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<pre>From: Mohamed El-Kholy

Dear Allan & Judith

No your trees are definitely not dying. Further and based on the
symptoms you have described (among which: leaves are turning black
and falling off and stakes exhibit same oiliness appearance), I do
not believe that you have a scale problem on those very specific
trees. In fact they shall not be infected with scale for quite some
time until they recover as they are currently drying out of their
natural sap, which attracts such pests.

You have been totally right. Increased oil concentration at the end
of each 20 liters tank application has caused this and therefore if
you look at your grove with a hawk eye, you will find the unhappy
trees in distinctive spots. If your trees are similar in size meaning
that they consume similar amounts of the spraying solution, you will
even find that these spots have a symmetrical repeatable pattern
(i.e. every certain number of trees). If you can memorize your
spraying operation, you will ascertain that these trees were the last
sprayed ones from each tank. For many different reasons and whatever
growers are spraying, I always recommend that they should mark the
last sprayed tree of each round with a ribbon for future assessment
and data base establishment.

Carry on some more investigations and you will notice the following:
Ø Marking these trees on your grove drawing which should
indicate the location of all trees, you will identify the "hawk
eye"
pattern.
Ø Corregiola have larger, wider and flattened leaves than the
Nevadillo, thus they do not allow the spraying solution to drain
readily.
Ø Cut few inches below the growing tip of some of the twinges
and branches showing symptoms of defoliation or burning (turning
black) leaves and you will clearly identify pale greenish sections
with brownish core of non-dead wood with reduced sap content. On
advanced stages of drying out, you might find that the whole section
is completely brown, nevertheless is distinguished from dead wood by
containing sap traces.
Ø The leaves and wood look very dusty as the oil catch dust or
smoke from the air especially if the trees are close to unpaved roads
or the exhaust of combustion engines.
Ø Rub the wood and the leaves with a small piece of white
cloth, and you will clearly identify the surplus dirty oil and the
minute you do it, you will recognize your trees suffering and most
probably will feel sorry for them.
Ø New shoots are bursting from unexpected advantageous buds
directly from the wood, especially at lower sections of the trunk or
the root system. Their bursting is time dependant among other
factors, so if you do not see them now, be sure they will come out at
a later date.

The cause of damage is that the thin oily film left on the leaves has
caused their burning specially when associated with relatively high
climatic temperatures or direct sunrays and further prohibited the
leaves efficient transpiration and photosynthesis resulting in
dryness and less sap movement. Oil burning symptoms are very specific
and could never be misidentified with others.

Oil affected trees do not easily surrender and die, unless they were
originally unhealthy, and therefore they have sap traces in their
drying out organs. To recover quickly they need your help. Prune them
as per my last article of AOG issue 17 as I have already addressed
this case. The degree of pruning will be proportional to the degree
of oil and defoliation damage. The worst case might demand drastic
pruning. After pruning and on the hope of removing some of the oil,
which is choking them, wash them with a mild water jet, which should
not cause more defoliation.

Your more thinking and second diagnoses was right and this is a true
example of new growers who have to be more self-confident and must
trust their instincts.

Prof. Stan Kailis of UWA has identified some of the causes for olive
leaf loss and I would like to add two more to his list:
Ø Ageing, which should be clearly identified by growers so that
they do not get panic and ask for a remote advice over a distance,
which might cause unnecessary harm. Here I am also giving an advice
over a distance like many others, so please be cautious.
Ø Draught.

I might also add to Prof Kailis comments that nematodes cause leaf
loss but do not cause defoliation. In this case the leaves will
completely dry but will remain strongly attached to their branches.

Hoping my diagnosis vis-à-vis yours are correct and will help in
saving your non-dying trees (let us call them "temporarily
retarded
trees".

Happy olive growing to you both and to all of the good company on
this forum.

Mohamed El-Kholy

PS. In fact there are lot of subjects that I would really like to
contribute with my comments, but my problem is time. I wish I could
be as active as Peter Carid and Phil Bramley, whom I owe an apology
for a very delayed answer. Please forgive me and do not lose hope.
Olive growers must be patient as much as their trees.

TO UNSATISFIED OZ MANZANILLOS GROWERS: Again be patient and give your
trees another chance for a season or two as I said before. I have
been looking at oil yield figures of other cultivars from the same
regions having problems with the Ms. Surprisingly none of them
although purely oil varieties are yielding their promissed figures.
In fact they are far behind! I am just wondering: are these varieties
going to face same destiny? You need more time for appraisal
researching!
One thing I am sure of and that is (without hard feelings): Many
growers who claim to have fully irrigated groves need to develop
their practices of grove management as well as their targets.
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