Transmission of Maize Dwarf Mosaic Virus with Solid-Stream Inoculum. Raymond Louie, Research Plant Pathologist, USDA, ARS, Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. J. K. Knoke, Research Entomologist, USDA, ARS, Department of Entomology, and D. L. Reichard, Agricultural Engineer, USDA, ARS, Agricultural Engineering Department, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. Plant Dis. 67:1328-1331. Accepted for publication 6 June 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/PD-67-1328.

In the absence of 600-mesh silicon carbide, solid-stream inoculum formed by solid-stream nozzle tips was as effective as aerosol-abrasive inoculum formed by airbrush for maize dwarf mosaic virus (MDMV) inoculation to corn (Zea mays). In one test, inoculum (1:20, w/v) applied from a distance of 10 cm using a nozzle with a 0.7-mm-diameter orifice and line pressures of 2.1, 4.2, 6.3, 8.5, 10.6, and 12.7 kg/cm² resulted in 65, 81, 82, 93, 96, and 96% transmission, respectively. When 600-mesh silicon carbide was added to the same inoculum, transmission values for solid-stream inoculation ranged from 87 to 100% but were not significantly different from the 88% transmission for airbrush inoculation. In solid-stream inoculation with a 0.7-mm-diameter nozzle, percent transmission increased with a second and third inoculation pass. A nozzle orifice of 0.7-mm-diameter and line pressure of 6.3 kg/cm² were optimal for greenhouse use, but in the field, a nozzle orifice of 0.8 or 1 mm diameter and pressure of 12.3 kg/cm² were optimal. Compared with airbrush inoculation, advantages of solid-stream include fast rates of inoculation, consistent transmission, use of more dilute inoculum, and inoculation without silicon carbide. A major disadvantage is use of a greater volume of inoculum. In greenhouse inoculations, this problem is not insurmountable but in the field, the system is impracticable without a recirculating system, as described in this paper.

Keyword(s): mechanical inoculation.