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Rice bugs were scarcely found 1 day after dusting in the paddy field. Though the bugs were found on ears again 7 days after dusting, occurrence of pecky rice was controlled by dusting twice on the 7th and the 16th day after heading time.

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The larvae of Autographa mandarina were occasionally found to feed on leaves of the white clover in the mountainous area of Iwate Prefecture. The adults were caught in late June to early July and again in August. Under the illumination of 16 hours per day, the total duration for immature stages lasted about 33, 37 and 56 days in 26, 23 and 18°C, respectively. The highest temperature tested caused a considerable larval mortality. When exposed to the day-length of 8 hours in 23°C, the larval growth was remarkably suppressed in the older instars, giving rise to no pupation. A bivoltine life cycle with hibernation in the older larval stage was suggested for the species.

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A univoltine noctuid, Apamea sordens basistrigata Staudinger, is occasionally found to feed on grasses in Tohoku district. It overwinters as older larva, and may pupate after post hibernation feeding. The adult occurs mainly in June in lowlands, and July in highlands.

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In Iwate Prefecture, Mythimna grandis Butler, M. turca limbata Butler, M. conigera Schiffermuller et Denis, M. postica Hampson and M. pallens Linné were found in grasslands. Among them, M. grandis was most widely distributed, and M pallens ranked next. The larvae of these species fed on gramineae, and M. pallens did not avoid non graminaceous weed. Trap catches of the adults suggested a univoltine life cycle for M. grandis, and bivoltine ones for M. turca limbata, and M. pallens.

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Fluctuaion of nematode population depending on the depth of soil was examined.
1) When susceptible potato variety was cultivated, nematode population remarkably increased within a layer between 0 to 10cm deep, resulting in as much as 93.0% of that at planting time, which was followed by the layer of 11-20cm deep with 28.3% of that at planting time at a site within the row.
2) When resistant potato variety was cultivated, nematode population decreased up to less than 30% of that at planting time in a layer between 0 to 10cm deep within the row, and 70% at a site between rows.
3) Effect of Oxamyl (1%) treatment of 30kg/10a in combination with susceptible potato variety resulted into a high reduction in population within a layer 0 to 10cm deep, but less effective in the layer deeper than 11cm.

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Field tests were conducted to find out the effect of nematode trapping plants on the reduction in the nematode population, and their utilization was considered.
1) A high nematode invation of roots as well as very poor cyst formation was observed on following plants, Solanum tuberosum (resistant variety “Tunika”), Solanum nodiflorum, Lycopersicon peruvianum B 6001 (P. I. 126926), and Solanum nigrum.Planting of these plants resulted in a high reduction in the nematode population in soil.
2) S. nigrum highly reduced the nematode population by seeding of 2g/m² in May and June, or by intercropping in sweet corn in May, but seeding in wheat havested field at the end of August failed to reduce the nematode population.
3) Resistant, potato variety “Tunikaz” was found effective when planted into sweet corn field in May or June, and similarly even at the end of August immediately after harvest of wheat.
4) No nematicidal effect of Tagetes patula and T.erecta was observed.

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Races of H. glycines at Tokachi district of Hokkaido were determined by the standard soybean varieties proposed by Golden et al.(1970). Among 27 populations, 24 were found to be race 3 and 3 were race 1. One of the most prevalent resistant variety named Toyosuzu was found susceptible to all of three populations of race 1 as well as 10 out of 24 populations tested of race 3.

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In total 16 species belonging to 5 genera were collected by CO₂-baited traps. A. divittateinus, the larval habitat of which was in marshes, was most dominant at this arca.

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In total 10 species belonging to 4 genera were collected from cattle feces at 10 places. C. jessoensis and L.phanaeoides were widely distributed at this area.

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In total 5 species of tabanid flies anb 2 species of biting muscid flies were collected from pasturing cattle. Both flies were not abundant at this place.

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In total 16 species belonging to 3 genera were collected from pasturing cattle. A. bivittateinus and T. amaenus were most dominant in this place.

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In total 4 species of tabanid flies and 3 species of biting muscid flies were collected from pasturing cattle. The latter flies were relatively abundant at this place.

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In total 8 species were collected from pasturing cattle. T. chrysurus was most abundant and T. exoticus, a rare species, was recorded at this place.

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The 28 isolates of blast fungus from rice and other gramineous host from three. South Asian countries in 1978 were identified as to race and mating type.13 races were identified by inoculation tests. Both mating types were present in rice blast fungus from Thailand and Malaysia, but no perithecia were produced when 29 rice isolates including 18 isolates from Japan were crossed with each other.

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Crabgrass seeds infected with blast fungus were found in nature. The blast fungus survived in infected seeds even after the fall of frost.

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Optimum spray timing and the dosage needed for protective values of 0.9-0.6 of panicle blast control in 1980 cold summer condition were estimated from the relationship between protective value (H) and dosage (G); H=Gⁿ/(φⁿ.+Gⁿ).
Optimum spray timing were 5 days (early heading stage) and next 12 days (late booting stage) before heading stage. Comparing 1979 test result the 1980 cold summer affect its efficiency and the optimum spray timing. Optimum spray timing under the delaying condition of panicle heading by cold summer were proposed.

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Effects of aniti-blast fungicides, Kasugamycin (KSM), KSM + Phthalide, Phthalide, IBP, Isoprothiolane (IPT), EDDP were examined in the field where KSM-and IBP-resistant strains had been occurred. Disease development in the KSM-and IBP-treated blocks were not significantly different from that in the untreated block. As compared with the proportion in the untreated block, the ratio of resistant strains to KSM became higher when KSM and KSM Phthalide were applied, whereas it became lower when Phthalide, IBP, IPT and EDDP were applied. The ratio of resistant strains to IBP became higher when IBP, IPT and EDDP were applied, whereas it became lower wnen Phthalide, KM and KSM Phthalide were applied. The resistant strains both to KSM and IBP were observed in this field.

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Recently brown blotches on glumes of rice plant broke out wildely in Hokkaido. Since E. purpurascens were isolated in high frequency among them, pathogenisity test of E. purpurascens to sheath of booting stage or glume were carried out. Sheath or ear of rice were sprayed with aqueous suspension in about 10⁴ spores/ml, which were produced on rice straw in Sachs medium. Innoculated plants were incubated atlow (14-17C) or high (22-26C) temperature for 48 hr and then placed in a green house. Nolesion appeared on sheath at the both temperatures. Brown blotches and/or discoloration of glumes appeared at low temperature, but did not at high one.

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