142 



ing this disease it has been found more effective to allow the gas to 

 act for a slightly longer period than usual, say about forty minutes. 



A parasitic fungus, Ascherso>na tahitensis, has been found which 

 attacks and destroys the larvae and pupae of the mealy wing, and bids 

 fair to be of great aid in combating this pest. It forms small, wart-like 

 conical pustules, from 2 to mm. in diameter. At first these are 

 white or orange yellow throughout, but in the mature stage the spore 

 masses become orange red. This fungus is frequently found in groves 

 affected with sooty mould. It dots the under surfaces of the leaves 

 and may occasion alarm if its nature is not understood. Unless examin, 

 ed in an early stage of development, no trace of the mealy-wing scale 

 can be discovered without microscopic study. 



When sooty mould follows attacks of the wax scale, mealy bug or 

 orange aphis, thorough spraj^ng with the resin wash or standard kero- 

 sene emulsion will be found effective. The time when the treatment 

 should be made is not important in these cases, but if the resin wash 

 is used, a dry season should be selected, when the work will not be 

 rendered uncertain by the liability of rainfall. 



FOOT ROT OR MAL-DI-GOMMA. ) 



Foot rot or mal-di-gomma is a disease chiefly of the orange and 

 lemon, and is probably more widespread than any other citrus maladv. 

 It is known to occur in almost all countries where the orange is culti- 

 vated, but so far as known appeared first in the Azores Islands, where it 

 was very severe. According to the statement of Fouque("^) it was 

 first noticed in this group in 1834, on the island of San Miguel, where 

 it seems to have originated. From that time until 1840 he estimates 

 that fully one-fourth of the trees were destroyed. It reached its great- 

 est severity on the island in 1840 ; in 1842 it began to decrease, and in 

 1873 it had ceased to be very serious. F. Alphonso(^) says that accor- 

 ding to general report the malady appeared in Portugal in 1845, in 

 Hyeres in 1851, (^) in Lago di Garda in 1855, and in Messina in 

 1863. According to Briosi(^') the disease first appeared in Sicily in 

 1862, and afterwards spread to Naples, Liguria, and La > o di Garda, 

 everywhere destroying orange and lemon trees by thousands. Profes- 

 sor Wohler mentioned in Briosi's monograph referred to in foot-note) 

 found the malady very destructive on the Balearic Islands in 1871. 

 Statements differ in regard to the first appearance of the disease in 

 Florida, but it seems to have been noted here some eighteen or twenty 

 years ago. Dr. A. H. Curtis(^) says: "It appeared about nineteen 

 years ago, though few people remember to have observed it earlier 



(1) An account of this disease, prepared by B. T. Galloway, was published in Part 

 II of Bulletin No 8 of the Division of Botany, U. S. Department of Agriculture. 



(2) Voyages geologiques aux Acores, III, Les Cultures de S. Miguel (Revue des 

 deux Mondes, Paris, Apr. 15, 1873, p. 8S7). 



(3) Alphonso, F., La coltivazione degli aranci nelle Azzorre (Annali di agricol- 

 tura Siciliana, Vol V. 1873, p. 311). 



(4) Rendu, M. V., Note sur la maladie des oranges d'Hyeres, Extrait (Commis- 

 sionaires Jussieu, Gaudichaud, Decaisne) Compt. Rend., t. 33, 1851, pp. 681-633). 



(5) Briosi, Giovanni, Intorno al mal di gomma degli agrumi (Fusisporium limo- 

 ni, Briosi) (Atti della R. Acad, dei Lincei, Roma, ser. 3a, Vol. II ; Memoria della 

 classe di science fisiche ecc, meeting of May 5, 1878, pp. 485-496). 



(6) Curtis, A. H., Sore shin or gum disease (Ma. Ezpt. Sta. Bull. No. 2, June, 

 1888, pp. 29-35). 



