I have a dwarf Navel orange, in the ground a year, was looking pretty good early spring, covered with blossoms, new leaves pushing out. Then it started languishing, dropping leaves and some flower...I noticed the ends of some branches dieing back. I've tried to upload an image of it, hope it takes. I'd like some opinions as to the possible cause. Don't think it's overwatering, I have a 12" irrometer in the soil about 10 inches from the trunk, don't water until it reads 60-70. A 2 yr dwarf Oroblanco tree next to it, doing better in terms of leaves but might be showing one or two branch dieback also.



John
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From Four Winds:

http://www.fourwindsgrowers.com/solver/drop.html

"Leaf Drop/Twig Dieback
Leaf drop and twig dieback can be caused by lack of light. Citrus trees need a minimum of 6 hours of light. If growing indoors, it's possible that your trees will do better with a grow light for the winter. A sudden change in lighting can also cause problems, so be sure to move your tree gradually from one spot to another, or from inside to out.

If your tree receives adequate light, and experiences leaf drop improper watering is probably the culprit. Too much or too little water is equally likely to cause trouble. A lack of water can cause the tree to dry out and lose leaves, and an excess of water can cause the roots to rot, which leaves them unable to take water and nutrients up to the leaves. If you modify watering to provide even moisture, often the tree will recover, albeit slowly. A moisture meter is useful in determining an appropriate water schedule.

Should your tree lose all its leaves, don't despair. Prune the tree, improve the growing conditions, and it may put leaves out again."

According to TAMU
http://plantpathology.tamu.edu/Texlab/Fruit/citrus/ctd.htm

"Twig Dieback (various fungi)
Twig dieback can be caused by several fungi, as well as by other factors. Fungal infection often occurs following a freeze or mechanical or chemical injury. Affected young branches die back from the tip, sometimes producing gum exudation. Wood is discolored underneath the bark. Damage by twig dieback usually is not severe."

According to University of Florida:

http://edis.ifas.ufl.edu/HS141

"Dead Wood and Twig Dieback
The presence of a certain amount of dead wood is natural in the normal development of a citrus tree, and represents the tree's ability to maintain the appropriate shoot to root ratio(Figure 1). Selective pruning may reduce twig dieback in the interior of the tree canopy. Excessive twig dieback on the outside of tree canopies may result from a number of factors that cause defoliation including freezes, drought, severe pest pressure, declining diseases such as citrus tristeza virus, blight, water damage, greasy spot, spray burn, or other problems causing severe root damage or leaf drop."

If this problem is something serious, a virus, how can I find out? Is there an agricultural service that tests (for free?). If it is serious, is it just a matter of cutting back the dead twigs, or should I be pulling out the tree and burning it.

I'm waiting for a growth flush to see if the tree will grow normally, but it's just sitting there not doing much right now. Does anyone know this, are growth flushes based on the time of the year, or temperature, do they vary with the variety?

jc

I wouldn't worry about it that much.

Yes, I agree, would not consider that as serious....

But I would optimize watering to lessen those symptomes.

Nutrient imbalances in the soil, mostly predicated from lack of air movement in the root zone from compacted soils can cause the tip ends and shoot tips to drop their leaves with some resulting dieback to soon follow as well. I am seeing it happen right now from two container plants - Page Mandarin and Hamlin Sweet Orange from the same grower source. We've had both trees for over a year and now are starting to yellow out in color allover with some dropping of the older leaves with stunted new growth that is falling off the tree resulting with dieback such as yours. Our issue is lack of oxygen in the soil, so I'll be lifting the trees out of their fifteen gallon containers and giving them new soil later today, as a matter of fact, while at the misses home..

A lot depends on how far advanced the dieback later becomes. Some dieback is considered normal for older in ground trees in that some trees are capable of top pruning themselves to induce new root shoot development or trigger new growth elsewhere on the tree but what you have going on here is not natural dieback for so young a tree. You either have an issue with lack of oxygen in the soil that is not allowing the roots to readily absorb nutrients or you have an issue with the start of a severe nutrient deficiency. Could be due to lack of water not flushing salts out of the root zone as well. The dieback does not appear to be due to a fungus, bacteria or a virus to me at this time. Then again I cannot see the entire tree either.

If you think I may have it wrong then take a branch into your nearest County Cooperative Extension Office and have them assess the dieback but they may also call for a soil test to hedge their bet that the dieback may indeed be due to salt buildup/pH factor or due to a nutrient imbalance in the soil.

Jim

I am experiencing leaf curl; twig dieback and subsequent poor cycles of growth and failure. The photo may as well be the poster child of Phase One of the demise of citrus experiencing the lethal combination of criteria you are describing, snickles. In fact, I suspect you hit the nail on the head: soil-gas exchange.

I live in Carmel Valley which has very fine, ancient alluvial silt. My property has a bench that is over eight feet tdeep of the stuff. While that nice black soli looks very fertile on the surface, it may well be "the root of the problem".

I have been long concerned that this may be impacting the gas exchange from the roots and have been making sure that the soil dries out throughly prior to watering. But I may be exaberating the problem too. It appears to be a vicious circle from what you are describing of over-underwatering, and suffication.

Throw in the associated nutrient imbalances that can result from improper watering and you have 2-3 chains of deadly moving dominos all clashing together just beneath the soli.

My problem is that I did not begin to see this leaf curl / twig dieback until I indroduced some new plants this year from W&N (in your neighborhood). Then all helll broke loose.

Maybe the suggestion that nematodes have been introduced to the community has merit in this context too. They tend to feed on distressed plants. I may well be seeing a collage of problems. (I feel like that TV Show "House".)

Anybody have anything to advise as to corrective steps to suggest?

Please feel free to do this top down, from nematodes to soil to nutrition to watering.

Its high time I got a grip on this...(Thanks in advance!)

I probably over do the overwatering advice from time to time, but I believe overwatering is the problem. As I have said several times, once you have damaged the roots from overwatering the tree will show signs of needing water---because it can't take up water with dead roots--then you water some more and the tree never recovers.

If your soil does not drain well, you may have to grow your citrus on a raised bed.

I have sandy soil and we get pretty hot and dry from time to time. I have not watered my lemon tree any in the last 2 years (it is in the 5th yr) and it has never shown any sign of stress. I did water two of my mandarin trees once a week from March until the end of June to reduce fruit drop (it must have worked--I got about 20 fruit on each with only 35-40 flowers), but they have not been watered since except by rain. Our sandy soil drains well, so even when it rains every day we do not usually have any problems, but we also go for several weeks without water and the inground trees survive that without problems as well (without being watered).