evaluation of alternative compounds against xylella

Giuseppe Lima

Carmine Del Grosso

DipartimentoAgricoltura, Ambiente e Alimenti

Università del MoliseCampobasso, IT

E-mail: [email protected]

EVALUATION OF ALTERNATIVE COMPOUNDS AGAINST XYLELLA FASTIDIOSA PAUCA IN OLIVE GROVES

OF THE SALENTO PENINSULA OF APULIA

SESSION 4 – Towards Sustainable

Management Strategies

mailto:[email protected]

Xylella fastidisiosa pauca - Olive

Plant Pathology - Unimol

In the infected zone of the Salento PeninsulaIn addition to search for olive resistant/tolerant germplasm

There is a strong need to find new effective control toolsto preserve suceptible olive cultivars and also to improve

condition of resistant/tolerant cvs

Cellina di Nardò - Ogliarola Salentina

Xfp-suceptibleolive cvs

Monumental trees have a high environmental and cultural value

OUR EXPERIMENTAL ACTIVITY

Selection and evaluation of new products with

potential antibacterial activity against Xfp

- Mineral compounds (MC)

(macro and/or microelements)

- Organic compounds (OC)

(Seaweeds, polyphenols, tannins, flavonoids, chitosans, etc.)

- Synthetic compounds (SC)

(e.g. Zn and Cu systemic complexes)

ANTIBACTERIAL ACTIVITY IN VITRO

screening of several products


ASSAYS IN VITRO

against several species of phytopathogenic bacteria

Water

Water

Water

High and broad-spectrum activity of some tested products


SOME PRODUCTS, AT DOSAGE SUGGESTED FOR FIELD APPLICATION,

WERE ALSO EFFECTIVE AGAINST

XYLELLA FASTIDIOSA PAUCA DE DONNO STRAIN (XFP ST53)

SW - PP – TT –

Cu – Zn complexes

…….alone or in

combination

High inhibitory activity of some tested products in the range

of dosages suggested for field application (1-2%)

Assays carried out at IPSP-CNR, Bari, IT


…. AGAINST OTHER STRAINS AND/OR SUBSP. OF XYLELLA FASTIDIOSA

Inhibithion rate (mm) of the bacterial colony (20 mm= 100% inhibithion)


High effectiveness of some

products at field suggested

dosages (1-2%)




SW+PP BioFlav

(BSp1)

Dose-dependent activity and broad-spectrum activity - MIC determination.

(BSp1)

Water(Control)

Treated

4g/L

Treated

2 g/L

Treated

1 g/L

Treated

8g/L

Treated

0,5 g/L

EVALUATION OF BENEFICIAL EFFECT ON THE PLANT


In the model test used, some products at field

doses (0,5-2%) evidenced biostimulant activity

EVALUATION OF SELECTED PRODUCTS ON OLIVE

PLANTS IN GREENHOUSE

Some of the most promising products are being evaluated against Xfp on pot-grown olive plants


EXPERIMENT ON THE SUSCEPTIBLE OLIVE CV. OGLIAROLA


Experiments are in progress


Screening of several products

For further details on this activity see presentation

by Carmine Del Grosso

(Screening of natural and eco-friendly compound for their antimicrobial

activity against Xylella fastidiosa)

XF-ACTORS Session 3 –Tuesday 27 April 2021

Control of the bacterium in the host plants


FIELD TRIALS

IN DIFFERENT OLIVE GROVES

(XFP-INFECTED ZONE)

YEARS 2014-2021.. (IN PROGRESS)


Ogliarola and Cellina Ogliarola, Cellina and Leccino

CellinaCellina

Field trials in olive groves(Melendugno, LE – Two years (2017-2018) of foliar sprays with different bioformulates)

(Cvs Cellina di Nardò and Ogliarola)

Three foliar sprays per year with bioproducts, starting from the beginning of the vegetative season,

jointly with agronomic and chemical control measures against the vector insects, reduced by 50-60%

the progression of canopy desiccation caused by Xfp in comparison with the control!

Different letters on hystograms correspond to statistically different

values for P = 0.05 according to Tukey test.

Preventive measures against the vector insects

(e.g.: soil tillage from Febraury-March and organic insecticides from April) and no pruning!

McKinney Disease Index, based on an Empirical Scale

with 6 disease classes, from 0 (no canopy symptom) to 6

(80-100% of symptoms or dead plant).

0

5

10

15

20

25

30

March 2017 Dec 2017 Aug 2018

McK

inn

ey In

dex

(%

)

Date of assessment

Percentage of canopy with symptoms caused by Xylella fastidiosa pauca over 2 year

A-BCA1+MicroEl

B-BCA2+Biostim

C-BCA3+Syst-Cu

D-SWP

E-NatPP

G-Bioflav

F-Untr. (Control)

a

a

b

cc c

bc

a

0

10

20

30

McK

inn

ey In

dex

(%

)

Treatment

August 2018 2017-2018 - 3 treat. per year

0

10

20

30

40

50

60

March 2017 Dec 2017 Aug 2018 Dec 2020

McK

inn

ey In

dex

(%

)

Date of assessment

Percentage of canopy with symptoms caused by Xylella fastidiosa pauca over 4 year

A-BCA1+MicroEl

B-BCA2+Biostim

C-BCA3+Syst-Cu

D-SWP

E-NatPP

G-Bioflav

F-Untr. (Control)

28 moths after the treatments were stopped!

Field trials in olive groves(Melendugno, LE – Two years (2017-2018) of foliar sprays with different bioformulates)

(Cvs Cellina di Nardò and Ogliarola)

3 treat. per year with bioproducts + 3 treat. with insecticides

No treatment

Treated block(For three years: 3 treatmens with SW+P)

Untreated block

Untreated block

Field trials in olive groves(Collepasso, LE – 2015-2018 - Field 1, Foliar treatments with SWP)

(Cv Cellina di Nardò)

Year 2018

Note as in the treated block, the first symptoms of disease

appear laterally, on canopy parts facing the untreated

blocks – No insecticide applied!

Untreated block

Untreated block

Field trials in olive orchards(Collepasso, LE – 2015-2018 - Field 1, Foliar treatments with SWP)

(Cv Cellina di Nardò)

Treated block up to spring-summer 2018(For three years: 3 treatmens with SW+P)Untreated block

Untreated block

Field trials in olive orchards(Collepasso, LE – Field 1 - 2015-2018

Foliar treatments with SWP)(Cv Cellina di Nardò)

Year 2020

Untreated

Plants


Field trials in olive orchards(Collepasso, LE – Field 2 - Three years (2015-2018) of soil and foliar treatments with different systemic

formulates) - (Cv Cellina di Nardò)

Treated

plantsSWP, soil: 3-4 Kg

per tree, 1 treatment

at beginning of

March

+SWP, canopy: 3

treatments during

spring-summer

Year 2017


Field trials in olive grovesSoil treatments with a SWP formulate under the canopy projection of an adult olive tree

Overview of the treatment on the soil of an olive

adult plant in the Xfp-infected zone

Untreated


Field trials in olive groves(Collepasso, LE – Field 2 - Three years (2015-2018) of soil and foliar treatments with different systemic

formulates) - (Cv Cellina di Nardò)

Treated(up to spring-summer 2018)

Year 2019

Soil treatment

SWP – ASSAYS ON POT-GROWN PLANTS

Control3 soil treatments

per season

Nursery experiments on Olive plants cv Leccino(naturally infected with Pseudomonas savastanoi pv. savastanoi)

Foliar sprays

(2% p/v water extract)

(2% v/v on pot soil surface)

The soil treatment was more effective than foliar sprays .. !

As evidenced by chemical analyses, treated plants, respect to untreated ones, showed higher content of macro and microelements in the foliage

In progress field trials in olive grovesfrom 2018 – to present

The possible control of Xfp needs of a wide and opened Integrated Strategy(combination of different products, insecticides and agronomic measures, against both bacteria and vector insects)

(Cvs Cellina di Nardò, Olgliarola Salentina and/or Leccino)

Collepasso (LE) Calimera, Martano (LE)

Melendugno (LE)

Assessment of Xfp populations inside the plants

CONCLUSIONSIn the absence of control measures (agronomic, biological and / or chemical), in the Xfp infected area

of Salento the olive trees are destined to progressivelydeclineand die.

The new formulates we are investigating reduce the progression of Xfp symptoms. However, they

are not able to eradicate the pathogen inside the plant if singularly applied!

Based on our research experience, now in different olive groves we are studying an integrated

approach (AI) based on the combination of soil and canopy treatments with most promising products,

together with preventive agronomic and chemical measures against vectors.

In the absence of other sustainable alternatives, our approach could be useful to avoid the complete

loss of traditional olive cultivars, deserving also attention to the high number of monumental trees

(centenary and even millenary trees) characterizing culture and traditions of the territory and its

inhabitants.

Our IA could be a valid tool to manage also Xfp resistant/tolerant olive Cvs (i.e. Leccino and Favolosa

(are not immune to Xfp!).

To obtain appreciable results, the control measures should be kept over the time and applied in wide

areas and not only at single farmer level. The management costs are often not sustainable for olive

growers….. Regional, National and EC governments should better support olive growers.

Thanks toDonato Boscia, Maria Saponari, Pasquale Saldarelli and co-workers

IPSP - CNR, Bari, IT

Stefania Loreti and co-workersCouncil for Agricultural Research (CREA ()

Rome, IT

For providing us with non-quarantine

phytopathogenic bacterial strains

The Research Projects

➢ BIOLIX «VALUTAZIONE DI STRATEGIE DI DIFESA BIOLOGICA SU OLIVO

PER LIMITARE LA DIFFUSIONE DI XYLELLA FASTIDIOSA PAUCA E DEL SUO VETTORE PHILAENUS SPUMARIUS» Regional Government of Apulia, IT.

➢ OLIDIXIIT «OLIVICOLTURA E DIFESA DA XYLELLA FASTIDIOSA E DA

INSETTI VETTORI IN ITALIA» Italian Ministry of Agriculture, Food and Forestry Policies (MIPAAF) and Council for Agricultural Research (CREA)

Plant Pathology Team - University of MoliseCampobasso, IT

Technical and scientific support

Thanks for Your Attention

evaluation of alternative compounds against xylella

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