1910.] PUBLIC DOCUMENT — No. 31. 165 



be found on seed and may thus be transferred from one locality 

 to another. They were also found last season by Dr. G. E. 

 Stone of this department. 



As stated above, in ten samples of seed, two were found to 

 contain spores of onion smut, and in addition nearly all con- 

 tained mold spores, such as Penicillimn (blue mold), Mucor 

 (bread mold), etc. These mold spores may to a certain extent 

 be on the seed before it is gathered, but the probabilities are 

 that the seed becomes contaminated after gathering, during the 

 cleaning and drying processes, and results from improper drying 

 and cleaning or dampness in the storehouse. Other spores and 

 pollen grains were found which were in no way associated 

 directly M'ith onion diseases. These are perfectly harmless and 

 come from various sources. Among these may be mentioned 

 various conidia and rust spores which do not have the onion for 

 a host. 



Among the spores found which cause diseases of the onion 

 were Urocystis cepidce (Frost) (onion smut), Macrosporium 

 Porri (Ellis) (brown mold) and Peronospora Schleidenina 

 (D By) (downy mildew). The spores of these fungi do not, of 

 course, inhibit the germination of the seed. 



The presence of smut spores and others is objectionable in the 

 seed since the ones just mentioned are capable of causing infec- 

 tion to the crop, and the molds cause the molding of the seed, 

 thus lesseiiing the vitality of the seed and sometimes killing it 

 during a germination test. 



Macrosporium Porri, the so-called brown or black mold, affects 

 seed onions. Peronospora (downy mildew) spores were found 

 in many cases, and this disease has occasionally caused some 

 trouble in Connecticut and elsewhere. This disease, like the 

 preceding one, is confined to seed onions, the fungus penetrating 

 the tissue in all directions, causing a yellow, sickly looking 

 growth, eventually killing the plant. The summer spores, or 

 conidia, are very short lived, however, and do not retain their 

 vitality for any length of time, but the oospores or resting spores 

 are capable of propagating the disease from year to year. 



The kinds of spores found in each sample are shown in the 

 following table. 



