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The impact of combined environmental factors, such as temperature and CO₂, on the control of the powdery mildew of zucchini, caused by Podosphaera xanthii, and of different control measures has been studied on plants grown in phytotrons. Five experimental trials were conducted, and the powdery mildew severity of both treated and untreated zucchini plants was found to be significantly affected by the interaction between temperature (three different regimes: 16–18; 18–22; 22–26°C), CO₂ (two concentrations: 400–450 and 800–850 ppm) and the treatments. However, at the end of the trials, the efficacy of all the products was not affected by the different, tested environmental conditions. Sulphur consistently provided the highest disease control (75%–85% efficacy). Among the resistant inducers that were tested, calcium oxide was the most effective, in terms of powdery mildew control under all the conditions tested in phytotrons, reducing disease severity from 46% to 61%. Foliar applications of phosphite (14%–28% efficacy), Ampelomyces quisqualis (12%–23% efficacy) and potassium silicate (13%–24% efficacy) only slightly reduced the disease severity for all the tested temperature regimes and CO₂ concentrations, compared to the untreated control. The results obtained under our experimental conditions show that a possible increase in CO₂ concentration and temperature, which is expected for the next few years, should not influence the efficacy of the tested resistance inducers or of sulphur against powdery mildew on zucchini. Moreover, the suppressive effect of calcium oxide is in light of its possible use in greenhouses for zucchini powdery mildew control under 400–450 ppm of CO₂ and under enriched condition of 800–850 ppm of CO₂.

Seed-dressing with essential oils from aromatic plants (savoury and thyme) and with antagonistic bacteria strains (Pseudomonas spp.) was tested after a hot water treatment against Alternaria radicina inoculated on carrot seeds. Seed treatments by immersion in water at 55°C for 10 min improved the efficacy on pathogen control of the treatments with biocontrol agent strains more than the efficacy of those with essential oils. Pretreatment with hot water also increased the germination rate of carrot seeds. A mild phytotoxic effect was observed on the germination rate and the fresh biomass obtained from seeds treated with both essential oils. Treatments with essential oils and antagonistic bacteria presented positive results when combined with hot water dipping of seeds on control of A. radicina, but the effect was not completely additive. The formulation and the application method of the non-chemical products tested are critical on their development as an alternative strategy on seed disinfection.

The pathogenicity of different isolates of Fusarium oxysporum obtained from plants of Gerbera (Gerbera jamesonii), Chrysanthemum (Chrysanthemum morifolium), Paris daisy (Argyranthemum frutescens) and African daisy (Osteospermum sp.), all in the family Asteraceae, was tested on different cultivars of these hosts, to assess their pathogenicity. The reactions were compared with those of isolates of F. oxysporum f. sp. chrysanthemi and of f.sp. tracheiphilum obtained from the American Type Culture Collection. We found that isolates of F. oxysporum f. sp. chrysanthemi can be distinguished as three physiological races on the basis of their pathogenicity to the panel of differential cultivars. Sequencing of the intergenic spacer (IGS) region of ribosomal DNA (rDNA) and phylogenetic analysis showed that the Fusarium races fell into three phylogenetic groups, which coincided with those observed in pathogenicity tests. Analysis of the IGS sequences revealed a high degree of similarity among strains from Italy and Spain from different host species, suggesting that recent outbreaks in these ornamentals were probably caused by introduction of infected nursery material from a common origin.

The aim of this study was to evaluate the effect of potassium silicate administration and of electrical conductivity of nutrient solution in three experiments against Colletotrichum gloeosporioides infection on basil (Ocimum basilicum L. cv Genovese Gigante) grown in a closed soilless system. Potassium silicate was added at 100 mg/l of nutrient solution at three different levels of electrical conductivity: 1.5–1.6 mS/cm (E.C.1), 3–3.2 mS/cm (E.C.2, 0.70 g/l NaCl) and 4–4.2 mS/cm (E.C.3, 0.95 g/l NaCl). Basil plants were inoculated with C. gloeosporioides spores 21–31 days after sowing or placing the pots on the channels, applying 5 ml of conidial suspension to each treatment. The increased electrical conductivity of the nutrient solution generally reduced the incidence and severity of the disease, with the highest electrical conductivity (E.C.3) providing the best results. The addition of potassium silicate to the different nutrient solutions showed a significant reduction in both incidence and severity of the disease compared to a solution without silicate and the best results were given by the addition of silicate with the highest electrical conductivity (E.C.3) in all the trials carried out. The combination of high electrical conductivity and potassium silicate supplied gave good results. The possibility and benefits of applying Si amendments in practice are examined.

A total of 35 isolates of Fusarium oxysporum f.sp. eustomae obtained from diseased Eustoma grandiftorum plants in northern Italy, showing typical Fusarium wilt symptoms, were analysed for their genetic variability and molecular identification. Genetic diversity of the isolates was studied by using random amplified polymorphic DNA (RAPD). This analysis clustered the isolates into three groups at a genetic similarity of 69%. Sequence analysis of RAPD fragments led to the design of a pair of specific primers that amplify a 505-bp SCAR (sequence characterized amplified region) marker (SCAR 505 ) which was used to rapidly detect F. oxysporum f.sp. eustomae on Eustoma grandiflorum plants. In a temperature-controlled chamber, detection of the pathogen by PCR was 100% successful in root and stem samples of infected but still symptomless plants. The diagnostic procedure could be completed in 1 day and allowed rapid and reliable detection of the pathogen in asymptomatic plants in the early stages of disease development.

The random amplified polymorphic DNA (RAPD) technique was used to analyze the total genomic DNA of pathogenic isolates of Fusarium oxysporum on Gerbera jamesonii by comparing them to representatives of the formae speciales chrysanthemi and tracheiphilum. A close genetic relationship was observed among most of the new isolates from G. jamesonii. They shared RAPD markers with the tested representatives of the forma specialis chrysanthemi. Some isolates of those tested from diseased G. jamesonii were placed in a different cluster, which included representative isolates of forma specialis tracheiphilum. This is the first report of F. oxysporum f.sp. tracheiphilum on G. jamesonii. A rapid protocol for DNA extraction directly from fungal colonies grown on potato dextrose agar allowed complete analysis in less than 4 h.

In this work, a protocol for zoospores production of Phytophthora cryptogea, an economically important plant pathogen was optimized. Five different concentrations of zoospores (5 × 10 5 , 5 × 10 4 , 5 × 10 3 , 5 × 10 2 , 5 × 10 1 zoospores/ml) from four different isolates of P. cryptogea (Maria 1, Maria 2, S3 1-A, Amazzone) were used as inoculum on pot marigold (Calendula officinalis) and gerbera (Gerbera jamesonii) plants. Maria 1 was the most virulent isolate both on pot marigold and gerbera plants according to disease severity. A rapid and sensitive pathogen DNA extraction protocol suitable for large quantities of plant samples was adopted. Conventional polymerase chain reaction (PCR) was able to detect the pathogen in artificially inoculated symptomless pot marigold (collected day 12) and gerbera plants (day 8) after pathogen inoculation, with the suspension of 5 ×10 5 , 5 ×10 4 , 5 ×10 3 P. cryptogea zoospores/ml. Real-time PCR showed the possibility to detect the pathogen in artificially inoculated symptomless pot marigold (collected day 8) and gerbera plants (day 4) after pathogen inoculation, with the suspension of 5 × 10 5 , 5 × 10 4 P. cryptogea zoospores/ml. The first symptoms appeared on pot marigold plants 14 days after pathogen inoculation and on gerbera plants 10 days after inoculation. Real-time PCR showed the possibility to detect the pathogen 4 days before conventional PCR and 6 days before the appearance of disease symptoms both on pot marigold and gerbera plants.

The pathogenicity of five isolates of Fusarium oxysporum obtained from infected gerbera (Gerbera jamesonii), chrysanthemum (Chrysanthemum morifolium), Paris daisy (Argyranthemum frutescens) and African daisy (Osteospermum sp.) plants was tested on some varieties of the following Compositae hosts: C. morifolium, G. jamesonii, Argyranthemum frutescens (Paris daisy) and Osteospermum sp. and compared with the host range and pathogenicity of an isolate of F. oxysporum f. sp. chrysanthemi obtained from the ATCC collection. The results indicated that isolates of F. oxysporum from G. jamesonii as well as those from A. frutescens and Osteospermum sp. belong to the forma specialis chrysanthemi. The isolate from gerbera was virulent on all tested varieties of gerbera, C. morifolium, A. frutescens and Osteospermumsp. Similar results were obtained testing the isolates obtained from A. frutescens and Osteospermumsp. The strain from C. morifolium infected cultivar of gerbera, A. frutescens and Osteospermum sp. The pathogenicity of isolate of F. oxysporum f. sp. chrysanthemi obtained from the ATCC showed a different cultivar range particularly in the case of chrysanthemum and gerbera.

From 2002 to 2004, wilted plants of different species of rocket (Eruca vesicaria and Diplotaxis spp.) were found for the first time in Europe, in greenhouse cultivations in Piedmont and Lombardy, northern Italy. The causal agent of the disease was found to be Fusarium oxysporum. Vegetative compatibility analysis was carried out on 46 isolates of the fungus, 41 of them obtained from wilted rocket (E. vesicaria and D. tenuifolia) and five reference strains, in order to increase the knowledge on the causal agent of recent epidemics of Fusarium wilt on rocket in Italy. The analysis showed the presence of two vegetative compatibility groups (VCGs) (VCG 0101 and VCG 0220) pathogenic on both kinds of rocket. The two VCG populations, which were classified as formae speciales conglutinans and raphani, respectively, are spread in the area of epidemics but are not related to the host species from which they were isolated (D. tenuifolia or E. vesicaria). This finding shows the heterogeneity of the causal agent of Fusarium wilt on rocket in Italy.

A real-time polymerase chain reaction (PCR) assay using a TaqManprobe was developed to detect the causal agent of wilt and crown rot of basil from infec- ted plants and seed in Italy. The aim of the study was to diminish testing time, previously performed using nested-PCR, and to create the conditions for future automation. The sensitivity of the assay was shown to be similar to the detection limit of the available nes- ted-PCR procedure. The advantages of real-time PCR system include halving of the testing time, as well as the ability to identify both internally and externally infected seed to the sensitivity of 1 pg of genomic DNA. The assay was able to detect the presence of the pathogen in infected seed up to a sensitivity of 24 (SD: ±10) CFU per 100 seeds.

The random amplified polymorphic DNA (RAPD) technique was used to analyse total genomic DNA of 10 isolates of a new Fusarium oxysporum pathogenic on Argyranthemum frutescens (Paris daisy), by comparing them with representatives of the formae speciales basilici, chrysanthemi, cyclaminis, dianthi, gladioli, lilii, lycopersici, melonis, pisi, radicis-lycopersici, tracheiphilum, and a non-pathogenic isolate of F. oxysporum. A close genetic relatedness was observed among most of the new isolates from A. frutescens. These isolates also shared RAPD markers with the tested representatives of the forma specialis chrysanthemi. A single isolate among those tested from diseased A. frutescens was placed in a different cluster, which included representative isolates of forma specialis tracheiphilum. All the new isolates from A. frutescens, with the exception of the single divergent one, could be identified by their characteristic amplification profile, using selected random primers. A rapid protocol for DNA extraction directly from fungal colonies grown on Fusarium selective medium allowed the complete analysis in less than 4 h.