A b s t r a c tThe present study was carried out in the years 2010-2012 in the fields of the Strzelce Plant Breeding Company Ltd., belonging to the Plant Breeding and Acclimatization Institute in Radzików, and it included 39 oat genotypes. At the six-week seedling stage, the percentage of plants with root and leaf sheath necrosis symptoms was evaluated. In 2010 the percentage of seedlings with disease symptoms ranged from 6.5% to 25%, in 2011 it ranged from 17% to 34.5%, whereas in 2012 from 10% to 25%. In 2010 the disease index ranged from 1.4 to 5.7, in 2011 from 4.5 to 8.8, while in 2012 it was between 2.0 and 5.4.Mycological analysis showed that large numbers of Fusarium spp. colonies were obtained both from the roots and leaf sheaths. Isolates of these fungi accounted for 63.48% of the total fungi isolated from seedlings. Seedlings grown under the conditions of central Poland were damaged by the species F. culmorum, F. avenaceum, and F. solani. The investigation of the susceptibility of 15 oat genotypes to infection with two Fusarium graminearum strains -Tz 56 and Tk 235 -was carried out under growth chamber conditions at a temperature of 22-23 o C and relative air humidity of 85%. The F. graminearum strain Tz 56 proved to be the most pathogenic to seedlings of the breeding lines STH 0.9403 and POB 1316/08, for which the disease index was 80.5 and 75.5, respectively. The lowest pathogenicity of the a.m. strain was recorded in the case of the genotype DC 1832/05, for which the disease index was 26.5. The F. graminearum strain Tk 235 proved to be the most pathogenic to the genotypes STH 0.9403 and STH 0.9423, for which the disease index was 70.5 and 70.0, respectively, whereas this strain was least pathogenic to the breeding line DC 2112/05, in the case of which the disease index was 25.5.

The subject of the studies was the soil with introduced solutions containing 0,1% chitosan. These materials were obtained from the Institute of Chemical Fibres in L6d2 (in the form of a microcrystalline gel) and also from the Department of Food Biochemistry and Chemistry of the University of Agriculture in Lublin (in a liquid form,i.e.dissolved in acetic acid). In order to set an experiment in a growth chamber, grey brown podzolic soil formed from loesses and taken from a mechanically treated belt of black fallow was used. The soil (1000 g) was watered every 8 days with 100 ml of examined chitosan solutions per pot. Control soil was watered with sterile distilled water. Seven days after each watering, soil samples were taken for microbiological analysis. Then 25 runner bean seeds were sown into each pot. After six weeks of plants' growth the experiment was finished and the number of plants was counted, their healthiness determined and soil microbiological analysis was performed. Regardless of chitosan form introduced to the soil it stimulated the growth of bacteria and fungi, since in these experimental combinations was found a significantly higher number of microorganisms as compared with the control. A particular high increase in the number of microorganism colonies was observed with simultaneous growth of plants and the application of chitosan. A considerable increase of fungi colonies from the <i>Trichoderma</i> genus was found in the soil treated with chitosan in the form ofboth a microcrystalline gel and a liquid. The species of this genus are considered to be antagonists; it affects pathogenic fungi through competition, antibiosis and over-parasitism. An increase in colonies of saprophytic microorganisms, including antagonistic ones of <i>Bacillus</i> spp. and Pseudomonas spp. was observed in the soil treated with chitosan . On the other hand, in the soil after the growth of bean and treated watered with chitosan only few colonies of <i>Fusarium oxysporum</i> f.sp. <i>phaseoli</i>- bean pathogen were found. The healthiness of plants grown in soil treated with chitosan was significantly better as compared to the control. The populations of antagonistic microorganisms formed in the soil in these treatments probably limited the growth of pathogenic fungus.

The objective of the paper was to establish the protective effect of post-culture liquids of Trichoderma harzianum G 227 and Gliocladium fimbriatum G 156 for soybean against the soil-borne fungi. The use of those liquids for studies had a positive effect on the number, healthiness and yielding of soybean plants. Soybean seedlings were mainly infected by Pythium irregulare, Fusarium spp. and Rhizoctonia solani, while plants at anthesis were affected by Fusarium spp., Phoma exigua var. exigua, Rhizoctonia solani and Sclerotinia sclerotiorum. The use of post-culture liquids reduced the infection of plants by these pathogens

Investigations were carried out in 2007–2009 on the plots of the Felin Experimental Station belonging to the University of Life Sciences in Lublin, Poland. The studies comprised two breeding lines of spelt wheat (<em>Triticum aestivum</em> ssp. <em>spelta</em> L. Thell.) – STH 3 and STH 715. Two levels of chemical protection were applied in the cultivation with minimal and complex protection. Infection of winter spelt wheat roots and stem bases was recorded in each growing season at hard dough stage (87 in Zadok’s scale). After 3 years of the study, the mean values of disease indexes for the analyzed spelt wheat lines in the experimental treatment with minimal protection were 28.53 and 40.30 respectively for STH 3 and STH 715. In the experimental combination with complex protection, after 3 years of the study the mean values of disease indexes ranged from 25.96 (STH 3) to 26.90 (STH 715). The mycological analysis showed that <em>Fusarium</em> spp., especially <em>F. culmorum</em>, caused root rot and necrosis of stem bases of spelt wheat in the experimental combination with minimal and complex protection. Moreover, <em>Fusarium avenaceum</em> and <em>Bipolaris sorokiniana</em> caused root rot and necrosis of stem bases of spelt wheat. Investigation carried out in a growth chamber on susceptibility of seedlings of three lines of spelt wheat (LO 2/09/n/2, LO 5/09/13/3, LO 5/09/5/4) to infection with <em>Fusarium graminearum</em> No. 8 and <em>F. graminearum</em> No. 45 showed that the genotypes did not differ in their susceptibility. All of them were susceptible, as indicated by high values of the disease indexes. No interaction was found between genotypes and strains of the fungus. This indicates the differential pathogenicity of <em>Fusarium graminearum</em> species.

Field studies on the health of American ginseng cultivated in the Lublin district on poor sandy soil were conducted in the years 2004-2006. The studies involved treatment combinations with irrigation and without irrigation as well as foliar fertilization with Alkalin PK and Resistim of American ginseng plants. Mycological analysis was made of diseased ginseng parts with the aim of determining the quantitative and qualitative composition of fungi-like organisms and fungi threatening the cultivation of this plant. Fungi from the genera of Cylindrocarpon, Fusarium and the following species Alternaria alternata, Rhizoctonia solani, Sclerotinia sclerotiorum, as well as fungi-like organisms: Pythium irregulare and Phytophthora sp., were isolated from the infected parts of ginseng. The smallest number of fungi was isolated from the plants growing on the plots without irrigation and those where foliar application with Alkalin PK was applied