Xtremehorticulture

Xtremehorticulture of the Desert

‘Bonita’ Ash and Ash Decline Disease

Leave a Comment / ash death, ash decline, dying /

Q. I planted a very large ‘Bonita’ ash tree this year and was worried about ash decline disease. This last May we noticed there were not as many leaves growing as we expected and many of the ones that were growing scorched and fell off. After 4 months of very good care to water, fertilize, and condition as told, the ‘Bonita’ ash tree does not look as we were told when we bought it. While it has grown taller, it had not filled in much. ‘Bonita’ Ash Tree recently planted. A. Ash Decline disease can be confused with a lack of water. It may also be confused with poor planting practices and leaving the ash out too long before planting. Possible ash decline disease. The only real way to say it is ash decline is to send a sample to a plant pathologist familiar with the disease.                     Nearly all ash trees are susceptible to ash decline disease, particularly if it has Arizona ash genetics in it. ‘Bonita’ ash does. So do ‘Modesto’, ‘Raywood’, ‘Rio Grande’, and other ash trees commonly sold in nurseries.  That being said, this disease is usually not a problem on young ash trees as long as they are not stressed and there are no diseases present that might cause it to spread. Young ash trees are normally very strong and healthy. Disease Pressure             The keys to resistance are “disease pressure”; how much of this disease is present on ash trees in your neighborhood and the “health” of your trees. The disease agent that causes ash decline is not terribly virulent. It is not like a disease such as fireblight which can be terribly destructive under the right conditions. If the ash trees in your nearby neighborhood don’t show any symptoms (branch or limb dieback) and kept healthy, then most likely the tree you planted will live disease free for many years to come. Give Them Water and Fertilizer and See if they Recover             Make sure your tree are not water and fertilizer stressed. All ash trees are “mesic” in their water needs. Even desert ash trees, such as Arizona ash, grows near waterways. Like mulberry, all ash trees are dioecious; there are male trees and female trees. There is little difference in the health of a male vs. female ash tree. Ash tree surrounded by lawn and well fertilized and watered. They are mesic and can withstand a lawn.             Ash trees can get big. Make sure they get enough water as they get bigger.  Getting enough water is one key to having a thick and broad canopy and staying healthy. The irrigation under the tree should be enlarged every two to five years to compensate for their increase in size. Keep Ash Trees in Good Health             The other important ingredient regarding canopy density and health are annual fertilizer applications. At least once a year and its canopy density, apply a fertilizer high in nitrogen, the first number on the fertilizer bag. Examples might include 16-6-8 or 16-16-16. Ash tree about 3/4 mature and surrounded by grass. They can get big. Their need for water is not as much as mulberry but close.             Ash trees don’t care much for rock on top of the soil unless their roots are growing in a rich soil underneath it. Periodically rake any rock away from the trunk of the tree, enlarge the irrigation system, apply compost to the soil surface and fertilizer. The rock can be raked back the same day you are finished.

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Succulents for Las Vegas Gardens

Leave a Comment / dying, phytophthora, root rot, seed, stem cutting /

Q. I have a succulent garden which is under our patio cover.  Periodically a plant that seems to being doing well suddenly goes sour. I use a moisture meter and try not to overwater. When propagating plants from seed or cuttings sanitation is very very important. These are babies just getting started!!! A. All cacti are classified as succulents but not all succulents are classified as cacti. What we consider succulents from our deserts usually require more care than cacti from our deserts. This means they usually need more protection from the sun, wind and a bit more water. Sanitation I am a firm believer in keeping everything as clean as possible. First is the potting soil. When potting soil is reused, sanitize it or get new potting soil.             Do this easily by putting the moist soil, or the entire container a few days after an irrigation, in a clear plastic bag in full sun during the summer. Make sure there are no air leaks. Let it sit like this for about three days. Heating up everything to about 160F. for at least 30 minutes sanitizes it. This method is called solarization.              Sanitize or sterilize all of the equipment with 70% ethyl alcohol: particularly anything with a blade.             Sometimes the plant part (seeds or cuttings) were not healthy or strong enough until they grew roots. Some older fungicides, namely Captan, Thiram, Zineb (dust, powder or wettable powder), were available to protect the roots until the plant got established in the ground. We would put a small amount on the flat end of a wooden toothpick in a seed packet and shake it (seed treatment) or dip cuttings to protect the roots until the plants were established.

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New Texas Ranger Not Looking Good After Daily Watering

Leave a Comment / dead, dying, how often to water, irrigate, rangers /

Q. I planted a Texas Ranger shrub three weeks ago in some sandy and rocky soil. I have been watering it with about two gallons daily. I added one inch-deep bark mulch in a 1 foot circle around the plant. Now I am finding yellow, brittle leaves on the lower stems and curling leaves on top. Am I overwatering? A. Yes, it is definitely watered too often. Overwatering can be in two forms; giving too much water OR giving water too often or both at the same time. “Giving too much water” relates to the number of gallons you give a plant each time you water. “Watering too often” relates to how many times in a week you give water to a plant. Texas ranger hedge sheared and consequently the flowers removed             It is far more damaging if plants are watered too often rather than given too much in a single watering. Rangers do fine without wood mulch. They will benefit from it but they don’t really need it like other plants, such as roses and many fruit trees in the rose family, do.             Now, a second problem. If wood mulch is in contact with young tender stems of plants, it can contribute to a disease called collar rot. Collar rot basically rots the trunk of the plant in contact with continuously wet mulch just above the soil surface. Collar rot of bean but the principles are the same.             A third problem is just plain old root rot. This happens below ground and not at the soil surface. Root rot happens because the roots cannot “breathe” due to a lack of oxygen. The open spaces in the soil are continuously filled with water. Basically the roots “drown”.             Bottom line; pull the mulch away from the trunk about a foot or eliminate it. Make sure the plant is planted at the correct depth in the soil. Make a basin around the plant about 2 feet in diameter and fill this basin with water from a hose or bucket.             Set your drip emitters for twice a week during the summer. On the same days your drip emitters come on, fill the basin with water. This helps settle the soil around the root system.             When you see new growth, eliminate the watering in the basin. Use only the drip emitters from that point forward. Use enough emitters to deliver 1 to 2 gallons each time you water. Next year, add one more emitter but leave the number of minutes unchanged.             Fertilize once in January. Do not use a hedge shears to prune unless you intend it to be a hedge. If the plant is intended to stand alone, use selective pruning and remove one or two of the largest stems near the base of the plant every two to three years. A. Yes, it is definitely watered too much. Overwatering can be in two forms; given too much water OR giving water too often. It is far more damaging to plants to water them too often. Rangers do fine without wood mulch. They will benefit from it but don’t really need it. If wood mulch is in contact with young tender trunks or stems of plants, it can contribute to a disease called collar rot. This disease is in the soil and can spread into healthy tissue if the plant is stressed. The other concern is just plain old root rot. This happens because the roots cannot “breathe” due to a lack of oxygen to the roots. Basically the roots “drown”. Plant parts without light need oxygen. Plant parts that are green and exposed to light need carbon dioxide AND oxygen. Keeping the soil moist and having the wood mulch in contact with the trunk is a double whammy on this plant. If the soil is amended at the time of planting (University of Arizona discourages that) then you should water only about twice a week right now. We are in nearly the same climate zone. Bottom line….i hope it is not too late but pull the mulch away from the trunk about a foot or eliminate it. Make sure the plant is planted at the correct depth in the soil. Make a basin around the plant for the first few weeks and, in addition to your drip irrigation, water with a hose twice a week in the basin two feet in diameter surrounding the plant. This helps eliminate air pockets and settles the soil around plant roots. Actually you should be adding water to the planting hole when you are backfilling the hole with amended soil so the soil and water (mud) can flow around the plant roots. When you do this you will see air bubbles coming from the soil as the excess air is eliminated from the planting hole and around the roots. When finished planting, the plant should be solidly established in the hole. When you move the plant, it should not wiggle around in the soil. When you see new growth in a couple of weeks, eliminate the watering from the hose and go to emitters. Use enough emitters to give you 1-2  gallons each time you water. Next year, add another emitter. Fertilize once in January. Do not use a hedge shears to prune it but let it grow with little pruning.

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Never Plant or Transplant into a Dry Hole

Leave a Comment / die, dying, new fruit tree died, tomato transplant almost dead, tomato transplant died, transplant brown, transplant death, transplant dried up /

Compost and soils amended heavily with composts can present some problems with transplants and seeds if you are not careful. I did some of my own testing with some local composts and guess what I found out! People contacted me who had problems with vegetable transplants and even fruit trees after planting in composted soil. I did some of my own testing with transplants, seed and fruit trees.             When planting in composted soils you can create problems if you are not careful, particularly now when temperatures are getting hotter. Here are my recommendations.              Never plant directly into any dry soil. I realize it is easier sometimes to plant directly into dry soils. However, roots of transplants and fruit trees, particularly bare root, are very tender. When young tender plant roots come in contact with dry soils, they desiccate or dry out very quickly. Root desiccation and death can happen in seconds, not minutes.             This is called “transplant shock”. When tender roots dieback, the plant has to make new roots to replace them. The plant wilts, leaves may get brown edges or leaves may dieback. If the plant cannot recover from this “shock”, it can die. Transplant shock, if it doesn’t kill the plant, can set it back days or even weeks. In trees transplant shock can last a month or longer.             Transplant shock is worse on small plants because they cannot recover as easily as larger plants. It is also worse when it is windy, air temperatures are high and the amount of compost added to the soil is high.             Always make sure soil is wet when transplanting. Don’t think you can plant in a dry hole and quickly water the plant.              There are good salts and bad salts. Fertilizers are good salts. But too much of a good thing can also be bad. If the compost is particularly rich, it can damage plants if it is not kept wet when planting.             As a precaution when you have purchased or amended garden soil, water the soil and let it drain two or three times before planting. This helps to “flush” some of the salts from these “rich” soils.             Wet the soil before planting. This helps reduce root desiccation due dry soils and “dilutes” salts contained in the soil.             Water transplants thoroughly, immediately after planting in wet soil. Do not rely on just the drip system to water plants immediately after planting. When planting during warm weather months, from April through September, water twice a day with a hose for one week right after transplanting.

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How To Correct Winter Damage to Star Jasmine

Leave a Comment / dying, how to fix, leaf bronzing, star jasmine leaves yellow /

Q. What is the best way to fix frost damage to star jasmine? Give them nitrogen and iron? Wait for warmer temps? Or replace the plant? A. Mild freezing damage to many plants, including star jasmine, discolors the leaf causing it to yellow or bronze but not die. At lower temperatures the leaf may scorch, drop from the plant or dieback and still remain on the plant.             If winds are light, cold damage during mild freezes is more severe at distances further from the ground. The ground can radiate heat up to the plant, keeping the lower portions from freezing, if winds don’t continually blow it away.             If tender plants grow both above and below a wall, it is not uncommon to see the top portion damaged while the parts below the wall remain in good condition.             You sent me a picture of a star jasmine used as a ground cover. In the picture, most of the discoloration from cold is in the upper part of the plant. That discoloration is permanent to those leaves.             You have two options; let it grow out of it in the next couple of months and prune out some unsightly parts that still remain or make some deep pruning cuts inside the canopy. These deep cuts will be focused on stems with loss of leaves or discolored foliage.             Follow up with and all-purpose flowering tree and shrub fertilizer and some irrigations to wash it into the root zone. I would not replace the plants.

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Bottle Tree Losing Leaves

Leave a Comment / brachychiton populneus, death, dying, irrigation problem, limb dieback, overwatering, root rot /

Q. I have bottle trees planted next to the house and for some reason the one in the middle is losing leaves on the bottom branches. The trees are getting watered two times each week for 40 minutes. I cleared out the rock mulch and replaced it with cedar mulch around the base of the tree. I lost a bottle tree last year so I’m trying to figure out why. A. Bottle trees represent about 15 or 20 different types. All of them have a swollen trunk which, some people speculate, they use for storing some water during dry periods. We typically use only one type of bottle tree in the valley.             The cedar mulch won’t add any nutrients to the soil but it will slow evaporation of water from the soil surface. Bend side branches without leaves to see if they are dead. If they are still flexible and don’t snap, they may come back when it cools.             Remove any branches that are growing toward the house. Planting those trees in that location was not the best idea.             I remember these trees being brought into the valley as early as the late 1980s during our first push on desert landscaping. They were brought in by landscape contractors and architects because they were being used primarily in Southern California.             The first problem I remember was irrigation. People did not know that these trees required watering less often. They were watering them much like any other landscape plant. These trees are very susceptible to over irrigating.             Although not a desert tree like the Acacia, it does handle arid climates and infrequent waterings. These waterings, when they do occur, should flood the entire root system about 2 to 3 times a month during the summer. The next irrigation should not occur until the soil is dry or you run the chance of getting root rot and the tree may suddenly die during the summer heat.             The next problem was how they were being used. The tree needs to be in full sun. They should not be planted against hot South or West facing wall. Very young, green trunks of this tree can get severe sunscald in these locations followed by limb and branch death.

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25 Year Old Grapefruit Tree With Crystals Coming From Trunk

Leave a Comment / dying, grapefruit disease, insect /

 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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Rock Mulches Not Bad But Present Problems for Wrong Plants

1 Comment / dying, rock mulch, yellow /

Rose growing in rock mulch. Q. I have moved into a house that is about 3 years old with a wide variety of plants.  I have read your articles against rock mulch but I don’t know which of my plants can tolerate the rock mulch that is already there and which ones I should pull the rock away and use wood mulch.             I come from Northern Utah and do not have a clue how to handle these types of plants and all this rock. A. I am not against rock mulch but it should not be used for everything and not all plants should be planted into rock mulch.  My personal philosophy on desert landscapes focuses on using appropriate mulches for plants which can tolerate those mulches.              Generally speaking, those plants which originate from arid or desert environments can generally handle rock mulches.  Those plants which do not originate from arid or desert climates probably should not be planted in rock mulch.  There are always exceptions which never help when you are trying to make rules. Photinia growing in rock mulch.             The problem is that we intermingle desert plants with non-desert plants and then we use rock mulch around everything.  Those plants which can tolerate the rock mulch end up, over time, to do all right.              Those plants which are not true desert plants tend to decline and fail over time.  Plants such as bottle brush, photinia, Carolina cherry laurel, Japanese blueberry, butterfly iris, mock orange, and others usually begin to decline in 4 to 5 years after they are planted as soil amendments used at planting are depleted.              If you want to learn how to handle nondesert plants in rock mulches please visit my blog and search this topic. Bottlebrush growing in rock mulch.             The other reason for decline would be improper watering.  Make sure you get your irrigation intervals and the amount that you apply each time to be adequate for the plants.  Improper watering will cause plants to look terrible as well.

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Roses in the Hot Desert Do Well But Different From Growing in New Jersey

Leave a Comment / dying, iron chelate, Las Vegas, rock mulch /

Garden rose not doing well in our desert soils. They can do VERY well if you just follow some simple advice Q. This past spring I cleared a large “L” shaped area in my yard and planted 8 various rosebushes. They have sun from about 9 a.m. to about 5 p.m. They are watered in the evening and fed regularly. They are well planted with planting medium in large holes, and then mulched. All flowered during the spring and early summer. Now, however, they are very spindly looking. The leaves left on them are brown and the stems are turning brown. There are no bugs that I can see. I tugged on them and they are still firm in the ground. Have they died and should I replace them, or wait until spring and see what comes back? Should I cut them back, and if so, how much? I do not want to cut too much off. Leaf scorch on rose due to lack of soil improvement, no organic mulches used and not using an iron chelate as part of your fertilizer program A. Roses will grow best in an eastern exposure with protection from late afternoon sun. They can grow in full sun but they will be best grown in the exposure I mentioned. It is important to use a good compost mixed in the planting soil at the time of planting as well as a starter fertilizer high in phosphorus. Make sure your plants were planted the same depth as in the container or in the nursery if bare root. Make sure the bud union or dog leg on the stem is above ground and not buried. Make sure you stake the rose bush at the time of planting. The stake should not move if you do it correctly. I use a two foot piece of 3/8 inch rebar and tie the rose stem tightly to the rebar with green nursery tape and remove it after one growing season. Roses do well on drip irrigation. Use two emitters per plant or you can use drip pipe with inline emitters such as Netafim, Geoflow or equivalent product. If on drip it is important to note the amount of water the emitters deliver per hour and adjust your time on the emitters so that each plant gets about two to three gallons every time they are irrigated. Irrigations should be about two to possibly three times per week this time of year. Less often as it gets cooler but the length of time or hours should remain the same. Roses doing quite well in our hot desert climate and poor soils It is best to use a wood mulch rather than a rock mulch. All mulches must be pulled away from the rose stems at least 6 inches at the time of planting or the roses can get crown rot on the stem and die. Fertilize roses once in January with a rose fertilizer plus a soil applied iron chelate containing EDDHA. Follow label directions. You can fertilize again lightly after the heat of the summer has passed to help stimulate fall rose production. This should get you going. My guess is that they may have been planted too deep or the mulch touching the rose stems may have caused collar rot or irrigations may have been inadequate; either too often or not enough water. Just a hunch.

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