| Maize is one of the most important cereal crops in the world. It's also a main feed and industrial raw material. The cultivation area and total production of maize is lower to that of wheat and rice and occupies the third place in the world. There are many kinds of diseases taking place within corn growth duration and causing great losses in production. The northern leaf spot caused by Bipolar is zeicola is one of them. During 1960s to 1980s, it had caused big damage in corn production in our country.In several counties of Shanxi Province, China, leaves of mature corn plants with narrow and linear lesions were observed during investigation. 16 pure isolates from six counties were obtained by isolation from host tissue. Pathogenicity test and Random Amplified Polymorphic DNA (RAPD) analysis were performed; the results confirmed that the disease was caused by race 3 of Bipolaris zeicola.The temperature for colony growth of the race ranged from 5℃~35℃. The optimum temperature for the colony growth was 25℃. The fungal can growth in several tested media, the optimum medium for its growth is PDA. In media with different carbon source or nitrogen source, the race has different colony growth rate and cinidium morphology.Conidia could germinate in tap water, and glucose and sucrose could stimulate germination obviously. Conidia could germinate in the range of 5℃~35℃ and germinate best at 28℃; Conidia could germinate from pH 3 to pH 11. pH 5 was optimal for germination.Resistance of ten varieties widely planted in Shanxi was assayed, they were all high susceptible to the pathogen.Since this is the first report of the occurrence of the corn disease caused by Biolaris zeicola, and the tested varieties show that there is no resistance variaty found to the physiological race, in order to avoid great production damage we think it necessary to put more attention on it. |
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