190 



THE AGRICULTURAL NEWS. 



June 17, 1905. 



DETERIORATION OF POTATOS. 



The Scientific Committee of the Koyal Horti- 

 culfcural Society has had under discussion the subject 

 of the deterioration of potatos. The following summary 

 of the discussion appeared in the Ganh'verH ClimnicLe 

 of May 20. Many of the points raised apply also, to 

 a greater or less extent, to all plants propagated by- 

 buds, and the summary is therefore reproduced as 

 likely to be of interest to agriculturists in the West 

 Indies: — 



I. Do potatos deteriorate < It is important to note 

 that deterioration may take place from a connnercial point 

 of view, or from actual degeneration of the plant itself. 

 (See II. below.) 



1. In the broadsen.se tliey undoubtedly do deteriorate. 



2. But iletevioration, per se, also seems to occur. 



E.g., ' Butfs ' and ' Dons,' previously good, suc- 

 cumbed to dfsease in 184.5. 'Victoria' degenerated 

 in time both as a crojiper and in disease-resisting 

 power. ' Dunbar Regent,' with its acknowledged 

 excellent qualities, can have disappeared for no 

 other reason than because it had deteriorated. 

 Varieties degenerate .sooner or later both in 

 productiveness and resistance to disease, sometimes 

 in as short a period as six years from the raising 

 of the varietj'. 



II. What are the evidences of deterioration I 



1. As shown by the plant itself. — («) The leaves grow 



curly and stunted, (b) The plant does not develop 

 properly, or (c) even fails to appear above ground 

 at all. {(I) "The plant offers less resistance to 

 disease (in eight years a reputed disease-proof 

 variety becan.e much diseased). 



2. From the growers' point of view. — (a) The produce 



is much lessened (in one case cited by 50 per cent, 

 after two years) when grown on the .same soil. 

 (It) The .size of the tuber is reduced (' in fifteen 

 years the potatos were no larger than marl lies'). 



III. Why does deterioration occur? 



1. It may be brought about by local conditions. 



(f. Treatment. — (1) Wintering tubers uiiclor conditions 

 causing premature sprouting. (2) Growing con- 

 tinuously on the same soil. (3) Unsuitable 

 manuring. (4) Po.ssibly by selection of small tubers 

 (but this is by some regarded as unlikely). 



'/. Economic reasons. — (1) Supplanting by varieties of 

 greater productiveness or other desirable cpudity. 

 (2) Ease with which new varieties are raised. (3) 

 Novelty of later-raised varieties. 



2. But it is also due to inherent causes.— (a) Old age 



or disturbance in the balance between wa.ste and 

 repair, (h) Possibly the tendency to form seed, 

 but there is a marked exception in the Ashleaf. 

 (f) The potato is an exotic, and is, therefore, 

 never grown under absolutely natural conditions. 

 It may be that even after 300 years' cultivation it 

 has not become completely adapted to, or in 

 liarmony with, its environment. 

 l\. How is the fact that certain varieties (e.g., Ash- 

 leaf, Early Rose, Magnum Bonum, !Maincrop) do not appear 

 to have degenerated after long cultivation to be ex[ilaine(l in 

 view or the foregoing facts '. ft is probable that newly-raised 

 varieties vary in vigour as well as in other characters, some 

 Laving suthcient vigour to carry them through only six ycar.s, 

 others through very many. Gross-fertilization, as a rule, 



results in the production of longerdived varieties than does 

 self-fertilization. 



A'. Points of practical im])ortance. How may the life 

 (if a \-ariety be prolonged '! 



1. Greater care should be exercised by raisers in intro- 



ducing new varieties. Only those with plenty of 

 initial vigour should be offered to the public. 



2. Well-matured tubers should be chosen for ' seed.' 



Size of seed is not so important, but uncut tubers of 

 medium size give, in the long run, the best results. 



3. Selection of tubers in other directions can be expected 



to give little result, but ' sports ' do occasionally 

 occur, but are usually of no practical value. 



4. Sets should be stored so that they do not exhaust 



tlienjselves by premature .sprouting. 

 .5. The seed should be frequently changed ; the best 

 seems to come from Scotland, but even there 

 cliange of soil seems necessarj-. The second year's^ 

 crop is usually the best. 

 G. Probably excessive manuring with nitrogenous 



manures may lead to more rapid degeneration. 

 AT. The main objections to the idea of degeneratioa 

 naturally occurring in asexually-produced varieties were (1) 

 the fact that some varieties persist apparently unchanged for 

 long periods — this point is dealt with in paragraph IV. ; and 

 (2) the idea that plants produced asexually are entirely new 

 individuals, and not merely parts of one individual : this 

 question cannot be regarded as definitely settled. 



VII. Other points. The discussion also brought out 

 a considerable body of facts regarding other plants of great 

 use and interest, and provided suggestions for a very large 

 amount of exiierimental research. 



RUBBER IN BRITISH GUIANA. 



The Demerara Argosy of May 20 contains an 

 account of an expedition into the interior of the colony 

 under Dr. Bovallius, a rubber expert. Dr. Bovallius 

 spent some four months in the interior wdth the view of 

 making inquiries into the prospects of exploiting 

 rubber in the colony. He made the following statement 

 in I'eference to British Guiana rubber trees : — 



I found different species of trees yielding good quality 

 of rubber, but I regret to say that uji to the present I have 

 not found enough, the trees being scattered over wide areas. 

 The rubber is undoubtedlj- good, and we may be able to 

 devise the right method of curing it for the market. It can- 

 not, however, be treated in the s:une way as the very .same 

 rubber in Brazd, for the conditions are different. The land 

 between Ireng, Ecliilebar, Arnik, and Upper Potaro forms 

 the grant I api>lied for, but I have examined only 

 a conq;iaratively small part of this tract, wducli covers 

 thousands of square nnles. It is too early for me to .speak 

 of the possibilities of a permanent exploitation in that part 

 of the interior. What I know is that the rubber is of 

 satisfactory (piality, that the labour supply is there, and that 

 the climate is good. 



Sisal in Hawaii. The sisal plantation started by 

 the Jlawiiiian Fibre Company has now about 750 acres- 

 planted in sisal. To quote a report of that company 

 recently i)ublished : When first started the company 

 represented an investment of about $37,000 (say, £7,400), 

 but later, owing to the success of the enterprise, the 

 company increased its capital to )?75,000 (say, £15,000). 

 It is expected that the area of the plantation will shortly be 

 considerablv increased, if not doubled. 



