Pat Welsh Southwest Garden Advice, plus garden ideas for everyone » Trees

Italian Cypress Trees For Narrow Land Strip

Pat — Thu, 15 Jul 2010 08:47:22 +0000

Question from Nolanda:
1. I reside in Pasadena, CA. I have read alot of problems, mostly dust mites, killing italian cypresses after 3 yrs despite professional care & spraying. 2. Is the italian cypress too difficult to thrive in the CA valley now? 3.My alternate tree is the Skyrocket juniper due to its height, being taller than the Spartan juniper. 4. Which juniper do you prefer? 5. My land strip, full sun, is between a low retaiing wall and my garage. 6. Of course, I want the hardiest & fastest growing. My new neighbor is tragically cutting down all the mature & healthy boundary trees.
Answer from Pat:
Sorry about the loss of the trees next door!

I am very fond of Italian cypress (Cupressus sempervirens ‘Stricta’ , C. s.’Fastiigiata’). I know some people don’t like them, but I love the look of them and their atmospheric quality pleases me. They remind me of Italy, and fit in with the Mediterranean garden style. I have three in my own garden and have pruned off the lower branches so they look like the trees in Renaissance paintings. (But if this look is desired it should never be done until the trees are at least 10 or 15 feet tall.)

Italian cypress need good drainage. In general, since these trees are drought-resistant, deep infrequent watering is preferable to frequent and shallow watering. However, if you want them to grow fast you will need to fertilize and water for rapid growth. In heavy clay soil Italian cypress can die from root rot, so in this case they are not a good choice. Canker diseases have also been a problem in recent years and there is said to be no cure, but good health can help trees throw off problems. It used to be said that the best time to fertilize is in March, but those rules were for synthetic fertilizers. When fertilizing with organic fertilizers, earlier is better since it takes time for them to work. For example, applications of manure in fall before the rains are good, or apply adequate quantities of commercial organic fertilizer in late January and water in. Grow Power is not fully organic but plants thrive on it. If you choose that, I would apply it in mid-February.

Also, mulch the trees. Organic fertilizers and beneficial insects can help Italian cypress withstand attacks of spider mites. People who grow roses organically for example have no spider mites on their roses. My Italian cypress do not suffer from spider mites but I live near the coast so hot dry weather is not a problem. Cypress trees in the Hollywood hills are looking okay also. Strangely enough the smoke from last year’s fires probably smoked the trees in the hills and did them some good since they all got a big dose of carbon, and doubtless the smoke killed some of the pests also. Additionally flowering trees and plants doubtless benefitted from the ethylene gas in the smoke. (Nice to know that a fire that does so much harm also brings about some good.) When my town was filled with smoke for a whole week a couple of years ago, the growth and health of our trees and the number of flowers on flowering shrubs and trees were extraordinary for a whole year thereafter.

Though the problems with pests and diseases mentioned above have afflicted Italian cypress in recent years, I believe that good cultural practices (also explained above) can keep these problems under control so if these are the trees you love, why not have them? Other columnar type trees for a rapidly growing screen include several varieties of podocarpus, and as you suggested, junipers. You might not like x Cupressocyparis leylandii, but I’ve seen it growing in a narrow side yard and pruned to fit. (Their gardener did this job at regular intervals for 50 years.) It’s hard to choose between ‘Spartan’ and ‘Skyrocket’ junipers. I like the color of ‘Spartan’ Juniper better than ‘Skyrocket’, but ‘Skyrocket’ is a little faster growing, I think and it’s very narrow with the reputation of fitting into a narrow side yard with little problem. Monrovia Nursery grows both these varieties. ‘Spartan’ might be better adapted to growing in California since it’s said to grow even in Zone 10. Is there any chance you can view these varieties growing in a landscape near you? That is often a good way to make a choice.

Long Reach Pruner

Pat — Sun, 04 Jul 2010 08:52:09 +0000

Question from John:
Where did you get the long pole you used in one of your videos to reach under your plants. It was a long pole with a handle and a gripping part at the end. I have MD and it would be a great help to me

Answer from Pat:
Many years ago I purchased a tool called a “long reach Japanese fruit picker” from a well known garden tool company that is now out of business. Today you can purchase several types of this tool and they are now called “Long Reach Pruners.” I suggest you Google “long reach pruner” and choose from the various types that come up. Through the years I have found this tool to be one of the most indispensable of all my garden tools. I use it for pruning climbing roses, for pruning wisteria in summer, or even for reaching into flower beds and deadheading flowers, or picking up dead blossoms as you saw me do in the video. The kind I use has a “grab and hold” feature.

The kind I used on the video is the old type, it’s light weight, and these days unfortunately more difficult to find. Here is a link to a more commonly found type which is a telescoping long-reach pruner. It reaches further, but it is also heavier. I even have one that reaches 12 feet and is very useful for clipping off the twiners from wisteria growing on a tall pergola, but I find it a bit heavy for me to use.

Pruning a Caphor tree

Pat — Sat, 26 Jun 2010 08:05:39 +0000

Question from John:
I have a Camphor tree that was planed in August of 2010. It has since grown about 4 ft and has filled out. filled out so much that tow main branches almost snapped from the weight of rain. We have since tied them to large stakes.

When and exactly how do I trim and shape this tree with the hope of having a well shaped Caphor tree that will have an umbrella effect in our yard?

Answer from Pat:
I think I should start by telling you that Fact Sheet ST-157, November 19, 1993 of the US Forest Service on Cinnamomum camphora (camphor tree) states “Avoid upright multi-trunked trees” and also “It may be difficult to maintain a lawn under this tree.” Unfortunately I see you have a multi-trunked tree and it’s growing in a lawn. Now for your questions:

“Scaffold branches” are the major structural, trunk-like branches that originate off the trunk of a tree. Now let’s discuss the problem that you have a multi-trunked tree when what you require is a single trunk tree. You should remedy this situation immediately. Step one is to choose the strongest trunk and cut off the other competing trunks immediately down to the ground. Afterwards, if any more sprouts or suckers spring from the ground, always cut them off right away. You just want to let one upright trunk grow, not several.

After you have cut out all trunks except one I suggest you once again contact the landscaper and hold him to the terms of his contract to come and prune your plants or perhaps have a family member or friend phone for you and insist this be done. Your situation sounds like a bit of a sad tale to me because I get the feeling your landscaper is giving you the runaround and taking advantage of you because of your age and this is not right. Also he evidently sold you a multi-trunked tree which is a serious no-no.

If your landscaper never shows up, hire a certified Arborist to train the tree, or begin the training of the tree yourself, following the step-by-step instructions I already sent you. Taking your probable physical ability into consideration and if money were no object, it would have been better for you to begin with a boxed camphor tree from a tree farm that was already growing with one trunk and appropriately pruned for use as a street or landscape shade tree with proper scaffold branches in place. If you can afford it, perhaps you should have the existing tree removed and replaced with a boxed single-trunk camphor tree now.

For homeowners who have no problem with training a young tree, it actually is far better to begin with a small 15-gallon, single-trunk tree. Once in the ground and properly cared for, a smaller tree will actually out-pace the growth rate of a larger boxed tree and you will end up getting a proper shade tree sooner. But for elderly folks who have a problem shaping and training their tree and certainly don’t want to be climbing ladders, it would be better to begin with a boxed tree that is already trained and shaped.

Now in regard to your question about why you should leave the lower, bushy side branches on the bottom of the trunk, this is because they will help your tree to form a strong trunk. I explained this before but maybe I should say it another way which is this: It is unwise and improper to cut low branches completely off a young sapling shade tree. You can cut them short, that’s okay, but don’t cut them off since cutting them off will weaken the tree and make it take much longer for you to get a proper shade tree. It’s fine to prune the bottom ones so they are only a foot or two long and leaves don’t trail on the ground, but be sure to leave them attached to the trunk.

Perhaps you are having difficulty following the instructions I gave you. If so, I suggest you purchase a good paper-back pruning book, such as “Sunset Pruning Handbook” and follow the instructions in that book for training young trees. Get one that includes diagrams and then you will immediately understand what I’ve told you to do. (My Sunset pruning book includes diagrams showing the young shortened branches left on the bottom of the tree, like I have told you to do.) But the most important thing to do first is to be sure to cut off the extra trunks at ground level right away since they are sapping the energy of the main trunk of your tree and it will now may take another year at least for your tree to develop a proper head and trunk with appropriate scaffold branches and a rounded crown.

Regarding your fern pine trees (Podocarpus gracilior, Afrocarpus falcatus), prune these in spring or summer, so now is fine. Cut back the side branches to make them stronger, as your landscaper told you to do. This will encourage them to be bushy, but whatever you do don’t remove these side branches. Growers grow P. gracilior in two ways. One way is to grow them on a single trunk grown from a seed. This way of growing it makes for a strong trunked street or lawn tree. The other way is to start them from cuttings. Podocarpus grown from cuttings are sort of floppy and willowy. This type is used as a bushy hedge and this looks like what you have got. I am supposing that these are planted to act as a sort of screen hedge, not to grow to full size as trees. The branches will be floppy and flowing so you want to cut them short and encourage the tree to become a hedge. Another way to go is to wind the branches of one of them around the branches of the tree standing next to it and they will make a natural graft to create a sort of espalier and hide the wall. But be sure to pinch the tips. It’s up to you how you want to train them, either as columns or as a green, leafy hedge. You may need to stake them to keep them erect. Once you have trained these trees to the size and fullness you want you can then shear them with hedge shears, if desired.

Torrey Pine Trees

Pat — Thu, 24 Jun 2010 08:48:16 +0000

Question:
Can I legally prune or cut back Torrey Pine Trees. I have three native Torrey Pines in my yard. They were growing here when my family bought property next door in 1946. My neighbors are complaining that their view is being blocked. I do not want to prune. Can I use the legality as an excuse for not trimming? These trees are very big, since they have been irrigated for the past 40 years while we have lived here. Thanks for you help with this.

Answer from Pat:
You don’t mention where you live. The best way to find out if there is a law against pruning any tree would be to ask the city government where you live. For example, there is a law in Del Mar California against cutting down Torrey pines (Pinus torreyana) but none against intelligently pruning them. However, one can cut down a tree when it is too close to a house or another building. A permit is required to cut them down.

No permit is required to prune Torrey pine trees, and in some cases it’s necessary to prune them for reasons of safety. Torrey pines are not damaged by sensible pruning and often helped by it. Where there is plentiful ground water they have even survived unwise pruning such as topping, which is never a good idea with any tree. A Torrey pine, or any tree for that matter, should not be pruned in such a way that it becomes unbalanced. It is best to prune them in the cool weather of late fall and winter months, not in summer.

Torrey pine trees often invade pipes. In the wild, they are attacked by beetles during droughts, but if growing in gardens or on irrigated hillsides they are usually healthy. They easily throw off beetle attack and can grow to enormous size. Basically, they are not a good tree for irrigated gardens since their roots invade pipes and they grow too large, sometimes with shallow roots making the trees dangerous. There are many cases of large Torrey pine trees crashing down to the ground because of shallow roots in irrigated soils. Sometimes they fall on houses and other structures. Unusually long and heavy limbs can also fall off or break and hit the ground, though still attached to the tree. For this reason it is wise to remove any branches that have stretched too far out from the trunk with a heavy load of foliage at the tip and none down the branch.

There have been some cases of Torrey pine trees in gardens suddenly crashing down to the ground in the middle of the day or night when there is not even any wind. However, trees growing in canyons where roots can grow deep to get water rarely fall and often grow to immense size, creating a phalanx of foliage that can indeed cut off views and drip quantities of sap and needles on the ground below. Wise pruning may in some cases benefit the tree and the safety of your property. (Please see the article on Care of Torrey Pine Trees elsewhere on this website.)

25 Foot Tall 10 Year Old Mesquite Tree

Pat — Mon, 21 Jun 2010 08:08:43 +0000

Question from Holly:
I live in the High Desert of Southern California. I have a mesquite tree that has been fine until four weeks ago. I went to our most knowledgable nursery and they say to water it and wait 2 weeks to see if it revives. It had lots of beautiful leaves 4 wks. ago ,now 3/4 of the tree has lost it leaves and looks like it may be dying! This is my favorite tree the mesquite near it is fine. There is no leaking sap .

Answer from Pat:
Mesquite trees (Prosopis glandulosa) are one of the most common native desert trees in the Southwest. This tree may have a single trunk or it may be a large multi-trunked shrub. It’s deciduous and drops leaves in winter but not at this time of year. There is also a superior thornless selection called ‘Maverick’. Instances of sudden defoliation, such as you describe, have happened in the past to mesquite trees, but when a valuable shade tree such as yours suddenly looses its foliage it’s cause for alarm and wise to try to figure out what happened to it.

In most cases of sudden defoliation the problem is insects. If this proves to be the case, the insect in question may spread to your other tree and to trees in your neighborhood. Have you looked closely to see if insects are the problem? Sometimes thousands of acres of mesquite can suffer defoliation from insects such as locust or exotic walking stick or caterpillars, such as bag worms. It’s remarkable how quickly some pests can defoliate a tree. In the case of bagworm, they are pretty visible. But some insects that attack mesquites are not so noticeable. Some pests feed on foliage, others bore into the wood (check for holes in trunk), and still others feed on buds, flowers, and pods.

Some specific bugs in Texas that can decimate a mesquite tree in pretty short order include Texas psyllid (Heteropsylla texana) and Western flower thrip (Frankliniella occidentalis). In 1971 in Texas there was what I can best describe as a plague of cutworms that suddenly defoliated thousands of acres of mesquite trees, but I am happy to report that not a single tree died as a result. So there is hope for your tree.

Nonetheless, you cannot be too cautious. Since your tree lost its leaves so suddenly, this may be the beginning of an onslaught of insects, or of a particular pest, on other mesquite trees. I advise you to take any evidence you find on the tree such as twigs or damaged leaves, bag it in a ziplock bag, and report what happened right away to your local branch of the US Department of Agriculture or to your County Extension Farm or Horticultural Advisor. Certainly from this distance I can’t diagnose the problem or tell you what might be wrong with your tree or how to cope with it.

How to Cure Wet Soil and Trees That Can Survive in a Wet Soil

Pat — Thu, 17 Jun 2010 08:43:28 +0000

Question from Jonnie:
What plants can I plant in an area that doesn’t drain well. It appears to remain wet a few days after rain or sprinkling the lawn – On the north side of the house and we are in zone 8. Thanks in advance for your help.

Answer from Pat:
If it is clay soil, be sure to apply gypsum, as described and explained on pages 21 and 22 of my book. Additionally, if drainage is that bad perhaps you should call in a landscaper expert in correcting drainage problems. It sounds as if you need to install a drain or have the drain repaired if it’s no longer working. Drains sometimes clog with soil and roots and can be repaired and returned to working order. Having a wet spot on the north of the house could also affect the house or the foundations adversely, so it should be fixed.

I once had a wet spot in my garden and didn’t know enough to plant a weeping willow (Salix babylonica) in it. If I now had a wet spot in my garden, that is what I would plant. Weeping willow is beautiful and will sop up a lot of that water but roots may get into pipes. (Spray with BT in summer to control tent caterpillar. See page 157,158 on caterpillars and page 89 top of page on tent caterpillar.) Other trees adapted to wet spots that will grow in USDA Zone 8 include: Magnolia virginiana, Platanus racimosa, Acer rubrum, Alnus cordata, Castanospermum australe, Acer macrophyllum, Umbellularia californica, Populus fremontii, Alnus rhombifolia, Carpinus caroliniana, Casuarina cunninghamiana, Celtus laevigata, Clethra arborea, Liquidambar styraciflua, Platanus wrightii, Robinia neomexicana, Sequoia sempervirens, Thuja occidentalis, and Washingtonia filifera.

Most perennials that can take wet spots also need good drainage, for those that don’t need good drainage, look into plants that can survive in muddy ground such as umbrella plant (Cyperus alternifolius). This grows in Sunset Zone 8. (Papyrus (Cyperus papyrus) is handsome and atmospheric, but not hardy in Sunset Zone 8).

Pollination of Avocado trees

Pat — Wed, 16 Jun 2010 08:57:34 +0000

Question from Jon:
I am enjoying you book greatly and also enjoyed listening to you at the Master Gardner lecture you gave earlier this year.

I am interested in planting a Haas Avocado tree (24″ box). I would like to start harvesting in a year or 2. I was told that I need to plant another tree of a different specimen Avocado in order for them to cross pollinate and produce. Fuerte Avocado was recommended. . I really don’t want a 2nd specimen as Haas is the only one I’ve found with any flavor. What would you recommend? Thanks in advance.

Answer from Pat:
Homegrown avocados in areas where there are many avocado trees may bear a pretty good harvest without a pollinator, but it’s much wiser to provide a pollinator so you can be sure to get enough fruit. Fortunately there are several space-saving methods of accomplishing this. One way is simply to graft about three branches of a cross-pollinating variety onto the tree you have. Sometimes you can find trees that already have the correct type of pollinator grafted on the tree. Providing a pollinator can also help spread the harvest over a longer time span, but you do need one that blooms at the same time.

Avocado varieties differ in their types of flower, type A and type B. Cross pollination requires you chose a pollinator with the other kind of bloom. ‘Hass’ has excellent flavor and type A flowers. You will need a variety with type B flowers to pollinate it and ‘Fuerte’ fills the bill. ‘Pinkerton’ and ‘Reed’ are two other varieties with type A flowers that I personally find very flavorful but if you’re just growing one tree, ‘Hass’ is a better choice. There are also a few flavorful types that have B type flowers include ‘Yamagata’, ‘Sharwil’, and ‘Stewart’, any of which might also make a good pollinator for ‘Hass’. (The most recent edition of Sunset Western Garden Book has a list of varieties and their various characteristics on page 210. Some of these varieties may require a search, but several suppliers in Southern California grow them, including Andersons Growers and Growquest Nurseries in Santa Paula.)

Occasionally one can find a ‘Hass’ avocado tree with a type B pollinator already grafted onto it. Your nursery may be able to order it for you. If you can’t find one, and if you decide to go this route, I would suggest you learn to graft yourself or attend some meetings of the Rare Fruit Growers Society to find a person who can provide the scion wood and graft the branch onto your tree. (You may have to pay a fee for the service.) I have grafted deciduous fruit trees and had excellent success on my very first attempt, but I tried grafting an avocado and did not succeed, which leads me to believe that grafting avocado takes more skill and patience than grafting deciduous fruits. Once you have successfully grafted the branch or branches in place, then you need to prune to it, that is take off competing growth so it will develop into being an integral part of the tree.

But there is yet another space-saving way to go in the home garden and that is to purchase two types of avocado (types A and B) and plant both in one hole so they grow together and take up no more space than one tree. Prune out more branches of the one that is your chosen pollinator. In this way you will get more of the fruit you want.

Delighted you enjoy my book and last spring’s Master Gardener seminar.

Container Grown Trees

Pat — Tue, 15 Jun 2010 08:41:53 +0000

Question from Candace:
I have an open patio area (no patio cover) on the Southwest side of my house, which I would like to shade with trees in large containers. I live in Corona, CA so it’s very hot in the summer/fall months. I would prefer something native, if possible. Any suggestions? Thank you so much.

ps) I never thought I’d use any reference more than Sunset, but your S.C. Gardening book is now my go-to guide!!

Answer from Pat:

Get the largest containers you can afford. Some clay pots are especially made for trees. (See them in shopping centers.) Place one piece of broken crockery over the drainage hole of each pot. Hollow construction pots are best or wooden barrels, since hot sun hitting the side of a solid container can burn roots. Also make sure that the bottom of the pot is slightly raised off the patio or drainage can be stopped by roots and the tree will die from lack of drainage. Fill the pots with the best-quality potting soil you can find.

The following trees are the best choices for small shade trees to grow in containers: Citrus (A top choice. Withstands high heat in containers in Italy and France), Hibiscus ‘Agnes Galt’ or ‘Angel Wing’ trained as a tree, Wisteria trained as a tree, Rhaphiolepis ‘Majestic Beauty’ (my personal top choice. Prune after bloom into an umbrella shape.), Cassia leptophylla, Edible fig, Brugmansia ‘Charles Grimaldi’ (needs lots of water and fertilizer), and Persian silk tree ‘Albizia julibrissin’. Some of these plants won’t live forever. (Cassia will live 5 or 6 years in containers and albizia about the same.) The rest can be kept alive a long time in containers. I have seen all these growing in containers. I don’t recommend any native trees for this purpose. You might try Texas mountain laurel (Sophora secundiflora) but I have no idea whether it can survive in a container. (Seeds are poisonous.) Another idea is Western hackberry (Celtis laevigata var. reticulata) it’s good on patios and in heat but I have no idea if it will do okay in a container. You could try.

Another idea would be to install a shady cover like “Shade Sail” that attaches to the house and a post away from the house and provides partial shade or build a free-standing pergola next to the house and grow wisteria over it to provide shade in summer sun in winter when leaves drop.

Gray scaly bark on Crape Myrtle

Pat — Mon, 14 Jun 2010 08:54:18 +0000

Question from Jonnie:
My crepe myrtle was purchased with a gray scaly bark = it looks like fungus. What organic spray can I use to rid the plant of this fungus. What kind of soil would you use to put in ground for the crepes?

Answer from Pat:
Without seeing your crape myrtle (Lagestroemia indica) or a photo of the bark I cannot tell if there is anything wrong with it. However, though it may look a bit messy now, most likely nothing is amiss. People plant crape myrtles not only for their spectacular summer flowers but also for their interesting mottled gray, taupe, pink and fawn bark. Like sycamores, the bark of crape myrtle does not stretch or become furrowed as most tree bark does. Instead, as the tree grows its bark peels off in patches, revealing the new pink bark beneath. This mottled look is actually one of this tree’s most interesting characteristics.
With this tree you get a triple whammy: spectacular fall flowers, fall leaf color, and handsome bark that is especially
attractive in winter after leaves fall.

Crape myrtles grow best in interior climate zones where summers are hot and dry. They do not like water-logged
soil and perform best in well-drained soil with deep but infrequent irrigation, and light pruning in late winter or early spring to encourage new growth for summer bloom. Crape myrtle blooms on new wood. Letting the tree go slightly dry in late summer and withholding summer fertilizer will increase the display of blossoms in late summer and early fall. It is not a good idea to plant this tree in a lawn.

Crape myrtles are not good choices for Sunset Zone 24 where coastal fog and June Gloom blankets gardens in moist air. In such conditions crape myrtles tend to succumb to mildew. Mildew doesn’t affect the trunk. It affects the leaves and sometimes also the flowers. The general guidance for planting all trees is to plant them straight into unamended native soil, since the tree will eventually have to grow there anyway. That said, crape myrtles thrive best in soil that is well drained. Gardeners who plant them in heavy clay soil would be wise to provide a raised bed.

Such a bed does not need to be very high. Even four inches will save the crown of the tree from becoming water-logged. Fill the raised bed with good quality top soil mixed with nutrients and well-composted organic matter, but before doing so apply gypsum liberally to the native soil. Next dig some of your fill into the hard ground below, to create a marriage of soils instead of a hard line between the two. Then dig the planting hole straight through the top soil and mixed soil into the native soil beneath. Add more gypsum in the bottom of the hole and some slow release organic fertilizer in the bottom of the planting hole. Then plant the tree and refill the hole. Make a watering basin and keep the roots well watered until established then gradually lengthen out the times between irrigations.

Worms in Cherries

Pat — Sat, 12 Jun 2010 08:08:56 +0000

Question from Barbara:
My daughter called me last night, upset because she discovered that many of the cherries she and her son had been eating (from their own tree) contained little white worms.

They live in Pleasant Hill, CA (Contra Costa County) and have never had this problem before. The tree is several years old, located in her front yard which faces south.

We’ve searched IPM info, but can’t find any suggestions that would eliminate the problem for next year – except really serious pesticide spraying.

Is it possible to grow organic cherries? Do you have any suggestions?

Answer from Pat:
Tiny white worms are an increasing problem with home-grown cherries of both sweet and tart varieties. These worms are the larvae of the Western cherry fruit fly (Rhagoletis indifferens Curran), first discovered in Colorado in the late 1990’s. The first thing to do is to report this infestation to your local agricultural department or UC Farm Advisor. It’s important that these agenciest monitor this pest since it threatens commercial groves.

The larvae of Western cherry fruit fly don’t harm human beings who have accidentally ingested them since they are not adapted to living in human intestines, and they are mainly, after all, made up of cherry meat, but it is certainly a disgusting thought to know you have been eating worms. Western cherry fruit flies emerge in spring from pupa that have wintered over in the ground under the trees. As soon as they emerge they fly up into the tree. These black flies are tiny with striped wings are sluggish flyers. People seldom notice them, but yellow sticky traps can catch them and tell you of their presence. Most stay in the same tree but some are blown by wind to other trees. Their lifespan is about 15 to 35 days. They can lay eggs seven to ten days after first emerging when the temperatures are about 75 degrees Fahrenheit to 85 degrees in daytime. They eat aphids and honeydew. Once they mature, they mate and females pierce holes into fruit, laying one egg inside each cherry. The eggs hatch inside the cherry and tiny larvae commence munching. After the larvae mature and get fat inside the cherries they drop to the ground and bury themselves in the soil under the tree where they pupate and remain in dormant state until emerging as flies in spring. Then, once again the process repeats itself. Unless checked they will become worse every year and will spread to all other cherry trees in your area.

Unfortunately, the solutions given by experts are often to spray fruit repeatedly to kill the flies before they can lay eggs. Also with a pest that occurs in various stages experts may recommend attacking it with various specific products to kill the pest at different times of year. Otherwise you couldn’t possibly get them all.

The safe way to get rid of this pest would be to interrupt its life cycle in an organic or natural way without using pesticides, but I don’t have a cherry tree and cannot try out these controls. What I recommend is cleaning up fallen twigs and leaves under the tree, then spreading a layer of dry bagged earthworm castings now under the tree to kill the worms as they fall to the ground. Cover the ground from the trunk to the drip line and a foot or two beyond. Earthworm castings contain chitinase which destroys chitin, the exoskeleton of insects. Insects are killed when trying to burrow through a layer of earthworm castings. Renew the castings in late winter to kill any remaining flies as they emerge and keep it up from year to year. A few fruit flies will migrate into your garden but the castings will get them so they won’t be able to proliferate. This system works for giant whitefly on begonias which have a similar life cycle in the ground under the plants and then emerging to attack the foliage. If you try it please report back with your results.

The Colorado State Cooperative Agricultural Extension recommends putting yellow traps into trees to make sure when flies are first present, and then repeatedly spraying the trees with Spinosad every seven days to get the various generations of flies while they are present. Spinosad is an organic spray but harms bees if used where bees are found. Also, I fear that using it in great quantities will eventually destroy its efficacy.