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Wednesday, October 11, 2017

Increasing Pomegranate Fruit Size

Q. How can you increase pomegranate fruit size?
Beautiful fruit color and size of 'Sharp Velvet' pomegranate variety.
A. First, keep in mind that some varieties of pomegranates produce larger fruit than others. That and all red fruit color is why the variety called Wonderful was selected for commercial production in the United States. If you have a variety that can produce larger fruit it generally has to do with 4 considerations; the health of the tree, no water stress as the fruit is gaining in size, how it is pruned and the number of fruit on the tree.
Good size and the color is developing nicely on a not yet mature 'Wonderful' pomegranate.
Larger fruit is produced on flowers coming off of larger stems. This has to do with how it's pruned. Pruning should maintain older and larger wood. Pomegranates grown as a shrub with lots of stems coming from the ground will produce a lot of fruit but they will tend to be smaller. Larger fruit will be produced if 5 main stems are maintained coming from the ground rather than 50. Trees with 4 or 5 major stems will produce fewer flowers but the fruit that these flowers produce will be larger.
Producing a large percentage of large fruited pomegranate relies mostly on proper pruning and irrigation.
Make sure pomegranates do not get water stressed during the summer months as the fruit is beginning to get larger. I have found that a 3 to 4 inch layer of woodchips on the soil surrounding the tree help keep the soil from drying between irrigations.
When several pomegranate fruit all originate from the same spot and the tree has lots of developing fruit and flowers, there is a chance that removal of these fruit when they are very small may result in larger fruit that remain
Removing flowers or small fruit can help increase size of the remaining fruit (thinning) only if there are far too many flowers being produced. Proper pruning reduces the number of flowers and thinning is seldom needed.

Fertilize the tree in February or March just before new growth begins in the spring. Flowers are produced on new spring growth.

Watering Cacti and Succulents Outside in Pots

Q. I keep my landscape cacti and succulents on the dry side. But I am uncertain how much water these plants use when kept outside in small to medium sized pots. They don’t have a large volume of soil to contain their water supply.
Cacti are quite beautiful whether they are flowering or not. Thanks Agnes!

A. You are right. Cacti are watered less often when planted in the ground. They have a much larger root system compared to those growing in containers. Landscape cacti and succulents draw upon water their roots find in the surrounding soil. Potted plants are restricted to the water found only in their container.
Cacti growing in containers are managed and watered differently than cacti growing in the ground. Pay closer attention to water management and the soil needs to be changed every few years.
            Surprisingly, cacti and succulents of the same size kept outside in containers use about the same amount of water as those growing in the ground. But potted plants are watered more often but given less water during each irrigation.
Cactus should never be planted directly in most of our soils. Homeowners water them too often. For this reason the soil must drain easily. Soils that contain many small rocks, called course soils or coarse sand, can be used. When compost is used, make sure it does not more than 10% of the soil mix at planting.
            Water cacti and succulents more often in pots and containers. How often depends on the cactus and the soil.
            Cacti and succulents growing in the wild may have roots stretching distances 8 to 10 times their height. These large, extensive roots are important for their survival. When it rains, shallow roots “slurp” up the water quickly and put it into internal storage. After a rain, trunks, stems and fleshy leaves visibly swell with this stored water. They look “plump”. They react the same way after an irrigation.
Cacti and ornamental trees should not be mixed on the same irrigation valve. Either the cactus will get too much water or the ornamental tree will not get enough. There is no happy medium when mixing these plants together.
            Observe your plants to determine when to water next. To push growth, water more often. Water Opuntia or prickly pear cactus every three weeks during the summer to push new growth.             Watering frequently can cause excessive top growth with shallow roots. Eventually they fall over because they are top-heavy. Watering more often than this can kill it.
            ALWAYS allow the soil to dry between irrigations. Look at the cactus. If they are starting to shrivel, then it’s time to water. If the container is getting light in weight, it is time to water.
Most cacti roots are shallow and spread long distances. Watering cacti with drip emitters close to it is not a good idea or it can blow over in strong winds.
            Use a pencil. It is harder to push a pencil into dry soil than wet soil. Use a moisture meter. The meter should read “DRY” when it’s time to water again. Avoid glazed containers that are too small for a large cacti or succulents. Many cacti experts recommend porous, clay pots with drainage holes at the bottom. The width of the containers should be about half of the plants height. 

"Evergreen" Palo Verde Leaves Turned Brown

Q. We have several different Palo Verde trees.  Last winter one had brown leaves and looked like it was dying. Come spring, it grew new green leaves and looked fine during the summer.  This winter again several of them have brown, dead-looking leaves.  What is going on?
Is this Palo Verde tree dead?, The winter temperatures got cold enough to kill the leaves but not the tree. The leaves died and dropped from the tree.
A.  Sometimes Palo Verde are called evergreen when, in fact, they may not be in our climate.  Evergreen in a warm climate may not be evergreen in a colder climate.  Whether they keep their leaves green through the winter is a matter of climate, weather conditions, the type of tree and how the tree is managed.  
Palo Verde trees can get quite large as this native tree in Arizona can testify.

            Just because they are collectively called Palo Verde does not mean they respond to winter cold temperatures the same.  Some types of Palo Verde may be evergreen during warm winters but brown leaves or drop them during cold winters.  Some types of Palo Verde trees maintain their leaves through the winter better than others.  Therefore, you’re seeing differences among the several types you have.
A multi-branched Palo Verde can be a beautiful addition to a desert landscape.
            If winter temperatures are warm, the leaves remain green or evergreen.  During colder winters, leaves fade to a yellowish green after a moderate cold snap.  If winter temperatures get colder, leaves die and turn brown.  They may or may not drop.  Don’t worry.  New leaves emerge in the spring and replace the dead ones, just as yours did.
Flowers of Palo Verde are quite beautiful as in this Parkinsonia but they also shed a lot of pollen which can make life unpleasant for people with allergies.
            At temperatures, even colder than this, leaves as well as small branches might die. Temperatures still colder?  Leaves and small branches die and larger limbs might die as well. Temperatures even colder than this?  The tree might die.  How much of the tree dies depends on how cold it gets and for how long this cold temperature sticks around.
            Help trees that are winter tender by NEVER fertilizing with nitrogen fertilizers after July 1st.  Applications of phosphorus or potassium are fine, but no nitrogen.

Limbs Dying in 20 Year Old Arizona Ash

Q. My Arizona Ash tree is about 20 years old. Six or eight of it's limbs have dried up and died, within the last couple of weeks. Can you tell me the cause of this and what I can do to prevent more from drying up?

Ash tree showing gradual branch dieback from ash decline
A. Judging from your description, most likely your tree has a disease called ash decline. It is important to know the scientific or Latin name of this tree, Fraxinus velutina, because it is called by many, names in the nursery trades including velvet ash, smooth ash and desert ash among others.
Ash tree showing the first stage of yellowing due to ash decline
            For this reason I just tell people to not plant ash trees in general in the larger metropolitan areas associated with the Mojave, Sonoran and Chihuahuan deserts of the southwestern United States. There are plenty of nurseries still pushing these trees and they are aware of the problem. Caveat emptor, buyer beware.
Close-up of leaves yellowing and scorching due to ash decline.
            About 4 or 5 years ago I stopped recommending the planting of any type of Arizona ash or Modesto ash in the Las Vegas Valley. Arizona ash also includes Raywood and Fan Tex ash which are a type or cultivar of Arizona ash. We don't have a history yet of these trees, but I would be leery of ash trees labeled as Bonita and Fan West because they have Arizona ash genetics in them.
Advanced stage of ash decline where entire tree dies. This can take up to 10 years. Is ash decline capable of spreading from tree to tree? The answer is probably yes. This is the reason I am telling people to remove these trees after ash decline has been confirmed.
            In the mid-1980s in the Las Vegas Valley in North Las Vegas on Modesto ash and we tried everything we could to cure, rectify and remedy this problem with no success whatsoever. The trees ultimately died. We involved the state plant pathologist who sent tissue samples to Florida thinking it was a disease called ash yellows and it came back negative.
            Personally, if these trees are getting adequate water, not too often and not too little, assume it is ash decline and remove them as soon as possible. We don't know much about the disease, we don't know how it is spread so we should get rid of them and not plant them again until we can figure out what this problem is and how to stop it.
            Look for suitable replacement trees. If these replanted in a rock/desert landscape then replace it with a desert landscape tree that will give you the same benefits. To our knowledge this disease is not present in the soil and is restricted to certain types of ash trees so replacement trees should be fine if they are not ash.

Tuesday, October 10, 2017

Too Much Fertilizer Can Stop Fig Production

Q. I have a 15-foot tall yellow fig tree I cut back every winter to about 8 feet. It grows aggressively every year and usually fruits 3 times a year with large, sweet figs. This year the fruit wwas good but I only got about ten figs. I planted a kumquat tree near it and applied the recommended fertilizer. Did that fertilizer caused the fig to stop producing fruit? It doesn't look like it’s going to fruit again this year.
This fig tree was cut back severely. Look at the new growth when the trunk size is reduced. Fig trees can be cut back considerably and they will re-grow as suckers from the trunk. This can reduce the early crop of figs.
A. It is hard to say definitively but if the tree is given an abundance of nitrogen fertilizer it will grow lots of leaves and stems and sacrifice its fruit production. This is Doubly true if the tree has also been cut back severely.Cutting it back severely stimulates new growth. It's like giving it a big shot of fertilizer.
Another fig tree pruned back severely and look at its growth the following year. Severe pruning is done during the winter months.
            Plants are opportunists. If an abundance of nitrogen is available, they put excess nitrogen to the best use they can which is leaf and stem growth, not fruit production.The tree becomes more juvenile.
           When a tree has lots of available nitrogen and it has been cut or pruned heavily, it is forced to grow like a young tree. When the tree has grown big enough for its roots, extra nitrogen is put into fruit production.
This fig tree was 12 feet tall before pruning. Figs are produced on stems that grew last year and stems that grow this year. Basically 2 crops of figs. This 10-year-old fig tree was pruned back so the fruit produced is easier to pick from the new growth. Some of last year's growth remains so that the early crop can be picked as well.

            Fruit production slows leaf and stem growth. Nitrogen speeds up leaf and stem growth but it can also make fruit larger if there is plenty of water. So this next year it should be back in production if you reduce the amount high nitrogen fertilizers and continue winter pruning.

Fixing Exhausted Soil for Tomatoes

Q. After 17 years of growing tomatoes, I feel I have depleted most of the nutrients so I am going to dig it up, remove it and replace it with new soil. My idea is to lay down a layer of fruit pulp in a sufficient quantity and then cover with at least 12" of planter’s mix. I would do fish guts but I can't find any quantity. By the 2018 spring planting season I think I'll have a super soil. What do you think?
Compost is added to soil growing vegetables every year to replace nutrients that were "harvested" with the crops and rebuild the structure of the soil for better drainage, water holding and root growth.
A. Any time you use raw plant products, like fresh fruit pulp, it is best decomposed or rotted first before using it in a garden. Otherwise it causes numerous problems. The process of rotting releases nutrients tied up in fresh pulp in any raw vegetable or fruit. It’s also true of fresh versus aged or rotted animal manures.
            The process of “controlled rotting” is composting. The ingredients needed for composting include water, air and warmth and whatever it is you are trying to rot. As long as these ingredients are not restricted and in abundance, the speed of this “controlled rotting” is regulated by the size of whatever it is you’re rotting and temperature.
Compost can be made in a "static" method, piled and left to rot on its own. This takes longer than other methods. This is the "lazy man's" way to do it. Just water it and let it breakdown and rot.
            By burying fresh juice pulp under 12 inches of soil I fear you are restricting oxygen. This is a major ingredient. This type of rotting is dangerous to plants because the compost becomes “anaerobic”, without enough available oxygen from the air. Anaerobic composts produce large amounts of acids, sulfur dioxide (the smell of rotten eggs) and methane gas; all of them toxic to plants.
A good compost should be dark in color, fine textured and smell good.
            Pulp from juicing attracts a lot of varmints, mostly insects and rodents. Your garden area might be a magnet for varmints unless they are kept away from it when it first begins to rot. Once the rotting is firmly underway, it’s not a problem anymore..
            However, if you take this juice pulp, mix it with sawdust or very fine wood chips, and turn it on a regular basis, you could have something valuable to plants in 2 or 3 months; composting it with enough find wood products will make the gardener’s "Black Gold" or humus.
The ingredients in compost can be chopped up, watered and turned by  hand or a tractor. This speeds up composting alot. The finished time can be as quick as two to three months if you do it this way. 
            Regarding your current tomato growing area, the soil does not need to be replaced. It just needs to be again “enriched” with compost. A 3 to 4 inch layer of compost applied to the surface and “double dug”, or rototilled into the soil as deep as possible, will do the trick and you will be back in business.
            Soil nutrients are removed quite quickly from a soil depending on the crop grown, the intensity of growing and how plants are managed. A small amount of compost should be added to growing areas every 1 to 2 years.
            You should also be rotating your vegetables. If you don’t know what this is, “Google it”. Problems resulting from a lack in vegetable rotation cause declines in production and contribute to disease problems.

Brown Branches in Italian Cypress. Spider Mites?

Q. I think my Italian cypress has mites. Some of them are dying rapidly with pale leaves that hang out and crumble if you grab them. They are about 10 to 12 feet tall. 
Italian cypress is notorious for having brown branches at some point in the life. Spider mites can be the cause during the hot summer months but the usual culprit is watering too often. They are from a Mediterranean climate which is typically cool to cold and wet in the winter and hot and dry in the summer. They historically don't grow in climates with frequent rains or frequent irrigations. Water them with alot of water and then hold off on the next irrigation.

A. Make sure this problem is from spider mites and not watering too often. Italian cypress are Mediterranean plants that should be watered after the soil begins drying. Otherwise frequent irrigations rot the roots and causes problems similar to what you are describing.
Spider mites in Italian cypress happen during the hot summer months, not the cooler times of year. Often upon close inspection the branches have a "dusty" appearance.
            It would be a shame to apply pesticides when they aren’t needed. Pesticides are sometimes needed but applying pesticides, whether they are needed or not, always creates other problems. Sometimes the problems they create can be worse than the problem they solve.
Spider mites in Italian cypress usually have webbing that can be seen in the brown area. This is not true of all mite damage to plants.
            Spider mites are always present on plants during the heat of the summer. They are controlled naturally and kept in check by many different predatory insects including “good” or predatory mites.
            If you apply a pesticide to control mites, it kills the “good mites” as well as the bad ones. Once that happens, the bad my population can “blossom” back into a big problem and then it’s a vicious cycle between control and pesticide applications.
Webbing can be seen with spider mite damage on Italian cypress
            Most bad spider mites are “web spinners”; in other words, you should see webbing amongst the branches as well as a “dusty appearance” on the foliage if bad guys are active. This webbing is not true of all damage by mites. Some mites are not “web spinners”. “This dusty appearance can be from wind-blown dust but it can also be from large numbers of dead mites.
             The presence of wind-blown dust on the foliage can encourage spider mite problems. The dust interferes with “hunting” by predatory insects. Hose off Italian cypress after dusty winds and once a month during the heat of the summer. Let them hunt.
            Use a hand magnifying glass and look for eggs in the dust. Eggs are extremely small but round and translucent under a lens. Once mites are a problem, you will see lots of their eggs amongst the dust.
            Use a white paper test. Take a plain piece of white paper and “slap” a living but dusty branch against it 2 or 3 times. Hold the paper still in the sunlight and look for tiny specks the size of this period (.) to crawl around. These are mites.
            Browning of the leaves, webbing, a dusty appearance, round translucent eggs and little dots crawling around on a white piece of paper are clear indicators you have spider mite problems that need to be controlled.

Controlling Tiny Jumping Pests on Grapes

Q. This year my grapes are again infested with leafhoppers. Before the fruit came off, I used Safer insect killing soap approximately every 7 to 10 days. I kept them at bay for the first part of the summer. However, they are now infesting the grapes heavily. Since I took the grapes off, I have been alternating soap and pyrethrin every 5 to 7 days. 
Characteristic leafhopper damage on grape leaves.Notice the white spots on the leaf surface from feeding by this very small jumping insect.

A. Leafhoppers can be a huge problem on grapes grown in the Mojave Desert. They are often confused with other insects but if walking past your grapes and hundreds of tiny insects jump into your face, then they are probably leafhoppers.
            Once reaching large populations, adult leafhoppers are extremely difficult to control without hard pesticides. Hard pesticides are not “organic”. If you don’t start spraying early, these insects will be a huge problem later in the season and much more difficult to control.
Leafhoppers feed on the undersides of leaves. They leave behind black specks..poo...from their feeding. This can land on the grapes and make the fruit undesirable or cause some off taste on wine grapes during fermenting. This can be a problem on "organically grown" grapes.
            The key to effectively using “softer pesticides”, closer to organic types of control, is to look for the juveniles on the bottom of leaves early in the season. Use soft pesticides in rotation with each other and spray when the younger populations are on the rise.
            Softer pesticides are not necessarily “organic” but are safer for humans and the environment. These pesticides, used in rotation, include insecticidal soaps like Safer, neem oil, spinosad, pyrethrin and even horticultural oils when temperatures are cooler.
Closeup of leafhopper sent to me by a reader. Thank you! They are very small, maybe 1/8 inch long. Did I mention they jump? Right into your nose, eyes or mouth when you walk by the vines. A real pest when the populations are left unchecked. And leafhoppers can transmit diseases among vines.
            Rotating these pesticides means to use a different pesticide in your arsenal each time you spray. Begin looking on the bottom of leaves when grape berries are the size of large peas. Once leafhoppers are seen, spotcheck leaves every week. Remove leaves that surround the grape bunches very early. Very important for insect and disease control.
            Juvenile leafhoppers don’t look much like the adults. But adults will populate the undersides of the leaves with these “babies” quickly once they start. Inspect the bottoms of leaves weekly and spray if populations are increasing.
Extreme leafhopper damage to grapes when you stand back a bit and look at the vines.
            Use a different “soft pesticide” each time you spray. You may need to spray every week but this decision should be made after looking at juvenile populations. Remember, young ones are easier to kill than the adults.
            Non-organic, commercially grown grapes use hard pesticides. Hard pesticides knock problem pests back longer but are not as friendly with the environment, human consumption and other insects in the area nearby.
            “Softer” pesticides must be repeated more often. Use them in rotation. Check populations and look for the juveniles. Start spraying early when the juvenile population is building.

Fixing Brown Spots in Pear Flesh

Q. I have a Bartlett pear tree producing fruit with brown spots in the flesh. I understand this is because of a calcium deficiency and is remedied with calcium sprays to the tree. If I put calcium in the soil and let it soak in over the winter months, will this remedy this problem instead of spraying?
The dimples in the outer skin of this pear indicates that the flesh under the skin will have a brown spot in it. This calcium deficiency is called 'corky spot' in pears, "bitter pit" in apples. It can happen in soils full of calcium like many desert soils.
Here the outer skin of the pear is folded back revealing the brown spot in the flesh. It wou't hurt you but it makes the fruit hard to market.
A. No. There is plenty of calcium in our desert soils. That won’t solve the problem. This abundance of calcium is locked up by the soil and not reaching the fruit. There is plenty of calcium in the soil but it’s not released fast enough to satisfy a huge demand for calcium by the fruit.
            The only way to correct this problem is with calcium sprays. The calcium from the spray is absorbed directly by the fruit.
            In pears, this problem is called “Corky Spot”. In apples, it is called “Bitter Pit”. Corky Spot and Bitter Pit develops on fruit from older trees that have been harvested for many years. Brown spots develop in the flesh of pear and apple fruit because of a calcium deficiency inside the fruit.
Bitter pit on 'Mutsu' apple
            Fruits, full of calcium, are removed from the trees. A rapid uptake of calcium from soil by tree roots causes a “void” of calcium in the soil. Calcium is needed by the next crop of fruit the following year but it’s not available. 

Information on corky spot from Washington State University
            To solve this problem, we “feed” the tree calcium “backwards”; force the calcium inside the fruit by spraying the fruit rather than relying on tree roots. It may not make much sense when the soil is so chock full of calcium but spraying the tree with calcium is the only way to get rid of these brown spots.
            Calcium sprays are applied to the tree with most of the spray landing on the fruit. The most effective sprays are from calcium chloride dissolved in water. A wetting agent is added to the mixture to improve calcium absorption inside the fruit. These sprays are applied 5 times each year as the fruit is enlarging. 

Use 1 pound of food grade calcium chloride dissolved in 100 - 200 gallons of water (you do the math for a backpack sprayer). Add a wetting agent to the spray to help the calcium enter the fruit. Spray only until it begins to run off the fruit. Do it during a cool time of day. No, it will not burn the leaves at this concentration if  you do it in the early morning in the summer.