Diseases of Plants 307 
Unio. of Wis. Agric. Expt. Sta. 
Fic. 172. Ina field of cabbage that was almost entirely destroyed by yellows, 
a plant that had formed a good head was found. This plant was saved for seed. 
The most successful truck growers often spray crops 
subject to diseases that can be thus controlled, whether 
disease is present or not. They do this to prevent any 
appearance of disease. The home gardener should be 
prepared to use fungicides whenever diseases appear that 
can be thus controlled. Children should not be intrusted 
with the task, but should have the help of some older 
person, as a parent, teacher, supervisor of garden work, 
or scoutmaster. 
(5) Varieties resistant to disease. Sometimes certain 
plants of a crop are able to resist the attacks of a parasite, 
while the greater number of sister plants all about 
suffer or die. If seed is saved from these more resistant 
plants, a highly resistant variety may be obtained. 
The work of developing such resistant strains is best 
