lo Cou)RADo Experiment Station 
color. Small drops of a sticky amber liquid, which soon dries with 
a glistening finish, later turning brown and then black, may collect 
over diseased portion. In advanced stages, the stems shrivel, be¬ 
come brittle, turn black, and die. Diseased leaves show a water- 
soaked appearance and an orange yellow coloration along the leaf¬ 
stalk and midrib. Later, they dry up and become brittle. On one- 
year-old plants, the whole crown may become infected, turn black, 
and die. The disease is caused by a bacterium which attacks the 
first crop only and then lives over until next season in the soil and 
on old stems. In years when late frosts are prevalent, the disease is 
most severe. 
Control —As soon as danger from late frosts is past, clip the 
frosted alfalfa. By so doing, the stems split by freezing and hence 
subject to attack by the causal bacterial organism will be removed 
and new sprouts given a chance to grow. 
Plate I. Alfalfa leaf spot. 
