Contribution à la connaissance des stress biotiques affectant les céréales d'hiver

Abstract

Research on cereals in recent years, Indicate the risk of epidemic development of certain fungal diseases (rust yellow blotch, Septoria, etc.), and viral adequate measures of prevention and intervention are not taken in time (A.Ouffroukh. 2008; A.Ouffroukh, 2006). Crop losses arising are important. In favorable years the Yellow rust, for example, can take extents epidemic and destroy entire harvests. (A.Ouffroukh., 2008; A.Ouffroukh., 2006; B. Bahri, M. Leconte, A. Ouffroukh, C. Vallavieille-Pope, J. Enjalbert, 2009). Viral diseases in turn, are taking extension. Thus, the Barley Yellow Dwarf Virus (BYDV.) or (BYDV) was reported in several areas prospected and several cereal species (wheat and barley hard and soft). In general very little information is available on their epidemiology and economic impact, when the means of struggle, they have little or almost nonexistent (H. Stone and JP Signoret, 1978). BYDV (BYDV) little known in Algeria compared to other diseases, can be very important for our cereal and threatening, particularly since this disease is transmitted by insect vectors belonging to the genus including Aphidideae, including a dozen some species have been identified (A.Ouffroukh., 2006; L. Ayadi K. and Ayoub, 1994; Ouffroukh. A Khelifi. D, Dehimet. L, 2009). Also after his observation and detection, identity veered ¬ was confirmed by serological investigations have shown that the existence of two viral strains or Pathotypes (PAV and MAV), confirming the results obtained by H. Belkahla.et Lapierre (1999). The frequency of the disease varies annually from 8% to 18% depending on the region but is also encountered and generally on the different species at rates ranging from 8% to 28%. (L. Ayadi K. and Ayoub, 1994; A. Ouffroukh., 2008; Ouffroukh. A Khelifi. D, Dehimet. L, 2009). In terms of capacity vector, PR appears to be best vector and infected plants by this species appear most affected clinically, about the impact of contamination on cereal species studied, it appears that the barley species are most affected, while soft wheats are more susceptible to BYDV (BYDV) and durum wheats. Moreover, the influence of virus Barley yellow dwarf (BYDV) on cereal development is certain and it is especially important that the plant is subjected to water stress, it's more 'is that cultivars and genotypes most tolerant in general show a certain level of tolerance to drought. In epidemiological terms, and although the results we have achieved can not definitively conclude on the precise conditions of the regions studied, the fact remains that valuable information was obtained. It appears here the whole point estimates of aphid that are a fundamental element .indication of risk to crops and therefore the periods in which the actions of prevention and protection should be carried out.