Pruning Oleander into a Multi-Trunked Tree

Q. I have two, 7 foot tall oleander bushes about 8 feet apart. Can I turn them into trees by cutting all the branches to the ground except for the largest, fattest branch in the middle? I know the suckers will be a problem for a while. Also, is it safe to grow a small vegetable or herb garden between them? Is oleander flower and leaf mulch safe around the edible garden?

                    

A. Yes, you have the right idea. Oleanders can make very nice small trees but the suckers at the base will be a problem for several years.

Oleander pruned to a multi-trunked tree and in bloom.

They can be made into a single trunk or a multi-trunked tree. Multi-trunk trees are easier to manage. Select 5 to 7 stems, or branches as you call them, coming from the base and going in different directions. Odd numbers of branches are more pleasing to the eye than an even number. Those are the stems you will keep. They should be large and vigorous.

Oleander suckering from the base when pruned as a multi-trunked tree.

Remove all other stems as close to the ground as possible. A reciprocating saw with a pruning blade is an easy way to remove them than a saw or loppers. Remove side branches from the stems up to a height that looks good to you. The trunks should be cleaned of side branches. Make sure you cut these side branches as close to the trunk as possible. Clean the trunks anywhere from 2 feet up to about 4 feet.

New stems will sucker from the base throughout the growing season for several years. This is because oleander wants to be a shrub. You are forcing it to be a tree so it will try to revert back to a shrub.

As soon as suckers emerge from the base, remove them by pulling rather than cutting. If you pull them when they are very new they are easy to remove. Removal by pulling causes fewer suckers in the future than cutting them.

Oleanders are poisonous but research from California demonstrated that leaves and stems can be composted and returned to the soil without problems for other plants including vegetables. 

http://slosson.ucdavis.edu/newsletters/Downer_199829067.pdf

Beneficial Nematodes and Diatomaceous Earth

Q. Will the diatomaceous earth I have used in my garden and around fruit trees kill beneficial nematodes?

A. Diatomaceous earth has the same effect on beneficial nematodes as any other nematode. I don’t know of any solid research that shows diatomaceous earth will reduce nematode populations. You might be wasting your money.

When nematodes are damaging plants, most recommendations are to mix compost into the soils to reduce nematodes populations and encourage more rapid growth. Some fruit trees such as stone fruits are grown on rootstocks, such as Nemaguard©, that are somewhat resistant to nematodes.

Some sources will tell you to grow varieties of vegetables resistant to nematodes, reduce nematode populations periodically using a technique called “soil solarization” or abandon the spot. I wish they were easy to control but they are not.

Figs Producing No Fruit

Q. My fig tree produced almost no fruit and no new growth last year.  The leaves looked burned on their perimeter. Any recommendations?

A. This sounds like a water issue; not enough water applied or not watering often enough or both. Water and nitrogen fertilizer is what pushes new growth. They work together.

Fig trees could be considered desert adapted plants (Mediterranean actually). Lack of enough water is a common problem when growing figs here. I see this a lot with figs grown using drip irrigation.

Figs grown in Las Vegas raady for the Farmers Market

The amount of water depends on the size of the plant. Generally, productive figs that have been pruned correctly will require about 30 gallons of water once a week at this time of year. This amount will be applied twice a week around May 1 or when temperatures approach 100F.

Cover the soil with wood chips to a depth of 3 to 4 inches (minimum) and extend it to a distance of at least 3 feet in all directions from the trunk. This will help reduce fruit drop.

If the tree is irrigated with drip irrigation, increase the number of emitters or increase the number of minutes, until you approach the volume of water I am recommending.

Kadota figs grown in Las Vegas

Flood the area under the tree with water from a hose now and capture this water in a 6 foot diameter basin or moat around the tree. This should help flush any possible salts that may have accumulated in the watered area and get the tree off to a good start.

Rock mulch is not a good idea for figs. There is no reason why you cannot have a bountiful crop with nearly any variety of fig in this climate. They all do well here when they are managed correctly.

Clover-Like Weed Not Clover, Difficult to Control

Q. I have reddish, clover-looking weeds that have taken over my lawn.  Last year they nearly covered it.  I tried weed and feed several times but that didn't seem to get rid of them.  A friend of mine had the same problem and had to remove all of their grass and re-sod their lawn. They bought their own lawnmower made their landscaper use it because they said the lawnmowers that landscapers use can spread this clover everywhere.

Readers picture of "clover"

A. the picture you sent to me appears to be oxalis and not clover. Oxalis has a yellow flower. Clovers usually have white, pink or reddish flowers. They both have clover-like leaves.

            Oxalis is extremely difficult to control once it gets established. We see them growing in flowerbeds and shrub beds as well as lawns. In beds, it is usually brought in with the plant material as a weed contaminant in the container. But it also can be brought in on lawnmowers.

Oxalis

Focus on weed killers for lawns that include the weed “oxalis” on the label rather than clover. If you are not sure, give me the name of the product in an email and I can help you from there.

Control it now or in the fall, not during summer heat. If there were not too many, you could consider digging out the contaminated lawn areas to a depth of about 6 inches and replace it with sod.

In your case it sounds like it’s covering the entire lawn. There are many different lawn weed killers labeled for controlling dandelions. They contain several weed killers in different combinations to control a different array of weeds. Look at “dandelion” weed killers but make sure the label includes controlling oxalis. Use a product that is sprayed rather than a dry granular applied to the lawn.

Related links to this post

http://xtremehorticulture.blogspot.com/2014/02/clover-looking-weed-with-yellow-flowers.html

http://xtremehorticulture.blogspot.com/2012/11/this-clover-looking-weed-is-hard-to-get.html

Unknown Tree With Branch Dieback Not Ash

Q. I have a tree that appears to be dying but I don’t know what it is. I was reading your article about the disease on ash trees and tried to access the pictures of ash trees but couldn't find them. I believe the tree is about 15 years old.

Readers tree

A. Thank you for sending me pictures of your tree. I can tell you it is definitely not an ash tree. It was difficult to identify from the pictures but from the close-up of the leaves I think it is Japanese privet, sometimes called wax leaf privet.

This is a tree or sometimes grown as a shrub commonly planted in southern Nevada. If this is wax leaf privet you should see clusters of white flowers followed by black berries about the size of blueberries in the same clusters.

Privet with leaf drop and twiggy dieback due to irrigation

They frequently have the same problem here which is dieback of small branches which makes them look very “twiggy”.  I posted a picture of this plant growing in southern Nevada on my blog that shows this branch dieback and leaf drop I am talking about.

This plant doesn’t like our desert environment or drip irrigation very much. It definitely does not like rock mulch. They prefer growing in a much lusher environment.

The only time I really see them looking good is when they're surrounded by a lawn that receives a lot of water. You might try putting bedding plants that require watering water every couple of days and surround the tree with wood mulch or a very lush lawn.

They do great in East Texas all the way back to the Carolinas but do not look all that well in landscapes located in the dry or desert West.

See these links in this blog

http://xtremehorticulture.blogspot.com/2014/08/privet-dieback-due-to-irrigation.html

http://xtremehorticulture.blogspot.com/2011/07/q.html

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What Vegetables to Plant Now

This is the transition time between cool season vegetables and warm season vegetables in the Mojave Desert. We are still growing cool season or winter vegetables and planting warm season or summer vegetables as we harvest our cool season crops.

Plant SOME Winter Vegetables Now

There is time left to plant SOME winter vegetables like radishes/leaf lettuce/spinach/arugula and harvest them before it starts to get hot. I would not be afraid to plant vegetables now that you will harvest in the next 45 days. Always tweak information for elevation and microclimate. For international readers I would also include latitude.

Viragrow is just wrapping up its harvest of cauliflower now from its raised beds. It is too late to plant more cauliflower or broccoli at 2000 ft elevation in the Mojave but not too late to still squeeze a crop of radishes, spinach, lettuce, arugula in.

Freezing Temperatures

Historically, the last frost date (95% sure there will be no freezing temperatures) is March 15. Looking ahead at the weather for the next two weeks I am reasonably comfortable that we will not have any more freezing temperatures until late fall or early winter at a 2000 ft elevation. When setting out transplants early or growing from seed early it is best to protect warm season vegetable

Wall-o-Water is one product used to protect tomatoes from chilling temperatures at night when they are set out early. They are probably the most effective at modifying freezing temperatures and preventing freeze damage.

plants from chilling temperatures at night by using hot caps, Wall-o-Water or frost blankets. You will see improved growth and faster establishment.

Elevation

This information focuses on vegetables grown at the 2000 foot elevation in the Mojave Desert. Tweak this information earlier if you are growing at elevations of 1000 feet and later if your elevation is at 3000 feet. Lower elevations are seasonally warmer and higher elevations are seasonally colder.

Microclimates

Tweak this information for different microclimates of your garden. South and West facing gardens are warmer and planted earlier than gardens facing east or north. However, you can harvest later from east and north facing gardens. Take advantage of microclimates by placing growing areas in different locations in the yard.

Wind

Wind is always damaging to gardens. In winter, freezing temperatures are more damaging if there is wind. In summer, the heat is more damaging if there is wind. Even when temperatures are mild wind affects vegetables, Put up small windbreaks around your growing area. The most effective

Produce better vegetables with a windbreak on the windward side of a garden spot. Century fence with pvc slats is about an 80/20 mix of solid /openings to slow wind for  improved vegetable production.

windbreaks allow about 20% of the air to move through it while 80% is stopped. A good example is a Century fence with PVC slats inserted or reed fencing is attached. This type of windbreak is about an 80/20 windbreak. The effective area of a windbreak is downwind of it a distance equal to about five times its height.

Rotation

I know vegetable plots can be very small but whenever possible plant something different in spots in the gardens. This is called "crop rotation". When growing "by the book", "rotate" vegetables to different spots from different families. If tomatoes (Nightshade family) were grown in a spot, then grow onions (Onion family) or squash (Cucumber family) in this spot the next year Try to NOT grow something in the same family in the same spot for three years. This helps to reduce disease problems that remain in the soil.

Summer (and some winter) Vegetable Calendar

Key: s=seed; T=transplants

These are recommended months. Exact dates vary with elevation, variety and microclimate. The Las Vegas Valley is between 1700 to 2000 feet in elevation. Elevations lower than this are planted earlier in the spring and later in the fall. Elevations higher than this are the reverse. 

Some varieties of vegetables perform in heat or cold better than others. Consult information on the variety you are planting. Some landscape areas or microclimates surrounding the home are warmer or colder than others. Warm microclimates are planted earlier in the spring and later in the fall. Some of the herbs are perennial. Many herbs can be started from cuttings which is not noted below.

February

Beets (s), carrots (s), sweet corn (s) (later in the month), kale (s), lettuce (s), onion sets, potato (later in the month), radish (s), spinach (s), Swiss chard (s), turnip (s)

March

Bush beans (s), carrots (s), sweet corn (s), eggplant late in the month (T), green beans (s), pole beans (s), kale (s), kohlrabi (s), lettuce (s), onion sets, onions (T), peppers late in the month (T), potatoes, radishes (s), spinach (s), Swiss chard (s), tomato (T), turnip (s), rosemary (T), mint (T), oregano (T), mizuno (T), thyme (T)

April

Sweet corn (s), cucumber (s), eggplant (T), green beans (s), pole beans (s), melons late in the month (s), peppers (T), tomatoes (T), summer squash (s), basil (T), lemongrass (T), lemon verbena (T), cilantro (T), rosemary (T), mint (T)

May

Cucumber (s), eggplant (T), melons (s), peppers (T), sweet potato (slips), summer squash (s)

June

Melons (s)

July

Sweet corn late in the month (s), green beans (s), pole beans (s), melons (s)

August

Beets (s), broccoli late in the month (s,T), cabbage late in the month (T), cauliflower late in the month (T), sweet corn early in the month (s), green beans (s), pole beans (s), spinach (s), Swiss chard (s), winter squash at lower elevations (s), parsleys (T), cilantro (T), dill (T), fennel (T), chervil(T), salad burnet (T), sorrel (T), tarragon (T)

 How To Plant

Bone meal is a fertilizer used by organic growers at planting time

Before Planting in an Existing Garden: Apply 1 inch (1 cubic yard covers about 320 square feet) of good quality compost to the surface of the garden. Mix phosphorus fertilizer (triple super phosphate, rock phosphate or bone meal) to a depth of 8 to 10 inches in the row for planting seeds or with the

backfill around transplants.

Large Seed: Soak large seed (corn, peas, beans, melons, squash) in cool water 6–12 hours before planting. Soaking seed speeds germination and promotes even emergence. Form ½ inch deep planting trench with hoe or dibble. Place wet seed in trench or “hills” and cover seed with soil or mulch. Water lightly with a sprinkling can or hose breaker. During hot weather, cover seeded area with straw or horse fresh horse bedding to shade the soil surface. This is not deep but a light application. Soon after emergence, remove seedlings which are too close together by cutting them, not pulling. Sidedress or foliar spray seedlings with fertilizer one month after planting.

Small Seed: Lightly scratch soil surface with garden rake to create small furrows. Sprinkle or drop seed in rows created with rake. In Square Foot Gardens, distribute seed evenly throughout a planting grid. Cover seed with 1/8 inch compost or soil mix. Water lightly with a sprinkling can or Dramm^© hose breaker. During hot weather, cover seeded area with enough straw or horse bedding to shade the soil surface. Soon after emergence, cut off seedlings which are too close together. Lightly sidedress or foliar spray seedlings with fertilizer one month after planting.

To speed up germination, water seeds and then cover planting area with clear plastic. Remove plastic or cut slits in it to allow seedlings to grow above the plastic.

Add Compost Now

Compost is very important to add before planting summer vegetables and herbs. Use it in place of fertilizers to feed trees and shrubs, improve the soil and growth. Add it to backfill 50/50 with soil dug from the hole for improved plant performance, rooting and growth. Don't forget to mulch fruit trees after planting.

Viragrow sale on compost ends in 10 days. Bulk and bagged.
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Dormant Sprays or Dormant Oil?

Q. I have a peach tree that has been in the ground one year. I was supposed to spray it with dormant oil spray before leafing out. Is copper fungicide okay for spraying in the spring? Want to avoid bad pesticides because of birds, good bugs, etc. 

A. There is a confusion out there concerning dormant sprays and dormant oil. Dormant sprays can be a number of different types of sprays. The name “Dormant Spray” is a trade name and tells me nothing about its contents.

Dormant oils or horticultural oils help prevent insect pests in the coming growing season

If I have the trade name (Dormant Spray) and the manufacturer then I can look it up and I will know exactly what it contains. There is no hard and fast rule that you can apply when you are talking about dormant sprays.

However, dormant sprays are usually a traditional pesticide or combination of traditional pesticides that are sprayed during the winter or early spring. Sometimes they contain a fungicide that has copper in it and sometimes they contain an insecticide as well. They are not typically organic.

Dormant oils, on the other hand, are very specific. They vary a little bit among manufacturers but not like dormant sprays.

There is no reason for spraying a copper fungicide contained in the dormant spray if there are no problems to solve. However, dormant oils are very important to apply as a preventive measure for controlling some of the insects common on fruit trees.

There is no reason for spraying copper fungicide now unless you have a good reason for it. Be sure you have a SPECIFIC reason for doing this before you do it. On a one year old peach tree I doubt it unless you have disease pressure from Coryneum blight/shothole fungus. 

If we have extended periods of wet weather or rain you might consider it after the rain has finished. But otherwise I would not do it.

Small Area Will Fit Trellised Fruit Trees

Q. I have a very small back yard and a 20' x 18" planter against the back wall of our property that is now empty. We were thinking of espalier fruit trees in the space. My wife wants a Myers lemon and I like a peach or nectarine, pear, or even an apple.

A. You can fit about three fruit trees on a trellis 20 feet long. They don’t have to be dwarf except for the apple. The easiest trees to trellis are those which produce fruit on spurs; most apples, pear, apricot, plum and pluot. Citrus will work if the location is in a warm microclimate during the winter and protected from the wind.

Apple trellis to close to a century fence but not on the fence

Nectarine can be difficult because it frequently requires a lot of spraying for Western flower thrips to prevent the scarring this insect causes to the fruit.

Peach can be more difficult because it does not produce fruit in spurs. Purchase these trees at any local nursery or garden center but reference my list for the best varieties. You will find it on my blog or email me and I will send you a copy.

Buy a small tree if you are going to trellis. The wires for trellising should not be against the wall but away from it at least a few inches so you can prune behind it.

Trellis wires start at a height of about 18 inches from the ground and vertically spaced 18 inches apart. Everything growing towards the wall is pruned off.

In the first year cut the top of the tree about 2 inches above the bottom wire. The growth closest to the cut is directed to the next wire above it. Two side branches are tied tightly to the bottom wire.

Next year repeat this process at the second wire, then the third wire and finally the last wire. Once the tree occupies the entire trellis any branches growing above the top wire are removed. Branches growing away from the wall are cut back to three or 4 inches.

Cut Oleanders down Now

Q. You had an article awhile back about trimming oleander down before spring. I have five in my backyard and have never done that. I am afraid to trim them down. Let me know because I am ready to fertilize.

A. If oleanders are getting old and unsightly you have two choices if you want to improve their locks. You can cut them down to the ground leaving stubs about 3 to 4 inches above the soil and they will sucker and regrow from these stubs.

This eliminates flowers early in the season but it will start flowering probably around July when it gets old enough. You can cut them back now. They grow back very quickly when it’s warm and they have plenty of water.

The second option cuts back a few of the oldest and largest stems in the same way but leaves the smaller ones unpruned or only cut back with some of the foliage remaining. The advantage of the second way is that you don’t leave and open space and the remaining smaller stems will flower much earlier.

Pruning them with a hedge shears in the spring and summer removes the future flowers and you’re faced with a green plant until it regrows and flowers.

Fertilize them and water them after they are pruned. This is important if you want them to grow back quickly.

Here are some places on my blog to check out  http://xtremehorticulture.blogspot.com/2012/07/proper-way-to-prune-and-hedge-oleanders.html  

http://xtremehorticulture.blogspot.com/2014/08/best-time-for-pruning-oleander.html

http://xtremehorticulture.blogspot.com/2015/12/when-and-how-to-prune-lantana-and.html

Pine Tree Dripping Sap from Holes

Q. I have a one-acre lot in east Las Vegas with large pine trees. One of the trees recently started dripping lots and lots of sap. Upon inspection, we found some horizontal lines of holes in the bark.  Other areas the sap is just dripping from the natural seams of the bark.  I looked online and it suggests a bird rather than a borer if the holes are in lines. Are there woodpeckers in Las Vegas?

A. Yes, we have the yellow-bellied sapsucker here which is in the family of woodpeckers. They cause the kind of damage you are seeing and drill holes in horizontal lines which can drip sap. It looks a little bit like someone took a drill and drilled holes in the tree close together and in a straight line.

There is not much you can do except to try to exclude these birds from the trunk which is difficult. The good news is that these trees can live many years with this type of damage from this bird if the tree is healthy and growing.

Big pine trees use a lot of water so make sure yours is receiving enough water in the spring and summer months so that it will grow enough and recover from the damage.

If damaged trees do not grow enough to recover from the bird damage then it can be a problem for the tree. 

Try looking here on my blog

http://xtremehorticulture.blogspot.com/2011/08/someones-drilling-holes-in-my-trees.html

http://xtremehorticulture.blogspot.com/2014/04/holes-in-trees-due-to-woodpecker.html

http://xtremehorticulture.blogspot.com/2015/01/what-caused-holes-in-my-tree.html

http://xtremehorticulture.blogspot.com/2015/01/time-of-year-for-holes-to-appear-in.html

Lemon Tree Leaves Eaten up

Q. I have a lemon tree with the leaves eaten up by something. I have been spraying with soap and water weekly but I’ve not seen any improvement. Any ideas?

A. I looked at the picture of the leaves you sent. Damage caused by critters is frequently characteristic to the feeder. The leaves are chewed from the tips and entire portions of the leaf are gone.

Commonly we see root damage but this does not look like root weevil damage. Root weevil damage leaves a characteristic “notching” along the edge of the leaf.

Rabbits can damage citrus but they usually eat the small twigs or branches and entire leaves. This damage usually extends only as high as they can reach. For cottontails it is about a foot. For jackrabbits it can be 2 ½ feet or more.

Rabbits also damage the trunks if the trees are fairly young. It does not look like rabbit damage but I will not rule out rabbits. Look at where the damage is located on the tree and see if it extends to a certain height only which might point at rabbits.

This damage resembles grasshopper damage to the leaves but I would not expect damage from grasshoppers this time of year because they are not active now. Perhaps this damage happened awhile back and you are just now seeing it.

Soap and water sprays will not leave behind a toxic residue that kill pests. Soap and water sprays will only kill insects that you spray.

Traditional pesticides like Sevin insecticide will leave behind a toxic residue. Try spraying with Sevin if the lemon tree is not in flower. The damage resembles the chewing from insects such as grasshoppers and Sevin insecticide should do the trick.

Citrus leaves eaten diagnosis from University of California

Presidents Day Farm to Table Brunch in Moapa

It is not too late to register and go! Have a fabulous time in rural Nevada and enjoy beautiful Moapa!

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.

http://xtremehorticulture.blogspot.com/2012/07/grubs-in-container-of-garden-soil.html

http://xtremehorticulture.blogspot.com/2014/05/is-grub-guard-safe-to-use-in-my.html

http://xtremehorticulture.blogspot.com/2015/10/control-root-eating-grubs-organically.html

http://xtremehorticulture.blogspot.com/2014/09/controlling-grubs-is-big-topic.html

http://xtremehorticulture.blogspot.com/2014/08/poor-growth-of-lantana-due-to-grubs.html

http://xtremehorticulture.blogspot.com/2015/05/look-for-plants-dying-because-of-grubs.html

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.

http://www.buglogical.com/beneficial-nematodes/ 

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.