27 



are nevertheless often exposed to drenching rains when growing under 

 natural conditions, and the thick-leaved varieties are well adapted 

 to shed water. Growers generally believe that the proper syringing 

 of plants with water under a pressure of 20 to 2o pounds is valu- 

 able, and the writer's observations lead him to the same conclusion. 

 It nuist be remembered, however, that this work should be done in 

 bright, clear weather, so that the foliage will dry thoroughly before 

 night. Proper syringing of plants instead of favoring stignionose is 

 an important factor in holding it in check, as it keeps down red spiders, 

 and in a measure helps to reduce the number of aphides, thrips, and 

 similar insects. To keep down aphides, however, tobacco in its various 

 forms nuist be mainly relied on. Carnation growers are so familiar 

 with the methods of using tobacco that nothing need be said upon this 

 subject here. It must be borne in mind, however, that healthy plants 

 can not be obtained unless the insects and spiders are prevented from 

 getting too much of a start, hence fumigation and syringing should be 

 so timed and so carried on that these pests will be held in check. 



The various forms of tobacco extract used in liquid form, and also 

 when evaporated by means of hot irons, bricks, etc., have certain 

 advantages, chief of which is that the flowers are less injured by the 

 disagreeable odors. Hydrocyanic ac-id gas has been found eti'ective, 

 l)ut it can not be recommended unqualifiedly, owing to the fact that it 

 is likely to injure certain varieties. Scott, Garfield, Meteor, and 

 McGowan can stand one-tenth gram of 98 per cent potassium cyanide 

 per cubic foot of space for fifteen minutes without material injury. 

 This will kill about 90 per cent of the aphides, but will not kill thrips 

 or spiders. A stronger dose of gas or a longer exposure can not safely 

 be recommended. 



It has been found that different plants of the same variety react 

 very differently to the punctures of both insects and spiders, and this 

 shows the importance of a rigid method of selection for the purpose 

 of building up a vigorous strain of plants. In propagating plants 

 preference should always be given, other things being equal, to those 

 which show- the least evidence of stigmonose. Some plants will be 

 found almost entirely free from it, and it would probably be well to 

 start selection work on a small scale from such stock and continue it 

 from year to year until a more resistant strain is obtained. The 

 writer is satisfied that such a practice would result in much benefit at 

 once, and that within three to five years the vigor of the stock might 

 be materially increased. 



CONCLUSIONS. 



(1) The disease of carnations characterized by the symptoms 

 described in this bulletin is wid*espread, and under certain conditions 

 unfavorable to the plant it is quite injurious. 



