CULTURAL DIRECTIONS 
225 
times. It is controlled in practically the same manner 
as the common asparagus beetle. The Asparagus miner 
( Agromyza simplex) sometimes causes damage. The 
adult is a small black fly, but the stalks are injured by 
the maggot, which mines under the skin in the lower 
part of the stalk. The eggs may be destroyed on lure or 
trap plants, which are burned in late June or early July. 
287. Rust is practically the only disease that has 
caused any damage to asparagus. It made its appear- 
ance in this country in 1896, and has since caused heavy 
losses in almost all important asparagus-growing dis- 
tricts. Hexamer (“Asparagus,” p. 138) describes this 
fungous disease as follows: “When an asparagus field is 
badly infested with the rust the general appearance is 
that of an unusually early maturing of the plants. In- 
stead of the healthy green color there is a brown hue, as 
if insects had sapped the plants or frost destroyed their 
vitality. Rusted plant's, when viewed closely, are found 
to have the skin of the plants lifted, as if blistered, and 
within the ruptures of the epidermis the color is brown. 
The brown color is due to multitudes of spores borne 
upon the tips of fine threads of the fungus, which aggre- 
gate at certain points and cause the spots. The threads 
from which the spores are produced are exceedingly small 
and grow through the substance of the asparagus stem, 
taking up nourishment and causing an enfeebled condi- 
tion of the victim, which results in loss of the green 
color and the final rustiness of the plant, due to the mul- 
titude of spores formed upon the surface. These spores 
are carried by the wind to other plants, where new dis- 
eased spots are produced; but as the autumn advances 
a final form of spore appears in the ruptures that is quite 
different in shape and color from the first ones produced 
through the summer. The spores of late autumn, from their 
dark color, give an almost black appearance to the spots.” 
Rust resistant strains of asparagus have been devel- 
