Decsmbbb 11, 1919. 



The Florists^ Review 



35 



SNAPDRAGON RUST SPREADING 



^/svii/s\ir/svir7S<(irrSYir«vir/s\ir)«\ir/svir«tir^>(ir^r^r/SYirirs^ 



lURING 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 no economic 

 importance, has since, by virtue of its 

 having spread into other states, affect- 

 ing seriously the snapdragon crops of a 

 considerable number of growers, come 

 to be regarded as a serious pest by all 

 florists who depend upon the popular 

 antirrhinum for a part of their revenue. 



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 antlrrhini (Diet, and 

 Holw.) However, within a month after 

 the station was apprised of the presence 

 of the rust in the region north of Chi- 

 cago, four new areas of infection had 

 been located within a radius of fifty 

 miles from the point at which the dis- 

 ease was first reported. 



Then, in September, 1914, the writer 

 learned that snapdragons growing on a 

 private estate in northern Ohio were 

 suffering an attack of the disease. The 

 report was substantiated by the receipt 

 of a quantity of diseased material from 

 that locality at the station. Later two 

 new areas of infection were located, one 

 about a mile from the infection just 

 mentioned in Ohio and the other in the 

 western part of central Indiana. From 



So many Inquiries for Information concern- 

 ing inapdragon rust bare been received that The 

 Review has exhausted Its supply of the issue 

 carrying the following article and therefore re- 



grlnts this report on "The Bust on Antirrhinum," 

 y Charles O. Bees, Elorlcultural Pathologist, 

 Agricultural Bxperiment Station, University of 

 Illinois, Urbana, 111. 



all that could be learned, the rust in In- 

 diana and Ohio was noticed on the an- 

 tirrhinum for the first time during the 

 latter part of August, 1914. One grower 

 in the northern part of Indiana report- 

 ed the loss of 6,000 cuttings. It has 

 also been reported that a rust quite 

 similar to, if not the same as, Puccinia 



Fig. J.— Ru$t] Pustules on Antirrhinum. 



Fig. 2.— Badly Infected Antirrhinum. 



antirrhini has been found on the wild 

 Linaria vulgaris, commonly known as 

 butter-and-eggs. This linaria 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 pus- 

 tules begin to replace these spots. (See 

 Figure 1.) These pustules continue to 

 increase in number until practically 

 every leaf 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 estab- 

 lished itself. 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 cut- 

 tings 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 diseased 

 plants in the field, the pustules may 

 show up on the upper leaves as soon aa 

 they do on the lower ones. The reason 

 for this is obvious, as the disease was 

 already established on the plants in the 

 field from which the cuttings 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 report- 

 ed 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 related to the an- 

 tirrhinum. Under these conditions the 

 linaria, growing wild, would furnish an 

 excellent medium for the transportation 

 of the infection to the extreme limits 

 of its habitat. 



The discovery of the teleutospore, or 

 winter stage of the rust, on the material 

 from Indiana permits the conclusion 

 that the disease is carried over from 

 year to year in the field by these spores, 

 which establish themselves during the 

 early fall on the stalks of the snap- 

 dragon. (See Figure 3.) 



A Warning. 



It is hoped that this article will serve 

 to place every grower of antirrhinum 

 on his guard against the ravages of the 

 rust, which gives every indication of 



Fig. 3.— Teleuto or Winter Spore Stage. 



