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Wednesday, February 10, 2016

Don't Confuse Leaf Drop with Ash Decline

Q. I have an ash tree which appears to be dying. I am considering taking it out but would like to have someone look at it before I do.

A. The usual problem here with ash trees has been a disease called ash decline or ash dieback. I have posted questions I received regarding this problem on ash trees along with pictures of what it looks like and what to do if you have it.
Ash decline
            Send some pictures to me of the tree showing the problem when you see the problem. I need close-ups of the leaves as well as a picture of the entire tree. Look at the pictures I have posted here or on my blog to confirm it. This disease is quite easy to identify from pictures.

            If you are certain the tree has this disease it should be removed. There is no cure for it.

This email was confirmed as ash decline and the tree removed.

Greenhouse Space Heaters Need Air Mixing

Q. I have a small greenhouse I would like to heat at night to prevent the freezing of some seedlings. I am guessing I will only need heat for the month of February. I was thinking of a small space heater.

A. It is much easier and more effective to provide bottom heat to warm seedlings than a space heater that only warms the air. Provide bottom heat by using waterproof heating mats beneath the seedling containers or trays. They are available locally from nurseries and garden centers.
            Many vegetables that grow during the summer months require warm soils for good germination. Seeds like tomatoes and peppers will fail or germinate very slowly if the soil is not warm.
Years ago we would place seedling trays on top of the television or refrigerator where it is warm enough to complete or speed germination. As soon as they germinated, they would be placed in some light or directly under very bright lights.
Drape plastic or a light blanket over the seedlings and heating mat at night and remove it during the day. Seedlings require 6 to 8 hours of full sunlight, or the same intensity from electrical lights, as soon as they germinate. Sunlight intensities or durations shorter than this will produce spindly transplants that will grow and transplant poorly.
You don’t need expensive grow lights for growing transplants. Fluorescent lights or LEDs are fine but they must be placed within an inch of the leaves to produce enough intensity to support good plant growth.

Be very careful when using incandescent bulbs, or lightbulbs, for growing seedlings. They produce a lot of heat and damage plants at distances close enough to produce enough light intensity. I leave electrical lights on about 16 hours each day when growing transplants.

Plum Sap Not Always Disease or Insects

Q. My plum tree has sap coming from it in bubbles. Does it have some sort of disease?

A. Sap coming from a tree is a response by the tree to some sort of damage. Damage that causes sap to ooze in bubbles from the trunk or limbs can be caused by the environment, disease or insects.
Plums are normally very sappy. When plums are pruned during the growing season they respond to fresh wounds by releasing a large amount of sap. Trees that produce sap in response to damage or an attack is their method of protecting themselves.
Sap losing from cut limb on plum
When insects that burrow into the tree and attack it, such as borers, the release of sap can engulf these burrowing insects and suffocate them. If the burrowing insect is still active, chewing and feeding away when sap is released, these bubbles of sap will be dark in color but cloudy. The sap is cloudy because it is full of sawdust or wood chips from the feeding by these chewing insects.
If the tree successfully engulfs and kills this destructive critter, the sap continues to be dark but free of sawdust or wood chips and therefore clear. Sap also helps flush disease organisms from wounds.
The presence of sap from plums and apricots does not always mean there are disease or insect problems. Sometimes environmental damage to the tree can cause sappiness. Environmental damage can occur from intense sunlight, heat and water stress.
Take a sharp knife and remove the bubbles of sap all the way to the surface layer of the tree. Remove the surface layer of the tree so that you can see what’s going on just under the bark. Look at the exposed area under the bark and inspect it for insect damage. You may find the insect itself.
Regardless, it is a good idea to remove the sap bubble and inspect the exposed limb or trunk just under the bubble. If an insect or its damage is present, clean out the damaged area so that everything looks healthy and the tree can heal on its own.

There is no reason to apply anything to this wound afterwards if the knife was sanitized first. Use alcohol to sanitize the knife, heat from a lighter or household sanitizer such as Pine-Sol. Be careful with bleach, (even though it is a good sanitizer) because it rusts tools and destroys clothing.

No Fear of Disease after Spraying Liquid Fertilizers

Q. Can foliar spraying micronutrients like iron on fruit trees cause bacterial leaf spot to form or spread? I have had problems with bacterial leaf spot on my nectarine trees but last year the leaves weren't affected as much. I don't want the pathogen to spread again.

A. Where do you live? Who made this diagnosis? I have not heard of bacterial leaf spot forming in the dry desert. In more humid climates it can be more common. The leaf spots on leaves should be surrounded by a yellow halo if it is bacterial leaf spot.
Some iron sprays can cause staining on developing fruit and can resemble disease. This is iron staining quince fruit. Use iron chelate sprays if fruit is present.
Bacterial infections usually require wet or humid environments and warm to hot temperatures or insects to spread the disease. And these wet/humid environments must be present over a long enough period of time usually many consecutive hours.
It would be possible if the plants are crowded together so that the leaves cannot dry or there is an air movement to help dry them. Overhead irrigation such as sprinklers could also contribute to a problem.
However, applying foliar micronutrients early in the morning so the leaves have a chance of drying before nightfall there should not be a problem. And spray early in the season.
Some diseases like shot hole fungus are prevented with properly timed fungicide applications containing copper. Copper fungicides can also be used to help prevent some bacterial infections like bacterial Leaf spot.
The pathogen or bacteria are already present on stems and move to the foliage early in the spring. The leaves just need the right environment (temperature and humidity or degree of wetness) to cause infection.
It also helps if the canopy is not dense so there is air movement to help dry the leaves. In your pruning you should create enough space between branches to allow for some sunlight to penetrate inside the canopy and reduce shading.

You probably have been told that there are not many pest control products for bacterial diseases but a fairly common fungicide like Bordeaux can give you some good protection if applied when temperatures get warm. Some of the disease potential can be removed through pruning in the winter.

Prune Lantana and Star Jasmine at Different Times

Q. When can we cut back star jasmine and plant lantana?

A. Because Lantana could still freeze back with some low temperatures it is best to wait until the end of February to plant them. Now is a great time for planting anything not damaged from freezing temperatures.
Flowers produced by one of the Lantanas
Dig a hole three times wider than the container. Use soil taken from the hole and amend it 50/50 with compost plus a handful of granular fertilizer high in phosphorus. As an alternative, mix a water-soluble fertilizer high in phosphorus in a bucket with water and use this solution when watering the first time.
Unopened flowers on star jasmine
            The general rule of thumb for when to prune plants appreciated for their flowers is to prune soon after the flowering period has finished. This is because the flower buds for the next cycle of blooms are formed soon after flowering is over. Pruning now could eliminate the spring flowers.
New spring growth from Lantana after it is been cut back to a couple of inches above the soil or rock mulch level
            After pruning, always fertilize plants. Flowering plants should receive a high phosphorus fertilizer at least once during the year.

Drop Olive Fruit with Chemicals but Don't Eat Them

Q. Last year our Olive tree had lots of fruit on it and was very messy. Can you tell me when we should spray the tree to keep it from fruiting next time?

A. Olive flowering peak is around mid-April. The usual homeowner chemicals are Olive Stop and Florel Fruit Eliminator. They work a bit differently.
European Olive flowers
Florel can be applied once before the flowers open, but Olive Stop must be applied two or three times. These times are when flowers are first opening, again when most are open and a third time when the late ones are opening.
The spray schedule for Olive Stop can last up to two weeks depending on air temperatures. Cooler weather causes flowers to open more slowly than hotter weather. This causes our spray season for fruit control to be longer.
European olive flowers growing in the axils of the leaves
For flower and pollen control, Florel is probably a better choice, but it is a bit more toxic to the trees than Olive Stop. For just fruit control, Olive Stop is fine. Any plants beneath the trees should be sprayed with water immediately after these chemicals are applied to remove what falls on the leaves and minimize any damage from the spray.
With Olive Stop, the chemical has to reach the flowers as much as possible. This is not necessary with Florel. Watch for sales on these products as we get closer to April.
Commercial applicators have a little bit more selection because they can use products that you can’t. They have products called Embark and Maintain, which are different from homeowner products.
Remember that these chemicals do not prevent flowering but only the production of fruit. To prevent flowering (pollen) use chemicals such as Maintain, a chemical normally applied by professionals.
Remember that olives coming from trees that have been sprayed should not be used for human consumption.

Prevent Grub Attacks Now Safely

Q. I seem to have grubs in one area of the planting areas around the house.  
What do you recommend to eradicate grubs?  I have roses and a few ornamentals in these beds.

A. Try beneficial nematodes for grub control. Once they have been added to the soil they live their a long time if they have "food" (grubs) to feed on. Safe for plants and animals.

I would like to connect you to a few of my posts on my blog.

You can find these sometimes in your local garden supply store or nursery. Or you can order them online. Try this place on the internet and read up about what they can and can't do and order the right amount and the right kind.


Use Traps on Fruit Trees Not Insecticides

Q. I was reading your blog about peach tree bore and I am planning to buy some pheromone traps. Which traps and lowers should I buy?

A. In southern Nevada we do not have peach tree borer. We have borers that get into peach trees but these are not peach tree borers. They are thought to be the flat headed Apple Tree Borer and/or the Pacific flatheaded borer. To my knowledge neither have lures and no way of trapping them using pheromones.

Pheromone traps can be very effective at removing some pests that attack fruit trees or fruit but there are not pheromone traps for every pest. Pheromone traps are highly selective and very effective at luring a very specific pest to the trap where it is stuck to a very sticky surface. You must be 100% certain of the pest you are trying to lure or it will not work.
This is the sticky bottom of a winged trap. The reddish-brown upright capsule in the center is made of soft rubber impregnated with the sex attractant called a pheromone.
            In this case you mentioned peach tree borer. This is not the insect we are trying to attract. We do not have this pest in Southern Nevada so if you buy a trap for peach tree bore you are wasting your money.It is a problem in more northern climates such as Central Utah, Colorado and California.

            The pest we are interested in is the peach TWIG borer, not the peach tree borer. The peach twig borer attacks new growth in the spring, killing it, then later generations attack the soft fruit causing “wormy peaches”. Occasionally we find this “worm” in apricots, nectarines and almonds.
This is the kind of damage we see very early in the season by the peach twig borer in new growth of peach and nectarine. This insect builds its populations through the growing season until finally it will attack ripe fruit. It may also attack apricots and almonds.
Pheromones are chemicals released into the air by one sex of an insect to attract the other sex so that mating is a sure thing. Pheromone traps use a capsule laced in pheromones that mimic this sex attractant. This capsule is placed inside a very sticky trap. The insect of opposite sex flies to this trap expecting to find a mate but gets stuck instead.
This is peach twig borer "worm" or larva in mature peach just harvested from the tree. This is the insect that is responsible for "wormy peaches". The adult is a small moth.
Pheromone traps were designed primarily to inform farmers when these bad insects were flying so that an appropriate pesticide could be applied exactly at the right time. Otherwise farmers are left to guess when to make these applications.

Coddling moth damage to apples or "wormy apples".

Under some circumstances pheromone traps can be placed in fruit trees to trick the opposite sex and catch them before they mate. If the pheromone trap is very effective at catching these insects then no insecticide needs to be applied. This type of insect control is sometimes called “mating disruption” or “trapping out” the problem insect.
Here is a winged trap for peach twig more hanging in a peach tree with the pheromone capsule located on the sticky bottom.
Pheromones are made for many different types of insects that are problems for farmers but the two insects I usually place pheromone traps out for in southern Nevada include the peach twig borer and coddling moth for apples, pears and quince. These will vary depending on where you live.
I prefer winged traps over the so-called Delta traps. I seem to get a better catch with the trap that is open on all sides.
This is the Delta pheromone trap. I think it works fine for detecting when the insect is present but I do not like it as much as the winged trap for mating disruption. I think the winged trap works better for mating disruption because it is open on all sides.
Even though it said it's not supposed to work, I have been very lucky trapping out both of these insects with lures and traps rather than applying insecticide sprays. I put my traps inside the Orchard perimeter so they get some protection from wind. I flood the area with the pheromone scent from these lures and it appears that they are confused enough that few find their mates.
Coddling moth damage on pear in Afghanistan. Damage is the same but the timing is different.

I start put out a single trap of each in about April in Las Vegas because I don't want to miss the first flight. However, I usually don't start catching them until about May. Their appearance coincides with heating degree days over a certain baseline temperature. These heating degree days can vary depending upon the weather so emergence can be earlier or later in some years. It also varies with the climate in your area.
Peach twig borer in the outer husk of almond. It usually does not get in the nut or kernel but can.
As soon as I start catching moths in the traps I immediately deploy the rest of them flood the area with this pheromone. I change out the sticky bottom once every two weeks or so and the lures are changed out monthly. I don't listen to closely to recommendations because they are for monitoring and not for mating disruption. Because I don't have hundreds of trees I choose to spend a little bit more money on lures and traps rather than pesticides and applying sprays.

I use one trap for about 20 to 25 trees. I replace the bottoms every couple weeks when trapping because of dirt and moths getting stuck in the traps and making them less sticky.

Buy enough sticky bottoms and lures to last from April until you harvest. Keep the lures in sealed plastic bags in the refrigerator until you are ready to use them. Technically you are not supposed to put them in the same refrigerator as food. Sticky bottoms and traps last from year to year but lures should be purchased fresh every year.

If you want a class on how to do this let me know and I will put one together.

Lemon trees in Containers Need Repotting

Q. I have two lemon trees, both about three feet high, in containers. My Myers lemon is about 10 years old but leaves get fewer and fewer producing only three lemons last year. When is a good time to repot it? 

A. Citrus does better in the ground than in containers. Extra management and care is needed when grown in containers. Containers allow more flexibility in freeze protection but trees growing in them are difficult to irrigate properly.
Newly planted 5 gallon citrus in 24 inch box. Box containers are good for a couple of years before they begin to fall apart and no longer hold water.
The usual reason for poor fruit production in citrus, particularly Myers lemon, is freezing temperatures around bloom time or shortly after. They like to bloom in January and February when freezing temperatures still occur. It only takes a light freeze to kill flower blossoms that are unopened, opened or small fruit that has just formed.
Be careful of soil mixes added to containers. Some soil mixes are not very good. Pick a soil mix that has a good reputation, not the cheapest one on sale.
A good time to re-pot them is now. Lay the container on its side and gently pull the plant and its root ball out of the container. Wash the inside of the container thoroughly.
With a spray nozzle, wash some of the soil mix from the root ball. Remove about one quarter of the roots with a sharp and sanitized pruning shears.
Look at the roots and see if they are healthy. The newest and smallest roots should be a creamy white color.
Slide the plant back into the container and push both upright. Locate the plant and root ball in the center of the container and add fresh container mix. Adding water with a hose will wash the soil mix into voids and remove air pockets. Gently lift the plant so that soil can wash under it and elevate the plant to the same depth it was previously.
Fertilize the plant with a fertilizer suitable for citrus. A rose fertilizer or fruit tree fertilizer will work if you can't find a citrus fertilizer.

Friday, February 5, 2016

Gardening Calendar for February

Gardening Calendar for February: Gardening calendar for January and February click here Gardening calendar for March will be posted here in late February Viragrow...

Viragrow Delivers!

Thursday, February 4, 2016

Desert Horticulture Meetup Moving to Yahoo Discussion Group

I will be moving the Desert Horticulture meetup I began to the Yahoo Discussion Group on Desert Horticulture instead. There was a charge for starting the meetup group which I didnt mind paying for six months. But when this meetup group grew to more than 50 tthen meetup wanted additional payments. 

The Yahoo Discussion group called Desert Horticulture has been in existence for quite awhile but somewhat dormant. Hopefully this will get it moving. Everyone who joins can post on it and discussion can be free flowing.

We will be working on an organizational structure for a Desert Horticulture group and new information on this group will be posted at this link.

https://groups.yahoo.com/neo/gro...­ and just ask to join. You must be approved to join which is a simple process of just asking. It helps to minimize people selling things.

Bob Morris

Fig Fruit Falling from the Trees

Q. I am in Kingman, Arizona, a transplant from Los Angeles. I brought cuttings with me from my fig trees there. Here these figs grow to the size of a 50 cent piece or larger, and then they ALL fall off. Or they mature to the size of a quarter and the birds get those. I get an over-abundance of figs but I never enjoy any of them because of they fall off. I open the figs up and discover that they are totally dried and brown in the inside although they are a beautiful green or black or brown depending on the species.

A. The type of fig should not make any difference. I have grown many varieties of figs here and have never had a problem with anyone of them. This is actually a good climate for figs. Kingman is a little bit on the cold side for figs and you may have some freezing weather at times that may cause some die back. This past winter was fairly mild and that should not have happened.
The major reason for having figs that never mature, dry up on the branches and fall off, is not enough water when the fruits are developing. Figs should really be considered an oasis plant like palms. They will be best irrigated if a basin surrounding the trunk is filled with water each time.
They will also benefit from a layer of wood mulch at least 3 to 4 inches deep covering their roots out to a distance equal to the spread of the tree. Drip irrigation will work but there has to be enough emitters around the tree and they must be left on long enough to thoroughly wet the roots to a depth of 2 to 3 feet.
Another possible reason is the dried fruit beetle which can attack the fruit. These insects come from old fruit that's left on the tree or that has fallen on the ground. It can come from any fruit remaining so sanitation of your Orchard area is extremely important.
If you are composting with fruit it is important to make sure the compost totally covers the fruit or is buried in the compost. Otherwise put any fallen fruit or fruit remaining on the tree in a container with a lid to prevent this insect from infesting your fruit.
Generally speaking however I think it is most likely because the tree is not getting enough water when the fruit is being produced. You can look at my blog and see if this fits your problem.

Presentations to Arizona Master Gardeners on Landscape Design and Irrigation

I recently presented a short overview of Desert Landscape Design to Save Water and Energy and a very short presentation on Irrigation and Plant Water Use to the Arizona Master Gardeners in Mohave County. The emphasis was on the basics of landscape design that were covered in my 10 week class in Las Vegas.

My presentation in Arizona for the Master Gardeners can be safely viewed and downloaded at the sites below.

Landscape Water Management



Transitioning your landscape


Sunday, January 31, 2016

Vegetable and Herb Presentation to Arizona Master Gardeners

I recently presented a short overview of vegetable and herb production under desert horticultural conditions. The emphasis was on overcoming some of the problems when growing vegetable and herbs under desert conditions. Specifically I addressed the topics of high light intensities, wind, low organic content in our soils, salts and salinity problems, irrigation, varietal selection and planting calendar.

My presentation in Arizona for the Master Gardeners can be safely viewed and downloaded at the site below

Monday, January 25, 2016

Add Compost to a Raised Bed Not More Soil Mix

Add Compost to a Raised Bed Not More Soil Mix: This is your scenario: Your raised bed is 1 to 2 years old.. Your raised beds were filled with a soil mix that contains compost. Maybe th...

Fertilize Fruit Trees With Compost for Best Result...

Fertilize Fruit Trees With Compost for Best Result...: Did you know that you can use straight compost to fertilize your fruit trees? Even though compost is not sold as a fertilizer it contains...

Viragrow Delivers! : What Rose Experts are Buying Now

What Rose Experts are Buying Now: Rose experts, or Rosarians, are now applying fertilizers and organic pest control products to their roses. Some are also renewing the soil ...

The Truth About Sulfur for Gardens

The Truth About Sulfur for Gardens: Sulfur is needed in horticulture for two reasons; first, it is a major plant nutrient required by plants and secondly sulfur helps lower th...

Viragrow Delivers!

Wednesday, January 20, 2016

Do You Love Magnolias?

2016 Magnolia “Seedling” Program

The Magnolia Society International is excited to announce a new scholarship program, the Magnolia “Seedling” Program. This seedling program is a new endeavor targeted to support a young magnoliaphile to attend an annual meeting by paying their expenses (travel, lodging, meals and registration). MSI wants to encourage someone who is just starting out in horticulture or research and has a specific interest (breeding, conservation, production, etc.) in magnolias. 

The 2016 annual meeting is April 8-11, 2016 in Philadelphia, Pennsylvania. More information about the meetings can be found at www.magnoliasociety.org. If you have a student that you feel qualifies for this travel scholarship please send a nomination including name of individual, statement on why you feel they deserve the travel scholarship and their specific interest with magnolias. There is a short deadline of January 30th, 2016. Please email nomination to:

Dr. Todd West

266E Loftsgard Hall
Dept 7670, PO Box 6050
Fargo, ND 58108-6050

Fax: 701.231.8474

Monday, January 18, 2016

All Rosemarys are Not Created Equal

Q. I use rosemary which I purchase from the store for cooking.  It is expensive and does stay fragrant very long if I don't use it all. I would like to plant rosemary in our yard so that I can use it in my cooking.  Is there a difference between rosemary used for "cooking" and rosemary used in landscaping?

A. There are several varieties of rosemary but most are selected for landscaping rather than cooking. Many of the landscape varieties have horizontal or prostrate growth. However, these landscape varieties can be used for cooking as well. But varieties selected for cooking are usually upright and often have a higher oil content. Upright growth is easier to harvest.

Rosemary comes in both upright forms and prostrate. Upright forms are easier to harvest.
Growing rosemary as an herb is different from growing rosemary as a landscape plant. Two traits are considered desirable in rosemary as an herb; upright succulent leaf and stem growth and a high oil content.

To grow rosemary for cooking, push new growth with nitrogen fertilizers and harvest before flowers are produced. Seldom is rosemary left to flower when used as an herb but the new growth is dried or used fresh. Flowers may be attached when sold at Farmers Markets.
Rosemary flowers contain the most and better oil. Commercial producers focus on leaf and stems for oil production because it is easier to produce even though the oil is not high quality.

The best oil comes from rosemary flowers. However, most commercial oil production is from leaves and stems which produces more abundant oil but it is inferior to the oil produced in the flowers. The same technique is used except high phosphorus fertilizer is applied to improve oil production and harvesting is done when flowers are present for higher-quality oil.

Some of the better varieties for cooking include Benenden Blue, Flora Rosa, Tuscan Blue, Majorca Pink, Arp, Albiflorus, Huntington Carpet, McConnell's Blue, Irene, Holly Hyde and Hill Hardy to name a few. 

Spittle on Rosemary a Common Problem

Q. My rosemary plant has white foamy droplets on the stems. I can spray them away when I water with a hose but they return. They do not seem to be harming the plant but what is it?

Spittlebugs are common on rosemary and live within the spittle for protection

A. The white foamy droplets are called spittlebugs and common on rosemary. They suck plant juices and are buried inside the spittle for protection. They can be knocked off the plant with a strong stream of water from a hose but they return quickly.
They are usually more of a nuisance than a problem unless you are growing rosemary as an herb. They can multiply and become a problem in the future so keep an eye on them.
Neem oil and horticultural oils will give some control of spittlebugs when sprayed directly on the plants. Spray a small section of the plant first to make sure the oils do not damage the rosemary.

Soap and water sprays wash the spittle off and leave these bugs unprotected. Follow this with an insecticide spray such as pyrethrum which protects the plant from becoming reinfected. This might need to be done several times, a few weeks apart, to get them back under control.

More Rosemary Dying

Q. My Tuscan rosemary is in trouble. It appears to be dying.

A. Tuscan is a nice upright rosemary variety with good color and density that is grown for cooking and its oil content. It has very few insect and disease problems. We will occasionally see aphids and spittle bugs but nothing to get overly excited about.
Tuscan is an upright rosemary variety good for herb production
            Rosemary prefers soils that have been improved with compost and organic surface mulches such as wood chips. The soils must drain well. They do not like rock mulch at all and frequently die a few years after being planted.
When these plants die it is usually due to soil problems. Roots have a tough time "breathing" because of poor drainage. Most of the time these soil problems cause the roots and stem of the plant to die. The plant collapses during the heat of summer because roots are dead.
Avoid planting rosemary in low spots or where water accumulates. These conditions suffocate roots. It is possible to replant in this spot but remove as much of the soil as possible and replace it with the soil that drains easily.

This particular root disease may linger in this infected soil and cause future problems. 

Rosemary Dying Usually Soil Problem

Q. Can you tell me what is killing our rosemary hedge, by inches?  The plant is 15 years old.  Other rosemarys of the same age on the property are still thriving.  Any help would be appreciated.  Picture attached. Thank you

A. There are a few insects such as spittle bugs that get on rosemary but there are not that many diseases that affected except some of the soil borne fungal diseases. In other words, these are disease organisms that are already present in the soil but they need opportunity in order to take advantage of rosemary. When soils remain wet, this stresses rosemary and makes it susceptible to these types of diseases. The usual advantage these diseases get is because soils are from plant stress because soils are kept too wet from frequent irrigations or the soils do not drain water fast enough before the next irrigation.
Rosemary dying is usually a soil or irrigation and drainage problem.

These diseases attack the roots of the plant and cause dieback of the top similar to what appears to be drought. It appears to be drought because the roots are dying and they can no longer take up water to the tops so, in fact, it is drought but drought caused by too much water present around the roots.

Like many Mediterranean plants, rosemary does not like wet soils in the summertime. They can tolerate wet soils as long as there is drainage and the soil has enough time to dry out between irrigations. These types of diseases frequently start at low spots in the irrigated area where water collects or puddles. Usually plants growing where the water has drained to low spots remain healthy.

Plants that have extensive root rot from soil disease organisms frequently will pull from the soil fairly easily or are loose in the soil when they are pulled from side to side.

The solution? The usual solutions are to water less often or improve the drainage in the soils or both. Rock mulches around rosemary will cause the soil to become more compacted and not drain water well. Organic wood chip mulches help to keep the soil "fluffy" and improve drainage. Organic wood chip mulches help to keep soils more moist so the frequency of irrigation typically has to be less. 

If this problem was caused from soil disease organisms it will be difficult to reap plant rosemary in that soil again. You might have to remove the soil from that spot and replace it with an amended soil before you replant another rosemary in that same location.

Rosemary Not Flowering

Q. I have an upright rosemary about four feet tall. It was sheared once on the top and the sides. It has never bloomed. Is there such a variety that never blooms or am I doing something wrong with this plant?

A. I have never heard of one not blooming. Most reasons plants do not bloom are planting them into low light levels (shade) or shearing them just prior to bloom. Normal bloom periods are spring and fall but in warm areas they might bloom all season long.
Rosemary is a prolific bloomer in the spring and fall if it receives enough light

Pruned during the summer months if you want the blooms. Pruning in the spring or fall cuts off the flowers. Make sure it receives plenty of sun and do not plant in the shade. Avoid high nitrogen fertilizers but use fertilizers recommended for other flowering plants such as roses.

Sunday, January 17, 2016

Prune Rosemary Now If It's a Bush

Q.  When is the best time to prune a rosemary bush? Our rosemary bush has grown too large.  I would like to reduce it to about one-half of its current size. Also any suggestions about how I should prune it would be greatly appreciated.

A. If you are pruning it once a year, now is a good time. If you are pruning it as a hedge or you have to keep it under some sort of size control, then prune it once a month. If you are pruning it to use it for herbs, cut it back now, let it regrow and harvest the new, succulent growth before it flowers.

You have a few alternatives. One method cut it to the ground and let it regrow from one or 2 inch long stems. Prune it now or just before new growth begins.

Another method requires more care.Trace the longest branch of the shrub inside the plant and remove it where it joins a main branch. Leave no stub. Select two or three other long ones to the inside and make the same kind of cuts. Do this every couple of years when it starts to get too large.

Your third alternative is to replace the plant with something that doesn't get so large. 

After pruning, fertilize it as you would normally to encourage new growth. One fertilizer application a year is all that is needed unless you are growing it as an herb that requires frequent harvesting. If you are harvesting frequently, fertilize lightly every 6 to 8 weeks with a balanced fertilizer containing nitrogen and phosphorus. Or apply your favorite compost to the base of the plant and you'll get more spectacular results.

Overgrown Privet Is a Goner

Q. I have a neglected privet that has overgrown its space. When and how far back should I prune it and keep its shape? My neighbor cut one back several years ago and it never came back at all.  Thanks.

A. I may have some bad news for you. I looked at the picture and I am guessing most of the leafy growth is out towards the edges of the plant and on the inside will be bare branches. 

If your pruning cuts are made back to the inside of this plant where there is no leafy growth, re-growth from these cuts will be either slow or they won't regrow. Regardless, this plant is going to look bad for a long time after these pruning cuts are made. 

This is really a case where you have a plant that was just too largeat maturity placed in a spot that was just too small. 

Really your best alternative will be to replace it if you want to look nice. It is possible to make some deep cuts and it may regrow but these cuts will have to be done just to the outside of some buds and done very carefully

Dog Urine and Lawn Problem? Follow me and find out.

I had a question submitted to me regarding dog urine on a lawn and how to stop the damage. It can be found here.... (mouse right click on the link below to read it)


I recommended following the dog with a bucket of water.

I received an email about a product called Dog Rocks.... You can follow the emails in the comments at the bottom of this post.

http://dogrocks.org/ (mouse right click on this link to learn about it)

I was contacted by the CEO Dog Rocks USA LLC & Dog Rocks UK Distribution Ltd and she agree to supply it if we would try it. I contacted the person with the question to me and he agreed to try it provided it was supplied by the manufacturer. I agreed to post the results...positive or negative...after trying it. The CEO is following up on this trial and I will be in the loop.

Follow me and find out the results later in the summer of 2016.

Saturday, January 16, 2016

ARS Rose Pruning Demo Saturday January 23

The South Valley Rose Society is holding its annual rose pruning demonstration on Saturday January 23, 2016 at St Rose Hospital-Siena Campus. It is located at the corner of St Rose Parkway and Eastern Avenue. 

It will be held from 10:00AM to 2:00PM. 

Consulting Rosarians of the American Rose Society will be demonstrating the proper way to prune a rose and will answer any other rose related question you may have. Coffee and refreshments will be provided.

Tuesday, January 12, 2016

Many Ornamental Grasses Can Be Pruned Now

Q. When is the right time of year to trim grasses?
Some ornamental grasses are quite attractive during the winter and may be cut back just before new growth in the early spring
A. Most ornamental grasses are cut to within a couple of inches of the soil surface just before new growth in February. With some grasses this is done every year and other grasses it may be every 3 to 4 years.
Many ornamental grasses can be pruned close to the ground since new growth comes from culms at the base. Smaller grasses can be cut closer to the ground. Larger grasses should be cut higher from the ground. Dead growth in the center may indicate the plant needs to be divided.
            Remove any dead growth remaining with a rake. Fertilize the plant with a high nitrogen fertilizer, or a bag of compost, and a deep watering.
They should regrow from the pruned, remaining culms at the base.

Ornamental grasses need to be divided, or split apart, when the clump gets too large. It’s too large if the center begins to die out or flowering severely reduced. The plant is dug from the ground, the clump cut apart, cleaned up one of the smaller divisions replanted.

Containers for Fruit Trees Need to Be Appropriately Sized

Q. I have two dwarf trees, a nectarine and a peach. I would like to move them from in-ground into containers. What would you recommend the minimum size container to use?  The nectarine is about 4' tall and 5' wide. The peach is about 3' tall and 3' wide.
Fruit tree to be moved from the ground into a container

A. Use a container about the size of a half wine barrel for these trees. Do it any time until new growth starts, approximately the first week of February in our climate.
Use a sharp shovel. People don't normally sharpen shovels but it's a good practice to get into. You can sharpen it with a file or a bench grinder.
Cut through the roots in one push rather than whacking on them with a dull shovel. Cut entirely around the outside of the tree about 6 to 10 inches smaller than the inside diameter of the container.
After making the cuts in the soil all around the outside, use a pick or mattock to cut a narrow trench just to the outside of these cuts to a depth of about 12 to 15 inches. Use your shovel for leverage and gently lift the root ball from several different directions to loosen it.
24 inch nursery box used as a container for dwarf fruit tree. A box like this may last several years before it needs to be replaced and the tree repotted
Once the root ball begins to move, use your loppers to cut any roots that might be holding the plant in the soil. At this point, you should be able to lift the tree out of the hole with most of the soil remaining around the roots.
Fill the bottom of the container with soil amended 50/50 with compost so that the root ball rests 3 to 4 inches below the "lip" of the container. Place more amended soil around the root ball inside the container and water it in.
Prune the top of the plant by removing about 1/4 to 1/3 of the canopy to compensate for the loss of roots. The compost should give you enough fertilizer for the first growing season.

Oleander Does Not Need Iron Fertilizer after Pruning

Q. You mentioned pruning oleanders about a month ago. Should they be pruned in January or February? Do they need iron? My dwarf oleander does not bloom as good as my white oleander. What can I do to help them bloom better?

A. It is best to prune oleanders during the winter months because they produce flowers on new growth. Avoid pruning them in the spring after new growth has started or you will cut off all the potential flowers.
Oleander can be pruned close to the ground using a technique called rejuvenation pruning. This does not work well on all shrubs, just those that sucker easily from the base.
I’ve told people to cut oleanders to the ground, a method called rejuvenation pruning, and they will come back very nicely with some applied fertilizer and water. You can’t do this to all shrubs but oleanders respond nicely. Shrubs that tend to sucker from the base respond well to this type of pruning.
Dwarf red oleander doing well in rock mulch in Las Vegas
How late in the winter to prune, December, January or February, depends on how long you want to look at short stubs sticking out of the ground. If looking at stubs is objectionable, then delay this type of pruning as late as possible but before new growth begins. On oleander this is usually early February.
Oleander seldom needs iron so you should never have to apply iron fertilizer to this plant.
Some varieties of oleander don’t grow as well as others here. Some oleanders are more sensitive to freezing temperatures than others. Some oleanders don’t tolerate desert soils as well as others.

Soil improvement might be needed by this oleander. Prune the red oleander to the ground in early February. Then, apply two, 5 gallon buckets of compost around the base of the plant followed by a three or 4-inch layer of wood chips on top of the compost. Finally soak the soil around the plant with water. Do all of this in February.

A great website to visit to learn more about oleanders is the International Oleander Society

Ruellia A Good Choice for Desert Landscapes

Follow Your Dog with a Bucket of Water

Q. I have two large dogs that use my backyard as their bathroom. They cause yellow spots that turn completely bare and kill the grass. Are there any grasses resistant to animal urine?
Dog urine damage to a lawn is usually surrounded with grass which is darker green and taller because of the diluted urea fertilizer contained in urine

A. There are no lawn grasses totally resistant to dog urine. The high concentration of "salts" in the urine is causing the damage.
These salts are actually "fertilizer" salts, not bad salts such as table salt. There is just too much of it. The salts are so concentrated that the grass is burned or killed in a 6 to 8-inch spot.
If you look closely at "dog damage" to a lawn, it looks very different from brown spots caused by diseases or insects. Insect and disease damage does not cause the grass to become dark green or grow faster around the edge of the damage. Dog urine does!
Salts from the urine become diluted in the soil further from the “point of impact”. Once diluted enough, salts from the urine act as a fertilizer and turn the grass dark green and push new growth.
The key to decreasing urine damage is the same as too much applied fertilizer. Dilution. Drenching the spot with water and diluting the salts is the simplest way to decrease damage to the lawn.
I know this might be a hassle and look a little odd to your neighbors but if you follow the dog around with a bucket of water and dump it on the urine spot immediately after it is done, you have a good chance of reducing or preventing damage.

Now, if you could just train your dogs to do it evenly over the lawn and turn on the sprinklers.

Wormy Apples Pest Problems Vary with Regions

Q. I have a Fuji semi-dwarf apple tree that is about 23 yrs old in Kingman, AZ. The last few years I’ve had a terrible problem with worms in the apples. I clean up all the leaves after they fall and remove any apples that don’t fall. I  I spray dormant oil right before the flowers buds emerge or sooner and spray all around the area including on the grape vines nearby. I have wood chip mulch about an 8 foot diameter around the trunk. I’ve even sprayed Neem oil once when the apples are about the size of marbles but to no avail. Now I’m wondering whether I should remove the wood chip mulch as this seems to be the only thing left to try other than continual spraying or trying stronger chemical type sprays which I’d rather not do. What do you recommend?

A. Most likely this is codling moth and they attack the fruit several times during the year. Codling moth is an international pest of apples and pears. Their emergence coincides with rising temperatures and if you do not get control of the first flight they can multiply rapidly and each new generation can bet worse. 
Codling moth on immature pear fruit in Afghanistan
Codling moth damage on apple in North Las Vegas, NV
I am getting ready to begin writing up how to use pheromone traps for eliminating codling moth, rather than pesticides, in backyard and small scale operations if codling moth is not a huge problem in the area. I may also offer some classes on how to use them. I have been trapping insect pests like these with sticky cards and traps for years. They can be a very powerful tool for insect management.

If codling moth is a huge problem in your area, this might not work for you but it is worth a try. Stay posted and follow me on my blog for more information.

Tree Died. Planting in the Same Hole.

Q. I have a major borer problem with my nectarine tree. I will be removing it and replanting. Do I need to treat the soil before I plant another tree?

A. No. The borers that are problems in our climate (Pacific flatheaded borer or Flatheaded apple tree borer) do not enter the soil during any part of their life cycle. The borer you may be thinking of is the peach tree borer which we do not have in Southern Nevada but is common in more northern climates. 
Adult Pacific flat headed borer picture from Oregon State University

The peach tree borer does not actually enter the ground either but can be found low on the trunk near the soil level which makes you think it does. Both of these borers spend their entire life cycle either in the air as a beetle (our borers) or a moth (peach tree borer) in flight seeking a mate and looking for food to sustain itself until it can reproduce. The rest of the time is either as an egg laid on limbs or the trunk or larva tunneling and eating in sapwood where it can find carbohydrates for nourishment and growth. The final stage is pupal, also inside the tree, where it transforms from larva to adult beetle or moth.
One of the flat headed borers in a damaged branch of peach

Control by chemicals is not very effective for our borer since we don’t know when it flies or where it lands until we see damage. Having said that, there is one chemical that is very effective for controlling borers that are inside the tree and it is labeled for fruit trees. The chemical name is
One of the products recommended for borer control containing imidacloprid
imidacloprid. It comes as several different trade or label names. One of the common names for homeowners is a Bayer product found in many local stores and nurseries. It is a systemic insecticide that moves up inside the tree killing insects that are feeding on the interior. The claim is for 12 month protection using this product. Personally, I have a problem applying systemic insecticides that last 12 months on plants which produce fruit that I'm going to eat in less than 12 months. But it is labeled to do this.

Instead I recommend that we focus on prevention by protecting trees like peach and nectarine from sun damage to the limbs, We do this by keeping the canopy full enough to shade these limbs or painting limbs with whitewash to reduce sun damage by intense sunlight. Sun damage seems to attract the adults and their egg-laying. 

Midsummer die back of peach limbs due to progressive borer damage.
On older trees, damage from these insects might be over several years before visual signs of damage appear. At advanced stages of attack over several years, we see limbs dying in midsummer. Early signs of damage can be seen the day after a good rainfall when brown colored sap oozes from damaged areas.
Sap coming from peach limb due to borer activity

During early stages of damage we can remove the outer bark of damaged areas with a sharp knife exposing where they are living and feeding and revealing them to potential predators and exposing them to the elements. When this kind of practice is done on a regular basis we might see about 80% of the damaged trees recover until the next onslaught. Borers in peaches and nectarines are the usual reason these trees seldom survive past 20 years of age.