A Rapid Detection Procedure for the HtN Gene Under Controlled Inoculation of Maize with Exserohilum turcicum. R. Reuveni, Division of Plant Pathology, ARO, Newe Ya’ar Experiment Station, Haifa 31-999, Israel. A. Bar-Zur, and M. Shimoni. Division of Field Crops, and Division of Plant Pathology, ARO, Newe Ya’ar Experiment Station, Haifa 31-999, Israel. Plant Dis. 77:580-582. Accepted for publication 18 December 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0580.

A technique for rapid and early detection of the HtN gene for resistance against Exserohilum turcicum, the cause of northern leaf blight, in maize (Zea mays) is based on quantitative inoculation (by air) with high inoculum pressure (100,000 and 200,000 conidia per square centimeter) on a leaf target, immediately followed by a long wetness period (48 hr). Under such optimal conditions for disease development, plants could be termed resistant or susceptible to E. turcicum as early as the five-leaf stage and 4–10 days after inoculation. In contrast to the commonly used drop inoculation, the technique suggested here does not allow the “escape” of susceptible plants as resistant. Currently, this technique is being used in our breeding program. It enables us to make practical use of the important HtN gene as a source for resistance to E. turcicum.