302 



THE AGRICULTURAL NEWS. 



v i i 'i i EE 11, 1915, 



FUNGUS NOTES, 



DISEASES OF LIME TREES IN FOREST 



DISTRICTS. 



Xir if the ] 



Ltle, 



perienced in districts where limes are planted in areas 



. al tempi has been madi 

 pre i of the si idj of the i in non 



techn 



So far tit : . re know rj on lime i 



only in ci ricts in I 1 i but since the causative 



occur in 

 other islands of the An till probably all 



distributed, th :pect similar 



lopments when suitable opj are provided in 



St. Lucia "la. 



The hi died Blai Is Ri iol I >isi a se ol limes is now shown 



to be separable into two distinct forms, I caused by 



the familiar root disease fungus of cacao, Rosellinia i' 



Pat., the specific id mtity "1 which has been at last revealed 



by the finding of fertile perithecia, the other by Rosellinia 



lei (B. et Br.), Sacc. The latter species has not 



zed on cacao, but occurs commonly in the 



affected districts on Hibiscus and Acalypha, has been recorded 



from Grenada on Castilloa and camphor, and is described in 



cent bulletin as the cause of extensive damage iii coffee 



plantations in Porto Rico. No doubt it had a part in the 



"blight' associated with the decline of coffee cultivation in 



I (ominica in the seventies of last century. 



While the damage done by Black Root Disease in lime 

 cultivation has been sufficiently severe, it is rather the 

 prospect of its continued extension that has given rise to 

 apprehensions. Reasons are given in the pamphlet under 

 discussion for the belief thai by the adoption of fairly simple 

 mres the disease can be kept in control, and confined to 

 sporadic cases of somewhat rare occurrence. Were this 

 result achieved the effects of the disease would be practically 

 negligible, since it i> its propensity for opening up gaps cov- 

 iring the sites oi some dozens of trees in a patch which has 

 'instituted the chief menace. 



The pamphlet should be fou"hd useful by cacao planters, 

 is a large part of H [nation respecting Rosellinia 



lisease applies equally to its occurrence in cacao cultivations, 

 md the measures of control are much the same in the two 



The qui i dealt with in consider- 



iil. Discussion is confined to means ol prevention, 



mpts at i me . unprofitable under the 



ailing cin cultivation and restrii 



i.pl\ I ■ of systems ol isolat 

 bes. 



An allusion immunity of SOUr 



s i ■ now being made 

 on i o best the resistance 



■ 



ilt with. 



1 1 :^li ri ise of forest d 



I valley 

 ible 



ind lias t' 



Tin Piiil I ' ■ of the twigs whicl the list, 



has not so far d lime trees. Il 



kills out small ai d there ii very moisl and 

 I . cacd 



-Lined in the V 



i tical pin! 

 Malay SI 

 The pamphlet is illustrated with five plates showing 



distinctive feal i rooti 



A BACTERIAL MANGO DISEASE. 



In the Annals of . ry II. pp. lit app 



iccount of a detailed research on a disease of mangoes in 

 South Africa by Ethel M. Doidge, M.A., I.L.S., Mycologist, 



1 tivision of Botany, Pretoria. 



The \ ii ulence of the such as to tin 



seriously to affect the expoi A large 



percentage of the fruit falls to the ground whilst 

 immature, and the mangoes which remain on the trees an 

 rendered unsightly and unfit for the market. Tin 

 was first reported from Barberton in the Transvaal in 1909 

 and is said to have appeared there after a hailstorm in 1906, 

 the infection starting in a corner of an orchard and spread- 

 ing rapidly with the prevailing winds. In 1908 not a single 

 fruit was obtained from sixty tree-. Each season since the 

 disease has been steadily gaining ground. Xo record I 

 been found by the author of any similar affection in other 

 parts of the world. 



The damage done is mainly to the fruit. Infection also 

 occurs on leaves and branches, producing lesions in which 

 the bacterium is carried over from one crop to the next. 

 < )n the leaves small angular water soaked areas, some 



2 3 mm. in diameter, appear, which later become dark brown; 

 the surface is somewhat raised and shining and frequently 

 there is a slight exudation of gum. Longitudinal cracks 

 produced in infected petioles On twigs and branches dis 

 coloured spots occur which are followed by gumming and 

 the development of deep cracks. By the time the fruit is 

 hall grown the whole inflorescence has frequently become 

 affected, and the death of the stalks causes the fruit to drop. 

 On the fruit itself the first sign of the disease is a small 

 water-soaked ana; this spreads considerably, and an irreg- 

 ular discoloured spot, intersected with cracks, is eventually 

 produced. The discoloration extends for some distance into 

 the flesh. 



All the commonly grown varieties are affected, but in 

 differing degree-. The disease has not Keen found on related 

 indigenous tree-. 



Extensive spraying- experiments with various mixtures 

 have so far given no evidence of the possibility of control by 



this means, nor have any other remedial measure- proved 

 effectual. 



Th- a to be a rod- 



shaped bacterium to which the name i:<t<-ill<< 



ound I 



parenchymatous ti discoloured areas. It ih.es 



in i. inpcrature for 

 ivth oi the organism under laboratory conditions is 



\ iWS very Slowly at 15 ( '. (1 13 I' I. 



Infection app> irs to he princ ally carried from trei 



by wind, and i 



dripping from int. sted lea 



W.X. 



