Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/1999
Publication Date: N/A
Interpretive Summary: Downy mildew is one of the major diseases of melons (cantaloupe, honeydew, etc.) worldwide. The most efficient, economical, and environmentally compatible way to control this disease is by growing melon varieties that are genetically resistant to the fungus that causes the disease. To develop these resistant varieties, plant breeders need to know which melon lines can be used as sources of resistance. The U.S. Plant Introduction collection of melon germplasm accessions from throughout the world is a potential source of such lines. These studies tested 1076 of these melon accessions and identified 68 which had plants with resistance to downy mildew. Resistant plants from these accessions can be used by plant breeders in the development of improved, downy mildew resistant varieties.
Technical Abstract: Field evaluations for resistance against downy mildew, incited by Pseudoperonospora cubensis (Berk. & M. A. Curtis) Rostovzev were conducted on 1076 U.S. Plant Introductions (PI) of Cucumis melo L. (melon). A disease index (DI) was calculated for each accession which had one or more resistant plants. Based on DI,PIs 271329, 307588, 313970, 315410, 370021, 378062, 401643, and 401644 were resistant (DI= 2.6, 3.0, 3.3, 2.7, 3.1, 3.0, 2.5, and 2.8 respectively). Resistant plants exhibiting reaction type (RT) 3 were identified in 68 accessions, and 100 accessions had moderately resistant (RT 2) plants.