Long‐term relationships between environment and abundance in wheat of Phaeosphaeria nodorum and Mycosphaerella graminicola

Abstract

Summary• Relationships between weather, agronomic factors and wheat disease abundance were examined to determine possible causes of variability on century time scales.• In archived samples of wheat grain and leaves obtained from the Rothamsted Broadbalk experiment archive (1844 -2003), amounts of wheat, Phaeosphaeria nodorum and Mycosphaerella graminicola DNA were determined by quantitative polymerase chain reaction (PCR). Relationships between amounts of pathogens and environmental and agronomic factors were examined by multiple regression.• Wheat DNA decayed at approx. 1% yr -1 in stored grain. No M. graminicola DNA was detected in grain samples. Fluctuations in amounts of P. nodorum in grain were related to changes in spring rainfall, summer temperature and national SO 2 emission. Differences in amounts of P. nodorum between grain and leaf were related to summer temperature and spring rainfall. In leaves, annual variation in spring rainfall affected both pathogens similarly, but SO 2 had opposite effects. Previous summer temperature had a highly significant effect on M. graminicola. Cultivar effects were significant only at P = 0.1.• Long-term variation in P. nodorum and M. graminicola DNA in leaf and grain over the period 1844-2003 was dominated by factors related to national SO 2 emissions. Annual variability was dominated by weather factors occurring over a period longer than the growing season.

Weather Conditions Associated with the Release and Dispersal of Zymoseptoria tritici Spores in the Argentine Pampas Region

“…In addition, the first authors indicated that the early phases of the epidemic were driven by temperature, which might determine the number of disease cycles that occurred in the following winter. Finally, in the UK, by studying a long period (1844-2003), Shaw et al [20] confirmed that the diseases produced by Z. tritici and Parastagonospora nodorum are greatly influenced by the amount of spring rainfall and the previous summer temperature (for the period before the start of the growing season in autumn).…”

“…For AV identification, only two-cell, elliptical, hyaline spores of 9-16 (18) × 2.5-4.5 휇m [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] were considered; the viability of the airborne spores was determined by recording their germination and formation of secondary conidia directly on Vaseline.…”

An evolutionary ecology perspective to address forest pathology challenges of today and tomorrow

“…(Hyde 2001;Brasier 2009;Schmit and Mueller 2007;Blackwell 2011). The lack of baseline data on fungal diversity and biogeography makes it difficult to say whether an emerging disease is caused by an alien species or a pre-existing pathogen, which has evolved increased virulence or been favored by changing environmental conditions (Jeger and Pautasso 2008;Shaw et al 2008;Linzer et al 2009;Shaw and Osborne 2011). Identifying the origin of fungal introductions solely from historical and geographical arguments is rarely feasible because temporal or spatial data retracing the chronology of invasion are often missing, and species descriptions are inaccurate, making it difficult to separate different putative population sources (see for example Kim et al 2010;Goss et al 2014).…”

Evolutionary bi-stability in pathogen transmission mode

“…This paper uses the data series described in Bearchell et al (2005) and Shaw et al (2008); quantification used fluorescent minor groove binder-conjugated TaqMan probes and was described in the original papers. The data on P. nodorum DNA span a period between 1844 and 2003.…”

“…Subsequently, we use a 160-year data series from a long-term experiment on the cultivation of wheat to investigate whether there is any evidence of such bi-stability in the balance between leaf-to-leaf (horizontal) and seed (vertical) infection by the fungal pathogen Phaeosphaeria nodorum (Bearchell et al 2005;Shaw et al 2008). Phaeosphaeria nodorum (anamorph name Stagonospora nodorum, widely known by the earlier name Septoria nodorum), is a fungal pathogen causing leaf blotch disease on wheat.…”