Feb. 17, 1923 
Parasitic Fungi Internal of Seed Corn 
499 
Hoffer (17) reports similar observations for sweet com— 
It is believed that the greatest damage to large numbers of seed ears by harmful 
organisms occurs when the ears are left in the field for long periods after maturity. 
Stover (34) in Ohio testing seed corn for germination mentions the 
presence of Fusarium-like fungi. Gilman (14) reports a Fusarium-wilt 
of com in Iowa. Isolations established the presence of a Fusarium in 93 
per cent of the cases with seedlings 6 inches high showing a brown dis¬ 
coloration of the vascular system at the crown. 
The literature as reviewed establishes the fact that exclusive of Dip- 
lodia, only species of Fusarium have been definitely established with the 
rot diseases of com. Germination tests have been observed to reveal the 
presence of the fungi, but no studies have shown the method by which 
the pathogenes are carried in what appears to be healthy, normal seed 
com. 
METHODS 
The manner in which infection is carried in seeds showing no external 
symptoms was determined by germination, cultural, and histological 
studies. 
A representative sample of over 100 kernels was selected from each ear 
of com, 10 of which were used for each germination. The germination 
test was conducted for the most part in a Geneva germinator and with a 
modified rag-doll type of germinator. This method of germination gives 
complete evidence as to the relative germination or viability. Such a 
test does not provide in all cases for an accurate determination of what 
fungi are being carried internal of the seed. The seed from harvesting 
to the usual time of germination is exposed to contamination by many 
saprophytic and in some instances parasitic fungi. The growth from such 
superficial adhering spores may be so rapid and abundant as to make the 
identity of the internal parasites impossible. At the end of 7 or 10 days 
the seedlings were examined for internal symptoms as suggested by 
Hoffer and Holbert (20) in their studies. This point will be discussed in 
more detail in a later paper on seedling and stalk infection. 
The most accurate test that we have found for determining the pres¬ 
ence of fungi internal of seed com, and one which at the same time 
readily permits of the identification of the fungi, is carried out by disin¬ 
fecting and planting the kernels or crushed kernels in sterile culture 
medium in Petri dishes as shown in Plates 3, 4, and 11. Fifteen or more 
kernels are disinfected in a test tube 150 by 20 mm. for one minute in a 
solution of 50 per cent alcohol containing 1 gm. of bichlorid of mercury 
in each liter. This solution is known as a 1 to 1,000 HgCl 2 in 50 per 
cent alcohol. Following this treatment the kernels are washed in the 
same tube with two successive washings with 20 cc. each of sterile water, 
and immediately 10 kernels are removed aseptically with sterile forceps 
and placed with the germ side down on 20 cc. of nutrient dextrose agar 
in a sterile culture dish. Further, 5 of the remaining kernels are each 
placed in a sterile culture dish, and with a sterile scalpel the point of the 
kernel, which is the portion that contains most of the internal infection, 
is cut off V 6 to Vs i n ch from the end; then with a strong sterile forcep 
each point is placed in the mouth of a heavy-walled tube (it requires a 
strong tube and strong forceps, as crushing is not easy) 150 by 20 mm., 
containing 10 cc. of sterile nutrient dextrose agar medium at 43 0 C.; 
the point is thoroughly crushed and shaken down into the medium, 
