346 
IOWA ACADEMY OF SCIENCE Vor. XXIX, 1922 
to open the line and thus permit the embryos of the seeds to 
obtain water. 
Iowa Stats College. 
THE RELATION OF CUCURBIT MOSAIC TO WILD 
CATNIP 
J. H. MUNCIE 
Cross inoculations from mosaic cucurbits to non-cucurbitaceous 
hosts, according to published records, have been unsuccessful 
except in a few cases. Doolittle obtained infection by aphis in- 
oculation from mosaic cucumbers to Martynia louisiana, while 
Jagger obtained infection on Lobelia crinus var. Gracilis and 
Helianthus debilis. Preliminary experiments by the writer show 
that cucurbit mosaic can be transmitted to Nepeta cataria by the 
insertion of crushed mosaic leaf tissue of mosaic gourd into the 
stems of Catnip. Typical mosaic symptoms appeared on the tips 
of the leaves of the catnip in about three weeks, and after six 
weeks practically every leaf showed the mosaic. ' Mosaic of cat- 
nip has not been observed in the field by the writer, but with the 
ease of obtaining infection and chances of insect inoculation, this 
perennial host may be a source of early infection to cucumbers in 
the field. 
Department oe Botany, 
Iowa State College. 
THE NODAL INFECTION OF CORN BY 
DIPLODIA ZBAB 
L. W. DURRELL 
Dry rot of corn caused by Diplodia zeae was very prevalent in 
Iowa the past season (1921), particularly in the central portion 
of. the state. The disease originates in the old stubble and stalks 
of the previous season from which the spores of the organism 
are blown to the corn plants. Under conditions of extreme 
moisture and high temperature the spores germinate, grow and 
attack the corn. 
Infection may take place on the roots, stems or ears of the corn. 
Seedlings growing over old Diplodia-infected stubble may have 
their roots attacked by the dry rot fungus. Spores blown to the 
