December 12, 190S 



HORTICULTURE, 



The Carnation Bud Rot 



The carnation bud rot is a constantly increasing 

 trouble of the carnation and it is causing some anxiety 

 to the growers. The first indication of the trouble is 

 that the (lowers are nulieeil opening abnormally and 

 though they usually show no external injury, a closer 

 examination discloses the fact that the inner petals cling 

 together at the top while the lower portions are decay- 

 ing. The peculiar unrolling of the outer petals is so 

 characteristic of the disease that it is not a difficult mat- 

 ter for anyone familiar with it to pick all infected flow- 

 ers while going over a bench. In the advanced stages of 

 the disease all the petals turn brown. If the decayed 

 portions are carefully torn apart there will usually be 

 found one or more glistening pearly white bodies. When 

 the flowers are in an advanced stage of decay, even when 

 the bud has become a dried mass of tissue, there are 

 usually a large number of these bodies. The writer has 

 counted over one hundred of various sizes in a single de- 

 cayed bud. These bodies are supposed by growers to be 

 the eggs of some insect. They are the gravid females of 

 a mite ( Pediculopsis graminum, Eeuter) and the shin- 

 ing bodies are the enormously distended abdomens filled 

 with eggs. This portion is so distended that it is often 

 difficult to see the head and thoracic portions of the 

 mite. Anyone can secure the males and non-gravid fe- 

 males by placing some fertile mites in a clear glass vial 

 and in a few days the tiny full grown mites will be 

 crawling about. 



The trouble is caused by a fungus ( Sporotrichum sp.) . 

 The mycelium of this fungus is usually seen as a cottony 

 mold in diseased buds that have become somewhat dry. 

 Inoculation experiments on buds of the Queen Louise 

 carnation were in all cases successful indicating that the 

 fungus is the real cause of the trouble. The mites ap- 

 pear to be the means of introducing the fungus into the 

 interior of the buds where the conditions are favorable 

 to its development. The relation of the fungus and 

 mite is shown in the following table : 



Total 



132 



90 



A microscopic examination for the non-gravid mites 

 possibly would have increased the figures in the second 

 column. While the fungus spores are disseminated by 

 other means it does not apparently gain entrance to the 

 buds except through the agency of the mite. 



The attention of the writer and his assistant was first 

 called to this trouble by the foreman of one of the 

 largest greenhouse establishments in Chicago in October, 

 1907. In this establishment it was especially injurious 

 to White Lawson. Since this time the writer has found 

 the same trouble at Bloomington, Springfield, Peoria, 

 Pekin and Champaign. A careful study and record was 

 made at Bloomington of the amount -of the trouble on 

 several varieties during each week from October to June. 

 The following table gives the results: 



Each flower produced was examined three times dur- 

 ing its development. 



The Genevieve Lord, Queen Louise and Red Sport as 

 well as the Enchantress, Lady Bountiful, White Perfec- 

 tion, Vesper, Estelle and Lawson were grown on adjoin- 

 ing benches. The conditions were similar and the 

 results comparable. 



As a class the white varieties are more subject to the 

 disease than others but they are not uniformly affected. 

 For example, in this establishment Lady Bountiful was 

 one of the worst injured varieties while Vesper was im- 

 mune. The former has been found affected wherever I 

 have examined it growing. White Perfection was seri- 

 ously affected with the disease in November but it dis- 

 appeared later nor did the trouble reappear on this va- 

 riety in the spring when it was again in full crop. Queen 

 Louise is a variety subject to this disease and like the 

 Lady Bountiful infected flowers were found all through 

 the winter but in greater numbers in fall and spring. 

 Queen showed some affected flowers but as it was thrown 

 out in January the record is not complete. 



Among the colored varieties Genevieve Lord, a pink 

 variety, was one of the worst injured. Most of this loss 

 occurred in a separate house containing one bench each 

 of Lord and Louise. Other benches of Genevieve Lord 

 were less affected but still to a greater degree than En- 

 chantress or Lawson. The latter were not susceptible 

 varieties. Estelle and Beacon were also more subject to 

 the disease than the two standard kinds named above. 

 Red Sport was the worst affected variety of all those 

 studied. This is especially interesting because the im- 

 pression prevails in some quarters that the disease is 

 practically confined to the white varieties and in still 

 others that Lawson is the kind particularly subject to 

 it. If the White Lawson is meant it should not be con- 

 fused with other Lawsons. 



The susceptibility of varieties was shown in one large 

 house which contained as well grown plants as I have 

 seen in ten years' experience visiting greenhouses. In 

 this house two benches of Louise gave 10 and 5 buds 

 respectively, one Genevieve Lord bench 5 and one bench 

 of Red Sport produced 99 rotted buds. In the low nar- 

 row house previously referred to, one bench each of Gen- 

 evieve Lord and Queen Louise produced 43 and 38 rot- 

 ted buds respectively. Here the conditions were very 

 favorable to the diseases during May because of the ex- 

 cessive rainfall. 



Comparing the two lots of Lord and Louise it will be 

 seen that in large, well ventilated houses the disease was 

 loss troublesome on these varieties but that other varie- 

 ties are very subject to it under the best of conditions. 



Although the disease and the mite are troublesome on 

 June grass the writer has not found it a regular conse- 

 quence of the use of rotted sod. On the other hand some 

 of the worst cases of this trouble that he has examined, 

 followed the use of other soil. It is his desire to get 

 more evidence on this point. 



The only remedy known at present is to pick and 

 destroy all the diseased flowers as they appear. This 

 will get rid of spores and mites. Under this treatment 

 I have not found a second infected bloom on a plant. 



CL.c -(ZL^, 



Champaign, 111. 



