k{aQ --- The Society of Plant Protection of North Japan

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Annual Report of the Society of Plant Protection of North Japan: Contents

No. 21i1970j

Tanaka, S. & Shiota, H. Transmission of Potato Leaf Roll Virus by Different Strains and Form of Green Peach Aphid (Myzus pericae SULZER) 1

Hukusima, S. & Miyafuji, M. Life Histories and Habits of Misumenops tricuspidatus FABRICIUS(Araneae : Thomisidae) 5

Kobayashi, T. & Oku, T. An Outbreak of the Spotted Spittlebug on the Orchardgrass and Its Insecticidal Control. 13

Ujiye. & Wakou, M. Residual Toxicity of Several Pesticides Against the Adult of Holcothorax testaceipes RATZEBURG (Hymenoptera : Encyrtidae) 17

Yanagita, K & Yaegashi, H. Effects of Primary Infection on the Resistance of Rice Plant to Blast Disease 21

Mogi, S & Yanagita, K. Reactions of the Zenith type Varieties of Rice to Races of Pyricularia oryzae in Japan 24

Takakura, S. & Yamamoto, T. Studies on the Nematode Genus Hirschmanniella I. The seasonal Fluctuation of the population Dencity of Hirschmanniella oryzae and H, immamuri in Hokkaido 27

Katube, T. & Koshimizu, Y. Node Blast due to Lodging of Rice Plant 32