SEED INSPECTION 59 



1. Kind of diseases represented: Number of Lots 



a. Free from seed-borne diseases 10 



b. Heavy Rhizopus contamination 6 



c. Heavy Penicillium contamination 6 



d. Both Rhizopus and PeniciUium 10 



e. Pronounced Diplodia infection 7 



f. Pronounced pink-lternel discolorations by Fusarium and 



Gibberella 6 



2. Effect 01 treatments on normal germination: 



a. Increased germination from both treatments 19 



b. Benefit from the liquid treatment only 4 



c. Benefit from the dust treatment only 4 



d. Reduced germination (injury) from both treatments 2 



e. Injured by tne liquid treatment only 2 



f . Injured by the dust treatment only 1 



g. No appreciable benefit or injury from either treatment. 13 



3. Extent of improvement in normal germination due to the treat- 



ments: 

 Mercuric chloride, 4 to 20%, with an average of 10.5% 

 Semesan Jr., 4 to 23%, with an average of 11.1%. 



4. Response of individual diseases to the treatments: 



a. The 22 lots contaminated with Rhizopus and (or) Penicillium: 



Benefited by both treatments 15 



Benefited by one treatment or the other 3 



No apparent effect shown 4 



b. The 10 disease-free lots: 



Benefited by both treatments 1 



Benefited by the mercuric chloride treatment 1 



Injured by both treatments 1 



Showed no benefit or injury 7 



c. The 6 lots heavily discolored by Fusarium: 



Benefited by the treatments 4 



Not benefited by the treatments 2 



d. The 7 lots noticeably infected by Diplodia: 



Increased germination from the treatments 4 



No apparent effect from the treatments 3 



It appears that increased germination from both treatments was most con- 

 sistent among the seed-lots that showed marked contamination or infection 

 by Rhizopus and Penicillium. The mercuric chloride treatment appeared to 

 be slightly more effective against these two molds than the organic mercury 

 dust; the Semesan Jr. dust treatment, more effective against Diplodia and 

 Fusarium; whih neither treatment proved beneficial to a majority of the 

 disease-free lots. 



It seems evident from the observations made in the 1934 sweet corn germina- 

 tion work that seed-borne diseases may affect appreciably the normal germina- 

 tion in both the laboratory and the field, showing a greater depressing effect 

 in the field; and that seed treatment with mercuric chloride or organic mercury 

 will considerably increase normal germination in the field in a majority of the 

 more heavily diseased lots. Common molds, such as species of Rhizopus and 

 Penicillium, are likely to be greater sources of injury to germination in the field 

 than other kinds of seed-borne disease organisms because of their unquestionable 

 pathogenicity and their usually greater abundance in seed corn. These molds, 

 however, respond very well to seed treatment. 



