270 PHYTOPHTHOEA MEADII H. Sp. ON HEVEA BRASILIENSlS 



of the discoloration (Translation). The fourth is the formation of burrs 

 when the third form is not dealt with. He states that the black-stripe has 

 only been found in estates strongly attacked by canker, and also all stages 

 between it and the typical red spots have been found. The cause of all these 

 appearances he attributes to P. Faberi, which also causes the canker of cacao 

 and the fruit-rot of cacao and Hevea ; but the hyphse of Phi/tophthora have not 

 been found in the third form, though it is always associated with the second. 

 It is not clear whether all the infective material he used for inoculating Hevea 

 was derived from P. Faberi from cacao, or partly from cacao and partly from 

 Hevea. His latest paper I have not seen. Dastur ^ in 1916 reported from 

 Burma the presence of fruit-rot and black-thread, which is very Uke the bark- 

 rot of South India, and said by Bryce to be the same as the one occurring in 

 Ceylon, and suggested the possibility of the PhytopMiora he found to be the 

 cause being the same as that in South India. The difl'erences, however, 

 between the two fungi are somewhat striking. His measurements of sporangia 

 on fruits and stems, viz., 20'7 — 35-7/x x 15-0 — 25 -S/x sometimes reaching 4:4-2// 

 in length and 29 -0/^ in breadth, the average being 28-5 x 20-4/x, come fairly 

 near those of P. Meorfn in water- cultures, wz., 20 — 44/x x 16 — 29/x, the average 

 being 32 x 23/x, but they are considerably smaller than those on fruits, viz., 

 32 — 67/x, X 14 — 28/i.; the average being 48 X 2]/i. The zoospores in a sporangium 

 number 3 to 10, while in P. Meadii they number 14 to 23 and very occa- 

 sionally up to 30 and 40. Then resting conidia are present in the Burma 

 Phytophthora, but they have not been seen in P. Meadii. Antheridia, oogonia 

 and oospores are absent from the Burma Phytophthora, while they are present 

 in P. Meadii both in culture and on fruits. We exchanged cultures of the 

 two fungi and grew parallel cultures ; but the Burma Phytophthora did not 

 produce oospores in my laboratory, while the South Indian one did in Pusa. 

 Different climatic conditions might well account for these differences, but till 

 oospores are found in the Burma Phytophthora, we cannot be quite certain 

 of their identity. Pratt ^ reported " black thread " or stripe canker or 

 cambium rot from Sumatra, and gave details of remedial measures. Belgrave 

 and Norris^ reported it from Malay in the same year, and attributed it to a 

 species of Phytophthora isolated from the diseased wood, and got 100 per cent. 



i Dastur, J. F. • Phi/tuphthna sp. on Hecea brasilieasii." Mem. Depf. Aijrk., India. 

 hot. Series, VIII, pp. 217—232, 1910. 



2 Pratt, H. C. " Preventive- nu-asures against Black Thread. "' 2'rop. Agric, XLVIII, 

 pp. 304—306, 1917. 



3 Belgrave, W. N. C. and N(,nis, F. de la M. " Notes on Bark Cankers and their Treat- 

 ment." Afjrk. Bull., F. M. States. VI, pp. 2—7, 1917. 



