570 



THE AGEICTJLTUEAL NEWS, 



August 12, 1916. 



PLANT DISEASES. 



A NEW CANE DISEASE IN PORTO 

 RICO. 



The following nccount of a tlisease of sugar-cane not 

 previously recognized in the New World will be read with 

 some concern by sugar planters. It is taken from the report 

 of the Pathologist in the Fourth Keport of the Board of 

 Commissioners of Agriculture of Porto Piico, 1914-15. 



Cytuspora sacchari. This is a comparatively new disease 

 of cane, for which no common name has as yet been proposed. 

 It was first discovered in 1912 by the former pathologist, on 

 foreign varieties of cane at Itio Piedras, and there seems no 

 reasonable doubt but that it was introduced with some one 

 of these varieties, large numbers of which were brought in 

 from all parts of l he world until the establishment of the 

 plant quarantine. The only other known report of its occur- 

 rence outside of Porto Paco is from British India, where it 

 was described as a very unimportant disease of the stalk and 

 leaf sheaths. 



To date it has been found in Porto liico on the following 

 cane varieties: at Rio Piedras on Barbados Nos. 7169, 

 6385, 17.53, 8660, 7245, 3696, 3859; Demerara No. 109. 



Near Carolina a well developed case was found in Rayada 

 cane, though still confined to a small area, and in the ea.stern 

 end of the island, B.135.5, P..39-.'2, D.117, C4C.759, and 

 GC. 47 were attacked. 



The symptoms of the disease are well marked. \'oung 

 shoots are killed outright, others checked in their growth, 

 and at least the lower leaves killed. The leaf sheaths are 

 bound firmly together about the stalk by the mycelium of 

 the fungus, the leaf blades drooping in a characteristic 

 manner. The exposed portions of the leaf sheaths are a dull 

 dark-red in colour, and are covered in profusion with the fruit- 

 ing bodies of the fungus, the long sharp-pointed necks of which 

 project beyond the .surface sufficiently to be readily seen, 

 and give a rough sensation when the hand is rubbed over the 

 area. 1 )uring wet weather a minute yellowish globule of 

 conidia can be seen with a hand lens exuding from the mouth 

 of each pycnidiuni or fruiting body. 



In addition to killing outright young shoots, the older 

 stalks are invaded with a resulting dry rot which renders 

 them worthless for sugar production. 



Because of the fact that this fungus, of no importance 

 in other parts of the world, has been able to attack a number 

 of varieties of cane here, and do some damage fears have been 

 entertained that it would become epidemic. The situation 

 is being closely watched, and an atten\pt will be made to 

 eradicate it completely in tho.se localities where it has 

 appeared. 



THE ABSENCE 

 FROM 



OF CITRUS 

 PORTO RICO. 



CANKER 



A matter of interest to citrus growers, from the same 

 source as the above, is the report of the quarantine measures 

 taken against citrus canker, and on the results of a search 

 ior the disease, in Porto Rico. 



As soon as the serious nature of this disease and the pos- 

 sibility of its entry into Porto Rico was realized, a press notice- 

 was issued as a warning to the growers. A quarantine- 

 measure was provided by the Board of Agriculture in Decem- 

 ber, prohibiting the entry of all citrus material from the Gulf 

 States. The regulation was broadened in April to include all 

 living plant material from the citrus-producting States, and 

 citrus material from all parts of the United States. Great 

 care has been taken to enforce this ruling, various packages 

 of plants having been turned back or destroyed. Since the 

 di-sease existed in Fkirida and other of the Gulf States for 

 .some time before it was discovered and announcement of it 

 made, there was the possibility that during that time 

 it might have reached the island on shipments of 

 citrus or other nursery stock sent from infected nurse- 

 ries. Since the disease is bacterial in its nature and 

 very resistant to known methods of treatment, ordinary- 

 quarantine precautions such as fumigation as practised 

 against insects, defoliation, etc., would not have availed, to- 

 prevent its entry. Consequently the necessity arose of inspect- 

 ing all shipments of plants to Porto Rico from the infected 

 States, for as far back as the disease was known to have been 

 present. The carrying out of this task was made po.ssible by 

 securing a list of all such shipments from the quarantine 

 records. Then, as rapidly as possible, a careful search for 

 canker was made on all plants included in these shipments in 

 the various groves and gardens where they had been planted. 

 This work has, to date, yielded no traces of canker, though 

 certain of the plants have been examined several times. 

 It is felt that at the present time Porto Rico is free of 

 canker. Whether or not this freedom can be maintained, 

 depends largely upon the attitude of the growers themselves. 



PLANTS THAT STUPEFY FISH. 



In Dominica, some years ago, fruits of a tree known 

 locally as the Bois Bambarra, were obtained from the Pointe 

 Mulatre estate and forwarded to Kew for identification. 

 These, in due course, were reported to be the fruits of a 

 species of Diospyros. Owing to the absence of complete her- 

 bai-ium material, it was not possible to give the specific name. 

 This matter remained in abeyance for several years, until a 

 specimen of Bois Bambarra ttowered in the Botanic Gardens. 

 On receipt of this material at Kew, the tree was identified as 

 Diospyros Ebenaster, Retz. , 



To the present, con.siderable doubt has existed in the 

 minds of botanists as to the habitat of this plant. From 

 careful enquiries made, there can be no question that 

 Diospyros EhenasUr, Retz., is indigenous to Dominica. It 

 occurrs in the forest as a large tree, and is fairly common 

 near the coast on the Windward side of the islaml. It 

 prefers localities in which the rainfall is ample, consequently 

 it does not occur on the dry Leeward Coast. 



In Dominica the fruits of Bois Bambarra are used for 

 stupefying fish. The fruits are collected in quantity, then 

 reduced to a pulp, which is placed in sacks or baskets for 

 submergence in the deep pools in the rivers. In the case of 

 fast flowing rivers, attempts are made to divert the rush of 

 water as much as possible away from the pools about to be 

 poisoned. 



In the list of Dominica timber trees the Bois Bambarra 

 is described as 'a large tree 4 to 5 feet in diameter of trunk; 

 wood tough and strong, employed for oars, mortars, pestles, 

 etc., timber also available for inside house work.' 



An interesting article on Dyospyros Ebenaster, Retz. 

 appeared in the AVic Bulletin, No. 2. 1915. 



