

THE AGRICULTURAL NEWS. 



Novembeb 20, 1915. 



DISEASES OF PLANTS. 



NEW LIGHT OF THE WITCH-BROOM 

 DISEASE OF CACAO. 



,p from the buds, causing 

 w ..in swo orted, and quicklj killing 



them, 3 ■ ■■<<>■ i; " ' ■ 



fi cts ..n the industry. 

 I of 7 million It.. 



bo less than 2 million in 

 1904, and only m that year to 1913. 



ninations bj vai ions mycologists, 

 I .1 J. vanHalland A.. W. Drost, working in the country, 

 stensive study of the disea to the 



a ion, whii h ■ ■ ■■ accepted, that thi 



{ thi as well as of a hardening of the pods also 



peculiar to Surii in i fungus which thej named CoHeto 



,n. Their paper appeared in 1907. Thej 

 bting back all the branches 

 to within a shoi of the main forks, spraying with 



Bordeaux mixture, and then removing by hand such of the 

 new shoi ' -" d signs of infection. This involved the 



total loss of a year's ion oi the ucceeding 



crops foi one or two years, and did not, moreover, get rid of 

 It has : d that thorough annual spray 



ing, with careful removal of th d shoots, though less 



lately effective in reducing the disease, is economic- 

 al^ .. sounder policy, and it the one now followed by 

 a majority 



The app disea i urallj caused 



.some apprehension in other cacao-growing countries. In 

 [91] \|i' .1. B. Etorer, Mycologist to the Trinidad Board 

 of Agriculture, visited Surinam for the purpo 



with th i ranee of the disease 



eld, and was able to report on his return 



that it was different from any disei icurring in 



Trinidad. In 19.13 he paid a longer visit, as a consequence 

 f win. h hi drew attention to the fact that the mycelium 

 found in the di op connexions which 



show that it belongs to another division of fungi than 

 containing van Hall and Drost's fungus. This objectio 

 strengthened by the fact that the latter fui urs in 



Trinidad, bui does not give rise* to either witch brooms or 



As of Rorer's criticism question ol 



causation of the di ted l.\ Dr. 



0. Stahel, of the Surinam Department of Agricultun 

 he results arc publi ! ; li, English ai -I Gem 



in x,, ; . oi that I 1 '. dated Si ptember 1915. 



Stahel obtaii revious investigators had 



d , by cuttinj 'i ilized piece ol a di 



.1 t and pi on nutriei Tl lium never 



pores, and w] riments 



• li.l not give rise to the di So far the work i 



' Went and Rorer, with the si results. 



The infection problem was now approached from another 

 B ;de. Obsei that upon the dead witch brooms 



ictifications of Basidiomyceti i, which 



have mycelium with clamp i 



irred. < >ne ol M ly resembling 



the well-known species which causes root .lis. ugar- 



F< i thi ii i "ii it was chosen first for experim. 

 Fruit bo 1 so that sp. ires would fall d 



buds. < >f the I sued 



out of forty-six buds: 



nine: and of the third The white 



myceliam with clamp > I roin the 



oots so infected. Pot 



[■'• intation pro from the 



disease. The au lior wo : . a to be justified in his claim 

 to have absolutelj proved that the Marasmius is the cause of 

 i be di iasi 



It has not been p that 



i he in. lnr.it ioi ed, but 



the indirect evidence to that effect is very str 



The fum eribed bj the author as a new species 



under the nam ol Mara , The fructification 



is of the toads . i. e., umbrella shaped, verj small, the 



cap usually from \ to 1-inch in diameter, ■ and the stalk 



i il iur is white, with 



a faint crimson tin on t be p and a typical 



dark red spot iii ii centre. Th far 1 



found in any other situation thai indun 



and infected flower cushi ins of the cacao I 



The hearing which the discovery of the cause of the 

 disease has up v< i.\ direct one, but it 



will enable recommendations to be made with greater 

 certainty. I '!.■ i uslj the removal of infective material can be 

 more effectively carried out now that it is known exactly in 

 w bat forms it ...■.•urs. 



The 3pores of the fungus, when dried, lose the power of 

 germination within an hour, which suggests itself as an 



explanation of the author's observation that shaded trees an 



much more susceptible than unshaded ones, ft would seem 

 that the danger of infection reaching the West Indian cacao- 

 growing islands is May small so long as living plants and 

 pods of cacao are not imported from Surinam. 



W.N. 



The idove industry of Zanzibar, according to Col" 

 Reports Annual No. 823, dates from 1818, and in 1860 an 

 output of about T.i'iHi.dni' Hi. in weight had been obtained. 

 In 1872 the plantations in Zanzibar were devastated by 

 a hurricane, and therefore most of the trees in the island at 



qI date from that time Pi ba, however, escaped, and 

 the large plantations there are consequently much older, 

 varying from sixty to ninety years. It i- estimated (1913) 



that there are in both islands about 60,1 acres under el. .v. 



cultivations and about 51 million trees in bearing. 



In connexion with the suggested pork and bacon 

 oi the Wi t Indies, ' s >n ..I i hose interested 



may be called to an on the Sitchin Bacon Factory, 



which appears in the Journal oj tit, Board of Agricultun 

 (England) for July L915. This gives detail i 

 the meat in the factory. In connexion with curing, it is 

 stated that aftei the sides have been chilled for from thirty- 

 six to forty hours thej are '\>y - ilted, which in tin 



injecti fa pickli of salt and saltpetre II smoked bacon 



tired, the ri washed and dusted over with pea 



Hour, hung in the no! ed bon es, and iw I ed and dried with 

 hardwood saw lust for from tie iccording to 



the weather. 



