Subject
- Agricultural pests -- Control -- Congresses32
- Mineral industries -- Oregon15
- Natural gas -- Prospecting -- Oregon15
- Petroleum -- Prospecting -- Oregon15
- Geology -- Oregon -- Field work5
- Geothermal resources -- Oregon5
- Apples -- Diseases and pests -- Control -- Columbia River Valley4
- Cherry -- Diseases and pests -- Control -- Columbia River Valley4
- Fruit -- Diseases and pests -- Control -- Columbia River Valley4
- Grass seed industry -- Oregon4
- Insecticides -- Research4
- Metallurgy -- Oregon4
- Pear -- Diseases and pests -- Control -- Columbia River Valley4
- Pesticides -- Application -- Columbia River Valley4
- Spraying and dusting in agriculture -- Columbia River Valley4
- Grasses -- Seeds -- Research -- Oregon3
- Hazelnuts -- Varieties3
- Rural poor -- Oregon3
- Seed industry and trade -- Oregon3
- Seed technology -- Oregon3