Croatian Olive Grower Innovates to Overcome Drought, Pests

In recent years, extreme sum­mer droughts have become a sig­nif­i­cant chal­lenge for Croatian olive grow­ers.

The dry peri­ods are get­ting longer and more extreme as spring pre­cip­i­ta­tion becomes increas­ingly scarce and water reserves in the soil are not renewed.

However, Josip Pavlica, a 28-year-old agron­o­mist and olive grower from Zadar, Dalmatia, has devel­oped some strate­gies to help farm­ers make the most of the rain that does fall ahead of the har­vest.

“In order to encour­age bet­ter water accu­mu­la­tion in the soil, I first did an autumn tillage,” said Pavlica, who is also the sec­re­tary of the Association of Olive Growers of Zadar County. ​“Then I add min­eral fer­til­izer with an empha­sis on phos­pho­rus and potas­sium to the soil, as well as indis­pens­able organic fer­til­izer.”

This ensures a suf­fi­cient amount of nutri­ents and reduces the pop­u­la­tion of weeds, which com­pete with olive trees for water and nutri­ents.

Furthermore, at the begin­ning of spring, in his olive grove in the north­ern Dalmatian region of Zemunik Gornji, Josip imple­ments top-feed­ing with an empha­sis on nitro­gen. He also per­forms shal­low tillage to pre­serve the exist­ing mois­ture in the soil.

Also, in the spring and sum­mer, he car­ries out foliar feed­ing sev­eral times with a com­bi­na­tion of fer­til­iz­ers con­tain­ing macro and microele­ments. Finally, he adds a bios­tim­u­lant to pre­pare the plant for the stress caused by arid con­di­tions.

Starting in the cur­rent grow­ing sea­son, he also started treat­ing his olives with a prepa­ra­tion based on kaolin clay pre­serves mois­ture in the trees’ leaves and deters olive fruit fly infes­ta­tions.

“The white color causes the sun’s rays to be reflected, which warms the tree to a lesser extent and reduces evap­o­tran­spi­ra­tion and thus water loss,” Pavlica said.

He adds that kaolin clay has proven to be very good in prac­tice against the olive fruit fly, the most per­ni­cious olive pest.

When it cov­ers the fruit, the clay cre­ates a bar­rier the fly can­not pen­e­trate. The white color also makes the fruit unrec­og­niz­able to the fly.

“This kind of treat­ment is com­pletely eco­log­i­cal and does not leave any residues in the oil,” Pavlica said.

However, he added that all these mea­sures are unnec­es­sary if the olive trees are not get­ting enough water to pro­duce fruit in the first place.

“All these pre­vi­ously men­tioned mea­sures are very use­ful, but water is sim­ply an irre­place­able ele­ment that enables high-qual­ity, reg­u­lar and con­tin­u­ous pro­duc­tion,” Pavlica said.

Therefore, he is con­sid­er­ing whether to look for an under­ground water source to pre­serve the qual­ity and quan­tity of the crop. This is usu­ally a rather expen­sive under­tak­ing, but it is increas­ingly likely that it will become inevitable.

Encouraged by the exam­ple of the award-win­ning pro­ducer, Ivica Vlatković, Pavlic intends to plant new olive vari­eties that come from sub-Saharan Africa, which tol­er­ate high tem­per­a­tures much bet­ter than the native Oblica vari­ety.

Furthermore, the irri­ga­tion of olive groves requires large amounts of water, with each tree requir­ing sev­eral hun­dred liters of water per round of irri­ga­tion.

Some olive grow­ers, includ­ing Vlatković, have already begun to tackle this prob­lem by irri­gat­ing the canopies of their trees.

With sig­nif­i­cantly lower water con­sump­tion, the sprin­klers must include a mist­ing sys­tem at night when the air is the cold­est, and the least amount of water will evap­o­rate.

The crown of each tree has its own noz­zle that sprays. The water then flows from the branches down to the ground beneath the tree.

The leaf sur­face man­ages to absorb very small par­ti­cles of water, and the result is vis­i­ble in a very short time. Water con­sump­tion is also sig­nif­i­cantly reduced com­pared to the clas­sic irri­ga­tion sys­tem, Pavlica con­cluded.