Interactions between fungi colonizing the stem base of winter wheat

<em>In vitro</em> conditions, the interactions betecen the fungi most frequently isolated from the stem base of winter wheat were determined. These were the species from genus <em>Fusarium (F. culmorum, F. avenaceum</em> and<em> F. poae</em>) and <em>Rhizoctonia cerealis, Pseudocercosporella herpotrichoides, Alternaria alternata</em> and <em>Aureobasidium bolleyi</em>. Some saprotrophes showed stimulating effect on <em>R. cerealis, P. herpotrichoides</em> and F. poae. Certain species in combined cultures showed exceptionally favourable relationships.

Use of polimerase chain reaction (PCR) for detection of Pseudocercosporella herpotrichoides in winter wheat cultivated in different production systems

<i>Pseudocercosporella herpotrichoides</i> was detected by PCR in winter wheat cultivated in different production systems in 2000 and 2001. In all tested systems only pathotype R of pathogen was detected. Detection of fungus depended on production system and weather conditions. Pathogen was not detected in both tested cultivars only in ecological system but only in season with less favourable conditions for disease development

The evaluation of winter wheat roots and leaf sheath diseases diagnostic methods

The maltose and mineral media for isolation of <i>Gaeumannomyces graminis</i> 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 <i>Fusarium</i> occurring on winter wheat leaf sheaths were identified by mycological analysis and PCR, while the fungus <i>Pseudocercosporella herpotrichoides</i> 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.

Immunodiagnosis of eyespot disease in winter wheat cultivated in different production systems

The aim of the study carried out in the years 2001-2003 was to determine the occurrence of <i>Pseudocercosporella herpotrichoides</i> in winter wheat cultivated in different production systems using traditional visible disease assessment and ELISA technique. Pathogen was detected by ELISA test in all years of the study and attained highest level in 2003. The greatest quantities of <i>Pseudocercosporella herpotrichoides</i> were observed in integrated system and monoculture and significantly lower in conventional production system.

Influence of fungicides on occurence of Fusarium spp. and other stem base diseases on winter wheat

From 1999 to 2004 the occurence of fungi: Pseudocercosporella herpotrichoides (Fron.) and Fusarium spp. was evaluated in small plot field trials on seven varieties of winter wheat. The efficacy of fungicide protection against stem base diseases and influence on yields was monitored in field conditions in Velká Bystřice near Olomouc.For diagnostic of casual fungi two methods were used: 1. Method of coloring mycelium in stems, 2. Method of cultivation of mycelim on agar.Results from detection of casual fungi are following: Pseudocercosporella herpotrichoides (Fron.), Fusarium culmorum (W. G. Sm.) Sacc. and Fusarium graminearum Schwabe.For high efficacy of protection against roots and stem base disease the following fungicide variants should be applied: Sportak Alpha 1.5 l . ha−1 (BBCH 30)/Cerelux Plus 0.7 l . ha−1 (BBCH 51), Sportak HF 1 l . ha−1 (BBCH 30)/Cerelux Plus 0.7 l . ha−1, Alert S 1.0 l . ha−1 (BBCH 30/Cerelux Plus 0.7 l . ha−1 (BBCH 51). The application of fungicides positively influenced yields. Yield increased at average by10–20 % after the aplication but the rise in yields was not in total correlation with the efficacy. These results can be possibly used in the system of integral control of winter wheat against stem base disease in wheat.

Performance of the Biocontrol Fungus Piriformospora indica on Wheat Under Greenhouse and Field Conditions

The endophyte Piriformospora indica colonizes roots of a range of host plants and increases biomass production and resistance to fungal pathogens and, thus has been considered a biocontrol fungus. However, the field performance of this fungus has not yet been tested in temperate climates. Therefore, we evaluated the performance of this fungus in different substrata under greenhouse and practical field conditions. Roots of winter wheat were colonized efficiently, and biomass was particularly increased on poor substrata. In greenhouse experiments, symptom severity of a typical leaf (Blumeria graminis f. sp. tritici), stem base (Pseudocercosporella herpotrichoides), and root (Fusarium culmorum) pathogen was reduced significantly. However, in field experiments, symptoms caused by the leaf pathogen did not differ in Piriformospora indica-colonized compared with control plants. In the field, Pseudocercosporella herpotrichoides disease severity was significantly reduced in plants colonized by the endophyte. Increased numbers of sheath layers and hydrogen peroxide concentrations after B. graminis attack were detected in Piriformospora indica-colonized plants, suggesting that root colonization causes induction of systemic resistance or priming of the host plant. Although the endophyte is not well suited for growth at Central European temperature conditions, it remains to be shown whether P. indica is more suitable for tropical or subtropical farming.