4 James Stewart Wiant 



With the more recent development of reforestation projects and the 

 consequent establishment of large coniferous nurseries in the United States, 

 there has been a corresponding development of knowledge concerning this 

 disease. Modern investigations have centered largely about the problems 

 of etiology and control. 



As pointed out by Hartley (1921 : 7), the only fungi definitely connected 

 with the disease as it is discussed in the older European literature appear 

 to be Fusarium spp. (Fusoma spp.) and Phytophthora fagi R. Hartig (P. 

 omnivora De Bary in part). As far as the writer knows, F. fagi has not 

 been reported from conifers in the United States. 



Early reports of Fusarium damping-off in this country are those of Jones 

 (1908), Gifford (1911), and Spaulding (1914). The 'last-named author 

 finds forty-four different strains 2 capable of attacking pines. Hartley, 

 Merrill, and Rhoads (1918) summarize the previous inoculation tests 

 with Fusarium, and record the results of their own experiments with four 

 common species. They agree with Spaulding that more than one species 

 are involved and that F. moniliforme Sheldon (Gibberella moniliformis 

 [Sheldon] Wineland) is one of the more virulent. More recently, Lindfors 

 (1922) has isolated six species of Fusarium from pine in Sweden. His 

 data indicate that these and two other species tested are pathogenic on 

 conifers, but that four of the eight are decidedly more virulent than the 

 others. Dounin and Goldmacher (1926) call attention to the prevalent 

 opinion in Russia that but one species, F. blasticola Rostrup, is involved. 

 From their tests they conclude that four additional species are pathogenic, 

 but the data which they present are limited. It is of interest to note that 

 these investigators claim to have isolated and studied a species of bacteria 

 capable of producing damping-off in the absence of fungi. No details 

 of their inoculation tests are given. Sibilia (1925), in Italy, has described 

 several species of Fusarium from conifers, but evidently has not conducted 

 inoculation tests. 



Accounts of the relation of Pythium debaryanum Hesse to damping-off 

 of conifers are given by Hartley (1910), Hofmann (1912), Spaulding (1914), 

 and Hartley and Harm (1919). In a later paper, Hartley (1921) reports 

 extensive experiments which definitely prove the pathogenicity of this 

 organism on pines. He demonstrates also that strains differ in their viru- 

 lence, and shows that on the basis of morphology and pathogenicity 

 the conifer strains as a group are not different from those attacking 

 angiosperms. 



Duggar and Stewart (1901) are evidently the first to have recorded the 

 association of Rhizoctonia with the disease on conifers. Later reports 

 are made by Hartley (1910) from Nebraska, and by Clinton (1913) from 

 Connecticut. Hartley, Merrill, and Rhoads (1918), and Hartley (1921), 



- The writer uses the term strain throughout this publication to indicate the fungus obtained in pure 

 culture from a single isolation. 



