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BULLETIN 1045, U. S. DEPARTMENT OF AGRICULTURE. 
DISEASES OF SUNFLOWERS. 
Rust 9 is the most destructive disease of sunflowers. (Fig. 8.) 
It is common in southern Eussia and has been reported at several 
points in the United States. Rust was prevalent on these plants 
at Hays, Kans., in 1920, and has done considerable injury to sun- 
flowers in experiments at both the Michigan and Wisconsin stations. 
It decreases very decidedly the yield and also results in a poor 
quality of silage. 
The best method of preventing rust injury appears to lie in the 
development of a rust-resistant variety. Frank Spragg and E. E. 
Down, in reporting on a variety test of sunflowers at the Michigan 
Fig. 8. 
-Mammoth Russian sunflowers with the lower leaves killed by rust at the Hays 
Branch Station, Hays, Kans., 1920. 
station in 1918 (see Mich. Agr. Quar. Bui., v. 2. no. 3, p. 128-129, 
1920), claim for the South American variety Kaeurpher a certain 
measure of rust resistance. It may be, therefore, that a resistant 
variety will soon be found. 
Some work in breeding a rust-resistant sunflower has been done in 
Russia. It was found by the investigator, F. A. Sazyperov, that 
the ornamental sunflower {Tlelianthus agyrophyllus) is resistant 
to the rust. None of the ordinary commercial varieties are known 
to be rust resistant. Hybrids were therefore made between one of 
the commercial varieties and the ornamental sunflower. In the 
second generation one-fourth of the hybrid plants were found re- 
sistant to the rust, although the season was exceptionally favorable 
to the spread of the disease. Among these resistant plants were 
9 Rust (Puccinia helianthi Sehw.), the damping-off fungus (Pythium debaryanum 
Hesse), downy mildew (Plasmopara lialsted'ii Farl)„ powdery mildew (Erys-iphe ri- 
ch oraceariim), and wilt (Sclerotinia sp.), in addition to the parasitic plants Orobatwhe 
citmana Wall, and Homeosonia neiulella Hb. are all said to attack sunflower plants. 
