HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hooker, A. L. Search for Related Content PubMed Articles by Hooker, A. L. Agricola Articles by Hooker, A. L.

Southern Leaf Blight of Corn—Present Status and Future Prospects¹

ABSTRACT

Two races, T and O, of Helminthosporium maydis Nisikado & Miyake cause southern blight of corn (Zea mays L.). The new race T spread widely in the USA in 1970 and to a lesser extent in 1971. It produces a pathotoxin specific to cms-T cytoplasm of corn plants and infects the leaf, leaf sheath, husk, and ear parts. Race O, normally confined to the warmer parts of the USA, does not produce a specific pathotoxin and infects leaves primarily. Other races may exist or appear in the future.

Resistance to race O is based on nuclear genes, and in most sources is quantitative in expression and polygenic in inheritance; one source with recessive gene inheritance expresses chlorotic lesions with reduced fungus sporulation. Resistance to race T is both cytoplasmic and nuclear. Normal cytoplasms and many cytoplasms for male-sterility such as the cms-C and cms-S types are highly resistant in the field. Resistance in cms-T cytoplasm is partial and probably due to the same nuclear genes that give resistance to race O.

A diversity of cytoplasms within hybrids and the selection of high levels of nuclear-gene resistance in a stalk rot resistant background are suggested as breeding and seed production objectives.

Key Words: cms-T cytoplasm • disease resistance • Helminthosporium maydis Nisikado & Miyake • seed production

¹ Paper presented before Div. C-1, Aug. 19, 1971, in New York City at the annual meeting of the ASA.

² Professor of Plant Pathology and Genetics, University of Illinois, Urbana 61801.

Received for publication December 13, 1971.