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稻纵卷叶螟在我县一年发生4—5代.其中2—4代数量较多,在后季稻从秧田开始发生危害,到大田后期仍有威胁.后季稻在我县栽培面积最大,占全县稻田90%以上.因此,必须探索稻卷叶螟在后季稻田发生规律,以便指导防治工作.一、二代稻纵卷叶螟在后季稻秧田期的发生比前季稻大田偏晚,早播秧田受害较重1978年后季秧田二代稻纵卷叶螟的孵化高峰期为7月20日,比前季稻大田二代第二孵化高峰期(7月15—16日)晚4—5天.其原因与水稻生育期有关.后季稻秧苗6月20日左右开始播种,而二代稻纵卷叶螟常年在6且底7月初就出现第一发蛾高峰,此时秧苗只有2—3张叶片,苗矮苗小,不易招诱成虫产卵,故避过了二代前期害虫的危害.7月中旬初,秧苗已长至5叶左右,生长比较茂密,适宜成虫产卵,故二代后期的成虫成为后季稻秧苗的主要虫源.
Cnaphalocrocis medinalis occurred 4-5 generations a year in our county, of which 2-4 generations are more in the late rice from the seedling began to endanger the threat to the late late rice fields later rice cultivation area in our county The largest, accounting for more than 90% of the rice fields in the county.Therefore, we must explore the rice leaf roller occurred in the following season rice law in order to guide the prevention and control work.First and second generations of rice leaf roller in the late season rice seedling occurrence than the previous season Rice fields late, early sowing heavier damage seedling field 1978 second season seedling second generation of rice leaf roller thunderstorm peaked on July 20 than the previous season rice field second generation of the second incubation peak (July 15- 16 days later) 4-5 days late.The reason is related to rice growth period.Second rice seedlings began to sow around June 20, while the second generation of rice leaf roller perennial in the beginning of 6 and early July appear the first hair moth Peak, this time only 2-3 leaves of seedlings, seedling sprouts small, easy to attract adults to spawn, it has avoided the harm of the second generation of pre-pests .In early July, the seedling has grown to about 5 leaves, growth comparison Dense, suitable for adult eggs, so the late second generation of adult rice become the main source of rice seedlings after the season.