Pseudomonas fluorescens strains III107 and II21 and Bacillus mycoides strains JC192 and K184, stimulating growth of winter wheat, were chosen for the studies. The bacterial strains inhibited on agar nutrient medium the growth of Gaeumannomyces graminis var. tritici (Ggt) - the pathogenic fungus causing take-all on wheat. Both strains of pseudomonads synthesized relatively high amounts of Fe³⁺ chelators. The strains of bacilli were characterized by the very fast spreading on agar media. Furthermore, strain II21 was highly cyanogenic, and strain JC192 highly chitinolytic. Bacterization of winter wheat seeds (especially with strains III107 and JC192) significantly reduced the percentage of the plants infested with the pathogen in the 28 day glasshouse pot experiment. In the plot experiment, the winter wheat seeds were inoculated with a mixture of strains III107, II21 and JC192. Due to the bacterization the yield of wheat grain and straw was higher in comparison to the series with Ggt alone by 122% and 75%, respectively, but it amounted only to 45% and 43% of the control series not contaminated with Ggt. The decrease of percentage of wheat ears with weight less than 500 mg from 61% in Ggt-series to 25% in Ggt-bacterized-series, and especially the decrease of percentage of wheat ears with weight less than 200 mg from 43% to 14% additionally indicate the partial protection of the winter wheat against Ggt by the rhizobacteria. In the experimental series not contaminated with Ggt the percentage of these wheat ears fractions did not exceed 3% and 0.5%, respectively.
Throughout the world, charcoal rot, caused by Macrophomina phaseolina, is one of the most destructive and widespread diseases of crop plants such as soybean. In this study, the biological control capability of 11 Trichoderma spp. isolates against M. phaseolina was investigated using screening tests. Among all the tested Trichoderma spp. isolates, inhibition varied from 20.22 to 58.67% in dual culture tests. Dual culture, volatile and non-volatile tests revealed that two isolates of Trichoderma harzianum (including the isolates T7 and T14) best inhibited the growth of M. phaseolina in vitro. Therefore, these isolates were selected for biocontrol of M. phaseolina in vivo. The results of greenhouse experiments revealed that disease severity in the seed treatment with T. harzianum isolates was significantly lower than that of the soil treatment. In most of the cases, though, soil treatment with T. harzianum resulted in higher plant growth parameters, such as root and shoot weight. The effects of T. harzianum isolates on the activity of peroxidase enzyme and phenolic contents of the soybean root in the presence and absence of M. phaseolina were determined in greenhouse conditions. Our results suggested that a part of the inhibitory effect of T. harzianum isolates on soybean charcoal rot might be related to the indirect influence on M. phaseolina. Plant defense responses were activated as an elicitor in addition to the direct effect on the pathogen growth.
Efficacy of two strains of Pseudomonas aeruginosa (Pa-5 and IE-2) and aBacillus subtilis isolate alone or in conjunction with neem cake or Datura fastuosa was tested for the management of three soilborne root-infecting fungi including Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani and the root-knot nematode, Meloidogyne javanica on uridbean. Biocontrol bacteria used in combination with either neem cake or D. fastuosa gave better control of the root-rot and root-knot infection with the enhancement of growth of uridbean compared to the use of either component alone. Neem cake 1 % w/w mixed with P. aeruginosa strain lE-2 caused greatest inhibition of the root-knot development due to M.javanica. P. aeruginosa and B. subtilis used with organic amendment also increased Bradyrhizobium-nodules in the root system.
A 3-year field experiment was conducted to study the effect of seed treatment (Raxil 060 FS and Raxil 060 FS + Latitude 125 FS) and plowing down stubble crop (white mustard) on wheat infestation by root and stem base diseases. Wheat was growninthe same field for two consecutive years with two tillage systems: conventional and no-tillage. The occurrence of root and stem base diseases was significantly reduced due to additional seed treatment with Latitude 125 FS (siltiofam). This suggested the presence of Gaeumannomyces graminis (Sacc.) Arx et Olivier in disease complex. The occurrence of infection was reduced to a lesser extent by soil tillage and plowing down stubble crop. These additional agronomic practices resulted in significant grain yield increase of wheat, on the average 13.8% after seed treatment with Raxil 060 FS + Latitude 125 FS, and 8.3% after plowing down white mustard. Grain yield and thousand grain weight of winter wheat were strongly negatively correlated with a degree of stem infestation, but they were not significantly dependent on root infestation. This indicated on a significant role of Pseudocercosporella herpotrichoides [Fron.] Deighton in pathogenesis. Effectiveness of both regenerative practices was slightly lower under no-tillage than under conventional tillage treatment with plough.
Badania przeprowadzono w latach 2000-2002 na polach uprawnych pszenicy ozimej odmiany ‘Kobra’ należących do Zakładu Doświadczalnego Instytutu Uprawy Nawożenia i Gleboznawstwa-PIB w Puławach. Określono choroby korzeni ich przyczyny oraz występowanie na pszenicy ozimej uprawianej w różnych systemach produkcji. Przeprowadzono analizę makroskopową korzeni i określono procentowy udział roślin porażonych. Gaeumannomyces graminis var. tritici oraz grzyby z rodzaju Fusarium były najliczniej izolowanymi grzybami z porażonych korzeni. Tylko w jednym okresie, tj. w trakcie niezwykle ciepłej jesieni 2000 roku F. oxysporum był najczęściej izolowanym grzybem z korzeni roślin uprawianych w systemie integrowanym, a w pozostałych sezonach oraz systemach ten grzyb izolowano sporadycznie, głównie z korzeni roślin rosnących w systemie ekologicznym i monokulturze. Jedynie więc w systemie integrowanym pszenica będąca poplonem bobiku stała się znaczącym gospodarzem drugorzędowym dla F. oxysporum. Ponadto otrzymane wyniki potwierdziły, że zgorzel podstawy źdźbła powodowana przez G. graminis jest poważnym zagrożeniem dla pszenicy, jeśli roślina jest uprawiana w monokulturze. Określono również patogeniczność F. oxysporum wobec pszenicy ozimej i bobiku. Grzyb wykazał patogeniczność w stosunku do obydwu testowanych roślin.
The occurrence and harmfulness of fungi towards Pastinaca sativa L. parsnip of White Gem cultivar were determined in 2005–2007. The mycological analysis of schizocarps with spots and without spots, seedlings and plants at the time of harvest was conducted every year. The fungi were identified on the basis of etiological symptoms visible on the infected parts of plants and on the basis of the results of mycological analysis. Parsnip schizocarps were colonized by various fungi species. Larger frequency of occurrence and biodiversity of fungi species on plants at the time of the harvest was found as compared to the seedlings. The fungus Itersonilia pastinacae, recognized as a cause of black cancer of parsnip in the regions where this plant is cultivated, was isolated for the first time in Poland. Alternaria alternata, A. raphani, Fusarium oxysporum, F. equiseti, F. solani and Stemphylium botryosum belonged to the species of fungi frequently isolated from various parts of this plant.
The maltose and mineral media for isolation of Gaeumannomyces graminis from roots were assessed. The differences in numbers of obtained isolates were found depending on the medium used and sampling date. Easier identification of pathogen was possible employing maltose medium. The fungi from genus Fusarium occurring on winter wheat leaf sheaths were identified by mycological analysis and PCR, while the fungus Pseudocercosporella herpotrichoides was detected by PCR and ELISA methods. PCR and ELISA methods enabled to detect pathogens also in periods before the disease symptoms on plants occurred.
Fields experiments were conducted at the Brody Experimental Station in 2011–2012. The aim of studies was to determine the affect of tillage systems (conventional, reduced and direct drilling) on stem base, root, foliar and ears diseases severity on winter wheat. The incidence of stem base and root has been shown to increase under reduced tillage and direct drilling to compare with ploughing system. The conventional tillage increased the incidence of leaf and ear diseases of winter wheat in relation to the ploughingless tillage systems. Only the incidence of Drechslera tritici-repentis was significantly higher under reduced tillage and direct drilling than under conventional tillage in the first year of experiment.