October 7, 1922 



NA TURE 



497 



Fruit-Growing and Research. 



'THE application of scientific methods and prin- 

 -*■ ciples is steadily gaining ground in fruit culture 

 as in other branches of agriculture, and the numerous 

 publications on the subject provide evidence of a 

 widening interest in the matter, both as regards the 

 scientific and the practical worker. 



The earlier work of Spencer Pickering and the 

 Duke of Bedford stimulated interest in the root 

 systems of fruit trees, and at Long Ashton 1 the matter 

 of root development under various conditions is being 

 followed up. It appears that the method of treat- 

 ment at the time of planting has little effect on the 

 type of root produced, a new root system being 

 derived from the collar region of the tree and little 

 growth occurring elsewhere ; aeration is considered 

 to be a dominant factor in determining the actual 

 point of origin of the new roots. Root formation 

 and growth are most active at the beginning and 

 towards the end of the season, the greatest increase 

 in root length occurring during the latter period, at 

 the time when shoot growth is rapidly decreasing. 

 Other experiments deal with the extension of the root 

 system throughout the soil, a matter which has a 

 direct bearing on the degree of overlapping of roots 

 when too close planting is practised. 



On the pathological side special attention has been 

 directed to leaf-scorch on fruit trees, and the trouble 

 has been found to be due to various causative agents. 

 Among the chief of these are unfavourable soil con- 

 ditions, due to deficient food or water supply or to 

 defective aeration owing to the mechanical character 

 of the soil. Scorching is also attributed to the direct 

 action of wind, to excessive heat falling on the leaf, 

 or to injury to the vascular system of the plant, such 

 as may be caused by ringing or by the presence of a 

 fungus which penetrates the vascular tissue and 

 interferes with the water supply to the leaves. 



The importance of spraying to combat disease is 

 now widely recognised, and at East Mailing - direct 



1 Annual Report of the Agricultural and Horticultural Research Station, 

 Long Ashton, 1921. 



2 Grubb, N. H. (1921), Journal of Pomology, II., No. 2. 



experimental work is being carried out with fungi- 

 cides on apple trees. Everv fungicide tested reduces 

 apple scab (Venturia incsqualis), though the degree of 

 effectiveness varies, Bordeaux mixture usually proving 

 the best. Generally speaking, the crop and the size 

 of the fruit are improved by spraying, with certain 

 exceptions, and there are indications that summer 

 spraying may improve the keeping quality of the 

 fruit by reducing attacks of brown-rot {Sclerotinin 

 fructigens) . An interesting point is that the effects 

 of spraying are cumulative, sprayed trees being less 

 heavily affected in the succeeding years. 



A critical examination of the stocks used for stone 

 fruits 3 shows that little or no attempt has hitherto 

 been made to group them as has been done for those 

 used for apples and pears, rapidity of growth and 

 general availability being usuallv the deciding factors 

 in the selection of stocks in any particular instance. 

 The descriptions worked out at East Mailing are the 

 beginnings of an attempt to set up a permanent 

 standard of classification and identification with the 

 view of the ultimate improvement of stone fruit 

 cultivation. 



In an interesting survey on progress in methods 

 of practical fruit - growing in the Journal of the 

 Royal Agricultural Society of England, 4 the whole 

 business, from the selection of a holding to the final 

 packing of the fruit, is traced. Laying out and 

 planting the fruit farm, raising and selecting trees, 

 pruning, manuring, diseases, and pests are all brought 

 under consideration in a way that provides suggestive 

 reading for all interested in the subject, and its value 

 is enhanced by a useful bibliography. In this con- 

 nexion also attention may be directed to the collected 

 leaflets 5 on fruit recently reissued by the Ministry of 

 Agriculture, in which various problems the practical 

 fruit-grower encounters in his work receive detailed 

 consideration. 



3 Hatton, H. G. (1921), Journal of Pomology, II., No. 4. 

 * Hatton, H. G., 1921, Journ. Roy. Agric. Soc, England. 

 6 Collected Leaflets on Fruit, 1921. Sectional volumes, No. 4. Ministry 

 of Agriculture and Fisheries. 



Volcanic Activity in Nigeria. 



TN Nature of July 15, p. 97, an account was given 

 *■ of volcanic activity in Nigeria during March- 

 May last. The following extracts, from the reports 

 of Mr. H. S. Cameron, acting Supervisor of Plantations 

 in Nigeria, furnish some later information. They 

 are placed at our disposal through the courtesy of 

 the Colonial Office : — 



On June 17 the manager of Bibundi informed 

 me by telephone that lava streams had commenced 

 to flow again ; also that heavy damage was being 

 done by floods. On June 18 I went to Bibundi, 

 and going by trolley to Dollmanshohe I found the 

 roadway of the bridge entirely swept away by floods 

 and also one of the four piers gone. I went up the 

 river, and after about a mile reached the first flow 

 of lava, which had been advancing the day before 

 but had now cooled and was stationary. Crossing 

 from there to Wernerfelde, progress was shortly 

 prevented by advancing lava ; the stream, here was 

 molten, but its advance, which was more " creeping" 

 than " flowing," was over a very wide area and on a 

 gentle slope, and it seemed probable that eventually 

 it would cool and turn the main lava stream down 

 the old course of the Njonge river and extend into 

 the sea, as part of the flow was then doing. 



NO. 2762, VOL. I IO] 



The flooding damage was considerable and I think 

 unpreventable ; the amount of water is so great 

 that it is impossible to direct it. More than fifty inches 

 of rain fell in the first seventeen days of June, and 

 the water from an area which formerly fed three 

 rivers and part of a fourth has now no channel : 

 not only is an exit lacking, but rain falling on lava 

 does not sink in and percolate through but rushes 

 at once to the lowest level, so free drainage is more 

 necessary than ever. 



On June 22 I received a letter stating that the 

 lava had broken through near Dollmanshohe bungalow, 

 followed the course of the stream, and was threatening 

 the hospital, which had been abandoned. On reaching 

 the bridge-end at Dollmanshohe on June 25, I found 

 that the whole of that division above the iron road 

 had been covered with lava, and cascades of molten 

 lava were flowing down the banks of the ravine. 

 It was really a wonderful sight. The river bed was 

 full of detached flows of lava fed from the Dollman- 

 shohe plateau, where it had been massing during 

 the past week. I inspected the whole length from 

 near the Thormahlenfelde bungalow to the director's 

 house, finding flowing lava everywhere. By afternoon 

 the ravine was filled, and by n p.m. the lava had 

 crossed the rail where the Government road turns 



