A portable, multiple-tanked spray apparatus has proved convenient and effective for field tests, particularly in steep and remote areas where more elaborate sprayers cannot operate. No hand pumping is necessary and the quickly interchangeable multiple tanks permit mixing and preloading of spray materials in the laboratory. The resultant saving of time in the field often means the difference between completion of a spraying experiment in 1 day rather than 2 or 3, a factor that increases in importance with the remoteness of the research area.