affected. When a fruit is attacked a portion of it is 

 taken out and falls away, just as if it had been bitten by 

 an insect. 



In the lemon the mature fruit suffers most. The fungus 

 enters usually at a bruise on the surface. A dark spot is 

 produced, and finally the whole surface of the rind becomes 

 brown. This is known as "lemon spot." 



In the orange and pomelo the fruit is apparently not 

 affected by the fungus. 



The following methods of treatment are recommended 

 by the United States Bureau of Plant Industry : — ■ 



For lime trees, spray with Bordeaux mixture as often as 

 is thought fit. For " lemon spot," spray with potassium 

 hydrogen sulphide (" liver of sulphur ") after the lemons 

 have been picked, or with ammoniacal copper carbonate, 

 7-10 days before picking. 



Careful pruning and good cultivation remove all the weak 

 parts of the plant and are strongly recommended. 



Diagnosis. — Acervuli scattered or loosely gregarious, 

 formed under the epidermis and becoming at length erum- 

 pent, depressed, blackish ; setae cylindrical, apex rounded, 

 continuous or sparingly septate, 40-90 by 5-6 microns, 

 black or dark-coloured ; conidiophores densely fasciculate, 

 cylindrical, rounded at the apex, continuous, 18-25 by 4-5 

 microns ; conidia acrogenous, cylindrical, straight, rounded 

 at both ends, hyaline, with granulose protoplasm, 16-18 by 

 4-6 microns. 



ROLFS : U.S. Dept. Agric. Bull., 52, 1904, Bureau of 

 PI. Indust. 



GLEOSPORIUM ALBORUBRUM, Petch. 

 (Die-Back of Para Rubber.) 



This disease of the Para rubber plant was first 

 investigated in Ceylon in the year 1905 ; since then it has 

 issumed more serious proportions, and in 1909 it was 

 reported to have caused the death of many of the rubber 

 trees in the island. 



The disease may well be divided into two parts, the two 

 being really separate diseases. The first disease takes the 

 form of the dying back of the leading shoot of the tree. 

 The fungus appears to attack that shoot at about the 

 middle of its length. The place attacked becomes dark 

 brown, and this discolouration gradually extends over the 

 whole shoot. The brown patch at first is rather soft, but 



50 



