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Fungicides are widely used to reduce Fusarium infections and grain contamination by mycotoxins and increase the yield in cereals, but the efficacy of fungicide treatments in varying climates has not been systematically explored. Field experiments with Estonian spring barley (Hordeum vulgare L.) cv. ‘Maali’ were carried out in three successive years 2012–2014 with strongly varying weather conditions to study the effects of three fungicides, Folicur (active ingredient tebuconazole), Falcon Forte (prothioconazole, tebuconazole, spiroxamine) and Archer Top (fenpropidin, propiconazole), on the yield, incidence of Fusarium spp. and on the contamination of grain with mycotoxins DON, HT-2 and T-2. The fungicides were sprayed once a year at spring barley flowering time. The weather conditions during the three years of study were extremely different. The content of cycotoxin DON, HT2 and T2 was low. The spraying with fungicides had not a clear effect on the barley yield and 1 000 kernel weight, and the study year was primarily the main factor that affected barley yield (p

Rust infection results in decreases in photosynthesis and stress volatile emissions, but how these changes vary among host species has not been studied. We demonstrated that the impact of the obligate biotrophic fungus, Puccinia coronata f. sp. avenae , on foliage physiological processes is stronger in the primary host, Avena sativa (cultivated oat), than in the alternate host, Rhamnus frangula (alder buckthorn). Photosynthesis decreased with increasing percentage of damaged leaf area (D A) in both species, but reductions were greater in A. sativa. In A. sativa , photosynthetic reductions resulted from reductions in stomatal conductance and photosynthetic capacity; in R. frangula , reductions were due to reduced capacity. Infection reduced photosynthetic biomass and key nutrients in A. sativa , but not in R. frangula. In A. sativa , stress-elicited emissions (methyl jasmonate, green leaf volatiles, long-chain saturated aldehydes, mono- and sesquiterpenes, benzenoids, and carotenoid breakdown products) increased with increasing D A from 0% to 40%, but decreased with further increases in D A. In R. frangula , volatile emissions were slightly elicited but, surprisingly, constitutive isoprene emissions were enhanced. Different hosts had characteristic volatile fingerprints, indicating differential activation of biochemical pathways. Fungal-elicited reductions in photosynthesis scale uniformly with stress severity. In the sensitive host, biphasic scaling of volatiles indicates that heavy spread of chlorosis/necrosis leads to an overall cessation of physiological functioning. [ABSTRACT FROM AUTHOR]

Global warming affects the abiotic and biotic growth environment of plants, including the spread of fungal diseases such as Dutch elm disease (DED). Dutch elm disease-resistance of different Ulmus species varies, but how this is reflected in leaf-level physiological pathogen responses has not been investigated. We studied the impacts of mechanical injury alone and mechanical injury plus inoculation with the DED-causing pathogens Ophiostoma novo-ulmi subsp. novo-ulmi and O. novo-ulmi subsp. americana on Ulmus glabra , a more vulnerable species, and U. laevis , a more resistant species. Plant stress responses were evaluated for 12 days after stress application by monitoring leaf net CO2 assimilation rate (A), stomatal conductance (g s), ratio of ambient to intercellular CO2 concentration (C a/ C i) and intrinsic water-use efficiency (A / g s), and by measuring biogenic volatile (VOC) release by plant leaves. In U. glabra and U. laevis , A was not affected by time, stressors or their interaction. Only in U. glabra , g s and C a/ C i decreased in time, yet recovered by the end of the experiment. Although the emission compositions were affected in both species, the stress treatments enhanced VOC emission rates only in U. laevis. In this species, mechanical injury especially when combined with the pathogens increased the emission of lipoxygenase pathway volatiles and dimethylallyl diphosphate and geranyl diphosphate pathway volatiles. In conclusion , the more resistant species U. laevis had a more stable photosynthesis, but stronger pathogen-elicited volatile response, especially after inoculation by O. novo-ulmi subsp. novo-ulmi. Thus, stronger activation of defenses might underlay higher DED-resistance in this species. [ABSTRACT FROM AUTHOR]

Potato is one of the most important agricultural crops in Algeria and worldwide. Each year, potato late blight, caused by Phytophthora infestans, is responsible for significant damage that leads to large production losses, and is thus a direct threat to food security in Algeria. In this study, 131 isolates of P. infestans and 92 DNA fingerprints captured on FTA cards were sampled from commercial and seed production fields in three major potato production regions (western, eastern, and central) during the main‐season and late‐season in Algeria over six cropping seasons (2010–2016). Genotypes of P. infestans and population genetic diversity were analysed using a 17‐plex simple‐sequence repeat (SSR) marker assay, and the mating type of all isolates was characterized. Both mating types (A1 and A2) were found, and often occurred in the same field. Differences in mating type proportion were observed between regions and between sampling periods. Analysis with SSR markers showed the prevalence of the EU_13_A2 lineage (70%) over EU_2_A1 (16%), EU_23_A1 (10%), and 4% of unknown multilocus lineage (MLL). The EU_13_A2 showed differentiation within the group. EU_23_A1 was found mainly in late‐season crops. However, the cropping region did not influence the distribution of lineages due to the dispersal of the pathogen in Algeria by seeds. Genetic structure did not reveal a clear variation in distribution of the three lineages throughout the sampling regions. These data provide important new information on the composition and change over time of P. infestans populations in Algeria and open the way for a better understanding of the local epidemiology of this important pathogen. [ABSTRACT FROM AUTHOR]

In this study, the effects of a winter cover crop (CC) and its combination with composted cattle manure (CC-M) on the development of potato late blight (Phytophthora infestans) and crop yield were investigated and compared with a system with no cover crop (NC). In the CC and CC-M systems, winter oilseed rape (Brassica napus L) was used as the winter cover crop before potatoes. The hypothesis that the cover crop could be used as a possible control strategy against late blight in organic potato cultivation was not confirmed. Although the progression of foliar late blight damage in CC treatment was significantly slower in the early stages of disease development relative to NC, CC did not significantly reduce late blight at the later stages, or over the full season, and it did not increase tuber yield. Adding cattle manure to the CC treatment favoured late blight development and the damage was significantly more severe than in the other systems and tuber yield was nominally lower (though not significantly). The late blight pressure differed between treatments, with early disease development significantly slower on CC plots compared to CC-M in both growing seasons, but still not different to that in the plants grown in the NC system. Based on the results, in regions where oospores are a primary infection source, making P. infestans a soilborne pathogen, the use of cover crops may provide a sustainable strategy for reducing late blight damage in an organic system, but further investigation is needed. [ABSTRACT FROM AUTHOR]

Nowadays, in sustainable agriculture growing winter cover crops and using organic manure have been widely implemented to improve soil quality which leads to increase of microbial activity. Six-year study was performed to evaluate the effect of cropping system on soil microbial hydrolytic activity, content of soil organic carbon (SOC) and total nitrogen (Ntot) under potato cultivation by considering various management systems, while comparing the soil parameters after previous crop. The experiment consisted of five-field crop rotation with two different organic (Org 0 as control and Org II with winter cover crops plus added composted manure) and conventional (Conv 0 as control and Conv II with mineral N, 150 kg ha–1) farming systems. The results showed that hydrolytic activity of soil microbes decreased in every farming system under potato cultivation. Interestingly, after potato cultivation, the lowest and highest decrease in the soil microbial hydrolytic activity were seen in Org II and Conv II systems, respectively. The highest soil microbial hydrolytic activity was measured in system Org II where incorporation of biomass from winter cover crops and cattle manure was used. Finally, SOC and Ntot were higher in organic farming systems and there no significant changes after potato cultivation. [ABSTRACT FROM AUTHOR]