Plant diseases a herald of environmental changes

Environmental changes can alter morphology and physiology of plants, and geographic distribution of both wild and cultural species. All these modifications reflect in plant-associated microflora and development of plant pathogens as well. Climate warming causes a pole-ward shift not only different plants but also their pathogens. Poster in 4th International Conference of Botanic Gardens from the Baltic Sea Region "Botanic gardens network for the development of the Baltic Sea Region", 29 September - 2 October, 2011, Gdansk, Polan

Discrimination of leaf diseases affecting faba bean (Vicia faba)

Faba bean is susceptible to several leaf diseases caused by pathogenic fungi. With the increasing importance of faba bean in northern European cropping systems, the importance of its leaf diseases is likely to increase. The aim of this study was to discriminate the diseases and to test agronomic strategies for limiting their spread in a five-year experiment. Chocolate spot disease caused by Botrytis spp. and leaf blotches caused by an Alternaria/Stemphylium complex dominated, the severity of rust was lower, and downy mildew occurred in only one year. The severity of the diseases depended on weather conditions and cultivar, but not on sowing rate. Application of fungicides significantly decreased the severity of chocolate spot, leaf blotch and rust, but not downy mildew, and in no case was the disease progress stopped. None of the cultivars showed strong resistance to disease. The Alternaria/Stemphylium leaf blotch is an emerging disease of faba bean in northern Europe. Work continues on the identification of the responsible species in the chocolate spot and leaf blotch complexes and the determination of their relative importance in causing disease.Peer reviewe

What influences the composition of fungi in wheat grains?

Wheat grains are inhabited by different fungi, including plant pathogens and fungi – mycotoxin producers. The composition of seed mycobiota can be influenced by different factors, including agronomic practices, but the results are still contradictory. The aim of this study was to evaluate the mycobiota of wheat grains depending on agroecological conditions. Wheat grains were obtained from a two-factorial field trial: A – tillage system (A1 – ploughing at a depth of 22–24 cm; A2 – harrowing at a depth of up to 10 cm); B – crop rotation (B1 – continuous wheat; B2 – oilseed rape and wheat; B3 – crop rotation). The mycobiota of grain were determined by mycological and molecular methods. The most abundant and widespread of the mycobiota were Pyrenophora tritici-repentis, Alternaria spp., Arthrinium spp., and Fusarium avenaceum. Higher amounts of precipitation increased the infection of grains with Fusarium fungi. Seven species of Fusarium were identified in the grain samples: F. avenaceum, F. poae, F. graminearum, F. culmorum, F. acuminatum, F. sporotrichioides, and F. tricinctum. The soil tillage method and crop rotation did not influence the total incidence of Fusarium spp., but the abundance of a particular species differed depending on agronomic practice. The research suggests that continuous wheat sowing under conditions of reduced soil tillage can increase the level of risk of grain infection with F. graminearum and, consequently, the accumulation of mycotoxins

Importance of Agronomic Practice on the Control of Wheat Leaf Diseases

Soil tillage and crop rotation are considered important tools in wheat leaf disease control; however, the results of investigations are inconsistent. The aim of the present study was to determine the effect of the soil tillage system and cropping sequence on the development of winter wheat leaf diseases in 2012–2017. The disease development was assessed in a two-factor experiment: (a) soil tillage system; and (b) crop rotation. Foliar fungicides were used uniformly in all variants. The results showed that tan spot (caused by Pyrenophora tritici-repentis) dominated in 2012, 2013, and 2016, but the level of Septoria tritici blotch (Zymoseptoria tritici) was essentially lower and exceeded the severity of tan spot only in 2015. The agronomic practice used significantly influenced only the development of tan spot. Reduced soil tillage and continuous wheat sowing substantially increased tan spot severity, especially when both practices were used simultaneously. Short crop rotation (only wheat and oilseed rape) provided sufficient control of tan spot in ploughed fields, whereas in non-ploughed fields, the level of this disease did not decrease. The results could be explained by differences in the pathogens’ life cycle: P. tritici-repentis ascospores in wheat debris is the main source of infection; in contrast, Z. tritici spreads by conidia from living plants

Nelku fialoforas vites ierosinataja Phialophora cinerescens izplatiba un biologiskas ipasibas

Available from Latvian Academic Library / LAL - Latvian Academic LibrarySIGLELVLatvi

Graudaugu seklu kvalitates fitopatologiskais izvertejums un veseliguma testa aprobacija Latvija atbilstosi Eiropas Savienibas direktivu un ISTA (Starptautiska seklu kontroles asociacija) prasibam

Available from Latvian Academic Library / LAL - Latvian Academic LibrarySIGLEMinistry of Agriculture of the Republic of Latvia, Riga (Latvia)LVLatvi

Importance of Agronomic Practice on the Control of Wheat Leaf Diseases

Soil tillage and crop rotation are considered important tools in wheat leaf disease control; however, the results of investigations are inconsistent. The aim of the present study was to determine the effect of the soil tillage system and cropping sequence on the development of winter wheat leaf diseases in 2012–2017. The disease development was assessed in a two-factor experiment: (a) soil tillage system; and (b) crop rotation. Foliar fungicides were used uniformly in all variants. The results showed that tan spot (caused by Pyrenophora tritici-repentis) dominated in 2012, 2013, and 2016, but the level of Septoria tritici blotch (Zymoseptoria tritici) was essentially lower and exceeded the severity of tan spot only in 2015. The agronomic practice used significantly influenced only the development of tan spot. Reduced soil tillage and continuous wheat sowing substantially increased tan spot severity, especially when both practices were used simultaneously. Short crop rotation (only wheat and oilseed rape) provided sufficient control of tan spot in ploughed fields, whereas in non-ploughed fields, the level of this disease did not decrease. The results could be explained by differences in the pathogens’ life cycle: P. tritici-repentis ascospores in wheat debris is the main source of infection; in contrast, Z. tritici spreads by conidia from living plants

DIVERSITY OF FUNGI ASSOCIATED WITH WHEAT STEM BASE DISEASES

Wheat stem base diseases can be caused by different pathogens – previous research has showed complex infections. Also, fungi from other ecological niches can be associated with wheat stem base. Wheat stems with disease symptoms were collected in a field experiment where agronomic practices (different soil tillage systems under various crop rotation schemes) were evaluated from 2012 to 2020. Causal agents and other fungi associated with stem bases were identified by mycological and molecular genetic methods to genera/species level. A high diversity of fungi associated with stem base diseases was determined – fungi from 30 different genera were found. Altogether, 48% of identified fungi belonged to typical causal agents of stem base diseases, 15% were pathogens of wheat leaves and ears, and 37% were saprotrophs or fungi with unclear ecological guilds. Most often, stem base diseases were caused by Oculimacula spp., Fusarium culmorum, and F. avenaceum. Other pathogens (Rhizoctonia spp., Pythium spp., other species of Fusarium, etc.) were found only in some cases. Important pathogens of wheat – Pyrenophora tritici-repentis and Parastagonospora nodorum – were determined frequently. The spectrum of pathogens differed depending on the meteorological conditions of the vegetation period. Further research is required to clarify the relationships between different fungi and their influence on wheat development