Olive leaves that are normally burned as waste from olive processing can instead be used as a beneficial mulch material. When applied as a mulch, the olive leaves compact together due to fungi and create a protective blanket on the soil. This mulch layer prevents weed growth, reduces evaporation, and extends the growing season for young olive trees by around 40 days compared to non-mulched trees. Olive leaf mulching provides benefits for crops and the climate by avoiding emissions from burning and can be considered an adaptation practice for withstanding extreme climate events. There is no pest or disease rationale for continuing to burn olive leaves, as mulching them is a more sustainable option.

1. Climate Change in the Olive Grove_1
It is important to give due attention to Climate Change. There is a number actions to carry out in the olive
grove that contribute to reduce the severity of climate change (mitigation) or that bring responsive
adjustments and make the grove better fitted to face the changed environmental conditions (adaptation).
Instead of dealing with the Climate Change issue on the whole, my idea is to mention and describe simple
activities that can be adopted by most olive growers. The first of these notes concerns the recycle of organic
matter that is commonly burned.
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Precious Waste.
Crops (but also the farmer who grow them) transform simple energy units in precious and more complex
products. Any agricultural output can be reused in other activities and turned into a resource or blindly
wasted and in this case it becomes a pollutant. This happen in the olive growing too and it is up to the
grower to benefit of an available resource or pollute.
Besides the olives that are transformed into oil, vegetation water and exhausted pulp, the olive press also
processes and separates another minor component: the olive leaves. They are normally eliminated by
burning which due to a wax layer on their surfaces occurs very rapidly. Nonetheless this material deserves
far more consideration.

2.
Relevant quantities of olive leaves
are available by any press
Observing the places where olives were cleaned and leaves remain in the field, it is evident that we are
dealing with a very peculiar material. In fact, very few weeds succeed in growing through the layer of leaves
that stays on the field for several months.
Leaves taken away from
harvested olives are still
recognisable in the grove in
spring as they are not covered by
weeds.

3. During the warmer months, leaves get entrapped and hold together by fungi that feed on the degradation
of their lipid content (wax). With their mycelium they compact the leaves and create a blanket performing
an extraordinary mulching1
effect. This is highly beneficial especially to young plantations (olive trees or
vines) and, due to the reduced evaporation of mulched soil, the duration of the vegetation season is
extended in rain fed plantation or the frequency of irrigation can be sensibly reduced in irrigated groves.
My observation
I observed olive leaf mulching in a young olive plantation in South Sicily. In summertime, the climate gets
so hot and dry that growth rate decreases or gets interrupted in non irrigated grove. I noticed that leaves,
blocked in their mycelium net, were not blown away by the wind and prevented wild weed growth.
Further, the soil kept enough moisture to extend the duration of full growth rate for about 40 days longer
than the non mulched control. The difference was evident.
Mechanisation
Due to the high volume to weight ratio of this material, it is crucial to properly manage its transfer and
optimize the mechanization. Leaves shall be imported from the press to the farm in the the same boxes
used to carry the olives. This can be done with no additional travels or expenses in the same day of olive
delivery; the boxes would be brought back to the farm anyway. The best machinery to carry out the
operation of distributing the leaves along the rows are manure‐spreaders with lateral dispenser or adjusted
for lateral distribution.
Press owners can also bail the leaves by mean of bailers or compacting devices for industrial wastes and
scrapes (in this case, nets should be used as enveloping material).
Pest control
The major issue supporting the habit of burning organic matter is that debris can hide and transfer pests
and diseases. This has no rational basis and no scientific support.
The peacock spot (Cycloconium oleaginum or Spilocaea oleaginea) is a key disease for olive leaves. This
fungus propagates by conidia that are spread by insects, the wind, the rain drops. In any case the presence
of the fungus can not be eliminated. Its diffusion must avoided by creating an environment hostile to its
epidemic development.
The olive bark beetles (Hylesinus oleiperda and Phloeotribus scarabaeoides) turn out to be dangerous
only if the tree is weakened or a disease is already present. There is no possibility to preserve trees away of
them. The presence of the insects is normally tolerated by trees and is a consequence rather than the cause
of decaying wood.
Conclusions
In consideration of the benefits that crops and farmers can get from mulching and its mitigation effect
toward climate change there is no point in going on and spoil such a precious material as olive leaves.
1
The FAO Glossary on Organic Agriculture (http://termportal.fao.org/faooa/oa/pages/pdfFiles/OA‐en‐
ar.pdf), define mulching as the establishment of a protective covering on agricultural soil, usually of organic
matter such as leaves, straw, or peat, placed around plants to prevent the evaporation of moisture, the
freezing of roots, and the growth of weeds.

4. Olive leaf mulching is a win‐win situation practice that avoids carbon dioxide, methane and nitrous oxide
emissions to the atmosphere from what the Food and Agriculture Organization states as the most
extensively cultivated fruit crop in the world with over 9 million hectares. Mulching can also be considered
an adaptation measure since protect the grove from extreme climate events.
Other reuses of organic matter from the olive tree are also recommended. There is no reason linked to
pest control justifying burning leaves or pruning debris.
Olive can be grown in marginal soils
and reusing organic matter
becomes imperative.
In the picture, the pruning debris
were chopped and distributed to
increase the organic matter content
in a very stony soil.