492 



DE Seabra (A.). Estudos sobre as Doencas e Parasitas do Cacaueiro 

 e de outras Plantas cultivadas em S,' Thom6. xviii. A Mol6stia 

 nova dos Cacaueiros na Ilha de S. Thom6. [Studies of the Diseases 

 and Parasites of Cacao and other Plants cultivated in the Island 

 of San Thome, xviii. The new Disease of Cacao in S. Thome.] — 

 Lisbon, Companhia Agricola Ultramarina, 1919, 43 pp. [Received 

 21st September 1920.] 



In 1916 an apparently new disease of cacao appeared in the Island 

 of San Thome and the danger to the plantations increased to such 

 an extent as to render necessary an investigation, of which the results 

 are given here. 



The disease is an aggravated form of injury due to two enemies 

 previously laiown in the island, a fungus, Lasiodiplodia theobromae, 

 and a thrips, Heliothrips rubrocinctus, Giard. 



The investigation covered 61*5 per cent, of the estimated area under 

 cacao, 35 per cent, of the plantations being affected. Among young 

 cacao (under 5 years old) the mortaUty sometimes amounted to 50 

 per cent. ; the old trees suffered much less. 



Bordeaux mixture containing at least 1 per cent, of copper sulphate, 

 and enough Ume to neutraUse the solution, is recommended against 

 the fungus. Measures against H. rubrocinctus are more difficult to 

 apply owing to the disadvantages attaching to a contact poison. 

 The formulae given by Russell for nicotine are advised [R.A.E., A, 

 i, 99]. Both enemies may be combated simultaneously by combining 

 nicotine with Bordeaux mixture. Natural enemies such as the 

 Coccinellid. ExocJiomus flavijjes, and three others stiU unidentified, 

 should be protected. Against the thrips, tobacco should be planted 

 experimentally, as it has been stated that the thrips is attracted to 

 the stems and leaves of green tobacco and dies before injuring that 

 plant. 



The paper concludes 'with a list of 51 insect pests of cacao in San 

 Thome ; of these the following either contribute to or precede the 

 development of the fungus : — Rhynchota : Aleurodes sp. , Selenaspidus 

 (Aspidiotus) articulatus, Morg., Morganella {A.) maskelli, CkU., A. palmae, 

 Mask. & Ckll, Aidacasjns ^jentagona, Targ., Dysdercus super stitiosus, 

 ¥.. HelopeUis sp.. Coccus {Lecanium) viridis, Green, Lepidosaphes 

 {Mytilaspis) bechii, Newm., Orthezia insignis, Dougl, Pseudaonidia 

 trilobitiformis, Green, Pseudococcus citri, Risso, Psylla sp., Toxoptera 

 coffeae thoniensis, Shr. Coleoptera: Haltica sp., Apate sp. Isoptera : 

 Cephalotermes rectangularis, Sjost., Microcerotermes dolichognathus, F. 

 Silv., Neotermesgestroi,¥.Si\v. Thysanoptera : Heliothrips rubrocinctus, 

 Giard, Heliothrips sp. Corrodentia : Psocus sp. 



DE Seabea (A.). Estudos sobre as Doencas e Parasitas do Cacaueiro 

 e de outras Plantas cultivadas em S. Tome. xix. A Seca dos 

 Ramos dos Caeaueircs. [Studies of the Diseases and Parasites 

 of Cacao and other Plants cultivated in the Island of San 

 Thome, xtx. The Withering of the Branches of Cacao.] — Lisbon, 

 Companhia Agricola Ultramarina, 1919, pp. 5-40. [Received 

 21st September 1920.] 

 Insect pests of cacao additional to those recorded in the 



preceding paper, include the termites, Neotermes pallidicollis, Sj5st., 



