01957nam a2200229 a 450000100080000000500110000800800410001910000130006024501050007326000160017830000110019450000720020552013410027765000150161865000160163365000100164965000100165965000260166965000130169565300100170865300090171814744662015-08-24       1980    bl uuuu  m   00u1 u    #d1 aCRUZ, I.  aImpact of fall Armyworm, Spodoptera frugiperda (Smith and Abbot 1797), on grain yield in field corn.  a1980.c1980  a162 p.  aDissertação (Mestrado) - Purdue University, West Lafayette, 1980.  aResearch was conducted in 1978 and 1979 to study the effect of fall armyworm, Spodoptera frugiperda (Smith and Abbot, 1797), infestation on cron yield. Five growth stages of corn, early-whorl, mid-whorl, late-whorl, tassel and silk, were tested for susceptibility to 1 fall armyworm egg mass per plant. Corn growth stages were determined by the number of visible leaf sheaths, plant height and exposure of tassel and silk. The most susceptible stage of growth was found to be the mid-whorl stage. An average yield reduction of 6.2, 6.8, 8.5 and 19 percent was obtained from plots infested at the early-whorl, tassel, late-whorl, and mid-whorl stages, respectively. No reduction in yield occurred in plots infested at the silking stage as compared with untreated plots. The relationship between the number of fall armyworm egg masses apllied at the mid-whorl stage of growth and yield was not linear. However, yield and leaf damage were found linearly and negative related. Reduction in kernel number was directly related to yield in plots infested with fall armyworm. as average yield reduction of 1.7, 4.5, 7.7, 17 and 17.1 percent was obtained from plots infested with 1.0 fall armyworm egg mass per 20 plants, 1.0 egg mass per 10 plants, 1.5 egg masses per 10 plants, 1.0 egg mass per plant and 1 egg mass per 5 plants, respectively.  aentomology  aEntomologia  aMilho  aPraga  aSpodoptera Frugiperda  aZea Mays  aMaize  aPest