Foliar application ofNosema pyrausta for suppression of populations of European corn borer

In 1974, an application of the microsporidan,Nosema pyrausta (Paillot, 1927)Kotlan, 1928, with a back-pack type sprayer (22.5×10⁷ spores/plant) to whorl stage maize infested with European corn borers,Ostrinia nubilalis (Hübner) reduced the number of larvae/plant by 48.1% and produced an infection of 15.3×10⁴ spores/mg of larval weight in 62.1% of the collected larvae. In 1975, applications of 24.3×10⁷ spores/plant to similar maize, in 2 separate tests, reduced the number of larvae/plant by 18.8 and 43.8% and caused an infection of 14.3 and 19.1×10⁴ spores/mg of larval weight in 65.9 and 63.3% of the collected larvae. Also, in 1975, applications of 24.3×10⁷ spores/plant to pollen shedding maize in 2 separate tests reduced the number of larvae/plant by 17.2 and 14.1% and caused an infection of 24.3 and 27.2×10⁴ spores/mg of larval weight in 99.2 and 95.2% of the collected larvae.