Vol. IX. No. 



!l.s. 



THE AGRICULTUKAL NEWS. 



283 



temperate climates, where tliey nuiy be applied during the 

 season when the trees are dormant, since insecticides of this 

 class very often cause a considerable amount of injury by 

 burning the foliage. Contact poisons containing arsenic are 

 more especially useful in sprays and ips dfor the control of 

 ticks on cattle and other animals. 



FLi MIC : ANTS. The most important of the insecticides which 

 may be applied in the form of a gas are carbon bisulphide, 

 hydrocyanic acid and sulphur dioxide. Carbon bisulphide is 

 specially suited for use against insects infecting seeds, grain. 

 Hour and all kinds of stored household vegetable products. It 

 is also useful against ants and other underground insects. 

 Carbon bisulphide is a volatile, iuHanimable liciuid, the 

 vapour being considerably heavier than air, and it is used by 

 being introduced into an enclosed space. A general account 

 of the use of this material appeared in a recent number of 

 the West Indian Bulletin, and of the Aijricultnral Xews. 



Hydrocyanic acid gas is produced by the action of sul- 

 phuric acid on potassium cyanide: it is a colourless, very 

 poisonous gas, which is e.specially suited for the destruction 

 of scale insects on growing trees, nursery stock, etc. It can 

 only be used, however, in an enclosure, and when it isap[>lied 

 for the destruction of scale insects on orchard trees, some 

 form of tent must be employed to retain the gas in contact 

 with the tree. For the fumigation of nursery stock, it is 

 employed in air tight boxes or compartments. It is also very 

 useful for the fumigation of dwelling houses, mill.s, store- 

 houses, etc., in the same way as carlmn bisulphide is used. 



Sulphur dioxide (fumes of burning sulphur) is very useful, 

 al.so, for fumigation in buildings and hoMs (if ships and in simi- 

 lar cases; it has an advantage over hydrocyanic acid gas in 

 its greater penetrating power, when used in connexion with 

 such .substances as cotton seed. 



EEi'ELLKNTs. Various substances are used for the 

 purpose of preventing insect attacks, because of their 

 disagreeable taste or odour. Carbolic acid, creosote and 

 similar preparations are the most common of these. 

 Timber used for building purposes, which has been treated 

 with coal tar, creosote, etc., is not readily attacked by 

 wood ants (termites); and tree borers may often be 

 deterred from entering the trunks of trees by covering them 

 with a mixture of lime, or lime and clay, to which car- 

 bolic acid or creosote has been added. (Jitronella and other 

 aromatic oils may be used to repel the attacks of mosquitos; 

 naiihthalene, camphor, lavender and similar materials are 

 employed to prevent the infestation of woollen fabrics, furs, 

 feathers, etc., by clothes-moths, beetles and silverfish. In 

 a similar manner, these substances repel attacks of flesh flie.s, 

 when mixed with dressings used for treating wounds on 

 cattle, horses and other domestic animals. 



EXPERIMENTS IN LEGUME 

 INOCULATION. 



In the following article, a review is made of experiments 

 that have been undertaken, in ditl'erent parts of the world, 

 with a view to ascertaining the effect of the application rif 

 bacterial cultures for the [lurpose of increasing the yields of 

 leguminous plants. The trials were chiefly made with the 

 preparation known as Nitro-Bacterine. 



An abstract of a paper given in the Exjieriment Station 

 Record of the United States Departiuciit of Agriculture, for 

 April 1910, shows that bacteriological examinations and pot 



tests with lupines, conducted at the Stockholm Ex[)eriMient 

 Station with nitro-bacterine, indicated that this did not contain 

 Banlliis radicicola — the organism that gives rise to nodules 

 on the roots of legumious |ilants and enables tehm to make 

 use of the nitrogen of the air — and that no nodules were 

 produced on the roots. It is recommended that soil 

 which is known to contain the required organisms should be 

 used preferably to either nitragin or nitrobacteriue An 

 abstract of another paijer, on the next pii;e of the same 

 publication, dealing with experiments conducted iu Ger- 

 many, shows that both of these inoculating materials 

 caused an increase in connexion with white lupines and sand 

 peas on calcareous sandy soil, especially where potash and 

 phosphates had been applied, the nitro-bacterine being more 

 effective than the nitragin; the action of the latter was 

 especially feeble on sandy soils deficient in lime. 



A letter in the Southern Planter for June 1910, from 

 the Director of the Virginia Agricultural Experiment Station, 

 recommends the use of inoculated soil from a field where 

 legumes of the same kind as those to be grown have been 

 raised, wherever it is possible to do this. The statement is 

 further made that the artificial cultures of legume bacteria 

 are a poor, but sometimes useful, substitute for soil of the 

 kind described; but that it is probable that the methods of 

 preparing artificial cultures will be perfected, so that their use 

 shall be preferable to that of soil, though this is not the case 

 at the present time. 



The Report on Field and Pot Culture Experiments, 1909, 

 of the Woburn Experimental Station of the Royal Agricul- 

 tural Societj- of England, contains information which indicates 

 that field exj)eriments in which soil that had been treated 

 with nitro-bacterine was spread upon the halves of individual 

 plots in which inoculated seed had been sown in the previous 

 season, showed that the inoculation either of the seed or of 

 the added soil had not been beneficial in any way, except that 

 there was a small increase in yield in the ca.se of Dutch white 

 clover. Pot experiments conducted in the same connexion 

 showed a slight increase in most cases where inoculation had 

 taken place, but this was too small to allow of any clear 

 deductions being drawn, especially in view of the negative 

 results obtained in the experiments just described. 



In the Tropical Agriculturist for June 1910, an article 

 by T. Fetch, U.A., B.Sc, Mjcologist to the Ceylon Depart- 

 ment of Agriculture, contains the following statement: Nitro- 

 bacterine has been tested fur two successive years at each of 

 two agricultural stations in Germany. In addition to the 

 the usual inoculations and crop tests, a bacteriological analy- 

 sis of the mixture has been made at the same time by 

 competent bacteriologists, accustomed to isolating and identi- 

 fying nodule-forming bacteria. The result of the analysis has 

 been the same in all cases, viz., that nitro-bacterine does not 

 contain any nodule-forming bacteria. Similar work has been 

 done in Italy, with exactly the same result. Nitro-bacterine, 

 theretore, falls into the same category as Moore's cultures of 

 nodule-forming bacteria. The latter were dried on cotton- 

 wool, and distributed by the United States Department of 

 Agriculture many years ago, but the distribution was aban- 

 doned, because it was impossible to preserve the bacteria in 

 that way, and therefore the cultures were valueless. When 

 nodule-forming bacteria are dried they die, and for that reason 

 nitro-bacterine cannot contain any. 



These results, and other considerations, would appear to 

 show that the preparation of cultures for inoculating soil 

 with legume bacteria has not reached a stage at which 

 dependence may be placed on such cultures, for this purpose. 



