VbL. VIIL No. 196. 



THE AGRICULTURAL NEWS. 



347 



FUNGUS NOTES. 



DISEASES OF GROUND NUTS. 



During the last few years, attrinpts have been made to 

 introduce into the Wtst Indies new varieties of ground nuts 

 from the luiited States noted for the large size of their nuts 

 and their heavy yield. The somewhat disappointing results 

 so far obtained have been reported from time to time in the 

 Ai/ricuJtand J^ews. (See Vols. VII, p. 117 ; VIII, p. 206.) 

 Tliese results are in part due to the severe attacks of fungous 

 parasites, some of which have alreadj' been mentioned, and 

 others still remain to be identified. 



A species of Uromi/ces, one of the rust fungi, is reported 

 as occurring on the leaves of ground nuts in 3t. Vincent during 

 1908. The attack, however,, was not of a serious nature. 



In the year 1907, another, or po.ssiWy the .same fungus, 

 described .as Uredo sp,, was reported from Montserrat, and 

 the attack was thought to be sufficiently severe to have 

 caused shrivelling of the nuts. The same fungus has been 

 found this year in Dominica on the Spanish and Carolina 

 Running varieties, though up to that time, no fungus had 

 appeared and the trials were jiromising. This fungus 

 occurred in Dominica in connexion with another, which may 

 prove to h&Septojloeuiii, arnchidis, causing a black spot on the 

 leaf. An account of this appears in the current volume of 

 the Agricultural Xews, No. 194, page 31."). 



Spraying with Bordeaux mixture was tried, but did not 

 prove effective. A mixture of equal parts of sulphur and 

 lime, dusted on to the leave.s, had some effect in checking the 

 disease, though it was not entirely successful. To save the 

 remains of the crop, the nuts were harvested and all the rest 

 of the plants burnt. It wotild be advisable not to plant 

 ground nuts again in the same soil for at least a year. 



To give some idea of the damage wrought by the disease, 

 probably the ' black spot ' fungus more particularly', it may 

 be stated that the yield of nuts from one plot was only 3-') lb., 

 as against 106 lb. from the same plot last year. 



A root disease was also found on ground nuts in the 

 same island, which is due to a fungus as yet unideirtified. It 

 causes the leaves of plants attacked to wilt, and about two 

 days later the plants die. The roots, pods, and probably 

 the nuts, are attacked, and in advanced cases the lower 

 parts of the stem, above the collar. The diseased portions 

 exliibit a fine, web-like, white mycelium, which, in its older 

 portions, is covered with straight, rod-like crystals. This 

 produces small white tufts which grow somewhat, become 

 yellow, and finally brown. They are about ^ inch in diameter 

 when fully grown, and roughly spherical in shape. 



In section, they show two or three layers of firm, brown 

 Lyphae, forming an outer covering, which encloses a mass of 

 swollen, colourless hyphae, completely undifferentiated. They 

 are probably of the nature of sclerotia. No other fruiting 

 bodies have yet been found. 



A similar di<ea.se, probably due to the same fungus, 

 attacks tomatos and egg-plants, and other garden crf)ps in 

 Dominica, and has also been found on Antirrhinum, some 

 aroids, and other plants in Barbados. It seems distinctly 

 probable that the root disease mentioned in the St. Kitts 

 report for the year 1908-9 as attacking the Spani.sh and 

 Tennessee lied varieties, was due to the same fungus, though 

 this is not yet known definitely. 



When the disease appears in a flower bed, or a ])lot of 

 ground nuts, all the plants attackid should be immediately 

 dug up, together with the earth round them, and buried with 

 lime in a deep pit ; the holes from which they have been 



taken should a1.^o be dressed with lime. Should this treat- 

 ment not be effective, it would be advisable to remove all the 

 plants from the bed, or all the crop, as soon as possible^ bury 

 them with lime or burn them, and dress the whole of the bed 

 or plot with lime, at llie rate of about J-lfc. to the square 

 foot. I' .-^honld then be allowed to lie fallow for one or 

 two montlis, and be subsc(piently planted with different 

 flowers, or a different crop. 



In all probability, the wet weather is largely responsible 

 for the increased incidence of the diseases mentioned, and it 

 has a further ill effect by causing the ground nuts to germinate 

 too soon, or to rot in the soil. It has been found necessary 

 in St. Lucia to plant the seed so that the ripening period 

 may fall between February and ilay. In Bengal, if any rain 

 falls at the ripening period, the ryots endeavour to save as 

 much of the crop as possible by ploughing up the land at, 

 once and exposing the pods. {Handl/ool- of CoMmercial 

 Products, No. 24, Imperial Institute Series.) 



In the case of the Dixie Giant variety of the ground 

 nut, it has been found that the .seeds frequently rot in the 

 ground, even when the soil is fairly light and has been care- 

 fully prepared. This was noted particularly in St. Kitts and 

 Nevis. It is possible that the trouble might be overcome by 

 carefully di.sinfecting the seeds with a solution of corrosive 

 sublimate of the same strength as is used in the case of 

 cotton seed. It is hoped that it will soon be possible to 

 undertake experiments at the Head Office, with a view to 

 finding out if disinfection can be effectively carried out with- 

 out injuring the germinating power of the seed. If this 

 treatment .should be found not to be injurious, it would 

 probably be of assistance in combating other diseases besides 

 the rotting of the seed. 



Although the results have been so far rather unsatisfac- 

 tory, yet it has been noticed in several of the islands that the 

 Carolina Bunning variety gives fairly good results, and 

 appears more resistant to disease than the other imported 

 forms. Moreover, it is possible that the latter in particular, 

 and all the varieties in general, may improve considerably as 

 they become more acclimatized, so long as they are planted 

 in a fairly light soii. This gradual acclimatization, both 

 local and general, is a factor which must always be taken 

 into account when dealing with newly imported varieties 

 of plants. 



Another method by which improved results may eventu- 

 ally be obtained is by crossing one of the more promising 

 imported varieties with a local hardy form, and subsequently 

 separating out, on Mendelian line.s, a variety which combines 

 the good cropping powers of the imported form with the 

 disease-resisting power of the local variety. 



It seems probable, then, that before long it will be 

 possible to obtain, bj^ a combination of the methods mention- 

 ed, a variety of ground nut giving good and reliable returns, 

 and thoroughly suited to the conditions in the West Indies. 

 Such a plant would undoubtedly form a valuable addition to 

 the agricultural products of these islands. 



DEPARTMENT NEWS. 



The Imperial Coraiuissioner of Agriculture return- 

 ed from Enorland to Barbados by the R.M.S. ' Atrato' 

 on October 26. 



Mr. H. A. Ballon, IVLSc, Entomologist on the staff 

 of the Imperial Depnrtnient of Agriculture, left by the 

 R.M.S. 'Berbice' for St. Lucia, on October 26, for the 

 purpose of making investigations in connexion with the 

 cotton industry in that island. 



