A study of Sitobion avenae (F.) and Oulema spp. in nine winter wheat cultivars
1997
Milevoj, L. | Trdan, S. (University of Ljubljana (Slovenia). Agronomy Department) | Salamun, M.
Fluctuations in the numbers of Sitobion avenae F., Oulema melanopus L. and Oulema lichenis Voet were studied on winter wheat crops. In all three locations, winged aphids were first observed in the third ten-day period of April and, largely on the shoots, in most of the cultivars in the third ten-day period of May (EC 41-61). The population of non-winged aphids was increasing from the first ten-day period of May to the first ten-day period of June (EC 58-69), while in the second ten-day period of May the population dropped over night due to a heavy rainfall. In the second ten-day period of May, the most winged aphids were found on cv. Pinka and the least on cv. lkarus. The most numbers of non-winged aphids were found on cv. Pinka, quite a large number on cv. Demetra, cv. Zitarka and cv. Justus, and the least numbers on cv. Ikarus. Beetles Oulenia spp. were found in the third ten-day period of April, and the first eggs were observed in the first ten-day period of May (EC 31-32). The first larvae developped in the second ten-day period of May (EC 37-47). The density of beetles and eggs was found to be the highest in the third ten-day period of May (EC 41-59) and the density of larvae in the first ten-day period of June (EC 60-69). Cv. Justus, cv. Hubertus and cv. Ikarus (late cvs.) were the most resistant to the pest, while cv. Olga (a medium-late cv.) was the least resistant.
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