Mz 5.1 Sclerophthora macrospora2018-04-09T12:05:07-05:00

National Seed Health System

Mz 5.1  Sclerophthora macrospora

DATE: 2001
PATHOGEN: Sclerophthora macrospora (syn: Sclerospora macrospora)
HOST: Maize (Zea mays)
COMMON NAME: crazy top downy mildew
METHOD: Mz 5.1 Direct Visual Method (CIMMYT) (formerly Cf 5.1)
METHOD CLASS: Standard (A)
SAMPLE: : 400 seeds, 8 replicates of 50 seeds


1. Place 50 seeds / replicate in a 250 ml beaker containing a combined solution of 5% NaOH and 0.02% Aniline Blue.

2. Soak seeds for approximately 36 hours to obtain adequate softening for internal tissue examination.

3. Pour resulting material into a 15 x 23 cm plastic box.

4. Squash embryos with a spatula and spread into a thin layer.

5. Examine under a microscope (at 50X magnification) for characteristic oospores that are hyaline to yellowish and 45-75 µm diameter.


Warham, E. J., Butler, L. D. and Sutton, B. C. 1995. Seed Testing of Maize and Wheat: a laboratory guide. CIMMYT. 1995. CIMMYT and International Mycological Institute. ISBN: 968-6923-70-5