ii66 



Plant Hygiene. 



[mar.. 



to which nurseries and seed firms are involved in this question, 

 and in pointing out that the grower deserves every assistance 

 to obtain clean and good material, he foreshadowed the pro- 

 bability of legislation to deal with this aspect of the matter. 



Under the heading of protection, the lecturer drew attention 

 to the necessity of proper watering and ventilation for crops 

 under glass, and the advantages of spraying and of soil sterili- 

 sation as an insurance against the attacks of insects, fungi, etc. 



It is difficult to draw a line between measures of protection 

 and of eradication, and certain measures included by the lecturer 

 under the latter heading apply equally to the former. Under 

 whatever heading they are included, they constitute some of 

 the most important precepts of plant hygiene, and the danger 

 was emphasised (i) of permitting the rubbish heap to become the 

 manure heap, and thus the breeding place of obnoxious plant 

 pests, and (2) of feeding pigs and other animals on diseased food 

 plants that had not been boiled. The lecturer pointed out 

 that the passage of fungus spores, unharmed, through the 

 digestive system of animals, entailed their return to the land 

 under conditions extremely favourable to the vigorous recur- 

 rence of disease. 



Referring to the question of pruning, the lecturer urged its 

 importance from the point of view of the removal of diseased 

 wood, as well as from the purely cultural standpoint, and 

 pointed out that to prune away diseased material without also 

 burning it was but labour in vain. Mr. Gough also spoke at 

 some length on the value of contact and poison insecticides and 

 of the winter washing of fruit trees. 



Of all matters relative to plant hygiene, the breeding of 

 varieties immune from disease presents, perhaps, the largest field 

 to the scientific investigator. The lecturer demonstrated by 

 reference to those varieties of potato immune from Wart Disease 

 that absolute immunity is an established fact ; he pointed out 

 the desirability of breeding varieties of crops immune from all 

 the diseases to which they are at present liable, and also of 

 combining this general immunity with good cropping and 

 feeding qualities. 



While it would be unwise to lose sight of the necessity of 

 careful drainage, cultivation, manuring, etc., in the raising of 

 healthy crops, attention to the measures outlined by Mr. Gough 

 will be of increasing benefit to the grower and to the nation. 



