12 
BULLETIN" 1156, U. S. DEPARTMENT OF AGRICULTURE. 
standpoint of quarantine administration of determining the host 
range in America requires the testing of all obtainable botanical 
relatives of the potato. Such tests have been carried on during four 
years both in the open at Freeland, Pa., and in the greenhouse at Wash- 
ington, D. C. The possibility of the wart pathogen attacking nonsola- 
naceous plants which occur in infested gardens, either native or 
cultivated, has been investigated, as previously reported 14 and also 
by the present writers, but no indication has been found that such 
extension of host range takes place. The species listed in Tables 2 
and 3 have not been infected by wart when grown in infested soil. 
In both the greenhouse and garden tests susceptible potatoes were 
grown under similar conditions as controls, and in all cases these 
developed wart infections. 
The solanaceous species listed in Table 2 have been grown in 
wart-infested soil in the greenhouse at Washington, D. C., under 
favorable conditions for wart infection, as shown by the results with 
controls. Infection of these species failed. On the other hand, 
infection of the black nightshade (Solarium nigrum L.) and bitter- 
sweet (S. dulcamara L.) has followed experimental inoculation. 
Table 2. — Solanaceous species of plants tested for susceptibility to potato vcart in pots 
in the greenhouse at Washington, D. C. \ 
[Infection of all these species failed.] 
Number and name of species. 
Number 
of plants. 
Number and name of species. 
Number 
of plants. 
No. 1. Solanum atropurpureum Schrank 
No. 2. Solanum gilo Radii 
5 
4 
4 
'1 
3 
1 
No. 3. Solanum lobelii Lenore (= integ- 
2 
2 
No. 4. Solanum pseudocapsicnm L 
No. 5. Nierembergia gracilis Hook 
No. 12. Cvphomandra betacea Sendt 
No. 13. Physalis sp 
No. 14. Solanum aculeatissimum Jacq... 
3 
10 
4 
6 
(D.ferox L.) 
i The writers are indebted to J. B. Hill, of Pennsylvania State College, for furnishing seed of all spe- 
cies tested except Nos. 4, 10, 11, and 12. 
The solanaceous species listed in Table 3 have been grown in 
wart-infested gardens at Freeland and Upper Lehigh, Pa., under 
very favorable conditions for the infection of susceptible potato 
varieties. Certain of these species have been tested for two years 
in different plats, but wart infection has not occurred. 
To the knowledge of the writers Solanum nigrum has not been found 
as a weed in any wart-infested garden, either in Pennsylvania or West 
Virginia, nor has it been observed in the quarantined area in eastern 
Pennsylvania. Similarly, Solanum dulcamara has been collected 
only occasionally within this district, growing cultivated in nonin- 
fested gardens. None of the solanaceous annuals, such as Solanum 
integrifolium, Datura tatula, and others, which have been grown 
possess underground parts which ordinarily would prove susceptible 
to infection by a parasite of the nature of Synchytrium. The stem is 
usually single below ground, without lateral shoots or buds, and the 
firm epidermis and tough cortex of the crown and taproot would 
m Lyman, G. R., and others. Op.cit. 
