Temperate Fruit Trees Like it Colder and Moist

Q. I was in Moab, Utah, when I ran across this apricot tree. It’s doing very well. I'm guessing the reason they are doing so well is because of the high organic levels in the soil and cooler temperatures?

Temperate fruit trees like apricot, peach, nectarine, plum and apple prefer cooler weather that elevation provides, organics in the soil, and watering like any other mesic tree.

A. You're right. Fruit trees prefer to grow in soils with higher organics than most desert soils unless those desert soils were “farmed” and extra water was needed for farming.

Fruit trees also prefer to grow in cooler temperatures than provided by hot deserts. At about 4000 feet of elevation, the Moab area is higher in elevation, so it has cooler temperatures than our 2000 to 3000 foot elevations.

Growing of citrus though, in either location, is borderline. Moab is still worse than our 2000 feet of elevation. Neither place is like Yuma or Riverside for citrus.

Sap Coming from Small Fruit Trees Usually Borers

Q. I have some newly planted peach and nectarine trees with sap coming from them. They don’t look healthy.

Sap oozing from newly planted fruit trees nearly always borers.

A. Borers are most likely the problem. On small, newly planted fruit trees it doesn’t take many borers to kill the trees. They usually “attack” the south or west sides of a trunk or the limb of a tree. That’s where there is sun damage. Painting these trunks and limbs with white latex paint lowers the surface temperature about 4 or 5 degrees. It may be enough in some cases. But shade is better.

Borers will usually start to damage the hot side of a tree, either west or south.

            The sun plays a role also. Direct sunlight on the trunk of a thin barked fruit tree can be a problem. The “smell” of sunburned and dying or dead limbs and trunks attracts female borers that are looking to lay their eggs, scientists believe. When limbs and trunks of newly planted fruit trees have sun damage, then borers are more likely to be found.

This is a locust tree. Borers "smell" or find their way to the sun damaged areas of any tree. Here the top of the branches have been damaged by the sun. The bottom of branches out of sunlight are undamaged.

            What to do? 

Shade the young tree from Western and Southerly direct sunlight. Paint the trunk with diluted white latex paint. As a last ditch effort, drench the soil around the tree after it flowers (if possible) with a borer systemic insecticide and don’t eat the fruit for at least 12 months after the application.

Which came first? Here sun damage eventually led to borer damage.

Fruit Trees Like Hot Weather if Prepared for It

Q. Now that it has gotten hot, my fruit trees (some new, some established) don’t look so good.

When fruit trees are fist planted, if they are not planted right they will look a bit rough. Their looks will improve with time if these deficiencies are corrected. If their size (and increased water use) and soil improvement is accounted for when watering they will look better and better.

A. When fruit trees are first planted, they may look good. That is because they are watered correctly for the first three or four years. After that fruit trees get bigger, and need more water applied wider and to the same depth. This means more water! Don’t change how often they are watered. When they are watered, they need to be watered to the same depth, to a wider area (which means more water) and with an increasing amount of water each time they are watered. This is because they are bigger, and water should be applied to a wider area.

When fruit trees are first planted (when the weather is cooler) they need water every other day, improved soil and soil put in a flat and level moat around the tree to capture it.

            What I find to be effective is to apply water to the area under a mature fruit tree (seven years in the ground and longer) that is about six to seven feet wide. Much of the area watered depends on the soil you have but most soils are (even though they are hard when dry) a sandy loam when irrigated. I prune fruit trees (in the winter) at seven feet and let them grow during the year to close to 8 or 9 feet tall, not their full size. This pruning allows for ladder-less fruit harvesting.

When the fruit tree is three or four years in the ground the tree is pruned to establish the major fruit bearing limbs

            To do this I water the fruit trees to about 18-24 inches deep in the soil. The area I want to apply water is about half the area under the fruit trees. This usually requires about 8 drip emitters (or two concentric rings of drip tubing with emitters placed 18 inches apart) when the fruit trees have been in the ground 5 to 6 years. The rings are spaced18 inches apart, too! The fruit trees are planted about ten feet apart in all directions. I prune them so they fit into this area, and you can walk around them to harvest, fertilize, and prune.

Limbs are only removed at the bottom if they touch the ground. Otherwise picking fruit starts at the lowest limb!!!!

            Figs are good to have in the orchard because, in my experience, they grow but will not fruit if they come up short on water. Fruit is the first to go, not growth. If you have fruit on your fig trees in July and August, then the other trees are getting the right amount of water too. Figs are a “water indicator” fruit tree for me.

Fig trees, as all fruit trees, are big solar collectors. If you cant reach the fruit it is wasted. If the fruit is too low it is wasted. If the fruit is too close together it is wasted.

Yellow Leaves on Potted Myer Lemon

Q.  I have a Myers lemon tree in a pot on a south facing patio. The wall near it faces east and there was a large pine tree out front so it receives shade in the afternoon. There are quite a few yellow leaves that just appeared. All the new fruit has turned black. It seems to me that maybe I just need to replace this tree. The lime tree is doing very well in a similar location.

A. The picture you sent to me shows a Myer lemon with ready to harvest fruit being grown in a small container with smaller plants growing around its base. Meyer lemon typically flowers sometime in January and February. The fruit can be harvested starting about now (December) with this harvest, finished by January, encourages new flower development for next year’s production.

Producing flowers and then fruit in midfall is early for Meyer lemon. Early flower development can be a sign that it is under some sort of stress. Certainly it's not normal for this type of tree at this time of year.

            All fruit trees and vegetables need a minimum of six hours of full direct sunlight. 8 hours is even better. In home landscapes the best sunlight for it in our hot climate in the summer months is during the cooler morning hours. Partial shade may be pleasant for people sitting on the patio but not for many plants that produce fruit or vegetables.

If shade is present during most sunlight hours, then I would recommend an ornamental plant for that spot with variegated or colorful leaves, not a flowering or a fruit-producing plant. A non-flowering ornamental handles shade better than a flowering plant, whether those flowers produce fruit or not.

Don't Plant Annuals at the Base of Perennial Trees

            Secondly, and perhaps more importantly, are the smaller plants demand for frequent watering compared to the tree. Growing a shallow-rooted plant or plants at the base of a deeper-rooted plant is a big “no-no” regarding how often water is applied. Shallow-rooted plants “signal” they need water applied more often than deeper-rooted plants, so they get water applied more often than the watering frequency needed for deeper-rooted plant needs.

This type of watering can suffocate the roots of a deeper-rooted plant. Watering a deeper-rooted plant too often can produce leaf drop, flower drop, fruit blackening, and a tree that's “loose in the soil”. Trees that develop “collar rot disease need to be staked after just a few years of growth. Does that sound like your fruit tree?

            I would replace this tree with a plant that requires moderate to low levels of sunlight. If you want to grow other plants along with it, select plants with a similar rooting depth and need for applied water.

Rabbit Chewing Damage to Peach

Q. I planted a peach tree late last winter but before I could protect it the rabbits began chewing on it a bit, not all the way around just a few spots. I’m not sure if borers have gotten to it. Do you think it can be saved or is it time to pull it out?

Rabbit damage to a peach tree. Rabbits love to eat fruit trees in the winter when not much else is around to eat. If you fear rabbit damage, use one inch hexagonal fencing to protect them when they are young.

A. Most trees, including fruit trees, can lose about half of their bark by chewing and still survive. If it were me I would tally up all of the damage and if this damage is less than 50% then it should be fine. You might lose some branches that are severely damaged but the majority should survive. 

A cylinder of 24 inch wide, one inch hexagonal chicken wire is usually good enough protection for fruit trees from rabbits.

Protect the rest of the tree from vermin damage and don't worry about it too much. The damage will heal on its own. If you want the tree to recover from damage faster, make sure it is getting enough water and fertilize it at least once each spring.

Hot Locations are Tough for Fruit Trees and ALL Plants

Q. I have a very hot location I want to plant. It’s facing West. I had a 'Pink Lady' apple tree in that spot but I think it was just too hot for it. It died in a couple of years. What do you suggest?

Hot locations are tough on fruit trees. Afternoon shade is better for the plant.

A. Hot locations are tough. From the look at the picture you sent there does not seem to be much air movement. Just a lot of reflected heat from high walls. In my opinion, that area will get super cold in the winter as well. I know you are in a hurry want to get it done. But do you want it to survive?

I would put a waterproof, recording thermometer in that area to track temperatures both during the heat of the summer and cold of the winter.

High/low battery operated recording thermometers have been around for decades.

Not having much air movement can have both good things about it and bad things. The main advantage to that “hot” location is blockage of the wind.

            In spots like that I would recommend first to cut back on reflected heat. Cover this area with about 50% shade cloth until the tree gets grows enough to cast its own shade on the walls and soil. While shade cloth is provided, grow a deciduous vine that likes the heat, such as catclaw vine, so that it covers the wall. Covering the wall during the heat of summer reduces the reflected heat to that area. Provide shade for that spot for about four to six years if the tree grows quickly. The fruit tree should start producing in the second to fourth year depending on what is grown.

            Let the temperatures recorded there dictate what to plant in the future. Personally, I think apples, pears and other related fruit trees may be a poor choice for that spot due to excessive heat. Most citrus, except Myer lemon, grapefruit, kumquat, and tangerine may work if the winter temperatures are warm enough. Apricot or pomegranate are better choices.

Borer Prevention

 Q. I have lots of borers in my trees. What can I do to prevent it from happening?

When borers are a problem it starts about mid summer. Often it begins in parts of the tree frequented by our intense sunlight like the upper sides of limbs that are not shaded.

A. First, prevent sunburn to all trees, particularly young fruit trees. Sun damage is a problem immediately after planting in our desert climate. Damage from the sun can lead to borer problems later down the road. If I were buying a fruit tree, I would buy a small tree and let it grow as a bush. This way the lower limbs will shade the trunk.

Let the Tree Grow Bushy

As soon as it starts to produce fruit, that next winter, I would remove the lower limbs only so the fruit does not touch the ground. Leave as many of the lower limbs as possible to shade the trunk. In fact, let it grow into a shrub.

The biggest mistake homeowners make with fruit trees is to buy large fruit trees with limbs high off of the ground. If lower limbs are present, they are removed to make a tree. Buy smaller trees and let them grow to the next size.

Shade the Trunk

It may be the right thing to do in other climates but not the desert. Desert fruit trees need tender trunk protection from the sun to about five or six years old. If you have a fruit tree and it is “limbed up”, then protect the trunk with diluted latex paint, tree wrap or protective collar that shades it.

A sign for a borer problem is limb death in the middle of summer; brown dried leaves clinging to one or more branches on the south or west side of the tree starting when it is hot. Use a borer soil drench with an approved pesticide for borers. You are not permitted to eat the fruit until 12 months have passed. This particular pesticide is best applied after flowering.

Use a Pesticide as the Last Resort

There are pesticides that can be used that will kill borers still in the tree. Be careful. Treat trees after they finish flowering to protect honeybees. Don't eat fruit from that tree for one season of production after you apply a pesticide. 

Prune Larger Shade Trees to Save Water and Be a Good Neighbor

 Q. I have a 20-year-old African sumac nearly 30 feet tall which provides great shade in my backyard. It needs another pruning when it cools off. I did a major cutback last fall at the request of my neighbor because of leaf drop. Any suggestions on how best to do so and keep the shade and cooler temperatures it provides?

Drop crotching an African Sumac that is too tall will save water.

A. Two things you need to know if you are doing this yourself; drop crotching and how to do a 1-2-3 pruning cut.

Stand away from the tree so that you can see all of it. Identify the limbs giving you the problems. Trace the limbs back to a lower crotch. A crotch is where at least two limbs come together. This is where the pruning cuts and lowering will be done.

In a 1-2-3 cut the first cut is made 12 inches from the tree trunk and upward to prevent a large limb from pulling the bark from the trunk

Make a 1-2-3 Pruning Cut

During cooler weather remove the limbs that are offensive. Use a 1-2-3 cut to avoid stripping the bark from the tree. A 1-2-3 cut is done first by making an undercut six inches from a limb to about 1/3 of its diameter.

The second cut is made outside of the first cut. Attached bark may strip down to the undercut, or first cut, so the falling limb will not tear the remaining limb and tree trunk. This is why the undercut is made first. A third cut is used to finally remove the remaining stub. It is a finished cut. The third cut is the smallest cut made that removes most of the stub remaining so the cut heals faster.

If you have never done it, for safety reasons and a better-looking tree, hire a certified Arborist to make these pruning cuts so that it will make the tree smaller and keep it beautiful. Part of your payment is for decisions that result in a prettier tree than you could have done.

Fireblight Causes Problems with Fruit Trees if Missed Earlier

 Q. I came back from vacation and my ‘Gala’ apple tree branch was dead.  The tree also has some black spotting under the bark. I'm hoping it's not damage from fire blight. 

Both pictures are fire blight in 'Gala' apple tree with an older infection. As this reader suggested, the earlier symptoms were not noticed and the bacterial disease has now invaded the trunk. Most likely the trees will either die or may serve as a host for further infection of trees. 

A.  I looked at the picture you sent of your fruit tree, and it looks like older fire blight disease that escaped earlier detection and is now in the trunk of your tree.

Fire blight is a serious disease that is highly contagious for many apples. It’s more damaging to some apples like ‘Pink Lady’ than others such as your ‘Gala’.  It’s particularly damaging to all Asian pears.  It can be damaging to some European pears, like ‘Bartlett’ and others, such as ‘Keiffer’, it doesn’t seem to affect much here.

This is fire blight disease on a recently planted 'Bartlett' pear. Sometimes this disease can come in on nursery plants from "dirty" growers.

It is damaging to some ornamentals like pyracantha and some cotoneasters in the rose family. The varieties of these plants may show differences. It just depends on the genetics of the plant combined with the genetics of the disease.

When I saw this disease in the spring it was heavily into Asian pears, some European pears and many apples and quince. What gave it away then was the early spring growth, which was black, hooked and had the presence of sap.

Fire Blight control is normally through removal of the infected limbs 10 to 12 inches below where the infection is seen.

What gave it away to me now are the dark cankers (black spotting) on the trunks of your trees and also the presence of sap.  The “sap” is what is contagious and can cause it to spread.  The dark cankers are probably from earlier fireblight infestations. Once this particular disease gets into the trunk the tree usually dies.

If the tree continues to look bad or worsens, I would cut these trees down and get the pruning off of the property. You cannot use this wood for wood chips or anything near plants or it can reinfest susceptible plants.

Remaining Fruit Tree Pruning Classes in January 2022

 

Fruit tree that was pruned to open center

2022

Friday, January 7                9 am        How to Prune and Thin Apple and Pear

Friday, January 14              9 am        How to Prune Pomegranate, Fig and Jujube

Friday, January 21               9 am       How to Prune and Fertilize Wine and Table Grapes

Friday, January 28               9 am       How to Fertilize Fruit Trees (Fertilizer + Iron)

What is covered?

Each type of fruit tree is different when grown in our desert climate. Topics will be discussed for each type of fruit tree and how our climate affects each type of tree.

Selection. Which fruit trees are best for this climate? What tree characteristics should I look for at the nursery?

Planting: Which trees are most wind resistant? How big is the hole? Compost vs soil amendment. How deep should I plant it? Is staking really necessary? How to protect the tree from rabbits?

Growing: How do I know if the tree needs fertilizer? How much fertilizer should I give it? When to fertilize? What fertilizer should I use? Will it grow in rock mulch? Does my tree need iron?

Water: How often to water in the beginning? How much water does my fruit tree need?

Insects: How to control insects that damage the tree? Which insects are the most damaging?

Disease: Which diseases are possible and how to prevent them.

Application of Insecticides Depends on the Label

Q. Please advise where I can find this borer control product you recommended to me for soil drenching. The product I found has only 1.47% imidacloprid in it. Is this strong enough for soil drenching?

A. This question opens a “can of worms” I tried to avoid earlier by only recommending a single product. Initially when evaluating a product for borer control as a liquid soil drench, two questions should be asked: 1. Does this product contain imidacloprid in the ingredients? 2. Do the instructions explain how to apply it as a soil drench to the type of plant I am treating? The instructions will tell you how to use it correctly.

Homeowner vs Professional Concentrations

            There is frequently a difference in concentrations of imidacloprid between “homeowner products” and “commercial products”. The obvious difference of course is availability to homeowners of commercial products but the other one is in the lower concentration that you mentioned.

            Homeowner products are frequently less concentrated than commercial products. This is because commercial applicators should have more knowledge about safe use of these pesticides and access to PPE (Professional Protective Equipment) when applying it. Plus, the homeowner uses less product.

            For commercial applicators, imidacloprid is contained in several products and atconcentrations much higher than 1.47%. “The dose makes the poison” and having a less concentrated product available to homeowners can be “safer” for the uninformed to use. It also means less “left over” product when finished.

Read the Label

            Is 1.47% strong enough to use as a soil drench?  Look at the directions for use. Does it say you can use it as a soil drench for your purpose? A reliable manufacturer will want you to be successful, tell others about your success and use their products again. A reliable manufacturer will give you the right instructions and concentration that will be effective.

This formulation of imidacloprid allow for a soil drench of vegetables and fruit trees. It has 0.233% imidacloprid and the label tells you how to mix and apply it. If the label doesn't allow it, then by law it is not allowed.

            It’s up to you to read the directions and make sure this product is applied correctly as a soil drench and for your purposes. Make sure it is applied after the plant flowers in the spring to avoid “honeybee” problems which it clearly states on the label.

Multiple Reasons for Spring Yellow Leaves

Q. My Asian pears look sickly again this year with yellow leaves. Last year after their planted the new growth was yellow and again it’s happening this year.

New growth on Asian pear is light colored or yellow. This can be for many reasons.

A. There are several possibilities why plants have yellow leaves when they’re young. Some plants have light colored leaves when they are young and get darker as they get older. If this is the case, don't worry about it. 

Chojiro Asian pear growing in the Las Vegas Valley in the Eastern Mojave Desert.

Planted too deep

The first is rather simple. Their planted too deep. Fruit trees must be planted the same depth they were when growing in the nursery. Those fruit trees that are grafted or budded must have the dogleg above ground.

            If the hole is dug too deeply and the soil is amended, it’s possible the tree will sink deeper after it’s planted and soil will fall around its trunk. Wet soil around the trunk can rot it. This is the reason it is best not to dig the hole deeper than is needed for the roots unless there is a drainage problem.

This pomegranate was planted in a depression in a lawn. Are the roots staying too wet? No way to know until you check the soil  and see how wet it is just before the next irrigation.

Soil doesnt drain water

 The first sign there is wet soil around the trunk and it’s starting to rot are yellow leaves. If not corrected, it can kill the tree. If the bud union is below the soil, water can rot the union and it will die. In milder climates the top part of the tree can grow roots and you will lose the benefit of the rootstock.

This is an apple tree growing in an orchard in the mountains of Lebanon on terraces. The soil was kept too wet near the trunk the tree developed collar rot.

Borers

Another reason for yellow leaves are borers. You would think that trees coming from a nursery wouldn’t have insect problems but they do. After supervising the planting of hundreds of fruit trees, I would estimate there are borers in two out of every 100. Trees most susceptible include peach, nectarine and apple. Others are also susceptible but less so in my experience.

Borers in ornamental plum

            Water drainage through the soil can also be a problem. If watering too often and the roots stay wet, they will begin to rot. Rotting roots decrease the plants health and this shows up as yellow leaves in the top. Check the soil moisture and make sure the soil is not watered daily.

Soil improvement

            Sometimes the soil is not improved enough at the time of planting. I like to see about 50% of the volume of the soil used for planting amended with compost if this is desert soil. Less compost is needed in other soils but it’s still a good idea.

            Compost improves water drainage through the soil but it also helps the soil hold water. I know it sounds crazy but the soil structure where air is contained is improved while also the channels for draining water are improved at the same time. It is either drainage/water problem, planted too deep, borers or lack of fertilizer.

If this lack of color continues, spray the leaves with a liquid fertilizer spray. 

Mixing a liquid fertilizer and spraying the leaves.

Use either a Fertilome, Grow More or even Miracle Grow product with high nitrogen. A lawn-type fertilizer would be good for young trees.

You will need:

• Distilled water (tap water in Las Vegas is pretty bad quality)
• Water soluble fertilizer
• Use liquid spreader (baby soap or Castile soap liquid or  EZ wet from Viragrow) to help fertilizer get inside the leaves and. Add what it recommends on the label or ½ tbs per gallon.

Steps

• Add water to the sprayer so it is half full
• Add water soluble fertilizer at rate on label.
• Finish adding water to the spray so that it mixes all well.
• Add spreader (EZ Wet) to the mix and stir.
• Spray leaves to runoff, top and bottom.
• You should see a change in leaf color in 48 hrs

Spider Mite Problem from Nursery Tomato 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