Xtremehorticulture

Tops Dying Back in Japanese Blueberry

Q. I’m having a problem with my Japanese blueberry trees. Some are fine but the two on the end appear to be drying out from the top down.  Do you have any idea what’s causing this? The soil is not dry and they all get the same amount of irrigation. A. The usual problem in damage or death to the top of a tree can be found on the main trunk just below the damaged area. I am guessing something has damaged the tree at that point.             The reason for the damage could be several. Borers cause mechanical damage to the trunk and shut off the water going to the top. Diseases in this same location can do exactly the same thing.             Because Japanese blueberry is relatively thin barked, sunburn from our intense sunlight can kill the trunk in that location and shut off water to the top. Humans can cause damage to the trunk and shut off its water supply as well. Top of dead stem on readers Japanese blueberry             I think we can rule out pathological diseases in our climate. The two most likely culprits are mechanical damage to the trunk by borers or the same type of damage caused by sunburn.             Inspect the trunk at the location just above the healthy area of the canopy. Use your fingers and see if you can pull away any loose bark. Borers tunnel just under the bark usually on the side towards the most sunlight. This kills that part of the trunk and the bark peels away easily.             If you don’t see bark peeling from the trunk at this location, look for discoloration of the trunk on this side facing the sun. Sunburn to the trunk can happen in one hour of intense sunlight during the midday or late afternoon.             If it is borers there is nothing you can do to raise the dead area back to life but you can protect the tree from extensive borer damage with an insecticide soil drench once a year.             In any case, you’ll be forced to remove the dead top from the tree with a pruning shears or saw this winter. Once you do this, it may open remaining branches for sunburn as well. Give them as much protection as you can.             I would not do it now because the sunlight is too intense and will probably cause even more damage to the lower, healthier part of the tree.

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Japanese Blueberry Tops are Dying Part I.

Q. I’m having a problem with my Japanese blueberries. Some are fine and the two on the end appear to be drying out but only towards the top? Do you have any idea what’s causing this? The soil is not dry and they all get the same amount of irrigation. Japanese blueberries tops dying back A. I would guess that something caused a problem on the trunk or large limbs at the bottom where it has turned brown. I am guessing it might be borers or some other critter that mechanically damaged the trunk/limbs. It is possible it could be sunburn as well particularly if they were open enough to allow direct sunlight on those branches/trunk for extended periods of time. I think we can rule out diseases in our climate except for the possibility of sunburn (non pathological disease). Look at the area of trunk/large limbs just in the foot above the healthy areas and let me know if you see peeling bark, discoloration or other types of abnormalities. If it is borers (the most likely), there is nothing you can do to raise it from the dead but you can protect it with a soil drench once a year using Feri-Lome’s soil drench. It contains an insecticide that should give you about one year of control from what I am hearing.

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Poor Canopy Development in Newly Planted Large Tree Could Be Lack of Water

Q. I think I this might be a pink locust tree. I’m seeing a lot of dead branches. The tree was planted last Fall. Should I give it some fertilizer to help it push out new growth? A. The tree looks a little skimpy on the foliage side but I don’t see anything from this distance that gives me much overall concern. Check to make sure it was not planted too deep. Some landscapers are notorious for digging a hole barely large enough for the root ball. This can also be part of the problem. I tell people now if they buy a large tree from a nursery, hire some people and dig the hole before they deliver the tree and buy good amendment for the backfill while they are at it. A thin canopy like that can also mean a lack of water. The lack of water would be on the quantity applied at each irrigation, not on the frequency of irrigation. Right now that trees should get by easily receiving water twice a week. But I would guess a tree that size would require the same amount of water as about half of the box that it came in. So if that was a 24 inch box I would guess it would need 20 to 30 gallons each time it was irrigated. Apply some good fertilizer and take a hose and soak it after you made sure it was not planted too deep. Do that about once a week for the next month and see what happens.   Sunburn on locust followed by death of that side of the tree. When the bark was pulled off, borers damage was seen. If this is an Idaho or Black locust like Purple Robe, they are very susceptible to sun damage to the trunk. Once the trunk gets damaged they frequently are attacked by borers. As a precaution it might be a good idea to give it a soil drench with Merit insecticide as a precaution. The same insecticide can be found in Ferti-lome’s tree and shrub systemic insect drench. I know Viragrow has a pretty good price on it if they still have the small containers.  If at all possible you want that tree to develop lower scaffold limbs to help shade the trunk.The canopy could use some light pruning. Remove crossed branches or branches growing on top of each other or too close together. You can do that now if you don’t remove too much or wait until this winter.

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Holes in Trees Due to Woodpecker?

Q. Do we have woodpeckers in Las Vegas?  This is the north side on the trunk of my Carob tree, at about chest high. The trunk is 5″ to 6″ in diameter.  The reason that I checked the trunk this morning is that I saw a bird perched there apparently pecking and went out to see if there were ants.  I found no similar pits in another carob tree that is older.  Readers picture of sapsucker damage to carob tree. A. We have sapsuckers that come through Las Vegas this time of year and they cause that type of damage. I wrote about this on my blog a couple of years ago. Trees can live quite a long time with this kind of damage. Birds frequently will come back to this tree in future years. I have had apples with over ten years of damage and still doing okay. Otherwise you have to do something to keep them from getting to the tree. Previous posting on sapsucker damage on Xtremehorticulture

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Science in Action: Controlling Borers in Landscape Trees

Options available for controlling borers have actually increased over the past few years. While the traditional approach of spraying an entire plant with a chemical such as Lindane, a chlorinated hydrocarbon, has become less available to pest control operators other types of IPM (Integrated Pest Management) control strategies have blossomed on the commercial market. The problem for most applicators is that the “security blanket” of a traditional pesticide approach is disappearing and the research to support the newer products is not available to give applicators confidence that they will work. The IPM model for borer control includes strategies such as cultural, chemical and biological methods. The most effective long-term control strategies are usually cultural in nature and should be our first consideration. Often times they are not used by commercial operators for a variety of reasons but usually get back to either economic reasons or lack of education on how to use them effectively.   Flat headed borer in small limb of peach tree. Sanitation would be removal of the small limb or cutting out borers from larger limbs with a knife When evaluating which method to use, we have to balance the efficacy of the control measure, it’s economic benefit to the customer and the operator and impact of the control measure on the environment. Lets take a look at each component in the IPM scheme. Cultural control options in traditional agricultural IPM include sanitation, crop rotation, tillage, host plant resistance and tolerance, mechanical or physical destruction of the pest and quarantine. Do any of these apply to controlling borers in landscapes? Sanitation refers to the removal of infested plants or plant parts which helps reduce the level of plant pest in the urban landscape. This may mean removal of entire trees heavily infested or removal of limbs to reduce the infestation level. This can be done on an individual yard basis or community wide if there is a community “epidemic” of a particular pest. Borer infested limb removed to save the tree from removal. A form of sanitation. We have seen communities, or entire sections of a community, devastated by certain types of borers. Clear winged borers, like the ash or lilac borer, can be serious pests in this regard since these types of borers are known to attack healthy trees and the number of these insects in a community may dictate the degree of infestation and damage. Community-wide borer control efforts need the strategy of a community forester or city arborist to make these efforts work. Crop rotation is the substitution of a crop (plant) with low pest susceptibility (host resistance) for a plant with high pest susceptibility. As an example, if we lose a tree to borers do we put the same type of tree back in that community or do we look for a reasonable alternative? As we begin planning a community or expanding a community are we checking to see what borers are problematic to the community or are we selecting plants only because they have aesthetic appeal? An example of this is the planting of weeping willows in climates like Las Vegas where they stress and become highly susceptible to attack by borers. These trees then become a source of infestation for other susceptible trees in the community. A proactive approach toward sound horticultural growth, balanced by future maintenance, requires public education and community coordination. Weeping willow planted in Las Vegas with borer damage from clear-winged moth. For this reason we never see weeping willows over about ten years old. Quarantine is a legal restriction or exclusion of infested plants being brought into a community. On a state-wide basis, inspection stations are established that control the entry of infested plant material or documentation is required by the buyer that plant materials have been inspected, and found clean of, certain pest problems. Sometimes plant materials are simply not allowed into certain communities due to the highly virulent or infectious nature of certain pests. This has happened with elm varieties, and some of its relatives, known to be susceptible to Dutch elm disease. Some arborists combine physical or mechanical control measures with their borer protection programs. Physical control can be as simple as noting borer activity in some young trees and carefully using a small knife to remove or kill the borer. This will work with borers such as some of the flatheaded types that that can be easily tracked and that feed near the surface of the trunk. A great deal of care has to be exercised so that the tree is not further damaged with the knife but with some experience it can be learned. Mechanical control includes barriers such as wraps that may help prevent sunscald and the physical entry of borers inside the tree. Some care has to be exercised that certain wraps don’t actually contribute to the problem by providing egg-laying sites for borers. We are all most comfortable with cover spray applications of chemicals for borer control. This strategy was either to spray the plant periodically through the entire growing season or time the spray with some sort of insect trapping device. Cover sprays applied a poisonous, pesticide barrier to susceptible plants. The traditional approach was to apply a pesticide to the trunk and major limbs of trees either infested with borers or “threatened” with borer activity. This cover spray was a prophylactic treatment aimed at preventing the entry of the borer inside the tree. Once the borer entered the tree, cover sprays were ineffective. Emerald ash borer damage to green ash which we do not have  in southern Nevada Our business practices, equipment and past education focused on chemicals for borer control. The problem with traditional cover spray applications of chemicals is that the chemicals traditionally used for this purpose pose a threat to the environment and human health, both by the nature of the chemical and how it was applied. This technique is still probably the most widely used one but is becoming more restricted with

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Replanting In Same Hole for Fruit Trees Usually Not a Problem if Borers are the Reason

Q. I removed a diseased (clarified by saying the only problem was borers) peach fruit tree.  How soon can I plant another peach tree in the same hole? A. If this is from borers, then you can plant immediately. Not a problem with borers and replanting. The entire lifecycle of the borers in our fruit trees are in the aboveground portion of the trees, not the roots or soil.             There is a problem potentially with something called replant disease but it is minor in this case and should be not a problem for you. Remove as much of the root system as possible before planting.

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Sap From Plums Not Always Due to Borers Dig to Find Out

Not the readers pic but this is sap oozing from a day old cut plum limb at the orchard just to show you how much they can bleed Q. I have three red plums in my front yard and I attached pictures of them.  These trees were planted in 2003.  One plum has sap oozing out of the tree in 5 to 6 spots on the south facing side of the tree.  I cannot find any holes in the tree where the sap is oozing out.  The other two trees do not have this condition.  I put down systemic insecticides annually and I have sprayed the trunk of this tree every week with Bayer’s Advanced Insect Spray.  I noticed the sap started oozing late this summer. more sap oozing from trunk from reader A. Plums can be a fairly sappy tree and this may or may not mean you have borer problems. Sometimes stress in plum trees can cause oozing sap. However, to find out, you will have to take a sharp, sanitized knife and remove bark and dead wood below the sap. You should do this as soon as you see it next time.             Your picture number three does look like loose bark caused by boring insects. Ultimately boring insects are attracted to trees which are weak or have been weakened or in poor health. Try to leave as much canopy on the tree as possible so that this canopy shades limbs and the trunk as much as possible.             Systemic insecticides for borer control must be used with a great deal of caution when applying them to fruit trees with the fruit intended for consumption even if the label says you can legally apply it this way.

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Italian Cypress Browning Not a Good Sign

Q. Help! My Italian cypress are drying out and dying mostly from the top down and they have their own bubblers for water. Italian cypress with foliage browning A. Major reasons for Italian cypress dieback: Too much water. Water deeply once 3 – 4 weeks in winter and no more than about once a week in summer. Too little water. Sometimes people put these trees on just a few minutes of water from their drip irrigation system. Water should be applied so that it wets the soil down 24 inches to an area at least four feet in diameter around the tree. Depending on how quickly enough water from your drip system is applied this might take up to several hours of applied water. Spider mites. Starts in hot weather because that’s what they like. Usually a problem on trees that were underwatered. Spider mites like dirty foliage. Wash trees with a high pressure hose nozzle after dust storms or a couple of times a year just to keep them clean. Periodic soap and water sprays are not a bad idea either. Webbing in italian cypress may or may not be due to the bad guys Borers. Several people have reported borers in Italian cypress but this has never been a common occurrence in the past. I could not find it reported anywhere else either. Usually a soil-applied insecticide for borer control applied around the roots would be recommended if this were the case. Get your irrigation under control and that should solve most of the problems.

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