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Friday, October 9, 2015

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 jalapeƱo 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

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.