Mechanical Harvesting


Mechanical Harvesting

by Don Mayo

(Adapted from the June 1997 Australian Olive Grower)


Don Mayo is the Vice President of California's Orchard Machinery  Corporation (OMC) and was the International Guest at one of the 1997 Australian Olive Seminars. OMC supplies advanced technology mechanical harvesting equipment into just about every country where fruit, nut and other  industries are mechanised. The following speech is a summary of Don's address at  Olives Australia on March 2nd, 1997.

Please note that with regular developments being made in mechanical  harvesting a number of the comments made in this speech have been questioned. Mechanical harvesting techniques and equipment are developing rapidly and what  is "best practice" today may not be so in ten years time. Please also remember that Don is a salesman for his machines!

"It's great to be back in Australia. I've been coming here for many years and  I love every visit. Thank you to the Archer family for inviting me to speak here today.

I know you've got lots of questions on mechanical harvesting so let's get  straight into it.

Orchard Machinery Corporation has been working with olives for many years. I remember going to Argentina in the 1970's to work on the early stages of  mechanical harvesting their olives. We have our shakers working right across the  world from Hawaii to Israel and Argentina to Australia. The majority of our  shakers in Australia are in the Murray Riverlands and at Moree on the Pecans.

In California we have close on 30,000 acres of olive orchards. As many  of you know, California now produces about 11% of the world's table olives. This  was not always the case. In the early days we planted many orchards for olive  oil but of course we found, as did Australia about 30 years back, that the low  production costs which were then in the Mediterranean meant that they could land oil in our shops cheaper than we could produce it. Because of this, many orchards were changed over to table varieties.

The olive oil industry in California is very small and is mainly based on the  cull fruit from the table growers.

TREE SHAPE - The main areas with established olive orchards are the  USA, the Mediterranean and Argentina. However, their biggest problem for  mechanical harvesting is the structure of their trees. In Australia you have an excellent opportunity to do things right in the first place. You can choose your varieties, tree spacings, pruning methods etc etc etc yourselves. You are  inheriting nothing from generations before and this is very much to your  advantage.

The majority of trees in the established countries are multi-trunked,  having three or four trunks per tree which makes tree shaking almost impossible  ... and because of the shape and size of the limbs and the terrain of the orchards, limb shaking is also out of the question on most of the trees.

I'd just like to make a comment here that I'll expand on later and that is, don't screw up on your tree spacing. I've seen major catastrophes in  countries such as Argentina where Mediterranean 'experts' have advised them to plant on spacings of 6m x 3m, 5m x 5m and even 4m x 2.5m! Never plant any closer than the 8m x 5m as you've heard recommended here today. We'll get back to  this.

Let's take a look at tree shape and pruning for mechanical harvesting. This  is another area where there seems to be much confusion. The first important  point is to have a single, clear, straight trunk of 1.0 to 1.5 metres from the  ground. This allows enough room for the harvester to safely and efficiently grip the tree. It also allows room to spread the catching apron around the tree.

The structure of your tree above this straight trunk should be some form of a  vase. From my experience I recommend three main branches. This helps with  the carrying of vibrations at harvest time and also allows for simple limb shaking many years down the track when the trunk is too large to shake. It is  best to keep an upright "V" in your vase rather than a flat "V" because again vibrations transfer more easily in an upwards direction. I'm no expert on  the horticultural side of the pruning but with olives, this vase shape also  helps to let sunlight and air into the tree efficiently.

I know that some growers are looking at the possibility of pruning in a monoconical system where the tree is simply a Christmas tree shape. The main reason for this, as I understand it, is to make vibration travel even more  efficient during harvesting. I know many people don't agree with me on this, but  I speak purely from a mechanical harvesting background in hundreds of orchards  around the world, and monoconical is not the best way to prune your olive.

There are two reasons for this. Firstly, in the harvesting business we have a  term called "end tree damage". This refers to what percentage of the  fruit is damaged during the harvesting stage. The majority of this damage comes  from two sources, fruit to branch bruising as it falls from the tree and then  impact bruising as it hits the ground or catching frame. Due to the careful design of mechanical harvesters, the dislodged fruit falls almost directly downwards. As such, in a monoconical shaped tree, the fruit 'ping pongs' from branch to branch as it falls down through the tree. In a vase shaped tree, the fruit falls almost directly from the tree to the umbrella with very little branch collision. As such, tree shape is the key to minimising fruit damage.

Advanced designs and materials used in our catching frames have reduced fruit  damage to an absolute minimum when it lands on the umbrella.

The second reason for my experience being against monoconical pruning and  upright tree growth comes from work that we do with mechanical harvesting of pine cones in the USA. When we apply powerful vibrations to the base of a pine  tree we find that although the cones can be removed very efficiently, the  vibrations travel very quickly up the tree and actually condense (increase in magnitude) as they focus towards the top of the tree. As these vibrations condense, the water in the cambium layer of the tree heats up and damages  the trunk. In fact, we've blown the tops clean off pine trees because of this  condensing effect. Just picture it, the top three feet exploding with a mass of  steam being shot out of the tree top!

This pine tree experience may not be as critical in shorter olive trees but  the condensing effect can still heat up the cambium layer towards the growing  tip of your monoconical tree.

So what I'm saying is that from a mechanical harvesting perspective, prune your trees into an upright "V" vase. From my understanding of your industry,  most growers are using this method already.

VARIETIES - A number of people have been asking me about the Fruit  Removal Force for various olive varieties. My experience on this is limited  to the main varieties being mechanically harvested in California and Argentina  but I'll explain a few points to you anyway.

In the early days we harvested Manzanillo's about two months, 60 days prior to when they were ready for green harvesting. Do you understand that? We  were harvesting extremely green Manzanillo olives which we then processed using  the 'black-ripe' method which you heard about last night. We were getting about  85% of the fruit off the trees. We have now improved our equipment and changed  our harvest time to standard green harvesting (60 days later) and we now get  about 95% success with the Manzanillo. Naturally, ripe fruit is easier  again to remove.

The 5% remaining, or the 15% as it used to be was harvested later and used for Manzanillo oil.

Sevillano (Queen of Spain) olives are very easy to harvest with about 95% coming off when green. Ascolano, a pickling variety we have in  California, bruises very easily. If I never see another Ascolano olive tree it will be too soon! Mission is the most difficult to harvest in California and yet we still remove 95% of the fruit when it is turning from green to black. I see no problem working with smaller fruit except that the shaking time will be  a few seconds longer to remove the same percentages.

Some people talk about using abscission sprays which cause the fruit to  loosen on the tree but we have no such sprays registered in California and so  we've simply improved the efficiency of our machines.

We achieve these high percentages because of the specialised design of our machines. We have what are called Omnidirectional shakers. That is, our machines have many different vibrating actions which can be adjusted to suit the  type of tree crop being harvested. With the olives we most commonly use a tiny vibration which moves the olives slightly in one direction and then quickly  changes direction thus using inertia to break the adhesion point of the fruit.  The next vibration, a fraction of a second later, moves any fruit remaining 15  degrees to one side of the first movement and then repeat the same fast change  of direction. This 15 degree change in direction is repeated over and over for  about two to three seconds after which most of the fruit has been removed.

During this same few seconds, the machine changes from high frequency to low frequency vibrations. This is done because olives at the top of the tree require high frequencies for removal and olives on the lower pendulous  type branches require low frequency vibrations for removal. Weeping branches are no problem with our harvesters because of this advanced design.

You might also note that we use mechanical harvesters on olive trees from  when their trunks are about 4" (100mm) thick. This means that you should be able to harvest from your first commercial crop in year three or four onwards.

SPEED OF HARVEST - We produce two main harvesting machines at OMC. One is called a Monoboom Shaker. This machine harvests about one tree per minute but does not catch the fruit. There are a number of these machines in operation across Australia especially in certain nut industries where the nut needs to lie on the ground for four or five days prior to collection.

The second machine is the Catchall III. This latest technology machine does have a catching umbrella for fruit collection and it can actually harvest  at about two trees per minute. When you compare this to the 30 to 60 minutes per mature tree for hand harvesting you can begin to see the major  benefits.

In the past we produced a two machine harvester where one machine would travel done one row with a shaker head to vibrate the tree and another machine would travel done the next row with a catching mat. We stopped producing  these machines for a number of reasons, the most obvious of which are the fact  that two engines, two men and two machines are much more expensive to run than a  single operator unit such as the Monoboom and the Catchall III. It was also very  difficult to find skilled drivers who could work efficiently together in the  synchronising of the two machine shaking and catching system.

A major factor effecting harvest speed is the terrain on which the  machine is operating. Last night you saw the various methods of caring for the  floor of your orchard. My recommendation is the same and that is that you  prepare your land as flat as possible prior to planting and then use herbicides and slashing to control weed growth.

Mechanical harvesters cannot work safely on slopes greater than 25 degrees and the steeper the slope the slower the harvest rate.

When estimating the length of time needed to harvest your trees, reckon on 10% down time for refuelling and adjustments etc. and then also take into  account the evenness of the terrain over which the machine will travel. The rougher the ground, the slower the harvest. Rough ground also takes its toll on  the machinery itself.

ECONOMICS - Other than the very obvious savings in labour, and by the way, with manual hand picking you can spend up to 50% of your gross income on harvesting ... the next factor of economics to look at is fruit damage.

With hand picking using the 'stripping' method, where a small tool or hands  are slid down the branch removing the olives onto a mat below, growers expect to have between 1.5% and 2% fruit damage. With the Catchall III harvester, fruit damage comes in at around 3%. However, when you consider that mechanical harvesting of olives costs about US$25 per bin and hand picked olives  cost about US$250 per bin you can see the vast differences in economy.

As I've already mentioned, Australian olive growers have an excellent  opportunity to do things right from the start. One of these standards should be in the bin size used across the country. In California, one of the best things we did was to standardise bins to four feet square and two feet deep. Get this sort of standardising through your industry as soon as possible.

In California we have about 35 mechanical harvesters in operation on olive orchards. However, some orchards still need hand picking because of wrong  tree shapes or wrong tree spacings. I can't emphasise enough the need for you to get your orchard layout right before you plant your first tree.

TREE SPACING - This is one of the most important factors in the  planning of your orchard. My job takes me fairly regularly into Adelaide in  South Australia and I've just spent two weeks there again. I am not prepared to  mention names but I'm very concerned at the tree spacings that some people are  promoting in that area. I've seen the same problem in New Zealand and Argentina. The recommended tree spacings are far too close for efficient mechanical  harvesting and I'm talking about for any machine. I don't know too much about the horticultural side of olives but I do know that ...

... spacings of less than 8m x 5m are going to cause a lot of  pain

to the growers at harvest time.


I was actually told about the problem down south by some major almond growers  who we supply machines to. They were very concerned at some of the information  getting around in the olive industry. You need to understand that ...

... planting closer than 8m x 5m is asking for trouble.

 If anyone is telling you to plant closer then you need to check them out very  thoroughly. They'll often tell you that the harvesting will be done with the two machine system which we've already discussed or with some sort of over the row  type of straddle harvester. You can take it from me that the two machine  harvesters are too inefficient and there is know successful over the row  harvester for olives anywhere in the world. Did you hear that? There is no successful straddle harvester for trees such olives anywhere in the world. There have been a couple of prototypes but nothing has been successful yet. To plant  an orchard at a tree spacing designed for harvesting by a machine that does not exist is ludicrous.

At OMC we spent a lot of time and money, and I mean a lot, trying to design  and construct an incredibly advanced harvesting machine. This machine was self  propelled, controlled by electronic sensors and harvested two rows of trees  at a time! It was by far the most advanced harvesting machine in the world.  But do you know what ... it didn't work. There are two many variables in tree shapes and heights, pruning methods, fruit sizes and removal forces for the  machine to be viable.

All I'm saying is do your homework well and unless you want to hand pick your  fruit,

... never plant closer than 5m x 8m.

 TREE DAMAGE -Todays OMC harvesters DO NOT DAMAGE TREES. That's right. We advertise in the USA that our Catchall III and Monoboom machines will  not damage the trees they are harvesting. Keep in mind that in the USA we are 'sue crazy' which means that if you even look at me the wrong way I'll sue you! Therefore for us to advertise this we need to be extremely certain of our facts ... and we are.

A University of Michigan study into mechanical harvesting concluded that "the  OMC mechanical harvesting system has the only non-damaging head available." We  fully understand that damage to a tree's bark is permanent and will reduce the crop of that tree for years to come.

The US Constitution says that "All men are created equal." And whether you agree with this or not is none of my business, but let me tell you that all shaker heads are NOT created equal! The greatest mechanical harvesting advancement in 20 years took seven years to develop and is now patented standard  equipment on all of our shakers. It is called the "Air Pad System".

Our old shaking heads and that of many other harvester manufacturers, consist  of rubber pads which grip the trees with various efficiencies. The harder the rubber, the less it moulds to the trunk and therefore the greater the pressure being applied at the contact points. When you switch on the vibrations, damage can often occur on or below the bark's surface. It's worth noting that tree  shaking should not be done within a few days after watering. Immediately after watering, the bark is not as strongly attached to the tree as when the tree is  slightly drier and the bark is more constricted on the trunk.

With the Air Pad System, two deflated 'footballs' are placed on the sides of the trunk. When they are completely in position, compressed air is released into  them causing them to inflate and thereby gently but firmly grip the tree. These pads surround almost the entire trunk rather than simply holding it on either  side.

Because of the heat which is generated during the vibrating process, air is  passed through each 'football' at 30psi and released through a valve on the end. This passing air absorbs the heat and releases it through the valve, thereby keeping the tree/football union as cool as possible.

There are many other features which place our machines at the leading edge of  mechanicalharvesting but you can see them on the brochures or videos which I'm leaving with Olives Australia.

PRICE - At present the Monoboom Shaker is selling for US$70,000 to  US$90,000 plus about US$4,000 to US$6,000 freight and insurance to Australia. The Catchall III is selling for US$140,000 plus about US$10,000 for freight and  insurance to Australia. The majority of OMC harvesters in Australia at present are the Monoboom Shakers, however, there is a Catchall III working with cherries  in Victoria.

Most OMC machines in Australia are currently working with stone fruits,  macadamias, walnuts and pecans.

In most cases, I expect that the harvesters will be purchased by investors wanting to run acontract harvesting company, large orchard owners, and associations and co-operatives buying machinery for their region.

Thank you again for your invitation to speak today. I wish you all the best  as you design, plant and tend your orchards in the most modern and economical manner. I look forward to spending more time with the Australian Olive Industry in the future."