130 



THE AGRICULTURAL NEWS. 



May 3. 1919. 



bi' of the least good for the fungi, and even if the 

 fungi were eliminateJ, theie would still be the other 

 physiological troubles. 



'The ground nut here is another good instance. 

 Ground nuts may be planted here up to the end of April 

 (the rains begin with the tornadoes about the end of 

 March or even earlier), or if the rains are late, into May. 

 Let us .say that up to the time when the vine has 

 stopped growing and is on the turn, it gets x inches of 

 fain. We used to plant (up to 1914) about June and 

 even later. Planting then, it is quite possible that 

 the crops, before the rains stop, will get x inches of 

 rain, at times more, at times less. But the bulk of the 

 plants will be stunted, chlorotic, or mottled green and 

 yellow, and instead of spreading normally (I am not 

 referring to normal erect-growing types) grow erect, the 

 leaves are very much reduced in size, and hardly any 

 nuts are formed, \yhen I came here in 1912 I never 

 questioned the time of planting. I took it for granted 

 SLS correct. I found myself up against this mottling 

 and bunching, could find neither insects nor fungi, and 

 the tubercles on the roots were apparently normal. 

 The natives do not grow them much here, and, truth to 

 tell, I did not think of asking them about the crop. 

 I could not get to Northern Nigeria, where I knew the 

 nuts must grow well, and had to make the best of it. 

 I tried all sorts of ideas, but mainly kept ray eyes open 

 for a field clue. 



'I got this indirectly when trying to solve a rather 

 similar cotton (native type) problem. Up to 1914' our 

 highest yield of groundnuts as harvested, amounted to 

 lust over 500 It), per acre, which would probably have 

 weighed about 300 lb. when dry (unshelled nuts). We 

 had many worse than that, which would not bear 

 recording, down to 11 lb. per acre. Now normally we 

 get from 1,000 to 3,000 lb. of well dried nuts per acre 

 (efjuivalent to about a ton as harvested). With the 

 aid of lime I secured 1,700 lb. once, but the liming had 

 nothing to do with disease. In a 10-acre field one 

 cannot see a "bunched" plant. 



'The cotton disease that gave me the clue was 

 solved in a different way. Up here "native" cottons 

 are affected by a serious and incur.ible disease, of 

 "physiological" origin. Flowering is greatly reduced, 

 and, of course, boiling. The Upland Cottons (Ameri- 

 cans of our introduction) were never affected. I found 

 the solution of that from shepr field observation. 

 Native plants near the coast, wh-rc the humidity 

 average is much higher, grow normally. The key to 

 the problem lay in the fact that the Americans were 

 Upland cottons. Their hirsuten^-ss is an upland 



character. The natives (G. vitifoliitm and per\i- 

 vianum strains) are glabrous. It took two whole 

 tours before these obvious facts sank into my brain. 



'The remedy for the disease was to grow the right 

 cotton in the right place. Uufortunately for the cotton 

 spinners, cacao has long since ousted cotton from the 

 high humidity belt. It was only from noticing a few 

 stray survivors of bygone cultivation at Bonny that 

 I tumbled to the cause of the troubles. 



'Before leaving the ground nut, I may say that my 

 theory to account for the facts is that it is not the 

 leguminous portion of the ground nut that suffers in the 

 mid-rainy season planting, but the nodule organism 

 that is "diseased" (perhaps from too low a soil tempera- 

 ture during the period immediately after it infects 

 its host, or perhaps even before it has become 

 "involuted"), or because the soil then being at its 

 maximum wetness, the organism in the soil has become 

 involuted. When it does infect the ground nut, it either 

 reverts to its ancestral parasitism, or, being icself lielow 

 par, while not becoming a parasite, is yet unable to 

 fulfill all the terms of the partnership. 



'Now you will see what I mean by field physiology. 

 I doubt if any of the problems I have mentioned could 

 have been solved in a laboratoiy, or at any rate only 

 with the utmost difficulty, and with good fortune. I do 

 not suggest that the problems are solved in the ulitmate 

 sense, but at any rate I know the practical remedies, 

 and this is a great deal.' 



With regard to bud lot of coco-nut trees, Mr. Far- 

 quharson seems to think that much of the trouble 

 attributed to that disease is possibly due rather to 

 physiological causes, as will be seen in the following 

 extract. This may be correct, but, on the other hand, 

 bud rot in some coco-nut-growing countries is a ve«-y 

 serious matter, as has been proved in Ceylon and Cuba 

 for instance. There is no doubt, however, that care of 

 the trees and attention to the soil enable them to be 

 more resistant to this disease: — 



'As you know, we have been having a great time 

 with coco-nut bud rot. In regard to that disease, it 

 seems to me that too much has been made ot Bacilkcs 

 coli ,and the elementary fact has been lost sight of that 

 dicotyledonous plants die back following asphy.\iation 

 of their roots, for want of drainage, or other adverse 

 soil factors. The first symptom is the death of the 

 growing point of the main a.\ is, if there is one, or of 

 that and the side branches. Now a palm has only 

 got one to go on with, outside its fronds, and when 

 that goes there is no hopa of recovery. Th.it growing 



