Mar. 22, 1924 
Nematode Disease Caused by Tyienchus tritici 
935 
Plate 4. It will be noted that, while the wheat is badly stunted, the 
barley apparently is uninjured. On the assumption that hull-less barley 
might be more susceptible than hulled barley, seeds of several hull-less 
varieties were sown at Madison, Wis., (1922) with a heavy inoculation of 
galls but in no case was infection obtained. As in the case of oats, com¬ 
parative data were taken on the inoculated barley and on uninoculated 
controls, and no differences were observed in comparative vigor, stand, 
or yield (Table IX). 
TabIvK IX. Yields of five io-foot rows of barley and oat varieties, three inoculated and 
two uninoculated with galls of the wheat 'nematode at the time of sowing, at Madison, 
Wis., in IQ22 
Variety. 
Inoculated. 
Uninoculated. 
Row 1. 
Row 2. 
Row 3. 
Average. 
Row 1. 
Row 2. 
Average. 
Barley: 
White Hull-less. 
Nepal. 
Himalaya. 
Black Hull-less. 
Oats: 
Golden Sheaf«. 
Wisconsin Pedigree No. 7 «.. 
Grams. 
no 
83 
141 
270 
220 
190 
Grams. 
105 
80 
*55 
311 
100 
300 
Grams. 
70 
86 
148 
293 
155 
250 
95 
83 
148 
291 
158 
247 
Grams. 
82 
86 
140 
254 
272 
270 
Grams. 
85 
82 
144 
252 
226 
460 
84 
84 
142 
253 
249 
365 
a Injury by sparrows makes results inconclusive. 
Grasses appear to be immune from the wheat nematode. In experi¬ 
ments extending over two years, Marcinowski (17, p . 67-/77), using 
nematodes from wheat, tried to infect 15 species of grasses belonging to 
seven genera. Although she used an abundance of inoculating material, 
several hundred galls per plant, she secured no infection. In many plants 
dissected and examined, numerous larvae had gathered about the growing 
point, but all the remaining plants matured normally and produced seed 
without any indication of gall formation. 
Similar experiments conducted by the writer at Madison, Wis. (1921- 
22), also gave negative results. Seeds of several species of Agrostis, 
Arrhenatherum, Festuca, Lolium, Phleum, and Poa were inoculated at 
time of sowing with both whole and ground galls. The inoculated plants 
at no time differed in any respect from the nninoculated control. Larvae 
in small numbers sometimes were found about the growing points of 
dissected plants, but no disease symptoms were evident and the plants 
matured normally. 
Neither do the nematodes producing galls on certain grasses seem able 
to infect wheat. Bessey (4) tried to infect wheat by sowing it with 
nematode galls from the following seven genera of grasses: Agropyron, 
Agrostis, Calamagrostis, Chaetochloa, Elymus, Sporobolus, and Trisetum. 
He secured no infection whatsoever. The writer 'inoculated wheat at 
seeding time with both galls and free larvae from Calamagrostis, but in 
no case were any symptoms of nematode injury observed or head infection 
secured. 
Tyienchus tritici is a highly specialized parasite requiring either wheat 
or a nearly related host in order to multiply rapidly. Therefore, land 
infested by the wheat nematode may be sown to grass or even to oats or 
barley without danger of perpetuating or spreading the disease. 
