22 MARKET NURSERY WORK 



of sucking insects like the aphis or the thrip, which, penetrating 

 the epidermis of the leaf with the proboscis, apparently leaves a 

 poison behind, which in time creates a developed disease very 

 much as poison would similarly do for us. Obviously, the thing is 

 to fight and destroy these sucking insects, and if this is done 

 thoroughly we cannot be troubled with bacterium. The disease is 

 not fatal ; strong plants can throw it off, but it is, so far, not amenable 

 to special treatment, and we are told that the only way to stamp 

 it out is to propagate none but the healthiest cuttings and, presum- 

 ably, to scrap affected plants at the end of the season. 



Again and again we have had occasion to talk of insect pests, 

 and no one can advance very far in carnation growing without 

 coming up against them. They come in whole battalions in the 

 most inexplicable way from nowhere, not many in variety, but in 

 number uncountable. Practically they are but three : green aphis, 

 red spider, and thrip. Either one of them, if left unchecked for 

 quite a short time, would completely ruin the best stock of carnations 

 in the country ; combined, they could bring disaster more complete 

 and more swiftly upon these than upon any other plant in cultivation. 

 At least, that is the conclusion forced upon us. Thus they con- 

 stitute a very serious menace, and no grower must place himself 

 in a position of disadvantage by being unprepared with remedial 

 agents. They can all be fought and exterminated by the same 

 methods. They begin their attacks in the summer weather outside, 

 and there they must be fought as we earlier described ; but when 

 winter comes and the plants are under glass the same methods 

 do not apply. Soft soap and paraffin insecticides must be discarded, 

 and reliance placed more on cyaniding or fumigating with nicotine 

 preparations. Very occasionally, and choosing the weather, a slight 

 spraying from beneath with nicotine extract is effective, and with 

 these a well-ventilated house, and the fire heat under proper control, 

 there should be little difficulty in keeping the plants free from 

 their enemies. 



