Xtremehorticulture

Arizona Rosewood Dying

 Q. I live in Oracle, Arizona, and my 15-year-old Arizona rosewood has some dying branches in it. Not the Arizona Rosewood mentioned in the question but it is used in Las Vegas landscapes. A. Dying branches usually indicate a water transport problem, mechanical damage, diseases, chemicals or borers. Arizona rosewood is a 12- to 20-foot-tall xeric tree native to the Sonoran deserts. It is considered a lower water use alternative to oleanders. Arizona rosewood is so new to the landscape industry (less than 30 years old) that not much is known about it. This may require some detective work on your part. It should start to flower and produce small fruit between 6 to 8 years of age so your tree should have started flowering nearly ten years ago.             It is in the rose family so check for damage from borers and fireblight. Other disease possibilities that may include single branch dieback include verticillium wilt.             Even though this is a xeric plant and can handle less frequent applications of water, make sure water is applied deeply and occasionally during the summer particularly during dry periods. Water applications should be about four times each year, particularly during the hot summer months, and to a depth of about 18 inches. The water should be applied to at least half the area under the trees canopy.             There is some discussion about its potential sensitivity to landscape weed killers. Make sure nothing was used close to this plant.

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Control Cottony Masses on Cactus

Q. I have small white nodules growing on my Indian cactus. Are they harmful? If so, how do I get rid of them?   Opuntia Or beaver tail cactus heavily infested with one of the cochineal scale insects. These insects can decimate cacti over time if left uncontrolled. A. I think you are talking about cochineal scale on the Opuntia or beaver tail cactus. This scale insect produces a white, fluffy mass on the pads on top of itself for protection. This insect is feeding underneath this white mass. Rubbing these white masses lightly with your finger, you find a royal purple color staining it. The insect beneath this cottony mass is dark red or purple. This is cochineal scale and makes a royal purple dye. Contrary to what some people have said, this is not the same cochineal scale the Spaniards sent back to Spain in the 1600s but a very close relative.             Depends on the cactus but they can devastate a cactus if not controlled.             First, control the ants. Ants pick up baby scale insects and transport them to pads that are underpopulated. These new pads are wide open pastures for scale insects to feed. Cochineal scale populate pads quickly. The ants harvest excrement from scale insects to feed their colony. This is a short video of a Weaver ant protecting another type of scale insect from its food supply. In this case, it’s my finger that is seen as a threat and the Weaver ant is protecting its horde aggressively. Video taken on our family farm in the Philippines.             Most ants are subterranean. One of the best methods I found to control ants is using a poison bait lightly sprinkled at the entrance to the colony. Usually these “ant holes” in the ground are easy to find but sometimes you must follow the ant trails to find them. (This doesnt work with Weaver ants because they don’t nest in the ground!)             I use an ant bait manufactured by Amdro. Follow label directions precisely. When applied correctly, it kills the entire colony, including the queen, in less than twenty-four hours. Borrowed a picture of the am drove container at Home Depot. Thanks to paulmirocha.com             Scale insects suck plant juices from the pads and build their populations quickly. Ants help them spread faster.             To remove white fluffy masses, spray the pads with a strong stream of water using a spray or sweep nozzle. This knocks the white fluffy covering off but doesn’t kill the insect hiding underneath it. They soon repopulate the pads. In summertime this could be weekly. In winter, perhaps monthly. Hosing off cochineal scale from the edible Opuntia cactus donated to the UNCE orchard by the University of Sonora – Hermosillo for demonstration trials. In the middle of summer, this had to be done weekly which none of the Master Gardeners like to do. If you don’t want to do it organically, which means frequently, then you’re faced with using conventional pesticides.              After spraying the pads with water, use organic or conventional insecticides to prevent scale insects, called crawlers, from repopulating the pads. Organic insecticides do not stay in the environment long so spray them more often than conventional insecticides. Neem oil varies in quality from different manufacturers. Unfortunately, there is not much quality control but if you find a good one, stay with it             Useful organic insecticides include Neem oil, soap sprays and other plant-based oils. Apply soaps and oils the day after spraying the pads. Reapply organic insecticides often. Organic insecticides I mentioned are total killers; they kill any insect sprayed so direct your sprays accordingly. Conventional systemic insecticides like this one works very well and requires fewer applications. But it is tougher on the environment.             Conventional insecticides last longer but are tougher on the environment. Useful conventional insecticides are systemic and applied to the “trunk” or soil. The poison moves into the pads from the point of application. Spray as soon as you see the cotton balls start to form.

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Cause of Ragged-Looking Japanese Privet Leaves

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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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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Black Spots on Watermelon Leaves Could Be Several Different Insects

Q. I have attempted to grow watermelons for the first time last summer and everything was looking good until it got hot. These tiny black specks appeared on the back of some of the leaves.  I was told it was aphids but they weren’t sure.  I hope you can see them clearly from the picture I’ve attached. Should I use insecticidal soap as recommended or something else?  A. I tried to magnify the picture so I could see the black spots better. I was curious if these were in fact from insects or not. I could not see it clearly but whatever it was, it appeared that it was no longer a problem and the leaves seemed nice and healthy.             Aphids are cool weather insects and so when the heat hit they should have disappeared. The big insect problems for you on watermelon would be aphids earlier in the season during cool weather, squash bugs shortly after planting and whiteflies (during the heat).             Yellow sticky traps can provide a method to determine if whiteflies are a problem or not. I will post a short video on my blog on how to make these rather than buy them. They are handy to place in the garden for insect monitoring.             Soap and water sprays are good but must be done about every three or four days and the underside of the leaves must be sprayed as well. Squash bugs are nasty and can be vacuumed or hand-picked or delay planting by seed until after June 1. If you are hand picking or vacuuming squash bugs then be diligent for about three or four weeks and keeping the plants cleaned off every couple of days by hand until mid-June to avoid most of the problems with this insect.       Thanks to Garry Pearson, Lead Greenhouse Managerat UC Davis CAES,                 Department of Vegetable Crops, during his presentations on greenhouses in Afghanistan.

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25 Year Old Grapefruit Tree With Crystals Coming From Trunk

 Readers grapefruit tree trunk with crystals coming out Q. My grapefruit tree is about 25 years old and has always produced an abundance of fruit.  A few months ago, I noticed a crystallized substance coming out of various spots on its lower trunk.  Also, some of the leaves had developed tiny black spots, had turned yellow and had fallen from the branches. I attached photos.             I would appreciate any help you can give me about this and what to do to stop the flow and save the tree. There are about a dozen or so grapefruit on the tree now. Are they OK to eat? A. I posted your photos on my blog for others to see. Probably my biggest concern for your tree is it getting enough water and applied at the right times and deep enough. Frequently this type of damage is associated more with stress than anything else. Readers grapefruit tree with crystals coming from limb             It is also possible that this could be the result of some cold/freezing damage from a previous cold winter. In other words, I do not believe it is due to insects or an active disease. It is possible it is due to some “disease” caused from environmental stress. This type of damage can revert to an active disease problem if you do not keep the tree healthy.             So my recommendation is to not put down any chemicals for insects or disease but to concentrate on plant health by fertilizing in the spring with a citrus fertilizer. This would be done around or prior to flowering.             Put the fertilizer near the drip emitters or source of water so the fertilizer is pushed into the rootzone of the plant. You might want to take a look at tree fertilizer stakes but keep them at least a couple of feet from the trunk. If the source or water for irrigation is close to the trunk, move it away the same distance.              It is okay to start with two drip emitters for new trees but in a few years you should be adding more emitters which will allow you to spread the water more evenly under the trunk and add more water at the same time which it needs as it gets bigger. Bigger trees need more water than smaller trees regardless of the type of tree it is.             This spring water the area under the canopy deeply and thoroughly. Add an iron chelate fertilizer when you are adding your other fertilizer as either granular, liquid or tree stakes. Like any fertilizer, it needs water to move these fertilizer salts into the rootzone.             Prune out any dead or dying branches, crossed branches, branches growing straight up or straight down. These are unproductive and just shade the interior of the tree.             The fruit is fine to eat as long as you have not applied any pesticides recently.

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Base of Nectarine Tree Rotting I Think

Q. We have a nectarine tree trunk that we have a question about. I am attaching photos of it. It looks like it’s rotting. We were going to wrap the trunk to further protect it but we don’t know if it’s the right thing to do. Please view the photos when you have the time and advise us on what we should do. Readers nectarine tree A. Nice pictures. I will post them on my blog. It looks like there is damage to the trunk as you suggest. I would pull the rock away from the trunk about a foot. Make sure that the source of the irrigation is not close to the trunk. Put the water source a foot to 18 inches from it if possible.      Secondly, make sure you are not watering too often. You should be watering right now about every 7 to ten days but with a large volume of water when you do… enough to wet the soil to a depth of 18 to 24 inches deep on at least two sides of the tree. Three or four emitters watering this tree would be better than just two as the tree gets bigger. Closeup of readers nectarine tree             Pull the bark away from the damaged area if the bark pulls away easily. If it doesn’t, then cut the bark away with a sanitized knife so the damaged area is exposed and clean for healing. Keep water off of the damaged area during irrigations until it heals, perhaps around May or June.             If the rock was put around the trunk and it keeps the trunk wet above the soil line for the first several years, you may very well encourage trunk rot or collar rot on young trees. On young trees it is important to keep mulch away from the trunk a foot or so for about 5 years or more until the trunk matures and is less susceptible to rotting. Secondly, never irrigate frequently but deeply and less often.

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