From 2009 to 2018, a total of 80 wheat crops were studied at plot and regional scales to predict stripe rust epidemics based on influential climatic indicators in Kermanshah province, Iran. Disease onset time and epidemic intensity varied spatially and temporarily. The disease epidemic variable was classified as having experienced nonepidemic, moderate or severe epidemics to be used for statistical analysis. Principal component analysis (PCA) was used to identify climatic variables associated with occurrence and intensity of stripe rust epidemics. Two principal factors accounting for 70% of the total variance indicated association of stripe rust epidemic occurrence with the number of icy days with minimum temperatures below 0°C (for subtropical regions) and below −10°C (for cool temperate and semi-arid regions). Disease epidemic intensity was linked to the number of rainy days, the number of days with minimum temperatures within the range of 7−8°C and relative humidity (RH) above 60%, and the number of periods involving consecutive days with minimum temperature within the range of 6−9°C and RH% > 60% during a 240-day period, from September 23 to May 21. Among mean monthly minimum temperatures and maximum relative humidity examined, mean maximum relative humidity for Aban (from October 23 to November 21) and mean minimum temperature for Esfand (from February 20 to March 20) indicated higher contributions to stripe rust epidemic development. Confirming PCA results, a multivariate logit ordinal model was developed to predict severe disease epidemics. The findings of this study improved our understanding of the combined interactions between air temperature, relative humidity, rainfall, and wheat stripe rust development over a three-season period of autumn-winter-spring.
Cereal cyst nematodes (Heterodera spp.) are distributed globally and cause severe production losses of small grain cereals. To investigate the occurrence of cereal cyst nematodes in wheat-growing areas of Algeria, a survey was conducted and 27 cereal cyst nematode populations were collected. The populations were initially identified based on their morphological and morphometric characters, followed by molecular methods using speciesspecific primers, complemented by ITS-rDNA sequences. The morphological and morphometric features of second-stage juveniles (J2s) and cysts supported the presence of three Heterodera species: H. avenae, H. filipjevi and H. hordecalis. All morphological values of these distinct populations were very similar to those previously described for these species. Using species-specific primers for H. avenae and H. filipjevi, the specific bands of 109 bp and 646 bp confirmed the morphological identification of both species, respectively. In addition, the internal transcribed spacer (ITS) regions were sequenced to study the diversity of the 27 populations. These sequences were compared with those of Heterodera species available in the GenBank database (www.ncbi.nlm.nih.gov) and re-confirmed the identity of the species. Nineteen sequences of ITS-rDNA were similar (99–100%) to the sequences of H. avenae published in the GenBank, six sequences were similar (99–100%) to H. hordecalis, and two were similar (98–99%) to H. filipjevi. The results of this study are of great value to breeding programs and extension services, where they will contribute to the design of control measures to keep damaging nematodes in check.
The author highly appreciates the fi rst issue of the third volume of the fundamental “Dictionary of folk stereotypes and symbols” (ed. prof. E. Bartminsky), dedicated to the symbolism of plants. This issue presents rich materials (language, folklore, ethnographic) related to cereals, which in the popular perception have a mythological interpretation, the daily bread is God’s gift, endowed with sacred significance.