July i, 1918 
True Nature of Spinach-Blight 
59 
(27) Since it has been found that the causal factor of the disease may 
be hereditary with the aphids, this pointed to the possibility of its sum¬ 
mering by this method. Experiments have shown that aphids collected 
on spinach plants left after the crop had been harvested may be virus 
bearers, as are also aphids collected from weeds growing later in the 
season in the same fields. 
(28) Experiments with aphids from plants other than spinach during 
the fall produced spinach-blight in a limited number of cases. The 
direct offspring of a known virus-bearing aphid reared during the summer 
in a field cage on pepper and potato plants produced blight when they 
were transferred to spinach seedlings in August, or about the time early 
spinach is coming through the ground. Infections were obtained in a 
small number of cases with several other species of Hemiptera. These 
are probably not important as blight transmitters, as they do not occur 
abundantly at the time blight^Is prevalent. 
(29) Spinach-blight has been found on Long Island and in western 
New York both on seed spinach and on scattering plants left from the 
canning crop. 
(30) Blight was also found in Ohio on spinach grown by market 
gardeners. 
(31) Experiments to date indicate that spinach-blight is not trans¬ 
mitted through the soil. 
(32) From the data collected it is probable that spinach-blight is not 
transmitted by seed. 
(33) The control of the aphids infesting spinach offers the most imme¬ 
diate possibilities for the control of spinach-blight. 
(34) Experiments are under way for the breeding of blight-resistant 
seed, but these do not offer any immediate solution for the spinach- 
blight problem. 
