NuVEMBUU 19, 1914. 



The Florists' Review 



17 



SNAPDRAGON RUST THREATENS 



LOSS TO GROWERS 



UEING the summer of 1913 

 the attention of the flori- 

 culture department of the 

 University of Illinois was 

 first called to a rust on 

 antirrhinum growing in the 

 region north of Chicago. 

 This rust, although it was thought at 

 the time to be of little or n.o economic 

 importance, has since, by virtue of its 

 having spread into two other states, 

 affecting seriously the snapdragon crops 

 of a considerable number of growers, 

 coiiie to be regarded as a serious pest 

 by . all florists who depend upon the 

 popular antirrhinum for a part of their 

 revbnue. 



History and Distribution. 



Prior to the summer of 1913, the rust 

 had been reported but from two western 

 coast states, California and Oregon. In 

 1895 it was determined as a new species 

 by Holway, an American botanist, and 

 named Puccinia antirrhini (Diet, and 

 Holw.). However, as has already been 

 mentioned, the station was apprised of 

 the presence of the rust in the region 

 north of Chicago about fourteen months 

 ago and within a month from that time 

 four new areas of infection had been 

 located within a radius of fifty miles 

 from the point at which the disease 

 was first reported. 



Then in September, 1914, the writer 

 learned that the snapdragons growing 

 on a private estate in northern Ohio 

 were suffering an attack of the disease. 



A. report on "The Rust on Antirrhinum," by 

 Chas. C. Kees, Florlcultural PatboloKist, Ajtrl- 

 culture Experiment Station, University of Illi- 

 nois, Urbaua, 111.' 4. 



-*(, 

 The report was substantiated by the 

 receipt of a quantity o% diseased mate- 

 rial from that locality at the station 

 only a few days ago. Ten days ago 

 two new areas of infection were lo- 

 cated, one about a mile from the infec- 



FJg. I.-Rost Ptistules on Antli*hlnom. 



Fig. 2.— Badly Infected Antirrhinum. 



tion just mentioned in Ohio and the 

 other in the western part of central 

 Indiana. From all that could be 

 learned, the rust in Indiana and Ohio 

 was noticed on the antirrhinum for the 

 first time during the latter part of last 

 August. One grower in the northern 

 part of Indiana has recently reported 

 the loss of 6,000 cuttings. The loss, 

 however, occurred three years ago. It 

 has also been recently reported that a 

 rust quite similar to, if not the same as, 

 Puccinia antirrhini has been found on 

 the wild Linaria vulgaris, commonly 

 known as butter-and-eggs. This lixiaria 

 is quite closely related to Antirrhinum 

 majus. 



Description. 



The disease is easily recognized and 

 each grower of antirrhinum owes it to 

 himself as well as to neighboring grow- 

 ers to examine his plants and cuttings 

 thoroughly for any traces of infection. 

 Within ten to thirteen days after a 

 plant has been exposed to the rust, 

 numerous grayish white areas the size 

 of a pin's head will appear on the 

 under sides of the lower leaves. From 

 three to five days later characteristic 

 rusty, brown pustules begin to replace 

 these spots. (See Fia^l.) These pus- 

 tules continue to indr^Mil^ti number 

 until practically every le^of the plant 

 is attacked. The stem also furnishes 

 a foothold for the disease. 



At this stage the plant begins to 



wilt; its period of usefulness has passed 

 and in a short time it is dead. Figure 

 2 shows, well the condition of a plant 

 two weeks after the infection had 

 established iteelf. The plant was taken 

 from the house. 



Cuttings have also proved themselves 

 to be quite susceptible to attacks of 

 the disease. Taken at a time when 

 their vitality is at its lowest point, the 

 cuttings fall an easy prey to the rust. 

 The disease appears on the cuttings as 

 it does on the older plants, grayish 

 white spots appearing first, followed 

 by the rusty brown pustules. However, 

 where the cuttings are taken from dis- 

 eased plants in the field, the pustules 

 may show up on the upper leaves as 

 soon as they do on the lower ones. The 

 reason for this is obvious, as the dis- 

 ease was already established on the 

 plants in the field from which the cut- 

 tings were taken. 



Cause of Spreading. 



Two theories have been advanced to 

 account for the presence of the rust 

 in these widely separated localities. 

 One is that the rust spores might have 

 been introduced on cuttings shipped 

 in from an infected territory. The 

 other is, since the rust has recently 

 been reported on the linaria, butter-and- 

 eggs, that the disease might easily be 

 carried over from year to year on this 

 wild host, which is so common in the 

 United States and which is closely re- 

 lated to the antirrhinum. Under these 



Fig. 3.— Teleuto or Winter Spore Stage* 





