What Caused Jalapeno Leaves to Be Stripped from My Plant.

Q. I went away for three days and when I returned all the leaves were stripped from my jalapeño plants. Do you know what did this?

A. Leaves stripped from vegetable plants is usually because of their tomato hornworm. Tomato hornworms are large caterpillars with the spine sticking from their rump. They can come in a variety of colors but we usually see green ones.

            They are voracious eaters and can remove leaves from plants at an alarming rate. They also leave behind a lot of large feces that could be confused with mice.

            They select only tender tissue and may leave behind more woody stems because they are not as delectable. When plants are very young and tender, they will consume the entire plant.

            You do not see them during the day because they hide and come out to forage at dusk and during the nighttime. To find them, go out at dusk with a flashlight or in the early evening hours.

            Another interesting way to find them is using a black light, the same way to find bark scorpions. Hornworms shine with an eerie green iridescence under a black light.

            Your plant will recover but you don’t have much time left for pepper production. When leaves are removed this stimulates the plant to produce new leaves from existing buds in the crotch or axil of the leaf. The problem is now the plant will focus on producing new leaves first rather than flowers and fruit.

            Protecting your plants from these creatures is easy to do by going out at night and removing them by hand. Protect plants with sprays of Bt or Spinosad which are considered organic controls. Just about any vegetable insecticide will control them as well.

Pine Top Dieback Means Damage Near Top

Q. The top of my pine tree died.  Bottom branches look as healthy as ever, green, supple new growth on all of them.  It is about 20 years old.  Its watering has been successful for my 14 years in this house, infrequent and deep - it has options to gather additional water from adjacent areas (lawn and garden) if it wants. Why did it die?   Can I remove the dead top?  And what will happen? 

A. I looked at the picture and I tried to identify the tree. The needles are not very long so it did not look like one of our common pines such as Afghan or Mondel pines. It actually looked like a spruce from the branches and the needle length. The kind of tree is very important in determining what caused the problem.

            Whenever we have a portion of the tree die and the rest of the tree appearing healthy, it usually pinpoints the problem at the trunk or limbs where the green foliage is closest to the brown or dead foliage.

            If I were on site I would get a look at the trunk or limbs at the juncture between healthy and dead areas. I would look for mechanical damage in that area. I can’t tell you why there would be mechanical damage but that’s what I would look for. This is not something we would normally see with pine trees.

            If this is a spruce and not a pine then it might be heat stress. Spruce trees cannot tolerate our climate and soils very well and have difficulty lifting water from the roots to the upper limbs. If this is a tree that is not tolerant of our hot dry climate or desert soils than this could be drought at the top of this tree causing it to die back.

Control Root-Eating Grubs Organically and Conventionally

Q. I found grubs in the dirt with my plants. I put some Triazicide around the plants. Will this help?

A. Triazicide is a conventional insecticide, found at any nursery or garden center, which is very effective at killing grubs. The major advantage of conventional insecticides like this one is the residue or residual left behind after the application. For those preferring organic methods, this is also a major drawback.

            There are organic alternatives to grub control which are very effective. These include pyrethrum applied as a soil drench for an immediate kill, milky spore bacterium and beneficial nematodes. Milky spore bacterium and beneficial nematodes also give you long-term plant protection from grubs.

            In your case, you need something to kill the grubs. Once you kill the grubs, it may be no longer necessary for a product like Triazicide to hang around in the soil.

            A residual product like Triazicide becomes important when protecting valuable plants from an infestation which may be imminent. In cases such as these, mark the calendar when the insect threat might occur and apply this type of product two weeks to a month before this date.

            I would not use this product around food crops but lawns and ornamentals are more suitable. But always read and understand the methods of application stated on the label.

            Triazicide comes in several different formulations (liquid concentrate, granules, ready to use liquid, etc.) and each formulation is applied a little bit differently. Basically the poison is applied to the soil surface and water is used to wash this poison to where the grubs are actively feeding. Applying too much water can move the product beyond the area where it is needed.

            Manufacturers want you to be successful with their products so you will use them again and recommend them to others. They try to provide the best information possible so that you are successful.

            Be cautious around your outside pets like dogs and cats since any insecticide, organic or
conventional, moves easily from the soil surface, through the pads of their feet and into their body. I would not let them walk in the area until the surface where it was applied is totally dry.

When to Cover Winter Tender Plants in the Mojave Desert

Q. When should we cover Pygmy Palm, Bougainvillea and other plants that will freeze here in Henderson?  I have burlap to cover them.

Bougainvillea freeze damage

A. Both of these plants can tolerate temperatures to near freezing and they don't seem to have problems at temperatures below 45° F that causes chilling damage to some plants. Some tropical plants such as tomatoes may show chilling damage to fruit at temperatures below 45° F. This is why it is best to not refrigerate tomato fruits.

            It seldom freezes in the Las Vegas Valley before Thanksgiving. After Thanksgiving you might expect freezing temperatures at the higher elevations such as in Summerlin or in very low spots in the Valley where cold air collects. In Henderson, this might be in the old Pittman area or along the wash.

            Cold air, being heavier than warm air, settles into low geographic areas. Cold air tends not to settle on gently sloping land or hills.

            Freezing temperatures are more frequent where plants are exposed to wind. Plants growing along major streets tend to freeze more often than those in protected backyards. Major streets are urban canyons that channel cold wind in the winter. Backyards are more nestled away from these exposed urban canyons.

Sehgal palm cold damage

            Plants growing close to brick or cement walls that face West or South are less likely to freeze than plants growing further away unless wind is involved. Brick and cement walls exposed to the sun store heat during the day and radiate this heat at night keeping the plants a few degrees warmer. If wind is involved, it removes this radiant warmth making these plants more susceptible to freezing temperatures.

            Bottom line, when the weather forecast is for freezing temperatures, cover the plants with an old sheet, blanket, or in your case burlap, before nightfall. Drape this covering over the soil or any surface that can radiate heat at night. Remove this covering the next morning after temperatures are above freezing.

            In open areas, expect freezing temperatures after Thanksgiving and up to March 1. In protected areas, expect these temperatures anytime between mid-December and mid-February but watch your local weather forecast closely and adapt this recommendation accordingly.

Imidacloprid a Problem for Pollinating Insects?

Q. Do you recommend using imidacloprid in the grass to kill grubs? Does it harm pollinators? What would you advise?

A. That particular chemical is suspected of possibly damaging pollinators. Nothing has been conclusive about it but logic tells us that if we have a systemic insecticide that can persist in a plant for 12 months that it is possible this chemical may be in flowers, pollen or nectar. We just don't know.

For this reason I tell people if they are going to apply it to plants that bloom then apply it immediately after they have finished blooming. I also tell them that it is safest to use on plants which do not have flowers that attract bees. Lawn grasses do not attract bees so I don't consider that to be a problem for pollinators.

Even though it is labeled for fruit trees, I would not personally use it on fruit trees if I am planning to use the fruit. If I were to apply it to fruit trees or any ornamental tree that has flowers that attract pollinators, I would not apply it until after bloom until we have more conclusive evidence that it is not a problem with pollinators. That's what I am currently recommending regarding this product.

Moon Lagoon Eucalyptus Good Desert Landscape Plant

Replacement Plant for Photinia

Q. I have several Red Tip Photinia that I use as a screen from my neighbor. I would like to replace them with some a bush that would be about 3 to 31/2 feet tall and handle our soil an weather better. I want to spend a little time trimming them. Texas Rangers are good but need a lot of trimming. Any Suggestions?

A. Bob Morris forwarded me your message.   I am a Certified Horticulturist working in the Las Vegas area since 1992.

 I suggest you look at Dwarf Myrtle and Dwarf Youpon Holly. Both are tough evergreen shrubs growing to about 4 feet by 4 feet.

Hope this helps.
Andrea Meckley, CH
Imn2plants@aol.com

How to Move Established Plants in the Landscape

Q. A one-year-old tree was relocated from the front to the backyard. After one day, it appears obviously stressed. It lost all of its leaves. Our landscaper put on a combo mixture that included B12. They didn't prune it. I always thought you should prune about a foot off in order to stimulate the roots. What do you suggest?

A. Trees that have been in the ground for 1 to 3 years should move to new locations easily provided it is properly done at the right time of the year.

            Yes, I would normally prune back a tree or shrub after relocating at. This is a very important step in transplanting to reduce transplant shock. The reason is not to stimulate roots but to bring a better balance between the severed roots and the canopy.

            Transplant trees and shrubs when temperatures are cooler. I looked at the air temperatures reported when you sent me this email. They were still over 100° F. We are approaching the right time of year for transplanting but those temperatures are still too high.

            The tree lost its leaves because the severed roots could no longer supply enough water to the canopy. The tree responded to this “transplant shock” by dropping its leaves. This was its defense mechanism to preserve its life.

What is transplants shock?

            Transplant shock can come in many forms. The most severe shock results in plant death. Dropping its leaves was the trees defense mechanism that hopefully will save its life. By dropping leaves, there may be enough water the roots can supply to keep the leafless tree alive.

            Successful transplanting of trees and shrubs results in minor transplant shock. Minor transplant shock results in little to no dropping of leaves but a slowing of growth for the next one or two growing seasons.

            Plants established with drip irrigation can exhibit almost no transplant shock because the roots of the plants are concentrated close to the drip emitters. This makes moving them to a new location much easier.

Some Tips for Transplanting

            Here are some steps to follow when transplanting trees and shrubs that are one to three years old. First, wait for the cool temperatures of fall. In our area this would be mid-October to about mid-November. Move these plants soon after an irrigation.

            Make sure the new planting hole has been dug and the soil used for transplanting has been amended with compost and a starter fertilizer before moving the plant. When moving the transplanted tree or shrub to its new location, it should be placed in the hole immediately, planted and watered.

           
Second, with a sharp, round-nosed shovel, sever the roots deeply all around the plant a distance 12 to 18 inches from the trunk or trunks. Estimate the weight and size of the root ball you will be moving. Take as much soil with the roots as you physically can handle regardless of the size of the plant. Larger root ball size decreases transplant shock.

           
Minimize the time plant roots are out of the soil. Move the plant to the new planting hole will by lifting under it, carrying it by its root ball. An old piece of carpet, burlap or strong fabric works well.

            Gently lower the tree or shrub into the planting hole so that it will be planted at the same depth it was previously. Fill the hole with amended soil while at the same time filling the hole with water from a hose.

Stake the plant so the roots cannot move in a strong wind. Remove about one third of the canopy with the pruning shears to reduce transplant shock.

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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Marble-Sized Mud Balls on Plant Leaves a Good Thing

Q. I sent you some pictures of a round object about the size of a large marble with an entry hole in it. I found it attached to the leaf of a cats claw leaf in my backyard of my Summerlin home.  I only have found one so I am not worried about lots of pests from this one vessel.

Potter wasp nest on cats claw vine leaf

A. I think this hard, mud-like ball with a hole in it, attached to a leaf, was left behind by a mason wasp. The mason wasp is also sometimes called a Potter wasp because of these round mud balls with a hole in it that resemble pottery. It has been theorized that Native Americans based some pottery designs from the mud balls left behind by Potter wasps.

            Wasps are generally divided into two categories; those that live with other wasps in a community which are called “social” wasps, and those wasp that live by themselves which are termed “solitary” wasps.

            Potter wasps are considered solitary; they live alone and build this mud nest for a single, solitary offspring. After building this pottery-like nest, the female finds a grub that will fit in it, paralyzes it by stinging and places it in the nest along with an egg. The developing youngster uses it for food.

            Potter wasps are not aggressive towards humans or other large animals unless they are provoked then they can sting multiple times without dying unlike a bee. They would be considered a beneficial insect in the garden area.

            Consider Potter wasp mud nests as one of the “good things” in gardens and landscapes. Just give the adult wasp its own space.

You can learn more about them here

https://polinizador.wordpress.com/2011/04/12/potter-wasps-and-mason-wasps/

https://en.wikipedia.org/wiki/Potter_wasp

Gardenia Needs Container and Extra Care in the Desert

Q. I love Veithcii Gardenia and I noticed that a local nursery has them for $10 for a 5 gallon plant. How do you keep the plant alive in the winter in Las Vegas and should it remain in a container and not in the ground? I have seen two of these plants in containers in Sun City Summerlin under a tree blooming profusely in the summer.

Gardenia In Las Vegas in filtered light

A. “Veithcii” is a popular selection or variety that has a longer bloom period than some others. Gardenias are grown by a number of home gardeners in our desert but you are right, they don't belong here so we have to put them in the right location and amend the heck out of that soil if we want them to do well.

            . It is best if they are grown in containers rather than growing them in garden soil. A good spot would be in filtered light which is what you would get growing them under some trees for protection from intense sunlight.

            Gardenias in general perform best in a bright northerly or easterly exposure. The soil should be 50% compost or at least high in organic matter. You can grow them in the ground but they will be more difficult to manage because the soil will slowly revert back to desert soil unless you continually add compost to the soil surface.

More about this Gardenia from Monrovia Wholesale Nursery

            It is also important to put a two or 3 inch layer of wood chips. I would use two drip emitters and never let the soil get overly dry. Fertilize 3 to 4 times a year and add a good iron chelate to the early spring application of fertilizer.

            The important things to remember is having a good soil, the proper exposure to light and irrigation frequency. The container should allow for drainage of water and you should see a small amount of water exit the container every time you irrigate. Good luck!

How to Rehabilitate Japanese Black Pine

Q. Are Black Pine, California Christmas Tree and Thumbergii all the same plant? I have 2 trees that are important in my landscape and have been doing well for several years. They were neglected recently so there is no place for deep watering and not fertilized in 2015. There is sap coming from the trunk. Should I try to rehabilitate them or replace them?

Japanese Black Pine

A. Japanese black pine is Pinus thunbergii so Thunbergii probably refers to Japanese black pine. I do not know if it is called California Christmas tree but I doubt it because Japanese black pine has a very unusual form making it a specimen plant in the landscape. It does not have the Christmas tree shape.

          Most of the textbooks say Japanese black pine tolerates alkaline soils but I have not really found them to be very tolerant of the hot desert and our soils. Many of them have been planted in Las Vegas but very few are still around which tells me many were removed.

          If you have Japanese black pine they are characteristically slow in growth and have a very distinguished form that adds character to a landscape. If you are looking for a Christmas tree pine this is not going to be it.

          They are slow-growing. If they have been neglected and do not look good they will rehabilitate very slowly. 

          Soil applied systemic insecticides that control borers would be a good if the trees actually have them. Pines can be “sappy” so make sure it is borers before you make the application. Wounding of the trunk and limbs can also cause them to bleed sap like borer damage.

          If you choose to rehabilitate them, put tree wells around the trunk about 2 feet in diameter to hold irrigation water. Give them a deep soaking with a hose once a month along with their normal irrigations.

          Fertilize them with 16–16–16 once a year in the early spring or apply it now if they haven't been fertilized this year. Punch some holes in the soil 2 to 4 feet from the trunk to a depth of eight or 10 inches. Put a handful of fertilizer in each of the holes and water them twice to activate the fertilizer and move it into the tree.

          Expect a very slow recovery if you choose to rehabilitate them. If they look bad now, I would suggest that you consider replacing them with something that you really like and can get instant gratification.

Air Pruning of Roots Another Form of Root Pruning

Q. I read about air pruning the roots of potted plants using either fabric pots or drilling holes in pots and lining with landscape fabric.  Supposedly, air pruning keeps the roots in "check" so that they do not outgrow the pot.  The idea sounds logical, but with our extreme heat and hot winds, could this work in Vegas?

A. Air pruning is allowing the roots of plants are exposed to the air and die. It is normally used in greenhouse production with potted plants. It can be used for plants growing in containers as well. It is popular where other types of root pruning may not be practical.

            If plants grown in containers are allowed to rest on soil or gravel, the roots of these plants can grow out of the holes on the bottom or sides of the container and into the wet soil beneath it. Once the roots leave the container and grow into the soil, the tops of these plants typically have big growth spurts.

            In the past, if these pots or containers were given a quarter turn twist, this would sever young roots and prevent them from getting anchored in the soil beneath them. This is an older method of root pruning.

            Another older form of root pruning was using chemicals such as copper sulfate applied to the surface of the soil or gravel just under the pots or containers. The concentration of copper would kill the roots of plants growing into it but would hurt the tops of the plant.

            Air pruning is another form of root pruning where the bottoms of containers are pots are suspended in open-air. Roots exposed to the open-air will die without moisture. As roots leave the container through drainage holes, the roots die and become “root pruned” by the air.

            This would work in our climate as well. However, in our hot desert climate I worry a bit about pots or containers left in full sunlight. The soils in these containers can heat up quickly and the roots “roasted” on the side of the container facing the sun.

            If pots or containers that you are using for root pruning are in full sun make sure they are white or shiny and reflect as much sun as possible. It would be best if they were shaded. Water the plants in the containers just before the heat of the day.

Canary Island Date Palm Dying May Be Disease

Q. I had a mature canary palm in my back yard for about 10 years. This summer it became infected and died. I have a monthly service with a landscaping company and, despite their efforts, was to no avail. Do you suggest I plant another one or buy a different type of palm? It was in the center of our yard and served as a focal point to our landscaping.

A. Depending on why the palm became sick will determine if you can replant in the same hole. In California this palm is susceptible to a disease called Fusarium wilt which can contaminate the soil in the planting hole and prevent you from planting a new one in that spot. To my knowledge, this disease has not been reported on this palm in southern Nevada but your description fits.

            Older or lower leaves sometimes die before the newest leaves in the center begin to turn brown and die. In some cases leaves or fronds in the center of the canopy may die while the lower leaves appear healthy. And in even other cases, leaves on one side of the palm may brown while the other side remains green.

            Often, leaf fronds turn yellow before dying so it’s possible to confuse it with the chlorosis such as iron chlorosis or other micronutrients like manganese. The yellowing leaves may be confused with over watering symptoms. Infected palms frequently die in a couple of months or in some more rare cases die a slow death over several seasons.

            This disease can be spread on pruning tools such as chainsaws so it is important that these tools be sanitized properly between trees and between cuts if the tree is suspected of having this disease.

            Another point of entry for this disease is through the roots. If soils around this palm tree are kept excessively wet by watering daily or the soil does not drain very well, this could increase the chances of this disease.

            This disease can sit in the soil and remain active for 20 years or more so I would not recommend planting another Canary island date palm in that same hole. You would select plants that are more tolerant to this disease when planting in this area.

            You should also amend the soil for better drainage and make sure the planting hole drains properly before putting another plant in the same or near the same hole.

Here is a picture of what this disease may look like in Canary Island Date Palm

Here is some information from the University of California regarding this disease in Canary Island Date Palms

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74148.html

FUSARIUM WILT

The fungus Fusarium oxysporum f. sp. canariensis causes Fusarium wilt, a lethal, vascular disease of Canary Island date palms (Phoenix canariensis). There are different forms of this fungus, and they typically are host-species specific. The form referred to as forma specialis canariensis causes disease only on Canary Island date palms. Other forms of this fungus cause wilts on other species in other parts of the world.

Identification and Damage

Symptoms usually appear in older or lower leaves before moving toward the center or newest leaves, although occasionally this fungus will affect mid-canopy leaves first. Leaves turn yellow then brown but remain hanging on the palm. Initially symptoms might affect the leaflets or pinnae on only one side of the leaf. Pinnae on the other side remain green, although they eventually also will turn brown and die. This pattern was once thought to be diagnostic for Fusarium wilt, but other diseases such as pink rot also can cause one-sided death of leaves. Pinnae death typically occurs first at the base then moves progressively toward the leaf tip, although this pattern sometimes is reversed.

Extensive discoloration along the petiole, the stalk connecting the leaf base to the leaf blade, is another common symptom of Fusarium wilt. External streaking is brown to black while internal, or vascular, discoloration is reddish brown to pinkish. Although incompletely understood, this pinkish discoloration might be a good diagnostic symptom of the disease.

Infected palms can die within a few months after symptoms appear, or they can linger for several years. Because wilt diseases decrease the ability of the host to take up water, palms with Fusarium wilt in cooler, more humid environments, such as near the coast, might show reduced disease severity and survive for many years. Infected palms in hotter, drier interior climates might show severe symptoms and die rapidly.

Because Fusarium wilt stresses palms, the opportunistic and mostly secondary disease pink rot frequently is present and can obscure or mask symptoms and hasten death. In fact, pink rot might kill a palm before Fusarium wilt runs its course.

In the landscape Fusarium wilt spreads frequently on pruning tools, especially chain saws. The pathogen enters cut petioles and, in extreme cases, the cut and exposed vascular tissue of severely pruned or skinned trunks. The pathogen can spread indirectly during pruning, because contaminated sawdust can drift as far as 100 feet.

The pathogen also can spread by entering the palm through its roots. Canary Island date palms tend to form a dense, extensive network of above-ground roots called pneumatophores, especially under excessively damp or wet conditions, which may facilitate pathogen entry.

Fusarium wilt can spread if people dispose of diseased palms or their seeds using a municipal yard-waste program that recycles debris into mulch. The pathogen can survive in the soil for at least 25 years.

Management

Because no cure exists for Fusarium wilt and it is nearly 100 percent fatal, prevention and exclusion are critical to disease management. Obtain palms from a reliable source and avoid poorly drained soils and excessive irrigation that can increase the formation of above-ground roots. Keep the area around the base of the trunk free of plants, because they can damage above-ground roots, and avoid using municipal-yard waste as mulch on Canary Island date palms.

Also avoid or minimize pruning if possible. Frequently pruned palms are more likely to suffer from Fusarium wilt than those in an unmaintained setting. If you must prune, thoroughly clean all tools by vigorously brushing them to remove sawdust and other particles. Disinfect the equipment for 10 minutes in a 1:3 pine oil to water solution, or heat saw blades for at least 10 seconds per side with a handheld butane torch. Use manual pruning saws rather than chain saws whenever possible, because the latter are difficult if not impossible to clean and disinfect adequately. If you have extremely valuable palms, consider using a new saw for each tree, which you either could discard after one use or dedicate for future use on that one palm only. Avoid pruning palms in windy weather to minimize the spread of infected sawdust.

Because a Canary Island date palm with Fusarium wilt eventually will die, it is prudent to remove it as soon as feasible. To avoid spreading the pathogen, excavate the root ball and use a crane to remove the palm with its crown of leaves, trunk, and root ball still attached. Use plastic or wooden barriers to contain any cutting, grinding, digging, or other operations that can spread diseased plant parts. After bagging all debris, prepare removed palms for incineration or removal to a landfill; do not use a waste recycling program.

It is unwise to replant another Canary Island date palm at the same location where a diseased palm once grew, because remnants of infected roots can remain in the soil and transfer the pathogen to the newly planted palm. Removing the soil might not prevent the spread of disease either, because just one small piece of infected root is all that is necessary to infect a newly planted palm. Avoid replanting with any palm species, because host range susceptibility to this disease has not been fully established.

If you must plant a replacement palm, some species to consider include Mexican blue palm, San Jose hesper palm, Guadalupe palm, pindo palm (Butia capitata), queen palm (Syagrus romanzoffiana), and Mexican fan palm. If you want the Phoenix or date palm “look,” consider staminate (male) plants of the date palm (Phoenix dactylifera), because they are more robust than the pistillate (female) fruit-bearing plants and more closely imitate the larger, robust habit of Canary Island date palms.

What Is an Amended Soil?

Q. You recommended that to grow a persimmon tree in our area, the soil needs to be amended. What is amended soil? Do you a technique you recommend to amend the Las Vegas soil?

A. Soil is amended by mixing it with something that improves the existing soil in some way. There are a number of amendments available but I prefer compost for most garden soils and fruit trees.

            Compost improves the desert soil chemistry, soil structure and its biological activity. Compost opens the soil improving drainage and aeration as well. Our desert soils have very tiny pore spaces between soil minerals. Larger pore spaces are important for roots to stay healthy. Roots need about an equal mixture of water and air between soil particles.

Desert soils have very small amounts of organic amendments in them making them very poor at growing vegetables

            Compost improves soil chemistry by reducing the alkalinity of desert soils and helps chemicals required by the plant to become more available to them.

Compost added to a vegetable growing area. The compost will be mixed with the desert soil and raised beds will be shaped from this amended soil

            I recommend that existing desert soil be removed from a future planting hole and this soil mixed about half and half with compost. Once the large rocks are removed, this amended soil is used to fill the spaces around plant roots when planting.

            Organic soil amendments like compost disappear in the soil over time so they must be replenished. Replenish soil amendments by adding a 1 inch layer of compost to the top of the soil every year. Compost slowly “dissolves” back into the soil, keeping the soil amended.

Woody Warts on Oleander Is Gall

Q. I live 8 miles northeast of Mesquite NV in Littlefield Arizona. I'm sending two pictures of some scaly growth like woody galls on the tips of my Oleander branches. There is also galling taking place on the branches and leaves. My oleanders are the only ones infected. How do I correct this problem? Will it kill the plants? Every plant is infected, about 300.

Oleander gall from the reader

A. This is called oleander gall in Arizona, oleander knot in California and Texas calls it bacterial gall. I wouldn't use any chemicals. Prune it out and sterilize pruners after cutting because it will spread on pruning instruments. If you use bleach as a disinfectant make sure you oil any steel that it comes in contact with.

This particular disease is spread from plant to plant on pruning tools. It can also be spread during wet, windy weather just after pruning. Avoid irrigating oleander with overhead sprinklers. Drip irrigation or bubblers would be a better choice.

            Even though it’s a bacterial disease, you can use chemicals such as copper fungicides to help reduce the infection but they are not necessary. Most of this can be handled with proper pruning.

            Make sure all pruning equipment is sanitized. In this particular case, you should sanitize pruning tools between cuts and between plants to keep from spreading this disease on pruning tools.

            I would use a 10% bleach solution applied to pruning blades or pruning saw with a spray bottle. Make sure you oil all pruning tools and blades when finished or the bleach will rust them.

            Plants that have a few of these galls present can be pruned and the galls removed. Prune 6 to 10 inches below the galls and sanitize your pruning equipment before each new cut.

            If a plant is severely infested with oleander gall, I would cut it to the ground this winter and let it regrow from the base.

            Fertilize the plants with a high nitrogen and high phosphorus fertilizer in January and give them a large volume of water each time you irrigate.

http://cals.arizona.edu/maricopa/garden/html/t-tips/diseases/olndr-gl.htm

Oleander Galls in the Low Desert

PLANTS MOST SUSCEPTIBLE: Oleander

SYMPTOMS:

Rough, fissured growths on twigs, branches, leaves, flowers, and seedpods, often appearing in chains. Galls start out as small bumps and grow into wart-like growths generally between 1/2 to 1 inch in diameter. Large galls may actually be several small galls that have grown together.

CAUSES:

These galls are the result of growth of the bacteria Pseudomonas syringae inside the plant. The bacteria can enter the plant through wounds caused by pruning, frost damage or other injury or through natural openings in the leaf, blossom and stem. Water can carry the bacteria from diseased plants to healthy ones in the splash from rain or sprinklers. The bacteria is also moved from infected plants to healthy ones by unsuspecting gardeners on their pruning tools.

MANAGEMENT:

Prevention: Inspect oleanders carefully prior to purchase, do not buy plants that have galls.

Management: Remove the galls by pruning several inches below. Treat each cut with 10% bleach solution. Dip pruning tools in a 10% bleach solution between EACH cut to reduce the possibility of spreading the bacteria. Bag and discard cuttings. Do not compost diseased plant material.

Prune during the dry seasons to avoid infection of wounds. Avoid sprinkler irrigation while pruning wounds are fresh.

Severe infection of large shrubs is difficult to control by selective pruning. Even if you cut down the entire shrub, the new succulent growth will still be extremely susceptible to infection. In certain situations, removal of the diseased plant and replanting may be the best method of control.

http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/DISEASES/bacterialgall.html

Oleander knot—Pseudomonas savastanoi pv. nerii

Pseudomonas savastanoi pv. nerii causes galls or knots on oleander stems, bark, and leaves. Twigs and branches can die back, but the overall plant health is usually not seriously threatened. Gall bacteria reproduce in fissured or galled bark and are spread by contaminated water, implements, or hands. Healthy tissue is infected through fresh wounds during wet weather. Susceptible wounds include frost cracks and any leaf scars on branches.

Solutions

Avoid overhead watering. Prune out and dispose of infected tissue during the dry season. To prevent spreading pathogens on infected tools, clean tools of debris after each use and thoroughly spray them with disinfectant or soak them in disinfectant for one or more minutes. Tools can be sterilized using a commercial disinfectant as directed on the product label. Homeowners on their private property can use household bleach or disinfectant cleaners diluted 1 part disinfectant to 10 parts water.

http://aggie-horticulture.tamu.edu/galveston/Gardening-Handbook/PDF-files/GH-038--bacterial-gall-on-oleander.pdf

Bacterial gall

Disease Pathogen Name: Pseudomonas syringae pv. savastanoi

Pathogen Type: Bacterium

Period of Primary Occurrence: after spring rains & cool weather

• The bacterium must have a wound site to enter the plant, and cold weather injury in early

spring after a rain is a common circumstance under which infection takes place

• Most common after a cool wet spring

Description / Symptoms

• The bacterium is systemic in the plant, and causes galls to form on flowers and stems

• Leaves also become galled

• Twigs and branches can die back, but overall plant health is usually not seriously

threatened

• Gall bacteria reproduce in fissured or galled bark and are spread by contaminated water,

implements, or hands

• Healthy tissue is infected through fresh wounds during wet weather

Best Management Practices (BMP)

NON-CHEMICAL CONTROL

• Bacterial gall normally will not kill the plant

• Infected plant parts can be pruned, but care should be taken not to disseminate the

bacterium on pruning tools

• Prune infected tissue well below the infection site, at least a foot if possible, and disinfect

pruners between cuts by dipping them in a 10% bleach solution (common household

bleach at 1:10 dilution) for a few seconds

• Be sure to rinse the bleach off tools when you are finished and apply an oil lubricant to

avoid corrosion of the metal

CHEMICAL CONTROL

• Severe infections can be controlled by applying Bordeaux mixture or a copper fungicide

beginning in the fall and periodically spraying through the spring as new growth

appears

• Bordeaux mixture (originated in France) as a 4-4-50 ratio. For a small amount of mixture,

the ingredients are:

- 3 1/3 tablespoons of copper sulfate and 3 tablespoons of hydrated lime, mixed in

one gallon of water

- The mixture will turn the tree blue; however, the color will eventually disappear.

Caution must be taken NOT to store a mixture of Bordeaux

- The ingredients must be kept separate and custom-mixed as a fresh spray

Fall Planting Guide and Constructing Raised Beds

Q. My husband and I appreciate your input in guiding us to our next planting season. I know it might be a little too late but I am open for ideas to continue our gardening on a raised bed. This summer we had a great time growing Kale, red and green chard and jalapeno peppers and basil.

 Any suggestions will be greatly appreciated.

A. I will give you my version of raised beds, the kind we built at the University Orchard for growing vegetable crops. I wrote some instructions for building these types of raised beds for Viragrow, Inc. as a consultant. I attached to these instructions so that you could follow them.

Raised bed made without sidewalls

The first part tells you what to plant in the fall and winter months and whether you can start them from seed (s) or transplants (T). The second part tells you how to construct raised beds without building sidewalls but just using the natural slope of the soil to retain their raised shape. 

Raised bed made from wood

Some people like to build sidewalls from wood, brick or cement block to surround these raised beds. This is entirely up to you. But once you have constructed raised beds you should not be walking in them unless you are preparing the soil. 

Raised beds should be wide enough so that you can access the entire bad by using either side. Walkways are 18 to 24 inches wide between them and this is where traffic should be kept. Walking on these beds transfers weed seeds, diseases and compacts the soil making the soil more difficult to grow vegetables. I hope this helps.

Depth of Rock or Wood Mulch Depends on the Size of Mulch

Q. I have been replacing gravel with wood mulch and I have to put the gravel someplace. What thickness of gravel can I place around the plants, none at the trunk, without causing damage?  Also, what is the maximum amount of wood mulch can be place around plants without being detrimental to the plant?

A. The depth of rock mulch depends on the size of the rock; the larger the rock used the deeper rock mulch can be applied. Roots need to “breathe” so there must be an exchange of gases between the roots and the air. This happens through the pore spaces in the soil.

Rock of a larger size can be used as mulch and applied more deeply than smaller rock

            Generally speaking, rock mulch is applied somewhere between 2 to 4 inches deep. If this rock mulch contains “minus” material (e.g., 1/2 inch minus, ¼ inch minus) then apply 2 to 3 inches. If the rock mulch does not contain minus material then apply it 4 inches or more.

            Course mulch without minus material can be applied right up to the trunk. Rock mulch with minus material should not.

            Most information out there tells us not to apply more than 3 to 4 inches of wood chip mulch around trees and shrubs. Where this recommended depth came from I don’t know but it is repeated over and over.

            I have no problems applying 6 inches of wood chip mulch or more around trees and shrubs provided this mulch is kept away from the trunk of the plant a distance of 12 inches during its first four or five years of growth. 

Reattach Broken Limbs Quickly

Q. My newly planted pluot tree produced one fruit this past season. I guess I pulled too hard and the branch where it was attached split. I taped the split back together with electrical tape. When can I remove it?

A. Limbs that have split will never grow back together unless you reattach the broken limbs within a few minutes after the split occurs. Once the crack or split dries, they will never “fuse” back together.

            Plants grow around wounds and surround new growth by burying this damage in older wood. If the split occurs in a strategic location that supports the weight of future limbs and fruit, it will probably never be strong enough to support increasing weight in future years.

Broken peach tree limbs due to the weight of a fruit load

            I don't know how rapidly you got the tape around the wound but if this happens again you must reattach the split tightly in a matter of a few minutes. I like to use the expandable green nursery tape that you can purchase from most nurseries are garden centers.

            I am guessing the split did not grow back together, is still there and the limb no longer structurally strong enough to support fruit or the weight of new branches growing from it. Remove the broken branch with the pruning shears and reshape the tree for future growth.