Topic
- Hay 4
- Plants 4
- Research 4
- Combines (Agricultural machinery) 3
- Farm buildings 3
- Harrows 3
- Haying equipment 3
- Hens 3
- Knowlton, Frank L. (Frank Lester), 1894-1940 3
- Pears 3
- Plants--Wounds and injuries 3
- Poultry 3
- Cultivators 2
- Henderson, Robert W. (Robert Wesley), 1914-2006 2
- Irrigation pumps 2
- Irrigation 2
- Johnson, R. G. 2
- Oregon Agricultural College 2
- Peach 2
- Pears--Diseases and pests 2