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When 136 samples of dying carrot seedlings from several fields were analyzed Alternaria radicina proved to be the most common seedling pathogen (41 %), followed by some Fusarium species (27 %, mostly F. avenaceum).The less common seedling pathogens were Pythium spp. (13 %), Phoma spp. (2.5 %) and Botrytis cinerea (1.4 %). Some other fungi (Bipolaris sorokiniana, Sclerotinia sclerotiorum, Stemphylium botryosym and Ulocladium consortiale) were found in less than 1 % of seedlings examined.
Acta Agrobotanica
|
2002
|
tom 55
|
nr 1
255-263
Seed treatment of root parsley was done to protect Petroselinum sativum seedlings against damping off. Fungicides used as seed dressers were applied in 3 doses: 3, 5 and 10 g/kg. Seeds were treated with 7 dressers (Table 1) used separately and in mixture with 3 g/kg ofRovral50 WP (50% iprodione) and 1 g/kg of Apron 35 SD (35% metalaxyl). Two seed samples of Berlińska cultivar were used: [rrst sample was strongly infected by Alternaria petroselini and A. radicina both 27,6% and .:a1so by Fusarium spp. 5,4% (Test I), and second sample revealed lower percentage of infection 4,6% and 1,2%, respectively (Test m. The experiments were conducted under laboratory, glasshouse and field conditions. Complete seedlings protection a11 experiments was achieved for treatments when fungicide mixture was used the highest dose (10 g/kg). Decrease of fungicides concentrations were connected with lower effectiveness of disease control. No phytotoxic effects of the tested fungicide mixtures were observed under the glasshouse or field conditions.
Over 10 % of seeds harvested in 1991 and 1992 (50 samples, 400 seeds in each sample) proved to be infested with various fungi. Fusarium spp. and Botrytis cinerea were the most common pathogens isolated. Fusarium avenaceum was the most common and highly pathogenic species. Fusarium semitectum and F. tricinctum were highly pathogenic to lupin seedlings but they were the least common Fusarium isolated from seeds. Similarily, Sclerotinia sclerotiorum was isolated only from 0.2 % seeds tested but this fungus was highly pathogenic to lupin seedlings. Some other fungi know as lupin pathogens (F. oxysporum, Stemphylium botryosum, Pleiochaeta setosa and Phomopsis leptostromiformis) were also noted in tested seeds.
Altogether 300 seed samples were collected during 9 years in 8 regions of Poland and the fungi were isolated and their pathogenicity to carrot seedlings was examined. Alternaria radicina proved to be the most important pathogen although. A. alternata was more common. The other important pathogens were Fusarium spp., Phoma spp. and Botrytis cinerea. The infection of carrot seeds by A. radicina should be used as an important criterium in seed quality evaluation.
The studies on root parsley pathogens inhabiting seeds were conducted during 1981-1988 and in 1993. Filter paper method with prefreezing and keeping under light was used. Each test sample comprised 500 seeds. Pathogenicity of collected fungal isolates was tested following two laboratory methods. 238 seed samples were studied. 18 fungal species were found but only 7 proved to be important pathogens of root parsley. The most common inhabitants of root parsley seeds were Alternaria spp. A. alternata occurred on 74,8% of seeds but only a few isolates showed to be slightly pathogenic while A. petroselini and A. radicina were higly pathogenic and inhabited 11,4 and 4,2% of seeds, respectively. The second group of important pathogens were species of Fusarium found on 3,9% of seeds. F. avenaceum dominated as it comprised 48% of Fusarium isolates, the next were as follow: F. culmorum - 20%, F. equiseti - 15%, F. solani - 8%, F. oxysporum - 7% and F. dimerum -2%. Some fungi like Botrytis cinerea, Septoria petroselini and Phoma spp. inhabited low number of seeds, respectively 0,4; 0,5 and 0,8%, but they were highly pathogenic to root parsley. The fungi: Bipolaris sorokiniana, Drechslera biseptata, Stemphylium botryosum and Ulocladium consortiale showed slight pathogenicity. They were isolated from 3,8% of seeds.
The investigations were done between 1990-1994. Seedlings collected from 120 plantations were evaluated. The fungi responsible for seedling damping-off occurrening most often were Alternaria spp., Fusarium spp. and Pythium spp. isolated from 46,3, 32,2 and 16,6% of infected plants, respectively. The most important pathogens were A. petroselini which infected 33% of seedlings and A. radicina - 11%. Among Fusarium species the most common was F. avenaceum, comprising 61% of total Fusarium isolates. The next were following: F. culmorum - 21%, F. solani - 12,6% and 3% for both F. equiseti and F. oxysporum. Damping-off of seedlings was also caused by the other fungi but they were noted in low intensity. Among them were following: Phoma spp., A. alternata and Rhizoctonia solani on 2,8; 2,3 and 1,2% of tested seedlings, respectively. The species: Sclerotinia sclerotiorum, Botrytis cinerea, Bipolaris sorokiniana and Septoria petroselini were isolated in total from 0,9% of seedlings. Drechslern biseptatu and Stemphylium botryosum caused seedling damping-off sporadically.
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