76 PROTECTION OF PLANTS, 1917-18 



acid applied at the rate of 60 to 70 gallons per acre has been used with good 

 effect. It is very important to spray while the plant is quite young. 



Shepherd's Purse {Capsellabursa-pastoris Medic). — A 20% solution of iron 

 sulphate will check it. 



Field Peppergrass {Lepidium campestre R. Br.). — Use 20% iron sulphate. 



Wormseed Mustard {Erysimum cheiranthoides L.). — Use 20% iron sulphate. 



White Cockle {Lychnis alba Mill.). — A 30% solution of iron sulphate applied 

 as the plants are coming into bloom has been recommended as a spray for this 

 plant but it is doubtful whether this strength of solution could be safely used in 

 a* grain crop. 



Purple Cockle {Lychnis githago Scop.). — Spraying with iron sulphate will so 

 injure it as to prevent the formation of seeds. 



^ Spurrey {Spergula arvensis L.). — Spray with 20% iron sulphate to prevent 

 the formation of seeds. 



Mouse-ear Chickiveed {Cerastium vulgatum h.). — Spray when young with 20% 

 iron sulphate to prevent the formation of seeds. 



Chickiveed {Stellaria mediaCyv'iW). — One thorough application of iron sulphate 

 (15% strength) will kill chickweed if applied when the plant is young. 



Blackberry {Rubus sp.). — After cutting and burning the dried stems the new 

 growths should be watered or sprayed at intervals with caustic soda (2 lbs. to 4 

 gallons of water) . 



A strong solution of common salt or the usual strength of arsenite of soda will 

 prove equally effective. 



Vetch {Vicia sp.). — ^A 10% solution of sulphuric acid applied at the rate 



of^60*to 134 gallons per acre will destroy vetches. 

 S— — - - 



Poison Ivy {Rhus Toxicodendron L.). — ^This plant may be killed by spraying 



several times during growing season. The first spray should be applied as soon 



as the leaves are fully unfolded and the second and third at intervals of 10 to 14 



days later. The following substances m^y be used: 



1. A strong salt brine made at the rate of 3 pounds of common salt per 

 gallon of water. 



2. Arsenite of soda at the rate of }4 pound per gallon of water. 



3. Orchard heating oil. 



4. Crude carbolic acid; a 12^% solution applied three or four times during 

 the season at intervals of about 3 weeks. 



