Interspecific relation peculiarities between soil and phytophatogenic fungi

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1 SCIENTIFIC WORKS OF THE LITHUANIAN INSTITUTE OF HORTICULTURE AND LITHUANIAN UNIVERSITY OF AGRICULTURE. SODININKYSTĖ IR DARŽININKYSTĖ (3). Interspecific relation peculiarities between soil and phytophatogenic fungi Danguolė Bridžiuvienė, Jūratė Repečkienė Institute of Botany, Žaliųjų ežerų st. 49, LT Vilnius, Lithuania, Ecological methods of biological control of plant diseases became more and more popular in recent years. The aim of the investigation was to select soil fungi applicable for protection from causative agents of cultural plant diseases. Antagonistic activity of fungi was studied by pairing method using cultural blocs, cultural liquid and volatile metabolites. 43 fungal strains were examined against Alternaria brassicicola, A. radicina, A. tenuissima, Cladosporium cucumerinum, C. tenuissimum, Colletotrichum linicola, Fusarium culmorum, F. oxysporum, F. solani and Phoma sp. It was found that 36 of them showed varying degree of antagonistic activity against treated strains. Most strains suppressed the growth of Cladosporium genus phytopathogens and the growth of Fusarium genus strains was stopped rarely. Some of screened strains excreted fungicidal compounds to cultural liquid (for example, Trichoderma virens and Penicillium sp.) and some acted through their volatile metabolites (Arthrinium sphaerospermum and Trichoderma virens). The optimization of cultivation conditions as well as the choice of duration of cultivation is important factor to fungi ability to produce fungicidal compounds. Key words: fungi, fungicidal action, fungistatic action, plant pathogens. Introduction. Sustainable agriculture should apply environment-friendly strategies to avoid pollution of soil, water and products by chemicals. Consequently, in plant protection field the main attention has been concentrated on the biological control of plant pathogens in recent years. It is probable that biological control acts rarely through a single mechanism. Biological control agents may simply operate by occupying the ecological niche of the target organism so preventing its establishment and reducing its population. In this way antagonistic fungal species displace pathogens. Production of inhibitory to pathogens substances, including soluble, nonvolatile and volatile components, as well as extracellular enzymes are other ways of biological control. An inhibiting action of antagonists led to the reduction of phytopathogen conidia production and suppression of growth (Calistru et al., 1997; Schoeman et al., 1999; Kalko et al., 2001). Not all soils are rich in fungi with antagonistic abilities. It was found that introduction of several indigenous Trichoderma strains into the soil considerably affected 19

2 the species composition. These changes influenced the phytosanitary state of soils and reduced the infectious lodging of conifer seedlings (Yakimenko, Grodnitskaya, 2000). It was noticed that fungi isolated from the same environment as pathogens are more effective. For biological control the native strains should be used better and their population should be enriched in soil. Many studies of biocontrol agents have focused on Trichoderma species but the attempt to find more species with antagonistic abilities are made as well. Grapes inoculated with Botrytis cinerea were protected from disease by Trichoderma viride 81.2 % and by T. harzianum 81.8 % (Machowicz-Stefaniak, 1998). Active strains against Fusarium wilt diseases were found among Penicillium, Trichoderma, Gliocladium and Nigrospora genera fungi (Srinon et al., 2006). The study of interspecific relations between soil fungi and plant pathogens may turn a background for biocontrol technologies. The aim of the investigation was to screen soil fungal strains with antagonistic properties against plant pathogens. Object, methods and conditions. For primary antagonistic activity screening, 43 fungal strains isolated from soil were used. As target fungi 10 phytopathogens were chosen: Alternaria brassicicola (Schwein.) Wiltshire 0722; A. radicina Meier, Drechsler et E. D. Eddy EŽ-25; A. tenuissima (Kunze) Wiltshire U-H-0; Cladosporium cucumerinum Ellis et Arthur 0721; C. tenuissimum Cooke 0679; Colletotrichum linicola Pethyrb. et Laff. U-L-07; Fusarium culmorum (W.G.Sm.) Sacc. 0691; F. oxysporum Schltdl. 0720; F. solani (Mart.) Appel et Wollenw and Phoma sp. B-G-04. Tests for the biotic interaction among the fungi were carried out on malt agar in Petri dishes. The test fungi discs (1 cm in diameter) were cut from 7-day-old colonies and placed on malt agar medium, which was inoculated with phytopathogen spore suspension. Plates were incubated at the temperature of 26 C. After 3 days of incubation, the diameter of fungicidal or fungistatic zones around agar discs was measured. The width of the resulting inhibitory zone was used as a measure of antagonistic activity (Билай, 1982). For detection of antagonistic effect of their culture filtrates, soil test-fungi were incubated in liquid Czapek medium for 7 days. Mycelium was removed by filtration. 5-, 7- and 12-day culture filtrates (0.1 ml) were placed in hole made in agar inoculated with target-fungi. Plates without the filtrate served as control. Plates were incubated at the temperature of 26 C. After 3 days of incubation the width of fungicidal or fungistatic zones around holes was measured (Билай, 1982). Detection of volatile antibiotics was performed by placing an inverted culture of a susceptible test-culture over that of the potential antagonist. Any reduction in the growth rate relative to control (expressed in %) by measuring colony diameter after 4, 6 and 8 days was estimated. Some modified Czapek agar mediums were used for estimation of medium composition influence on volatile antibiotic production (Wheatly et al., 1997). The carbon source sucrose in standard medium was replaced by 2 % of glucose and in another variant in latter medium nitrogen source NaNO 3 was replaced by 5 g of peptone. 20

3 Results. Fungi isolated from various soils and plant remnants were selected for the primary screening of their antagonistic activity. In total 43 strains belonging to 15 different genera were studied and 36 of them showed varying degree of antagonistic activity to phytopathogenic fungi belonging to genera Alternaria, Cladosporium, Colletotrichum, Fusarium and Phoma. The data of soil fungi interaction with various genera of phytopathogens are given in Table 1. Table 1. Number of soil fungal strains affecting the growth of phytopathogens from different genera 1 lentelė. Tirtų dirvožemio mikromicetų padermių, veikiančių įvairių genčių fitopatogeninius mikromicetus, skaičius Genera of soil fungi Dirvožemio mikromicetai Number of tested strains Tirtų padermių skaičius Number of active strains against phytopathogens Aktyvių padermių skaičius Cladosporium Fusarium (2 strains (3 strains 2 padermės) 3 padermės) Alternaria (2 strains 2 padermės) 21 others (2 strains) kitos (2 padermės) Acremonium 6 2* (1)** 2 (1) (4) 1 (2) Arthrinium 5 (2) 2 (1) (5) (5) Chaetomium (2) 4 Cylindrocarpon (1) (1) Clonostachys Cunninghamella Humicola (1) (1) Mariannaea Mortierella (2) 2 Oidiodendron 1 1 2(1) (1) (2) Paecilomyces (2) (2) Penicillium 8 4 (4) 7 (5) 6 (7) 6 (2) Talaromyces 2 1 (2) 2 (1) 1 (2) 2 (2) Trichoderma 5 2 (1) 4 (1) 2 (4) 2 (10 Umbelopsis 2 (1) 1 (1) 1 (1) 1 (1) In total / Iš viso (10) 27 (11) 18 (32) 20 (13) * fungicidal effect / fungicidinis poveikis ** fungistatic effect / fungistatinis poveikis The biggest number of antagonists suppressed the growth of Cladosporium genus fungi 27 strains (62.8 %) showed fungicidal activity and fungistatic activity was estimated mostly against Fusarium culmorum, F. oxysporum and F. solani (32 strains tested or 74.4 %). The greatest number of active strains was found among Chaetomium, Penicillium and Trichoderma species. It should be noted, that Chaetomium elatum Kunze 5OA; 8OA and Ch. globosum Kunze EŽ-27 affected the phytopathogens not only by stopping their growth around the discs (due to extra-cellular metabolites), but by overgrowth of the target fungi as well (due to their competitive abilities). Therefore, the inhibitory zones around Chaetomium discs reached 5 8 mm in pairing with Alternaria, Fusarium, Phoma and even 6 11 mm in pairing with Colletotrichum, Cladosporium

4 genera strains. Among Penicillium the strains P. simplicissimum (Oudem.) Thom EŽ- 25 and Penicillium sp were more active as compared with other strains studied, especially against Alternaria and Cladosporium (diameter of sterile zones reached 3 15 mm). Trichoderma virens (J. H. Mills, Giddens et A. A. Foster) Arx S29-1, T. hamatum (Bonord.) Bainier S37-1 and T. viride Pers S29-2 stopped the growth of the mentioned phytopathogens in 8 20 mm. Most active 18 strains were selected for further studies on ability to release antibiotics to nutrient medium. Four phytopathogens of different genus were chosen as target-fungi. The cultural filtrates of 15 strains affected fungistatically and/or fungicidally the growth of Alternaria radicina and Fusarium solani, 14 Cladosporium cucumerinum and 12 F. culmorum (Table 2). The obtained data showed that the inhibitory action of cultural filtrates differed in time ant specificity. The action of fungal cultural filtrates was mostly fungistatic and the width of growth suppression zone varied from 1 mm when, for example, Penicillium simplicissimum 5-day cultural filtrate was used against Fusarium culmorum, to 15 mm when Trichoderma virens S day cultural filtrate was used against Alternaria radicina. The growth of A. radicina most strongly was inhibited by 7-day cultural filtrate of Penicillium sp (fungicidal zone 18 mm), Cladosporium cucumerinum by 7-day cultural filtrate of Gliocladium sp. Cr-3d (fungicidal zone 8 mm), Fusarium culmorum by 5-day cultural filtrate of Acremonium roseum (Oudem.) W. Gams U-5-60 (fungicidal zone 5 mm) and F. solani by 5-day cultural filtrate of Penicillium sp (fungicidal zone 5 mm). Table 2. Antagonistic action of fungal cultural filtrates towards plant pathogen fungi (active strain number after 5, 7 and 12 cultivation days) 2 lentelė. Mikromicetų kultūrinio skysčio antagonistinis poveikis fitopatogeniniams grybams (aktyvių padermių skaičius po 5, 7 ir 12 augimo parų) Phytopathogenic fungi Growth days Fitopatogeniniai grybai Auginimo paros Alternaria radicina Cladosporium cucumerinum Fusarium culmorum Fusarium solani 5 4* (8)** 4 (9) 2 (5) 1 (6) 7 6 (8) 8 (5) 0 (8) 3 (10) 12 4 (8) 1 (8) 1 (8) 1 (12) * fungicidal effect / fungicidinis poveikis ** fungistatic effect / fungistatinis poveikis Antibiotic effect of fungal cultural filtrates depended on cultivation timescale and changed in the course (Fig.). Some of them decreased gradually. The cultural filtrate of Chaetomium elatum 8OA showed the strongest fungicidal effect towards Alternaria radicina on 5 th cultivation day and made up 9 mm width inhibitory zone. On 7 th day it declined to 6 mm zone and on 12 th day reached only 3 mm. The latter antagonist showed towards Cladosporium cucumerinum a dual effect (fungistatic and fungicidal) at the same time. 22

5 Fig. Dynamics of antagonistic activity of Chaetomium elatum 8OA culture filtrate on Alternaria radicina and Cladosporium cucumerinum Pav. Chaetomium elatum 8OA kultūros filtrato antagonistinio poveikio Alternaria radicina ir Cladosporium cucumerinum dinamika The action of Paecilomyces sp. S. p-20 cultural filtrate decreased as well, and even turned from fungicidal on 5 th day (5 mm inhibitory zone) to fungistatic on 12 th day (5 mm suppression zone). The antagonistic (fungistatic) effect of Penicillium griseofulvum Dierckx 0457 towards Alternaria radicina, on the contrary, increased in the course of cultivation and made up 2 mm suppression zone on 5 th and later reached 5 mm suppression zone. Mariannaea elegans G. Arnaud L14-3 has no antibiotic activity towards Alternaria radicina on 5 th cultivation day, but his cultural filtrate on 7 th day showed fungistatic effect (13 mm zone) and even fungicidal effect (7 mm zone) on 12 th day. Nevertheless, in most cases the highest antibiotic effect appeared on 7 th cultivation day. The action of volatile metabolites, produced by Arthrinium sphaerospermum Fuckel Pl-5/10, Mortierella alpina Peyronel 3OB, Penicillium simplicissimum EŽ-25 and Trichoderma hamatum S37-1 towards the growth of plant pathogens was studied (Table 3). The most effective producer of volatile metabolites was T. hamatum S37-1. For example, the growth of Alternaria brassicicola was suppressed in %, compared with control, (relative colony width was %, respectively) under the action of Penicillium simplicissimum EŽ-25, but even in % under the action of T. hamatum S37-1 (relative colony width was %, respectively). The volatile metabolites of Arthrinium sphaerospermum Pl-5/10 effectively suppressed the growth of Alternaria brassicicola (relative size of colonies comparing to control after 8 days was 24 %), Colletotrichum linicola (55 %), Fusarium culmorum (62 %) and Phoma sp. (67 %). Mortierella alpina was more effective against Alternaria tenuissima, but stimulated the growth of some phytopathogenic strains (Cladosporium tenuissimum and Fusarium culmorum). The volatile metabolites of Penicillium simplicissimum EŽ-25 were less effective (suppressed the growth of various strains 1 32 %). It was noticed that action of volatile metabolites was the greatest after 8 days growth, but in some cases it reached maximum just after 6 days (Arthrinium sphaerospermum Pl-5/10 and Mortierella alpina 3OB against Cladosporium and Fusarium genera strains). 23

6 Table 3. Relative colony diameter (%) of phytopathogenic fungi under action of volatile metabolite produced on malt extract medium after 4, 6 and 8 cultivation days 3 lentelė. Santykinis fitopatogeninių mikromicetų kolonijų, tirtų veikiant mikromicetų lakiaisiais metabolitais po 4, 6 ir 8 kultivavimo parų, skersmuo (%) Phytopathogenic fungi Fitopatogeniniai grybai Arthrinium sphaerospermum Pl-5/10 Mortierella alpine 3OB Penicillium Trichoderma simplicissimum hamatum EŽ-25 S Alternaria brassicicola Alternaria radicina Alternaria tenuissima Cladosporium cucumerinum Cladosporium tenuissimum Coletotrichum linicola Fusarium culmorum Fusarium oxysporum Fusarium solani Phoma sp The cultivation of Arthrinium sphaerospermum Pl-5/10 and Mortierella alpina 3OB on different media showed the volatile metabolite production dependence on medium composition (Table 4). Table 4. The effect of volatile metabolites of test-fungi Arthrinium sphaerospermum Pl-5/10 and Mortierella alpina 3OB grown on modified Czapek media towards plant pathogens (relative colony diameter after 7 cultivation days, %) 4 lentelė. Mikromicetų Arthrinium sphaerospermum Pl-5/10 ir Mortierella alpina 3OB, augintų ant modifikuotų Čapeko terpių, lakiųjų metabolitų poveikis fitopatogenams (santykinis kolonijų skersmuo po 7 kultivavimo parų, %) Phytopathogenic fungi Fitopatogeniai grybai Arthrinium sphaerospermum Pl-5/10 czapek czapek with czapek with with 2 % 2 % 2 % glucose glucose sucrose and peptone čapekas su čapekas su čapekas su 2 % 2 % 2 % gliukozės gliukozės sacharozės ir peptonu czapek with 2 % glucose čapekas su 2 % gliukozės Mortierella alpina 3OB czapek with 2 % sucrose čapekas su 2 % sacharozės czapek with 2 % glucose and peptone čapekas su 2 % gliukozės ir peptonu Alternaria brasicicola Alternaria radicina Alternaria tenuissima Cladosporium cucumerinum

7 Table 4 continued 4 lentelės tęsinys Cladosporium tenuissimum Colletotrichum linicola Fusarium culmorum Fusarium oxysporum Fusarium solani Phoma sp Glucose as a sole carbon source and peptone as nitrogen source (instead of NaNO 3 ) in modified Czapek medium favored the production of volatile metabolites of Arthrinium sphaerospermum Pl-5/10. The latter antagonist suppressed the growth of plant pathogens % (the relative colony diameter was %, except Fusarium solani). The volatile metabolites of A. sphaerospermum Pl-5/10 produced on Czapek medium with glucose suppressed most heavily the growth of Cladosporium genus pathogens and on Czapek with glucose and peptone Phoma sp., Fusarium oxysporum and F. culmorum. Alike tendency was observed in Mortierella alpina 3OB case. Growing on Czapek with glucose and peptone the suppression of plant pathogens reached % (except Cladosporium cucumerinum and Fusarium oxysporum). The best inhibition by M. alpina 3OB volatile metabolites on Czapek with glucose was noticed towards Phoma sp., on Czapek with sucrose towards Alternaria tenuissima and on Czapek with glucose and peptone towards Fusarium solani and Cladosporium tenuissimum. Furthermore this test-fungi growing on standard Czapek medium (with sucrose) stimulated the development of Colletotrichum linicola, Fusarium culmorum, F. solani and Phoma sp. Discussion. Species of Trichoderma and their biopreparations are mostly used against a number of fungal pathogens of agricultural importance (including the genera of Sclerotinia, Phytophthora and Botrytis) (Schoeman et al., 1999; Pięta et al., 2003; Stankevičienė, Snieškienė, 2003). However, the data about antagonistic features of other typical soil fungi was presented (Chung Soohee, Kim Sang-Dal, 2005; Soytong et al., 2006). Consequently, it is supposed that a wide spectrum of fungi for various plant protections under certain conditions (in greenhouses, for field cultures and houseplants) could be used. It is difficult to find the strains active against all plant pathogens; therefore, the selection of active fungi against certain pathogens is very important. Our results of pairing tests on malt agar medium showed that fungal strains from Chaetomium, Mariannaea, Penicillium, Talaromyces and Trichoderma genera could inhibit the growth of all plant pathogens studied and other studied strains act selectively. For example, Mortierella genus strains suppressed Alternaria, Fusarium and Phoma but failed to affect the pathogens from Cladosporium genus. 25

8 The tests with cultural filtrates and cultural discs of test fungi actions on plant pathogens showed different results. When Mortierella alpina 3OB discs were used they inhibited Fusarium solani growth, but its cultural filtrate showed no effect. The same tendency was established in case with Mariannaea elegans L14-3 and Trichoderma virens S29-1 cultural filtrates towards Alternaria radicina. These results confirm the idea of existence of different ways of interaction between fungal species. Some microbial antibiotics are nonvolatile and tend to diffuse through the liquid phase, in contrast to volatile metabolites, which spread as vapors (Schoeman et al., 1999). On the other hand, the same action of Penicillium sp towards Fusarium solani or Alternaria radicina was noticed, notwithstanding what discs or cultural filtrate was used. These results coincide with A. M. Abdel-Sater (2001) data obtained, which showed the similar antagonistic activity in solid culture as well as of culture filtrates. The results obtained with inverted test-cultures over potential antagonist elucidated the strains that produce active volatile antibiotics. Such was Trichoderma hamatum S37-1, which inhibited the growth of Fusarium oxysporum even to 50 %, though its cultural filtrate showed only fungistatic action. Great dependence of antibiotic production on cultivation time and medium composition was estimated. It was found out that different fungal strains produce antibiotic metabolites most intensively not at the same time. For instance, cultural filtrate of Chaetomium elatum 8OA accumulated after 7 cultivation days and Paecilomyces sp. SP-20 stopped most powerfully Alternaria radicina after 3 days though after 12 days only fungistatic effect was fixed. Much data presented on direct correlation between degree of inhibition of fungi growth and nutrient medium composition (Engelkes et al., 1997; Rosenzwig, Stotzky, 1980). Zh. I. Pavlovskaja et al. (1998) estimated that Trichoderma lignorum and Gliocladium catenulatum produce volatile metabolites against Fusarium sambucinum mostly on malt agar, whey and glucose. Our investigations with Arthrinium sphaerospermum Pl-5/10 and Mortierella alpina 3OB showed that the latter strains produce volatile metabolites mostly on modified Czapek medium with a sole carbon source glucose and nitrogen source peptone. The obtained results suggest that some fungi might be promising as biocontrol agents. The great species inhibition selectivity and antibiotic production (non-volatile and volatile) dependence on cultivation conditions requires exhaustive scientific inquiry. The ecological significance shouldn t be emitted and vegetative experiments and fungal complex action need to be studied, as well. Conclusions. 1. The ability to produce antibiotics was characteristic for 36 from 43 tested fungal strains. Antifungal activity varied between different species isolates as well as between strains within the same species. 2. The most active strains belonged to Chaetomium, Mariannaea, Penicillium, Talaromyces and Trichoderma genera. They mostly inhibited the growth of Cladosporium and Alternaria but were less effective against Fusarium. 26

9 3. The action of nonvolatile and volatile metabolites and great dependence on cultivation conditions was noticed. Arthrinium sphaerospermum Pl-5/10 and Mortierella alpina 3OB strains produced volatile metabolites mostly on modified Czapek medium with a sole carbon source glucose and nitrogen source peptone after 8 cultivation days. Gauta Parengta spausdinti References 1. Abdel-Sater A. M Antagonistic interaction between fungal pathogen and leaf surface fungi of onion (Allium cepa L.). Pakistan Journal of Biological Sciences, 4 (7): Calistru C., McLean M., Berjak P In vitro studies on the potential for biological control of Aspergillus flavus and Fusarium moniliforme by Trichoderma species a study on the production of extracellular metabolites by Trichoderma species. Mycopathologia, 137(2): Chung S., Kim S.-D Biological control of phytopathogenic fungi by bacillus amyloliquefaciens 7079; suppression rates are better than popular chemical fungicides. Journal of microbiology and biotechnology, 15(5): Engelkes C. A., Nuclo R. L., Fravel D. R Effect of carbon, nitrogen and C : N ratio on growth, sporulation and biocontrol efficiency of Talaromyces flavus. Phytopathology, 5: Kalko G. V., Vorobyov N. L., Lagutina T. M., Novikova I. I Inhibition of the phytopathogenic fungus Fusarium oxysporum by microbe antagonists in peat. Mikologya i fitopatologya, 35(3): Machowicz Stefaniak Z Antagonistic activity of epiphytic fungi from grape-vine against Botrytis cinerea Pers. Phytopathology Polonica, 16: Pavlovskaja Zh. I., Mikhailova R. V., Lobanok A. G., Moroz I. V., Kobzarova V. S Antagonistic effect of Trichoderma lignorum (Tode) Harz OM 534 and Gliocladium catenulatum Gilman et Abbot 453 on Fusarium sambucinum Fuckel. Mikologya i fitopatologya, 32(3): Pięta D., Pastucha A., Patkowska E The use of antagonistic microorganisms in biological control of bean diseases. Horticulture and Vegetable growing, 22(3): Rosenzweig W. D., Stotzky G Influence of Environmental factors on antagonism of fungi by bacteria in soil: nutrient levels. Applied and Environmental Microbiology, 39(2): Schoeman M. W., Webber J. F., Dickinson D. J The development of ideas in biological control applied to forest products. International Biodeterioration and Biodegradation, 43:

10 11. Soytong K., Srinon W., Rattanacherdchai K., Kanokmedhakul S., Kanokmedhakul K Application of antagonistic fungi to control anthracnose disease of grape. Journal of Agricultural Technology, 1: Srinon W., Chuncheen K., Jirattiwarutkul K., Soytong K., Kanokmedhaku S Efficacies of antagonistic fungi against Fusarium wilt disease of cucumber and tomato and the assay of its enzyme activity. Journal of Agricultural Technology, 2(2): Stankevičienė A., Snieškienė V., Trichoderma viride against some of pink rot and wilt agents. Horticulture and Vegetable growing, 22(3): Wheatly R., Hackett Ch., Bruce A., Kundzewicz A Effect of substrate composition on production of volatile organic compounds from Trichoderma spp. inhibitory to wood decay fungi. International Biodeterioration and Biodegradation, 39: Yakimenko E. E., Grodnitskaya I. D Effect of Trichoderma fungi on the soil micromycetes that cause infectious conifer seedling lodging in Siberian tree nurseries. Microbiology, 69(6): Билай В. И. (ред.) Методы экспериментальной микологии. Науковa думка, Киев. SODININKYSTĖ IR DARŽININKYSTĖ. MOKSLO DARBAI (3). Dirvožemio ir fitopatogeninių mikromicetų tarprūšinės sąveikos ypatumai D. Bridžiuvienė, J. Repečkienė Santrauka Augalų ligų ekologiški biologinės kontrolės metodai šiuo metu sulaukia vis daugiau dėmesio. Tyrimų tikslas buvo atrinkti dirvožemyje paplitusias mikromicetų padermes, pasižyminčias antagonistinėmis savybėmis prieš augalų ligų sukėlėjus. Antagonistinis mikromicetų aktyvumas buvo tirtas poravimo metodu naudojant kultūrų agaro blokus, kultūrinį skystį ir lakiuosius metabolitus. Tirtas 43 dirvožemio mikromicetų padermių aktyvumas Alternaria brassicicola, A. radicina, A. tenuissima, Cladosporium cucumerinum, C. tenuissimum, Colletotrichum lini, Fusarium culmorum, F. oxysporum, F. solani ir Phoma sp. atžvilgiu. Iš jų 36 padermės rodė didesnį ar mažesnį poveikį fitopatogeninėms grybų padermėms. Dauguma tirtų padermių stabdė Cladosporium genties fitopatogenų augimą, o Fusarium genties grybus dažniau veikė fungistatiškai. Kai kurios padermės (pvz., Trichoderma virens, Penicillium sp.) veikė išskirdamos antibiotines medžiagas į terpę, o kitos (pvz., Trichoderma virens ir Penicillium sp.) lakiųjų metabolitų pagalba. Fungicidinių medžiagų gamybos intensyvumui turėjo įtakos mitybinės terpės sudėtis ir auginimo trukmė. Mikromicetų gebėjimui aktyviai gaminti fungicidinius junginius yra svarbus auginimo sąlygų optimizavimas bei kultivavimo trukmės parinkimas. Reikšminiai žodžiai: fitopatogenai, fungicidinis poveikis, fungistatinis poveikis, mikromicetai. 28