7. Zebra‑necrosis.

Zebra‑necrosis, for which we propose the symbol (zn) is a new character that produces necrotic transverse areas in the leaves. It appears in plants that have developed about half way to maturity. The necrotic zones expand, covering the leaves almost entirely, producing a premature drying of the plant. The zn plants produce pollen normally and in vigorous stocks they even produce good ears. This characteristic appeared in the progeny of a selfed plant from culture 37,977 of the commercial variety "Colorado Klein". Zebra-necrosis is linked with Og as proven by the following backcross data:

Backcross:	+ Og	x	xn +
	zn +

Og +	Og zn	+ +	+ Zn	Total
36	4	10	44	94

Recombination Og - zn = 14.9%

S. Horovitz

Note: Dr. S. Horovitz's present address is as follows: Catedra de Genetica, Facultad de Ingenieria Agronomica, Caracas‑El Valle, Venezuela.