Study Sheds Light on Lowering Harvest Costs for Table Olive Producers

Recent research sug­gests that a mechan­i­cal table olive har­vester com­bin­ing trunk and canopy shak­ing is more effi­cient than either method alone.

The study found that the method improved effi­ciency – mea­sured as the per­cent­age of fruit removed from the tree over time – of mechan­i­cal har­vest­ing by 75 per­cent and yielded higher-qual­ity fruit.

In recent years, the pro­duc­tion of California table olives has declined sig­nif­i­cantly. The study noted that this is due to hand har­vest­ing costs, which often exceed 60 per­cent of the gross return.

As a result, the mechan­i­cal har­vest­ing method could sig­nif­i­cantly decrease har­vest­ing costs and increase the eco­nomic via­bil­ity of the state’s table olive sec­tor. 

“Well, noth­ing in tree pro­duc­tion is a big break­through; it is more a slow, steady progress,” said Louise Ferguson, the study’s author and a pro­fes­sor in the Department of Plant Sciences at the University of California – Davis.

“The first step or advance is that we can use dou­ble-sided pistachio/prune shak­ers eco­nom­i­cally enough to har­vest table olives, which are har­vested phys­i­o­log­i­cally imma­ture and have a fruit removal force of about 0.5 kilo­grams.”

Next, Ferguson said the researchers are inves­ti­gat­ing Accede, an eth­yl­ene-releas­ing com­pound man­u­fac­tured by Valent Chemical. This com­pound also appears to increase trunk-shak­ing har­vester effi­ciency.

The study eval­u­ated har­vester effi­ciency by com­par­ing an exper­i­men­tal canopy con­tact shaker and a com­mer­cial trunk shaker. Both demon­strated low har­vest effi­cien­cies and no sig­nif­i­cant dif­fer­ences in har­vester effi­ciency between the two, aver­ag­ing no more than eight per­cent.

However, simul­ta­ne­ously com­bin­ing both shak­ing meth­ods increased the price per ton earned by the pro­ducer by 63 per­cent com­pared to trunk shak­ing and 35 per­cent com­pared to canopy shak­ing.

While the new har­vest­ing method is a poten­tial game changer for table olives, Ferguson said it would not sig­nif­i­cantly increase the effi­ciency of har­vest­ing olives for olive oil.

“Oil olives are phys­i­o­log­i­cally mature and have a much lower fruit removal force,” she said. ​“Canopy con­tact machines appear to be highly effi­cient, so the trunk shaker is not an inno­va­tion for them. Current olive oil cul­ti­vars were bred for highly effi­cient over-the-canopy con­tact shak­ers.”

“However, Accede could very pos­si­bly be some­thing they could use as even at the high har­vester effi­ciency, get­ting even two to eight per­cent more olives off the tree at har­vest would be sig­nif­i­cant,” Ferguson added.

The trunk-shak­ing har­vester used in the research is avail­able for pur­chase or con­tract har­vest­ing, but Accede is still in the field trial phase.

According to cost stud­ies from UC Davis, hand har­vest­ing can account for up to 80 per­cent of table olive labor input and 60 per­cent of pro­duc­tion costs. 

The new study’s find­ings may reverse the decline of California’s major table olive, Manzanillo, which has decreased in the last three decades due to ris­ing labor costs and increased scarcity.

However, care­ful plan­ning is required to tran­si­tion an olive grove from hand har­vest­ing to mechan­i­cal har­vest­ing. 

According to Amanda Bailey, the chief exec­u­tive of the Australia-based Olive Center, the change involves a sub­stan­tial shift in har­vest­ing and prun­ing and man­ag­ing the logis­tics of pro­cess­ing a sig­nif­i­cant increase in fruit in a shorter amount of time – approx­i­mately 500 kilo­grams per hour. 

While mechan­i­cal har­vest­ing promises greater returns, it can­not hap­pen in iso­la­tion. ​“There is no mechan­i­cal har­vest­ing with­out orchard and canopy adap­ta­tion,” said Ferguson, para­phras­ing the Israeli mechan­i­cal har­vest­ing engi­neer Yoav Sarig.

First, trees must be planted in closer hedgerows – 200 to 250 trees per acre (490 to 620 trees per hectare) com­pared to the tra­di­tional 96 trees per acre (237 trees per hectare). 

The trees must be mechan­i­cally pruned to main­tain har­vestable height, width and vol­ume. Furthermore, min­i­mal hand prun­ing must be done to allow light to pen­e­trate the canopy and pro­duce flow­ers and fruit.

“We have demon­strated that mechan­i­cal har­vest­ing pro­duces the high­est effi­ciency; how­ever, the oil indus­try does not need it, and no man­u­fac­turer is going to pro­duce a new machine for the 12,400-acre (5,020-hectare) table indus­try,” Ferguson said.

“Bottom line… both indus­tries are strug­gling to get the five tons per acre (12 tons per hectare) needed for eco­nomic sus­tain­abil­ity,” she added. ​“That is why effi­cient mechan­i­cal har­vest­ing and pos­si­ble abscis­sion agents that decrease fruit removal force and increase har­vester effi­ciency are of such inter­est.”