Xtremehorticulture

Xtremehorticulture of the Desert

Spider Mite Problem from Nursery Tomato Transplants

Leave a Comment / disease, fruit trees, insects, nursery plants, transplants /

Q. Two years ago, you correctly diagnosed our tomato plants with spider mites from pictures we sent. Last year we got spider mites again. We started most of our tomatoes from seed last year but bought a few plants from a local nursery and planted them in each of the vegetable beds. Is it common to get spider mites from nursery plants?  A. I don’t know how common it is for pests to be brought in from plant nurseries but I know it is more common than I would like. I have personally witnessed and identified disease and insect problems coming from nursery plants (houseplants, transplants, fruit trees and landscape container plants) before they were planted. Some disease problems on locally purchased container fruit trees. Sometimes insects and diseases can be problems when purchasing nursery materials. This disease infection may have started in the wholesale nursery first and passed on to the local consumer by the retail nursery.Avoid buying problem plants and introducing them into your home garden or landscape.             Some plant problems are easy to see and others are not and don’t develop fully until later. Growing plants free of insect and disease problems requires knowledge about the pests, a clean growing area and a regular prevention and treatment program. Off-color leaves and spotting of leaves can be indicators that they are not healthy or they were poorly cared for. Purchasing nursery transplants can sometimes bring problems into the garden. It can be a problem when low prices are an expectation by the nursery or garden center which may encourage a lack of care or over application of pesticides by the greenhouse producer. Inspect your plants before purchasing and avoid buying those with problems at the get-go.             If possible, put plants in isolated areas until you are sure they are “clean”. This is a common recommendation when buying houseplants. Houseplants are frequently loaded with disease and insect problems and infest other plants once inside the house. Fireblight disease was brought into this planting of apples and pears by introducing an infected Bartlett pear tree from a retail nursery. Once established, this disease spread to other European and Asian pears causing a lot of destruction and loss of plant life.             When bringing home plants, spray them with oils and soap and water sprays before planting. Don’t bring home “bargain bin” or dumpster plants thinking you’ve got a deal. You are asking for trouble unless you know what you’re doing. Don’t risk contaminating pristine plants by mixing them with plants unknown to you.If you must do it, keep them isolated from other plants until you are sure they are healthy.             As far as spider mites on tomatoes are concerned, inspect plants using the “white paper method” and a hand lens. Remove weeds growing in the containers, remove dying or damaged leaves, spray plants with soap sprays, and alternate with neem and other oils when you see them. Inspect plants

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Cause of Ragged-Looking Japanese Privet Leaves

1 Comment / disease, insect, Japanese privet, Texas privet, waxleaf privet /

Q. I have in front of my house 5 big shrubs. Unfortunately I have no idea what they are called. They are getting water over our irrigation system.Today I took a closer look to my shrubs and found all 5 shrubs in really bad condition. 1. The leafs are full of white, at the edge brown dents, but only on the upper side. 2. I’ve noticed a lot of bees around and inside one of the shrubs.Perhaps cutter bees but I don’t have  circled bites on my leafs 3. On one shrub I have a small white net, perhaps a spider net? Here are my questions: Can you tell me the name of my shrubs and do you have any idea what my problem is? A. The plant you asked me to identify in the pictures is called wax leaf or Japanese privet. It is not a desert adapted plant so it should be managed the same as other plants which are not desert adapted. It is native to Japan and Korea and so it prefers non-desert soils, medium light intensity, cooler temperatures and rainfall. It is planted quite a bit in our desert and it always tends to look a little bad because it doesn’t like it here much. It prefers climates that are not desert. This is a plant that should not be grown in rock surface mulch but in the wood chip surface mulch instead. The usual reasons for this plant to decline in appearance is because the soil declines or becomes mineralized because of the loss of organics in the soil over time. The other reason it may tend to look badly is because of poor irrigation management. If rock surface mulch is surrounding these plants please pull it away from them down to bare soil. I would put about half a cubic foot of compost at the base of each plant and lightly work it into the soil and irrigate thoroughly. Next, I would check to make sure the irrigation is working correctly and there are enough drip emitters for each plant. Each plant should have at least two drip emitters located about 12 inches from the main trunk. I would apply about 3 to 4 inches of wood chip mulch, not bark mulch, around all of the plants. Remove by pruning any parts of the plant that are ugly in appearance. Fertilize the plants once a year in January with an all-purpose tree and shrub fertilizer. The easiest way to apply it is put a handful of fertilizer next to each drip emitter and water it into the soil. Irrigate these plants as you would any other trees and shrubs that are non-desert plants. Follow-up Q. So, your opinion is that all the white dents (scars) on the leafs are a  fertilizing and irrigation problem? I have no fungus or bugs? And also the cutter bees inside the shrub are not connected to the visual problems ? Should I buy some insecticide? Followup A. I know it seems improbable that irrigation could cause leaf damage like some of what you are seeing and I agree that is not the only problem. However, my experience with wax leaf privet is that they are out of their climate zone when grown in Las Vegas and growing them here puts a lot of stress on these plants. The way to decrease the stress on these plants is to give them better growing conditions. This means soil improvement, planting them in the right light and heat exposure in a landscape, using organic surface mulches to continually improve the soil and maintain soil moisture and elimination of rock surface mulches that tend to mineralize the soil. Once you begin to improve their health and decrease their stress most of the problems that you see will disappear. Then we can start looking for other things that are causing problems to these plants but the major problem you are seeing is due to their environment, either natural or manmade. We do not have a lot of disease and insect problems on these plants. The diseases that we do have on these plants are from watering too often and poor drainage of water from around the roots. If these same plants were grown in central Japan where they are native you would not see the majority of these problems. Las Vegas is not central Japan. Create an environment in your home landscape that is closer to the environment where they originate; soils have higher organic matter, light intensity is less, temperatures are cooler, humidity is higher. Try to re-create as much of this environment as you possibly can in Las Vegas; plant on the north and east sides of buildings where they receive shade from late afternoon sun, add organic material back to the soil, avoid rock surface mulches, etc. When growing plants in the desert that don’t belong here you must try to find locations that emulate where they came from as closely as possible. Apply management practices that emulate their original envrionment. Insects and diseases are not the majority of the problems with this plant. By the way, the attraction of bees to this plant is typically an indicator that one of the sap sucking insects that secrete honeydew is present; aphids, whiteflies, mealybugs or scales. The bee problem could be cleaned up with sprays of soap and water on the undersides of leaves. After the plants are in better health then start working on the bee problem.

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Nectarine Fruit and Dried Droplets of Sap

5 Comments / disease, flower thrips, insect damage, nectarine fruit damage, scarring /

Q. I have an Independence nectarine tree which I have been nurturing for two years. This is the first year I have had fruit! On the fruits I kept I am seeing something that looks like dried droplets of sap coming out of the skin. It is not sticky to the touch. Are you able to determine if I have some sort of blight with the fruit? Will I just need to take this plant out? A. Your nectarine fruit has damage caused by Western Flower Thrips. This is a very common problem with nectarine fruit here in the valley and elsewhere. Once you see your fruit damaged by this insect, you will see it in future years as well. Be prepared to spray.             Damage to the fruit starts before they are the size of a pea. The only control is to apply sprays to the fruit and leaves to protect the fruit from thrips damage. The most effective sprays are insecticides for organic production contain Spinosad in the list of ingredients. Follow the label precisely. Readers nectarine fruit with dried sap due to thrips damage             If you don’t mind applying an effective conventional insecticide, then look for one containing synthetic pyrethrins, sometimes called pyrethroids. The label must say it is approved for tree fruits. Again, it is very important to read and follow the label for best results.             These sprays must be applied to the fruit and leaves starting very early in the season when the fruit are still very, very small. Sprays must be repeated through the season for total protection. Chances are, you will still see some scarring of the fruit but it will be greatly improved.

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Tops Dying Back in Japanese Blueberry

3 Comments / borers, dead branches, disease, insect, Japanese blueberries, sunburn, top dead /

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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Warty Growths on Limbs Tree Solved

1 Comment / carob, disease, disorder, warts on limbs /

Recently some pictures were sent to me of some warty growths found on the limbs off crepe myrtle. But the tree did not look like crepe myrtle. And I did not recognize the warty growths. Read on to find out what was going on….. Q.I suspect this condition is related to a previous question about similar bumps on quince trees. I noticed these on my neighbor’s crape myrtle. You can see that the bumps cover not only the large, old trunk but are also all along the smaller branches. And these bumps are HARD! When you pick at them with a fingernail, they don’t budge. Crape myrtle is not usually susceptible to scale. But I don’t know what else it could be. A. This isn’t the same as the brown bumps on quince trees. Those were hard scale insects. These bumps are part of the wood itself. Crepe myrtle has some very characteristic leaves and flowers. This isn’t crepe myrtle. I have to admit that I was stumped. I sent some pictures to Andrea Meckley, the plant person, and she thought it looked like carob tree with a really big problem. Mature carob tree in Las Vegas with warty growth on limbs So I began doing some digging on carob. Carob grows well in the Las Vegas climate. We lost I think all of them in the Valley when we had a 50 year low temperature during the winter of 1989 to 1990. Temperatures in the North West part of the Valley dropped to about 2°F and even killed bermudagrass. We lost quite a few African sumac as well as the carob trees, many of our palm trees were damaged at hotels and around town. We lost a beautiful pine tree called Roxburghii pine. Remaining pines in the warmer parts of the city lost branches down to the trunk, but the trunk survived and to re-sprouted new growth. Those pines are still there across from Desert Springs Hospital on Maryland Parkway. If anyone is interested I will post some of those pictures of the survival of that pine. African sumac was replanted in town. Even though carob tree is a very good choice for our climate, it never regained any popularity. primarily because it is slow growing most likely. But it is relatively pest free just about everywhere in the world and a very interesting plant. Carob tree is a complicated tree sexually. Carob trees can exist as separate male and female trees or male and female flowers on the same tree. The scent from the male flowers is said to resemble the smell of semen so some might consider that offensive. It is grown commercially for the pods and seed which is ground and used as a substitute for cocoa. Unlike cocoa, carob does not contain the stimulant theobromine. There are different varieties of carob used for commercial production. As carob gets more mature it develops these warty growths near where the flowers are produced. This is normal. More on carob tree later. Thanks to Mindy for all the pictures!

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Japanese Blueberry Tops are Dying Part I.

Leave a Comment / borers, dieback, disease, Las Vegas /

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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Is This Verticillium Wilt in My Olive Tree?

Leave a Comment / disease, limb dieback on olive, olive diseases, olive dying /

Do you think the sparse looking tree could have verticillium that you mentioned in your newsletter? Q. I need your help again. I have two Swan Hill olives trees in the back yard. One has lost a lot of leaves and looks sparse and the other looks good. I have also taken a couple pictures of of the problem tree. Do you think the sparse looking tree could have verticillium that you mentioned in your newsletter? A. The tree looks pretty young and I would not expect it this soon in its life if it appeared at all. This disease is not common here.             It is hard to really know if the disease is present or not just by looking at a tree. Olive has few problems.             It is by deduction. Verticillium wilt causes limb dieback in trees. My olive tree has limb dieback. Therefore my olive tree has Verticillium wilt. That’s how it is diagnosed now without sending a sample to a pathologist.             Typical Verticillium wilt symptoms do not occur in olive like they do in other trees. Upon close inspection of an infected limb, olive looks normal instead of having the vascular streaking common to that disease.             Two things you can do; watch it and see if it gets worse or send a sample to the state pathologist with the Nevada Department of Agriculture. This would be in Carson City. His contact information is on their website or call their local office at 702-486-4690.             I would not cut any limbs or remove them until you have some better idea of what is going on from a source that does not profit from tree removal. In the meantime, water it frequently and deeply. Fertilize it now for good growth.

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Chaste Tree with Black Unhealthy Appearance on Trunk

4 Comments / chaste tree, desert, disease, sooty canker, vitex /

Q. I have two chaste trees in my back yard and for a couple of years now there is a black appearance taking over the trees.   It started at the root or base of the trees and has been traveling up the tree onto the branches.  It is a slow process but somehow this does not seem to be a healthy appearance to me – it looks like black soot although i have not touched it with my hands.  I have asked several people about this and they say the trees are getting old – but i have only had them for about six years and they are maybe 9 or 10 feet, small trees. Can you tell me what to do about this? A. I have not yet seen any disease or insect problems on chaste tree here in our climate and a quick look on the internet I have not seen any reports from reliable sources. This observation is a new one for me.            Vitex winter form. Aphids have been reported to be a problem on chaste trees in other places. If aphids are present you would see them in the spring and fall. Leaves might be cup-shaped due to their feeding.             Excretions from aphids are full of sugar and will cause a blackening of limbs and leaves due to a black mold that grows on the sugar. Even though extracts from seeds of related trees have been reported to kill aphids. I will take a closer look at some here in town and see if I see anything but so far I would have to agree with others. This is a good small tree for the desert with few pest problems except when people water it too often.             If there are no signs of the tree being sick other than this black soot on the trunk, I would guess it is natural aging of the trunk. We do see this type of thing happening on other trees as well.             Diseases like sooty canker you would see a decline in the tree, bark splitting or cracking and the “soot” (under cracked bark) would rub off on your fingers exactly like heavy soot from an active chimney. Sooty canker disease has black spores just under the bark that rub off on your finger like chimney soot.

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Puffballs and Other Mushrooms Comon to Desert Landscapes

2 Comments / decomposing, disease, mushrooms, puffballs, slime mold, soil growth /

Q. These odd things grow in my back yard from time to time and I was wondering what they are. Do you know? A. Try looking at this page on my blog.  Puffballs  I think they look like one of the puffballs that sits below ground. Fleshy, but they open up and look kind of disgusting. If this is it (hard to tell from the pic) then this should explain most of what you want to know. There is a rather complicated discussion about these living things online at several locations. Here is one by the self proclaimed “mushroom expert”. Puffballs from the expert Mushrooms growing in the wood mulch at the orchard after a rain. They are working on breaking down the wood mulch and recycling nutrients into the soil They are a mushroom and of course, like all mushrooms, feed off of dead, decaying organic matter rotting underground or on the soil surface. They are a fungal organism, a good one, most in the mushroom category called basidiomycete. They are decomposers, one of a many of different types of decomposers that aid in breaking down complicated, formerly living things, into much simpler components. They aid in enriching the soil in this process.    Underground mushroom, most likely a type of puffball called a peziza The spores or “seeds” of the mushroom begin growing with the right environment and food source. This includes enough moisture for growth and survival. In the desert the growth of these organisms frequently coincide with rain and warmer weather or some sort of irrigation presence. Germination of the spore leads to the spread of microscopic “webbing” or mycelium that acts much the same way that higher plants use roots, rhizomes and stolons. As this fungal organism matures most will develop some way to propagate itself in a way that is much more efficient over longer distances than developing the “webbing”.  Mushroom sexual stage, the one we recognize and draws our attention They develop a “sexual” stage (usually some sort of fleshy organ that can be somewhat similar in appearance to the mushrooms we buy in the store). These can appear to be like round balls growing on the surface of the soil (puffballs) or round balls below the surface. Each type has its own characteristic form or shape that helps us categorize them. Some mushrooms don’t have a form we can easily recognize but the sexual stage is what draws our attention like this slime mold that I get questions about every year. Again, usually after a rain during cooler weather. Slime mold, looks like “vomit” but can be easily destroyed with a rake and a stream of water I have had reports that dogs will eat these, usually resulting in the dog throwing up and having a sore tummy for awhile but seldom serious. Check with your veterinarian.

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Fig Limbs Hollow and Not Because of Borers

1 Comment / disease, hollow limbs, hollow trunk /

Q. I have a fig tree that is close to 30 years old. It was getting out of control so I have been pruning it. I noticed some holes in the trunk but as I am cutting the branches I find that some are completely hollow inside.  Other than a few dead areas that I am pruning out, the tree looks generally ok and is putting out new growth, even from the hollow branches. Since the main trunk seems to be involved I can’t really cut out all the part that is affected.  Can you tell me what is causing this and if there is anything that I need, or can do about it???  I noticed the hollow where I had cut out a branch from the trunk a long time ago, but did not worry about it.    I would like to save the tree, it has sentimental value and provides needed shade.   I have attached some photos.   Readers fig tree with hole in the trunk A. Your pictures through me for a loop a bit. I have not seen that on fig before but I have seen something similar on other trees. I knew it was not from borers but I was not sure why you lost the center of your fig trees.             When trees grow, they grow both upward and in girth. We know that upward growth is from the buds on trees. Growth in girth is not as obvious. Growth in girth is from some cylindrical layers just under the bark.             As a fig tree gets fatter, the center of the tree dies. As it continues to grow fatter and fatter, the dead wood in the center of the tree gets larger and larger. As long as the tree remains healthy and doesn’t get any infections, the deadwood in the center of the tree remains intact.             On some occasions, organisms such as fungi and bacteria can invade the center of a tree and begin feeding on this dead wood. These organisms are almost always feeding only on deadwood and not the living parts of the tree. Fig limb hollow             So these organisms technically are not disease organisms but wood-rotting organisms. Since the center of a tree is dead, these organisms continue to feed on this dead center of the tree and can hollow out a tree very effectively. I think we have all seen pictures or cartoons of animals living inside of trees. Well, this can actually happen.                The center of the larger trunk and branches of a fig tree are filled with dead wood that is fairly soft and pithy. Once these wood-rotting organisms get going they will clean out that central core of large branches and the trunk. The living portion of the tree is unaffected.                What you have is not a borer problem but a wood rotting process going on. There is nothing you need to do about it but keep in mind that these branches may snap more easily than branches which do not have the central core hollowed out.             This is one of the reasons I emphasize so strongly to clean your pruning saws and pruning shears before you start pruning. It is best to clean and sanitize them between each tree, not necessarily between each cut unless you know the limb is diseased.

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