424 



The Weekly Florists' Review. 



KEBBnABY 28, 1901. 



Carnation leaf si)Ot. proUiu-ed by St- ptuiia di; 



The Carnation in Health and Disease. 



selves to the house conditions much less 

 readily. The main loss, especially in 

 case of the two spot diseases named, was 

 during the period that the plants were 

 establishing themselves in the house. 



To avoid epidemics of these diseases 

 it is necessary to move the plants with 

 as little check as possible, give them 

 abundance of air and not too much wa- 

 ter, remove badly diseased plants, dead 

 and cli>easfcl lc;i\es. etc. After they are 

 thoi.ni.lili . i,ilili<licd in the houses not 

 mill li III: i_. ill !»■ done by these dis- 



ea.-i -- I iiij.i (if a check in trans- 



planlii.;,' rouM l.i- avoided by "indoor 

 culture." The advocates of this method 

 claim that there is less loss from stem 

 rot and other diseases where it is prac- 

 ticed. 



Prof. Woods stated that the vicwr; 

 .shown upon the screen were not from 

 drawings but from direct photographs 

 of sectiuns of tlie leaves, etc., taken 

 through the microscope. 



In the discussion that followed the 

 reading of the paper, Mr. Craig asked 

 whether spots on the leaves could not be 

 caused bj; other agencies than aphides 

 and thrips. Prof. Woods replied that 

 they might be caused by rod spider or 

 other puncturing and all sucking insects. 

 Mr. Craig said he had seen spotted 

 leaves on plants that he was sure had 

 never been subject to injury by insects 

 and asked as to the cause. Prof. Woods 

 replied that the plants had undoubtedly 

 at some time l)een injured by insects and 

 that the results were often not appar- 

 ent until some little time afterward. He 

 added that tobacco kills only about CO 

 per cent of the greenfly and that hydro- 

 cyanic acid gas is the only insecticide 

 that will entirely rid a house of them. 

 He had never seen the disea^ie in question 

 produced in any way than bj- the insects 



and it was exceedingly difficult to keep 

 the plants absolutely clear of them. H 

 the plants were kept perfectly free from 

 insects they would then never have this 

 spot disease. One peculiarity of the dis- 

 ease is a weakness of the plant due to the 

 withdrawal of the nitrogenous material 



by the insect. Th. 

 produced by any 

 roots of the plant , 

 too severely. Tlh i 

 that are particul.i 

 disease that ciiim 

 culiarity is tran.-n 

 tings. About four 



Id also 

 1 V to the 

 ig it back 

 I varieties 

 > to every 

 1 this pe- 

 ll the cut- 

 e cuttings 



from weak plants will be subject to dis- 

 ease. It is a pathological condition 

 transmitted through the cutting but not 

 through the seed. The reserve nitrogen 

 in the plant is reduced one-half by the 

 disease. 



Mr. Si-ott asked whv it was that the 



not gel a liiiil I;. 'Ill I I I" II. I lal.' t In- I. ;il 



stem rot and Prof. Woods replied that 

 there were two forms due to two dif- 

 ferent fungi. One is a sterile fungus 

 that does not produce any spores. It 

 has no means of dissemination through 

 the air but works entirely through the 

 soil. It is a root-like fungus and 

 grows near the surface of the soil, grad- 

 ually working its way into the plant at 



the surface of the soil. This form seems 

 to have been more prevalent among 

 plants that have been lifted from dry soil 

 when moved into the house, but it would 

 no doubt also attack healthy plants. It 

 is a dry rot. 



The other form is more parasitic and 

 is a wet rot. If you take hold of the 

 base of the plant and twist it between 

 your fingers the skin will come ofT. With 

 the dry rot this does not occur but if 

 you break the stem you find a sort of 

 pith inside. 



As to remedies for stem rot, if the 

 plants are once attacked nothing effect- 

 ive can be done. Stewart and Dugger 

 have recommended lime. This fungus 

 grows best in soil having high acidity 

 and the lime reduces the acidity. Heav- 

 ily liming the bench (as much as you 

 dare) will have a tendency to check the 

 disease, but it is not a cure. The only 

 way to clear the soil of all germs is to 

 sterilize it by applying steam for two 

 hours at a pressure of 140 pounds. 



Both fungi grow in the fields under 

 favorable conditions, and he knew of no 

 way to prevent stem rot in the field. 

 Carnations should never be grown again 



The Carnation in Health and Disease. 



in a field where stem rot has once been 

 noted. 



In sterilizing the soil by steam there 

 is a tendency to destroy the nitrifying 

 organisms and thereby impair its fer- 

 tility, but on the other hand the nitro- 

 gen becomes more avai'aii!.. by the dis- 



