'Bonita' Ash and Ash Decline Disease

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.

Succulents for Las Vegas Gardens

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.

New Texas Ranger Not Looking Good After Daily Watering

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?

Never Plant or Transplant into a Dry Hole

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!

How To Correct Winter Damage to Star Jasmine

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?

Bottle Tree Losing Leaves

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.

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.

Rock Mulches Not Bad But Present Problems for Wrong Plants

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.

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

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.