THE KINDS OF WEEDS 231 



by covering with straw. Cutting the plants just before the budding 

 period is destructive. To eradicate by cutting or cultivation no plant 

 should be allowed to show green leaves for a period exceeding a few 

 days. The most effective spray is sodium arsenite, H to 2 pounds per 

 52 gallons water ; or common salt, to i barrels to 52 gallons water ; 

 or copper sulfate, 15 pounds to 52 gallons water; or iron sulfate, 

 75 pounds to 52 gallons of water, sprayed on twice, one week apart. 

 Spray just before the budding period. Spray again after the crop is 

 harvested. Repeat the second year. Sodium arsenite is a very active 

 poison, and must be used with care. 



Dandelion (Taraxacum officinale). Perennial. Cutting below 

 ground is effective. Keep lawn heavily seeded to crowd out the 

 dandelion. Spray with iron sulfate, la to 2 pounds for each gallon of 

 water. Spray two or three days after mowing lawn, and do not again 

 mow until two or three days after spraying. Spray on bright, sunshiny 

 days. Heavy wetting within two days after spraying destroys the 

 weed-killing power. Spray at intervals of four to six weeks. 



New York State Station (Geneva) reports, 1911, that spraying 

 dandelions with iron sulfate was not successful. The second season 

 of treatment the grass was considerably injured. 



Sow-thistle (Sonchus arvensis). Perennial.- Spraying is not effective. 

 Practice bare cultivation for two seasons, allowing no green leaves to 

 appear. On small patches, smother by covering with straw or manure. 

 There are annual species of Sonchus. 



Quack-grass (Agropyron repens). Perennial. In small patches, 

 uproot in dry, hot weather and remove all underground stems. Cut 

 off closely in July, and smother with straw or manure. In large areas, 

 mow when in blossom, and break the sod shallow in mid-July. Back- 

 set in mid-August slightly deeper than before. Disc and harrow 

 throughout the fall, allowing no green leaves to show. Then plow 

 deeply in late fall. Plant cultivated crop next season, and dig out 

 every blade of grass. Or sow a heavy seeding of millet or other dense- 

 growing annual forage late in May on a well-prepared seed bed. The 

 drier the ground and the hotter the weather, the better the killing 

 effect of cultivation. 



White daisy, White-weed (Chrysanthemum Leucanthemum). Peren- 

 nial. Plow up old infested meadows. Spray with iron sulfate 

 at rate of 150 to 200 pounds per acre. Spray when blossom stalks 



