Maize is sensitive to the infection with myco-toxigenous fungi from the genera Fusarium and Aspergillus when the climatic conditions are favourable. The specific maize pests play an important role in the spread of the spores of the myco-toxigenous fungi among the climate conditions. The main Fusarium species are able to produce infections are the following: Fusarium verticillioides, Fusarium proliferatum and Fusarium graminearum. The first two species are producing mycotoxins from the fumonisines group (considered as carcinogenous) and the third produces mycotoxins by the types trichothecene and zearalenone. The most frequent species from the genus Aspergillus in crops is Aspergillus flavus. Near this species there can be found Aspergillus parasiticus. Both fungi are major aflatoxins producers strongly carcinogenous for humans and animals. The infections of these fungi are associated with the dry years, warm climate and the damages produced by insects. The insects play an important role in the epidemiology of those pathogens. This research was developed in a selection field formed from 21 lines of sweet corn placed in the perimeter of the Station of Agricultural Research and Development Lovrin (Timiș County). The purpose of this study is to set the interrelation between pathogens and pests and the implication of the last ones in the fungal epidemiology. The observations regarding the attack of the myco-toxigenous fungi Fusarium verticillioides and Aspergillus flavus were developed in conditions of natural infection. In parallel was noted the frequency of the attack of the pests Helicoverpa armigera and Ostrinia nubilalis on cobs and the density of the larvae on cobs. The incidence of the cobs infested with mycelia of Fusarium verticillioides was comprised in the interval 33 % – 100 % and the severity between 3 % and 17.5 %. In the case of the fungus Aspegillus flavus the incidence of the cobs with mycelium was comprised between 0 and 27 % and the severity doesn’t overpassed 15 %. There was noticed the high incidence of the cobs damaged by Helicoverpa armigera between 40% and 100% and that coincides with the frequency of the cobs infested by Fusarium. The density of the Helicoverpa larvae on cob was one, rarely two and three. Comparative with Helicoverpa armigera, the incidence of the cobs attacked by Ostrinia nubilalis was lower than 40%. The density of the larvae on cobs was similar as in the case of Helicoverpa. The obtained results show the indirect implication of those two pests in the dissemination of the above mentioned myco-toxigenous fungi. The infections level with Fusarium verticillioides was higher on the cobs damaged by larvae, those being entirely covered with white, pink or salmon colour mycelia, characteristic for this fungus.

Fusarium verticillioides, Aspergillus flavus, sweet corn, mycotoxins, Helicoverpa armigera, Ostrinia nubilalis.

biology

Presentation: oral