name I won’t mention because I don’t quite remember it, showed that trees possess cells that form a barrier to decay just beyond the junction of a side branch and the trunk. You can see this little raised ridge, known as a collar.
Pruning just beyond this collar leaves the protective cells intact. It is true that a callus of bark would quickly form over a flush cut, but rot would permeate the trunk. Some trees became like a glove, with a healthy-appearing exterior but a decaying interior.
In my time as a landscape contractor, I used a variety of procedures that improved on previous methods but were later superseded.
At one time, conventional wisdom held that the planting holes for shrubs and trees should be twice as wide and twice as deep as the root ball. Later, the thinking was revised to twice as wide but only as deep as the root ball. Then the recommendation changed again: to twice as wide but square. The most recent advice I have read suggests digging a saucer-like planting hole that is two inches less deep than the root ball is high.
These revisions happened when people realized that the roots mainly grow in the top 18 inches of soil. Roots require oxygen, and there is little available below that depth. Gardeners and landscapers also realized that disturbing the soil beneath the plant caused the plant to sink later. A certain way to kill almost all shrubs and trees is to plant them with the crown beneath the soil. The square hole was intended to counteract the tendency of plants grown in round containers to keep circling their roots.
Another commonsense practice is to shear a plant before transplanting it. The thinking was that roots damaged by transplanting would have less demand placed on them. But now we know that this thinking is incorrect.
The top most stem of the tree or shrub generates a hormone known as auxin. This hormone inhibits lower side stems or branches, thus keeping the main stem dominant. As auxin flows down the connective tissue, the phloem, it diminishes sugar flow to leaves that, being in shade perhaps, are using more sugar than they are producing. But the major effect is that, upon reaching the roots, auxin greatly promotes root growth.
The roots also generate a hormone, cytokinin, which has the opposite effect. Cytokinin inhibits root growth but promotes shoot and leaf growth. Consequently, the best preparation for transplanting is to shear the plant but leave the main stem intact. The auxin from the main stem promotes root growth, which generates cytokinin, which promotes top growth. These hormones provide the best chance for plants to quickly flourish in their new location.
As we understand more of the inner workings of a healthy plant, we are better able to supply the care it needs. And the more we know, the more we realize how staggeringly complex nature is.
Workshop: Napa County Master Gardeners present a workshop on “Edible Landscape Design” on Saturday, October 5, from 10 a.m. to noon. Location is American Canyon Library,
300 Crawford Way in American Canyon. Design your garden to be both beautiful and edible. Learn what to consider and how to integrate edible plants into your ornamental garden. Bring a detailed plan of your garden to work on with guidance from U.C. Master Gardeners. Learn about books to help you with your design from Napa County Library as part of the Eat, Move, Read program. Seating is limited. Register online at http://ucanr.edu/ucmgnapa or call 707-253-4147.
Garden Tour: Napa County Master Gardeners will host a self-guided garden tour, “Down the Garden Path,” on Sunday, September 22, from 10 a.m. to 4 p.m. Visit seven unique gardens in and around downtown Napa, all maintained by Master Gardeners. Tickets: $25 advance/$30 day of event. For more information and to purchase tickets, visit http://ucanr.edu/ucmgnapa or call 707-253-4147. Find us on Facebook under UC Master Gardeners of Napa County.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions?