RUBBER (HEVEA) DISEASES 33 
MOSSES AND FERNS 
In wet shaded situations the trunk and branches of Hevea may 
support quantities of epiphytic mosses and ferns. Only where 
there is an accumulation of growth of such plants in the forks or in 
old open cankers caused by unhealed tapping wounds may any 
damage result. These plants help to hold the moisture in such 
places and promote the growth of fungi and probably harbor in- 
jurious insects. 
LEAF DISEASES 
SOUTH AMERICAN LEAF-BLIGHT 
The leaf-blight caused by Dothidella ulei P. Henn. is widely dis- 
tributed in the Amazon Valley and is apparently coincident with 
the range of the host in South America. It has not been reported 
outside of Trinidad and the mainland. 
At practically all the stations visited in the lower Amazon region 
the fungus was found. causing more or less damage to planted rub- 
ber. The disease was less in evidence in the upper parts of the 
valley. 
The attack on young trees in the lower valley was sometimes very 
severe. It is without question the most serious leaf disease of Hevea 
in the American Tropics. 
HISTORICAL 
Hennings first described the ascigerous stage of the fungus in 
1904 under the name of Dothidella ulei. This material was col- 
lected by Ule in August, 1900, on the Jurua, in August, 1901, at 
Jurua Miry in Acre Territory, and in July, 1902, at Iquitos in Peru, 
on the Amazon, the last collection being considered the type. At- 
tention was called to the fungus as a possible important parasite. 
From the same material Hennings described the pycnidial stage as 
Aposphaeria ulei. HoAvever, the early investigators from insuffi- 
cient field observations did not regard the fungus as a serious para- 
site. When it was first observed in British and Dutch Guiana in 
1907 it was not regarded as capable of causing much damage. 
Drost reported on a disease of nursery plants at Paramaribo in 
Dutch Guiana in 1910 which was undoubtedly the disease in ques- 
tion. Both a pycnidial and a Ramularialike conidial stage were 
observed. Although he called, attention to the effect of the disease 
on leaves, stems, and twigs, he did not regard it as serious. 
In 1911 Kuyper described the disease in Dutch Guiana with con- 
siderable detail under the name of Fusicladium macrosparum- and 
observed that nursery plants were frequently seriously attacked, 
but that the injury to mature trees was negligible. He figured and 
described a pycnidial stage, but failed in infection experiments to 
demonstrate a higher fructification. In 1912 Kuyper again re- 
ported on the disease from Dutch Guiana, but did not regard it as 
especially dangerous, although trees of low vigor died when at- 
tacked. Griffon and Maublanc in 1913 studied the organism on 
material collected in 1912 by V. Cayla on cultivated Hevea at Para 
(Belem). They considered the conidial or Fusicladium stage and 
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