New Treatment for Xylella-Infected Trees Is Working, Researchers Say

Researchers have developed and tested a new bactericide that can help olive trees affected by Xylella to return to full production.
Apr. 13, 2020 11:04 UTC
Ylenia Granitto
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The appliยญcaยญtion of an organic treatยญment, comยญbined with good farmยญing pracยญtices, can allow the olive trees to return to full proยญducยญtion after sufยญferยญing from an outยญbreak of Xylella fasยญtidiosa, accordยญing to new research from the Council for Agricultural Research and Agricultural Economics Analysis (CREA).

โ€œWe experยญiยญmented with a comยญpound based on zinc, copยญper, and citยญric acid โ€“ proยญtected by an interยญnaยญtional patent โ€“ that can be used in organic agriยญculยญture and is potenยญtially capaยญble of reachยญing the bacยญterium in the olive tree xylem,โ€ Marco Scortichini, the research direcยญtor of the Olive, Fruit Trees and Citrus Center at CREA, told Olive Oil Times.

Our olive trees have manยญaged to recover well (from Xylella fasยญtidiosa), and we have always remained in proยญducยญtion with good figยญures, in terms of both quanยญtity and qualยญity- Francesca Minosi, Lecce-based proยญducer

โ€œAccording to studยญies carยญried out in the United States, zinc and copยญper ions show the greatยญest conยญtainยญment capacยญity of the bacยญterium, which can be also curbed by the proper manยญageยญment of micronuยญtriยญents in the plant,โ€ he added.

Based on the European regยญuยญlaยญtions for the manยญageยญment of quarยญanยญtine pathogens, such as Xylella fasยญtidiosa, the eradยญiยญcaยญtion of the bacยญterium is the first soluยญtion proยญposed as a means of restorยญing infected areas.

โ€œWe have to conยญsider that the sucยญcessยญful elimยญiยญnaยญtion of phyยญtopathยญoยญgenic organยญisms from a terยญriยญtory should be based on well-defined premises includยญing the immeยญdiยญate idenยญtiยญfiยญcaยญtion of the disยญease agent, an infected area of reduced dimenยญsions and favorยญable bioยญlogยญiยญcal charยญacยญterยญisยญtics,โ€ Scortichini said. โ€‹โ€œIn my opinยญion, at the time of the disยญcovยญery of the disยญease, none of these criยญteยญria was manยญageยญable in a deciยญsive manยญner.โ€

See Also:Xylella fasยญtidiosa News

Xylella fasยญtidiosa lives not only in the olive tree, but also in sevยญeral culยญtiยญvated and wild plants. It is transยญmitยญted by a very proยญlific and wideยญspread insect carยญrier, Philaenus spumarยญius.

Previous attempts to elimยญiยญnate the bacยญterium from all the infected terยญriยญtory, which includes arable land, unculยญtiยญvated areas, parks and garยญdens, appeared techยญniยญcally impracยญtiยญcaยญble to the researchers and desยญtined not to resolve the sitยญuยญaยญtion.

Then they began experยญiยญmentยญing with the aforeยญmenยญtioned organic comยญpound, comยญbined with approยญpriยญate farmยญing pracยญtices. These include removยญing weeds and other vecยญtors for the spitยญtleยญbug that may be growยญing in the groves and prunยญing the olive trees in order to allow betยญter absorpยญtion of the comยญpound.

After three years of triยญals and folยญlow-ups, the research group conยญcluded that the prodยญuct is an effecยญtive bacยญteยญriยญcide and remarkยญably sysยญtemยญatic, leadยญing to a sigยญnifยญiยญcant reducยญtion of sympยญtoms and bacยญteยญria popยญuยญlaยญtions inside the trees.

The triยญals also conยญfirm that the comยญpound is not phyยญtoยญtoxic to olive trees and no residue from the comยญpound could be detected in the oil proยญduced from the olives of the trees.

Over time, sevยญeral farms started to adopt the proยญtoยญcol and have been conยญstantly monยญiยญtored by the research group.

โ€œWe started to impleยญment this treatยญment and, pretty fast, we had good results visยญiยญble with the naked eye, thereยญfore we conยญtinยญued,โ€ Francesca Minosi, of the Lanciano Elisa farm in the province of Lecce, said.

โ€œOur expeยญriยญence began about four years ago, when some of our olive trees showed sympยญtoms of desยญicยญcaยญtion,โ€ Minosi, who manยญages olive groves comยญposed of Ogliarola salentina and Cellina di Nardรฒ variยญeties, said.

โ€œWhile lookยญing for soluยญtions to this new disยญease and disยญcussing them with other olive growยญers and peoยญple in the secยญtor, we found this set of pracยญtices which we first decided to apply to 200 trees,โ€ she added.

After a year of treatยญment, Minosi met the researchers and agreed to allow them to monยญiยญtor and colยญlect data from her orchards.

โ€œThe sympยญtoms of desยญicยญcaยญtion pracยญtiยญcally disยญapยญpeared, shortly after we started,โ€ she said.

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Over the years, espeยญcially in late spring or early sumยญmer, Minosi had observed spoยญradic episodes of desยญicยญcaยญtion in her groves. However, she stopped noticยญing them after the appliยญcaยญtion of the organic comยญpound.

โ€œOur olive trees have manยญaged to recover well, and we have always remained in proยญducยญtion with good figยญures, in terms of both quanยญtity and qualยญity,โ€ she added.

Since the iniยญtial trial, she has extended the proยญtoยญcol to all her groves โ€“ a total of 1,200 trees.

โ€œWe did not want to explant our cenยญteยญnary trees because, at the time, nobody was cerยญtain of what would hapยญpen,โ€ Minosi said. โ€‹โ€œEradicating and implantยญing them seemed too hazยญardous. We felt this was the most approยญpriยญate way to hanยญdle the emerยญgency.โ€

The researchers point out that the use of the comยญpound is aimed at growยญers with medium and small operยญaยญtions who, for varยญiยญous reaยญsons such as traยญdiยญtional harยญvestยญing or logisยญtiยญcal difยญfiยญculยญties, canยญnot manยญage replaceยญment operยญaยญtions in their olive groves.

In the provinces of Lecce and Taranto, there are two disยญtinct groups of olive farmยญers testยญing out the researchersโ€™ comยญpound: a group of farmยญers enterยญing their fourth and fifth year of the appliยญcaยญtion and another group enterยญing their third year.

โ€œThey all reached an averยญage annual proยญducยญtion, dependยญing on the harยญvest, between four and six tons per hectare (1.6 to 2.4 tons per acre), meetยญing norยญmal proยญducยญtion stanยญdards,โ€ Scortichini said. โ€‹โ€œMoreover, all these farmยญers are preยญservยญing the hisยญtorยญiยญcal, culยญtural, and landยญscape herยญitage, as well as the unique germplasm of Salento.โ€

As Southern Italy enters the full throes of spring, farmยญers are mowยญing the grass in their groves in accorยญdance with the low-enviยญronยญmenยญtal-impact agroยญnomic and physiยญatric phyยญtosanยญiยญtary meaยญsures recยญomยญmended by the Puglia regional govยญernยญment.

โ€œThe most effecยญtive tool to comยญbat the spread of Xylella on the regional terยญriยญtory is to preยญvent its spread over short and medium disยญtances, and to do this, it is very imporยญtant to elimยญiยญnate vecยญtors,โ€ the regional authorยญity said. โ€‹โ€œApril is the most strateยญgic month for the fight against vecยญtors, since the insect is still in its juveยญnile stage, staยญtic and vulยญnerยญaยญble, and easยญily localยญized on wild plants.โ€

โ€œIn this month, it is essenยญtial to elimยญiยญnate the sponยญtaยญneous flora on which the nymphs live, with plowยญing or shredยญding, to sigยญnifยญiยญcantly reduce the juveยญnile popยญuยญlaยญtion of the vecยญtors present in the fields and in parยญticยญuยญlar in the olive groves,โ€ the authorยญity added.





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