xiii. A, 4 Reinking: Philippine Economic-Plant Diseases 



177 



threads accumulate usually at 

 the lower surface of the spots, 

 producing the cushions of coni- 

 diophores and conidia. In pure 

 culture it grows very slowly. 

 On potato agar a raised, more 

 or less leathery, dark brown 

 mass of mycelium is produced. 

 As yet no spores have been 

 observed growing in pure cul- 

 ture. 



Control. — The disease may 

 be held in check by the growth 

 of resistant and acclimatized 

 varieties. The leaf spotting is 

 most severe on the lower leaves, 

 indicating infection from spores 

 in the soil. Crop rotation 

 will eliminate this last source 

 of infection to a marked 

 degree. 



Septogloeum arachidis Rac. Germi- 

 nating conidia (X 350) ; germ 

 tubes entering host tissue by way 

 of stomata. 



ROOT ROT: SCLEROTIUM 



Symptoms. — Frequently peanuts are attacked by a fungus 

 causing a rot of the root and the lower stems. Sclerotial bodies 

 are always associated with the disease. As a rule the disease 

 does not cause serious damage. 



Causal organism. — The organism is a common soil fungus 

 attacking a large number of plants. It is similar to that dis- 

 cussed under coffee. 



Control. — Crop rotation should be practiced. 



ARECA CATECHU LINN. BUNGA, BETEL PALM 



The' betel palm is attacked by a large number of fungi. 

 Pestalozzia palmarum Cooke, Exosporium pulchellum Sacc, and 

 Exosporiuni hypoxyloides Syd. cause leaf spots similar to those 

 discussed under coconut. On dead leaves may be found Guignar- 

 dia arecae Sacc, Diplodla arccina Sacc, and Phomopsis palmicola 

 (Wint.) Sacc. On dead leaf sheafs may be found Colletotnchum 

 arecae Syd., Gloeosporium palmarum Oud., and Zygosporium 

 oscheoides Mont. On dead petioles may be found Phomopsis 

 arecae Syd. and Anthostomella arecae Rehm. On dead fruit 

 may be found Gloeosporium catechu Syd. On dead trunks may 



