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Monday, April 9, 2012

Caliche May Determine How to Plant Fruit Trees

A caliche rock at the orchard
Q. While preparing my holes to plant my fruit trees I encountered caliche.   I’m able to dig down to about 18” by 24” across. I filled the hole about half way with water and the next morning it was all gone. Everything I read discourages planting over caliche. I was thinking of barrels.

A. You are fine with a depth that will accommodate the root system (18 inches deep) as long as you have good drainage. Go ahead and plant. As long as these are smaller fruit trees (less than 20 foot or so) you will be fine. They could get by with 12 inches (I would rather see it deeper) if they have to as long as you have good drainage. I would not put them in barrels unless you had too.

When to Fertilize Fruit Trees Including Citrus and Grapevines

Q. Is there a recommended schedule for fertilizing fruit trees in the valley?  Also for citrus and grapevines?  The schedules I’ve read for each of these are differ depending upon who wrote the article and are not specific for the valley.
Fertilizer applied around the source of water to the fruit
tree, in this case a bubbler which will wash the fertilizer
into the root zone

A. It does not make that much difference as long as the plant has nutrients available during times of fruit production and fruit bud development but generally speaking we avoid applications which might encourage a flush of succulent growth just before winter sets in. This just means try not to apply fertilizers after about mid-July.
            You can get by with a one-time fertilization in the early spring (January) for most fruit trees if you want to. The next thing you can do is a half application in the spring (January) and the other half after harvesting the fruit.
Here fertilizer stakes are pounded into the soil close
to the source of water going to the tree but not close to the tree

            The third way is very light applications of fertilizer sprayed on the foliage or leaves of the trees, monthly, suspending applications from August - November as the tree sets up for winter dormancy. I usually use one of the granular fertilizers that dissolve totally in water such as Miracle Gro or your favorite organic liquid fertilizer. We fertilize just about all our fruit trees and vines once in January with a soil application and that’s it.

Star Jasmine Stopped Blooming? Cut it Back Hard

Q. My gorgeous, dark green, full and old Jasmine has stopped blooming.  I have tried several remedies and none has worked. Can you give me some pointers to get back the heavenly white fragrant blossoms?
Star jasmine
A. By jasmine I take it to mean star jasmine. This vine can also be used as a ground cover and must be supported on a trellis if used as a vine. It blooms in the spring only and so it may not be the time of year for it yet.

            Just be patient. There is no secret formula. Fertilize with any good fertilizer for flowering shrubs in early spring (January through February or now even).

            Be careful when pruning you do not prune out flowering wood. Do your pruning immediately after flowering is finished, not during the winter unless you know where the flowering wood is located.
            An old horticultural adage is that if a plant is not performing well and you are considering getting rid of it then cut it back hard. Of course this will damage flowering for awhile but you may get the plants “attention” and they will sometimes respond very positively.

Borers in Fruit Trees and Buggy Grapevines

Q. Through the years I have planted many fruit trees and lost many to borers especially stone fruit trees. My grape vines have been devastated by whiteflies to the point where I could not harvest one healthy grape leaf last season. I have tried soap water but to no avail. Also, I have tried Lindane against borers but their work keeps appearing on my plum trees.

A. Whiteflies can be a difficult problem. We have not experienced whiteflies on grapes. The closest insect which might be confused with whiteflies, and is a common problem on grapes, are leaf hoppers.
Please make sure you are not confusing whiteflies with leaf hoppers because the treatment is very, very different. Whiteflies are like dandruff and usually fly in a cloud of small white insects when the leaves are disturbed. They usually leave a sticky substance on the leaf surface from feeding.

Click here to see some Whitefly pictures

Leafhoppers on their backs, maybe 1/8 inch long
Leaf hoppers on the other hand jump and are brown in color but they can accumulate in thousands on grapes and jump in your face, your nostrils and eyes as you pass the grapes and disturb the foliage. Both are nearly the same size but whiteflies are white and fly more delicately while leaf hoppers jump and are brown.
If soap and water sprays are used religiously on the grapes when these insects are small it should give fairly good control. If soap and water is delayed until they are mature adults, then control is probably iffy at best.

Whiteflies are listed on the University of California and pests lists for grapes but not a common pest.
Leafhopper feeding damage on grapes
Click here to learn the Common Pests of Grapes

If they are whiteflies then sprays such as pyrethrins might be a good choice but the label must include grapes if you are to use it within the law. If these are leaf hoppers, then sprays applied in May such as spinosad might be useful when this insect is still juvenile. In both cases when these insects are adults they are much more difficult to control.

Sap oozing from cut limb of plum
Regarding the borers in your plum tree, Plum can be attacked by boring insects but it is not as common as some other fruit trees like peach, nectarine or even apple. Please check and make sure that this is in fact borers causing damage and not just sap oozing from a stressed out tree. When plum is stressed from water, intense sunlight or heat stress they will ooze sap.

There is no insecticide you can use on fruit trees once they are attacked by boring insects and still safely eat the fruit in my opinion. Most insecticides recommended after fruit trees have been infested are usually systemic in nature. This means that the insecticide could also be in the fruit, not just on the surface.

Tumors on Cherry Trees and Bioengineering

Q. I have a problem on some fruit trees on a property I have in Tonopah. These cherry trees have large swellings like tumors on the trunk. I spoke with some nursery people in California and described the problem and they knew what the problem was immediately. 

            She concurred with me to get rid of the tree and the nearby rose bush because the rose bush carried the disease and transferred it to both of the fruit trees.  The cherry I chopped down as it was dead all the way through. She told me the whole and area around it would be bacteria infested for a while and even if I put in the soil the product she gave me to kill algae and bacteria, it might still come back.

A. The only thing I can think of that comes close to your description is a relatively benign disease called crown gall. And this is probably what your cherry tree has. This bacterium does infest the soil. It is not typically transferred from plant to plant so getting rid of the roses is not necessary.  A healthy tree can become infested if contaminated soil comes in contact with a fresh wound of the plant.

            Actually this is a very interesting plant disease and was used in the early pioneering days of genetic engineering. When plant tissue is infected with this bacterium the plant cells multiply uncontrollably producing a large woody or corky “tumor’ or swelling on the trunk or roots. The reason it is called “crown” gall is the typical site which the gall or tumor is seen.

            The crown of a plant is the general location where the trunk meets the soil. However these “tumors” can appear less commonly on roots and stems as well. I will try to post more about this disease and how it is used in genetic engineering on my blog.

            Plants can live for many years with crown gall and appear to be quite healthy. It is possible I guess to transmit it from plant to plant by cutting into the crown gall and then cutting another plant with the same unsanitized tool but otherwise you will not transmit it. The usual method whereby it infests a plant is from contact of infested soil with a fresh wound, usually at the time of planting.

Images of Crown Gall