50 PROTECTION OF PLANTS, 1920-21 



Cabbages, etc. suffer from black rot and bacterial wilt, which are seed 

 borne diseases. 



Stevens and Hall (Diseases of Economic Plants) recommend soaking the 

 seed in the following solution : — 



1 part of corrosive sublimate. 



2 parts of hypochloric acid. 

 1000 paVts of water. 



On the other hand Duggar recommends a bath of fifteen minutes in a sol- 

 ution of corrosive sublimate 1 in 1000. Howitt finds that the same results are 

 obtained by using formalin 1 in 1000 for fifteen minutes. 



Finally Geunaux finds that for the root rot of cabbage copper sulphate (1%) 

 can be used in place of formalin if the injury is serious. 



Onion bulbs are disinfected by using commercial formalin 1 in 300(Geu- 

 naux) . 



In order to control onion smut contaminated soil should be disinfected 

 with formahn 1 in 300. This requires 125 to 150 gahons per acre (Howitt, Ont. 

 Bull. 258). Another method consists in sowing the seed and watering with 

 dilute formalin solution before covering the seed. 



Beans and peas infested by weevils can be treated with carbon bi-sulphide 

 in a closed vessel. The vapour — dangerous to handle because it is very inflam- 

 mable — kills the insects in the seeds in 48 hours. It is used in a concentration 

 of three ounces to a barrel. 



In certain cases soil treatment replaces seed treatment when the spores 

 live over in the ground and not on the seed. 



In order to prevent diseases. in the seed bed of tobacco, one sterilizes the 

 soil with formalin 1 in 100 or with steam. The same method is used in avoiding 

 lettuce drop. 



In forestry nurseries the soil is disinfected with formalin 1 in 50, or with 

 sulphuretted hydrogen (Truffaut), or with carbon bi-sulphide. 



In some districts growers complain of the ravages of rodents which attack 

 and destroy corn when sown. Farmer's Bulletin 932 states that this trouble 

 occurs in certain of the western sections. It is suggested that to control the 

 following method be employed. A soup-spoonful of tar is added to a gallon of 

 boiling water which is then allowed to cool. When cool the grain is poured in 

 and stirred about for some minutes. No injurious effect is noticed in the germi- 

 ination of corn so treated. ^Ye have not had occasion to observe the ravages of 

 rodents in Quebec in anything like an epidemic. 



