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Gravi attacchi di Pseudomonas corrugata Roberts et Scarlett su pomodoro coltivato fuori suolo
No full textSevere damage caused by Pseudomonas corrugate Roberts et Scarlett on tornato soilless grown.
Severe damage caused by Pseudomonas Roberts et Scarlett occurred, on tomato cultivated by New Growing System (NGS), in greenhouse in Sardinia. Early simptoms consisted in yellowing of the lower leaves, adventious root formation, root necrosis, vascular discoloration and pith necrosis. Infected plants collapsed, wilted and died J'seudomonas corrugata was isolated from plants and from nutrient circulating solution. Pathological, biochemical and serological tests on isolated strains confirmed that isolates belong to P. corrugata. Polymerase chain reaction (PCR) performed by using specific primes, revealed the presence of either one of two bands (600 bp and 1100 bp) typical of corrugata, representing I and I I groups. An atypical band obtained from a sardinian strain IPV-SS6FP suggest the presence of an insertion sequence of 20-50 bp. ELISA results on infected plants and nutrient circulating solution probably rely on bacterial concentration. Suitable control means to prevent or contain this disease are suggested
A new bacterial disease of Chrysanthemum: a stem rot by Pseudomonas corrugata Roberts et Scarlett
No full textA stem rot of chrysanthemum (Chrysanthemum [Dendranthema] morifolium) was observed in different greenhouses in southern Sardinia in the autumn of 1990, 4-5 weeks after planting. Cultivars White marble, Yellow marble, Dark pink marble and Splendid marble were all affected to the same degree. On the basis of pathogenicity, cultural, physiological, biochemical and serological tests, the pathogen was identified as P. corrugata. The main biochemical and physiological characteristics of the isolate (98a) are listed, together with those of numerous other P. corrugata isolates reported in the literature. This is the first report of P. corrugata infecting chrysanthemum. Methods of controlling the disease are suggested
Riduzione dei danni da gelo sul carciofo mediante il contenimento biologico e chimico dei batteri criogeni
No full textReduction of frost injury to artichoke by biological and chemical control of INA-bacteria.
The results of biological and chemical control of INA (ice nucleation active) epiphytic bacteria and their effects on frost injury in artichokes "Spinoso sardo" in Sardinia (Italy) are reported. Two non-INA antagonistic Pseudomonas fluorescens strains (MG3 and 12PV), which were isolated from field-grown artichoke leaves, and some chemicals (streptomycin + tetracyclin, kasugamycin and cupric hydroxide) were tested.
The bacteria on the artichoke leaves were both INA and non-INA P. fluorescens and P. syringae strains; three INA strains of P. syringae were also pathogenic to young artichoke plants.
In vitro, the two non-INA P. fluorescens strains showed an antagonistic activity against two INA P. fluorescens and P. syringae strains, due to the production of siderophores and antibiotics.
In field trials, both the two antagonistic strains and chemicals, especially the antibiotics, reduced the size of the populations of INA bacteria present on leaves as well as the amount of frost damage to leaves and heads
L'«Avvizzimento» del cartamo (Carthamus tinctoriusL.) causato daVerticillium dahliaeKleb.
No full textThe wilt of safflower (Carthamus tinctoriusL.) byVerticillium dahliaeKleb., hitherto unreported in Italy,
has been found on last two years in Sardinia.
The disease symptoms and the pathogen characters are described.
Artificial inoculation tests allowed to state that our isolate is highly virulent to this host
Characterization of Burkholderia gladioli strains causal agents of saffron (Crocus sativus L.) bacterial rot
No full textBurkholderia gladioli is the causal agent of a bacterial disease
recently reported in saffron (Crocus sativus L.) grown in central
Sardinia (Italy). The symptoms were rot of emerging flowers and
shoots, and spots on leaves. In the last two years the disease has
been particularly harmful, reducing flowering by some 80%. Isolations
on nutrient glucose agar from symptomatic plants produced
two types of colony. The first type (ten isolates) was round,
wrinkled, and yellowish. The second type (fifteen isolates) was
round, smooth and colourless. In pathogenicity tests, the twenty
five isolates reproduced symptoms on saffron plants, while only
the first type of isolate was pathogenic on gladiolus leaves. The
twenty five isolates were analyzed with the computerised BIOLOG
system, conventional tests and genomic tests such as PCR
and PCR-RFLP. BIOLOG, conventional tests and PCR using
LP1 and LP4 primers, identified all isolates as Burkholderia gladioli.
PCR-RFLP analysis using three restriction enzymes (AluI,
DdeI and BssKI), identified only ten of the isolates (nine wrinkled
and one smooth) as B. gladioli pv. gladioli. Our evidence indicates
that other B. gladioli forms are also involved in this bacterial rot
of saffron, and further studies are under way to verify this
Risultati di un triennio di lotta all’oidio del carciofo in Sardegna
No full textThree-years of control trials against the powdery mildew of artichoke in Sardinia
The results of field trials carried out in 1999-2001 in Sardinia against powdery mildew [Leveillula tourica Lév.) Arn. f. sp. cynarae Jacz.] on artichoke {Cynara scolymus L.) are reported. Treatments were performed by applying several registered or experimental compounds. The efficacy of quinoxyfen and azoxystrobin, which was tested alone or in rotation with others fungìcides, was compared with specific chemicals usually applied on artichoke to control powdery mildew.
Quinoxyfen and azoxystrobin, alone or in rotation with penconazole, proved to be very effective against powdery mildew even in the presence of high disease pressure. A satisfactory control was provided by pyrifenox, fenarimoi, nuarimol, hexaconazole, penconazole, tetraconazole and, to a lesser extent by dinocap. Control of powdery mildew with mixtures of hexaconazole + copper oxychloride and nuarimol + copper hydroxide was unsatisfactory, due to a negative influence of copper compounds
Le Malattie crittogamiche del carciofo e relativi metodi di lotta
No full textVengono descritte le malattie fungine (oidio da Leveillula taurica f. sp. cynarae; peronospora da Bremia lactucae; marciume dei capolini da Botrytis cinerea; “marciumi del colletto” da Rhizoctonia solani, Sclerotinia sclerotiorum e Sclerotium rolfsii) e batteriche (marciume radicale batterico da Erwinia carotovora subsp. carotovora) del carciofo. Condizioni climatiche tipiche dell’Isola e tecnica colturale adottata (forzatura e sistemi di irrigazione) rivestono ruolo fondamentale e rappresentano fattori essenziali nella predisposizione della coltura agli attacchi parassitari. Per prevenire e contenere le malattie fungine, si riportano strategie di lotta e principi attivi frutto di anni di sperimentazione. Per quanto riguarda il contenimento del marciume radicale batterico, non disponendo al momento principi attivi efficaci, vengono riportati le strategie di lotta indiretta
Caratteri patogenetici, microbiologici, sierologici ed elettroforetici di alcuni isolati di Pseudomonas corrugata.
No full textCARATTERI PATOGENETICI, MICROBIOLOGICI, SIEROLOGICI ED ELETTROFORETICI DI ALCUNI ISOLATI DI PSEUDOMONAS CORRUGATA. Pseudomonas corrugata Roberts et Scarlett, segnalato per la prima volta in Inghilterra nel 1978 quale agente della "necrosi del midollo" del Pomodoro, è ormai presente nei principali paesi ove viene coltivata la solanacea. Oltre che su radici asintomatiche di erba medica il batterio è stato re¬centemente rinvenuto su Crisantemo, ove provoca il "marciume del fusto", e su Peperone nel quale è responsabile della "necrosi del midollo".
Esso presenta adattabilità patogenetica e mostra variabilità in alcuni caratteri microbiologici e sierologici degni di maggiore considerazione e approfondimento.
La "necrosi del midollo" del Pomodoro è presente anche in Sardegna e in Sicilia ove P. corrugata è stato ripetutamente isolato ed identificato.
Nel presente lavoro sono stati presi in considerazione tredici isolati (11 da pomodoro e 2 da crisantemo); di questi è stata saggiata la patogenicità in diverse specie e varietà ortive e floricole; sono stati studiati i carat¬teri morfologici, biochimici, fisiologici e sierologici ed è stata eseguita l'ana¬lisi elettroforetica (CHEF) dei frammenti di restrizione del DNA cromosomale. Gli isolati hanno indotto caratteristici sintomi di necrosi del midollo su pomodoro e reazioni variabili (imbrunimenti e/o necrosi del midollo) su lattuga, peperone, garofano e crisantemo; cavolfiore e cavolo rapa hanno mostrato iperplasie e accrescimenti definiti a carico del midollo con conseguente fessurazione del fusto.
Gli stessi isolati hanno mostrato variabilità nella morfologia delle colonie, nella produzione di pigmenti diffusibili e nella risposta ai più importanti tests.
I saggi di agglutinazione su piastra (ODD), immunofluorescenza ed ELISA, hanno rivelato, nei confronti dell'antisiero usato, risposte variabili.
L'analisi CHEF ha evidenziato un certo polimorfismo dei frammenti di restrizione ottenuti dopo taglio con enzimi di restrizione a bassa frequenza di taglio (xbai e DraI). I profili ottenuti sono risultati caratteristici e differenti da quelli di altre Pseudomonadi (P. syringae e P. fluorescens)
Bacterial stem rot in greenhouse pepper (Capsicum annuum, L.) In Sardinia (Italy): occurrence of Erwinia carotovora subsp. carotovora
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