1 12 



THE AGRICULTURAL NEWS. 



Apkix 24, 1915. 



FUNGUS NOTES. 



A BACTERIAL DISEASE OF LACHNO- 

 STERNA GRUBS. 

 li has oft iiirse of ii vestigations in 



the Lesser Antilles with regard to the grubs of 

 spp., and the allied Pit ' (the brown hari 



thai the larva ■ in the fi m which 



es shiny black patches to appear on the skin; further, thai 

 larvae n, be found showing various stages of 



ction of the li as a black 



results in one i - ! ' tstly, thai a verj 



large pn i] i if the spi " live for si 



unless they ai I transported with exti erne 



I irk brown, and 'li''. 

 I'll. di ;iven are 



strictly comparable with thi b© the subjed of an 



investigation in Mi Mi Zae Northrup, the insects 



pjp., which are very destruc 

 live to crops in thai State. The results of the enquiry are 

 published as Technical /.'• No IS of the Michij 



I . 1 1 inn t Si '. 



A bacterium to which the nani X' 

 is given was isolated from diseased larvae, and cultures on 

 artificial media were used for infection experiments. Unin- 

 jured Lachnosterna grubs were not infected when placed 

 in inoculated soil, but one specimen in which an incision was 

 made developed a black spol on the site of the wound. Other 

 attempts failed owing to the difficulty of making incisions 

 whieh were not of themselves fatal. 



An attempt to transmit the disease to cockroaches 

 (Peripla.ne.ta americana) resulted in infection and loss of 

 portions of the legs of two of thi se insects. 



The larvae of an Allorhina, belonging I" the same 

 family as Lachnosterna, were placed in inoculated soil and 

 developed spots, but since later collections showed the spots 

 when received, infection may very well have been also 

 present from the beginning on the earlier examples. 



It is to be noted that under ordinary conditions the dis- 

 ease is not claimed to be particularly fatal. Larvae infected 

 with it lived for weeks nr months. In the ease of a consign- 

 ment of Allorhina a large percentage of the naturally infected 

 larvae developed into beetles, although only I percent, of 

 them were regarded as tree lioin infection when received. 



Excessive watering of thi -oil in which infected larvae 

 were kept led to their early death, but in view of the 

 delicate constitution of these grubs, and in the absence of 

 recorded controls, it would not bemfeto assume that death 

 was in any way connected with the infection. 



It is recorded that although the affection had not 1 n 



rved in Porto Rico yet 100 per cent, of a consignment of 

 larvae from that island were : less infected. 



Reference is made to the common occurrence if 8 

 producing bacillus associated with the disease, and the author 

 - to the pari played by the two org misms in 

 the origin and especially the fatality oi the disease. In 

 ., footnote it is explained thai the rapid browning oi the 

 diseased laivae, first regarded as a generalization ol the 

 ction which causes the black spots, is nest probably due 



to the invasion, secondaryoi primary, oi the above- utioned 



bacillus, which app Bimilai to Krassilstochik's 



bacillus of inseel septicaemia /»'. tepticus insectorum. 

 Apparently tin- rapid.i many ol the larvae brought 



in from the field, referred to it the outset of this review, is 

 accompanied by the get lopmenl of this or a similar 



erium. In the eiperienc ol the present writei with 

 Phyta ..nt of loss from this cau 



proportional to the care taken ii handling the larvae, and not 

 previous ii with the black spot disease. Soini 



of the insects bearing the spots are amongst those whicl 

 survive whi ipparently quite free from them are lost. 



\li" Sortlmip's pap-:, while contributing to oui 

 knowledge of cannot 1" 



regarded a I ba 



disea 



W.N. 



A SUCCESSFUL INTRODUCTION OF RESIS- 



TENT VARIETIES OF GROUND NUT. 



We take the following interesting note from thi 

 report of the Imperial Mycol sfisl India for 1913-14: 



The relation between the incidence of the tikka diseasi 

 of ground 4iut and the amount of cultivation and export ol 

 rop was the subject of at inquiry during the year under 

 review. Between I894and 1902 the export of groundnuts 

 fell from 78,48m tor to 2,890 and thi practi- 



cal^ extinct. The tall in the exports was due nol to 

 deterioration in the quality of the produce, but to a marked 

 decrease in the yield per acre, which appeared to !■■ 

 the result of the fungal disease, known locall) as tikka 

 [Septogloeum arachidis]. Treatment with fungicides had 

 no effect in stopping the disease and. in 1902, the 

 Bombay Department of Agriculture commenced the inti< •- 

 duction of exotic varieties. These varieties were also 

 attacked by tikka. but si. me. which ripened early, did 



not have their yield appreciably affected. Two varieties 

 from Japan were especially useful in forming their nuts 

 before the disease was sufficiently established on them to 



damage the produce As a result of this, the exotic varieties. 



introduced by the Bombay Department of Agriculture, have 

 now replaced the indigenous in all district- except the Poon 

 district. Moreover, by 1912 the tikka disease had decreased 

 to such an extent that, in the whole Bombay Presidency 

 diseased .specimen- could only be obtained on the Manjri 

 Farm. Coincident with the- introduction of exotic varieties 

 and the decrease In the amount of tikka disease the exports 

 began t" rise. In 1902 they were 2,890 tons, in 190b' they 

 were 6,">27 tons, in 1909, 23,934 tons, and in 1912, 48,801 

 tons. This is probably one of the most marked case- oi 

 record where a crop disease has been checked and a trade 



rejuvenated bj the introduction and acclimatization of new 



varieties. 



An instructive article on the planting of Manihot rubbei 

 in the french Cong., appears in the India Rubber Wort 

 March 1. 1915. This rubber requires a dry climate and the 

 trees are planted 12 to 15 feet apart. Notwithstanding it- 



I results, the fish bone method of tapping is still in use in 



the Congo, but the employ nt of this method frequently 



leads to the illtreatment of the tree, Othei methods have 

 been recommended in consequence, one which is ga 

 favour, being the U .man Lewa method. Some plant 



grow Manihol directlyfrom - I; the larger plantation-, bow 



ever, follow the nursery, system, later transplanting the 

 stumps to theii proper pla 



