Vol. XVI. No. 390. 



THE AGRICULTURAL NEWS 



107 



CONTROL jrEASURES. 



In every country where locusts abound the methods of 

 destruction have to be adapted to local conditions It may be 

 mentioned that in E^ypt vegetation is practically nun-existent 

 except where the land is artificially irrigated, and there is no 

 irrigated land which is not closely cultivated. Conseijuently, 

 the only food available for locusts consists in cultivated crops, 

 so that in view of the value nf the crops it is essential to 

 destroy the locusts before they can begin feeding This 

 necessity for killing the locusts bt^-fore they can attack the 

 crops rendered impracticable the use of stomach poisons, 

 such as arsenate of soda or Paris ereen, or the inoculation 

 of disease cdtures of Coccoljacillus acridiwwn, as these 

 cannot act unless consumed along with the food. There 

 remained, therefore, such methods of control as collecting 

 of adults and e-'g-inasses, destruction of nymphs by driving 

 them into prepared trenches and burying them, or spraying 

 with contact insecticides. 



Before the arrival of the expected invasion circulars 

 were distributed to the headmen of the various villages 

 throughout the Nile Delta and lower valley These contained 

 full instruciions as to dealing with the invading swarms of 

 adults, the egg-masses which would be subsequently laid, 

 and the young nymphs. Accompanying these recommendations 

 were illustrations of a locust laying eggs, of the eggs 

 themselves, and of young nymphs 



AcC')rdingly. the first swarm, as soon as it arrived, was 

 vigorously atta:ked, and the campaign was carried on 

 throughout the first half of the year 1915, during which 

 time the invasion was at it.s worst 



The work of destroying the adults and eggs was paid 

 for at rates previou.-ly fixed by the Government, while 

 digging of trenches for burying the nymphs was carried 

 out under the existing system of organized unpaid 

 labour {con'k) in each village. The invading swarms were 

 collected in large numbers in the early mornings when they 

 arc paralyzed, and then killed either by burning or by bnryiny 

 in pits, the latter method bemg the most satisfactory. 



The systematic destruction of eggs was carried out 

 everywhere, either by hoeing over the egg-deposits and expos- 

 ing them to the heat of the sun, or by ploughing up the 

 land two or three times. In some places the egg-masses 

 were als'i collected and burnt, while in other localitie- the 

 land was flooded in order to smother the eggs: this latter 

 melhfid seems to have been more su;;essful in heavy land than 

 in light .'^audy soil. However, in spite of the extensive cam- 

 paign against the adults and eggs, such an immense number 

 of nymph- still hatched that their .subsequent dL'Struction 

 constituted the maior part of the problem of control. 



As stated above, it was soon found that pois.jned baits 

 could not be used, since the nymphs did not feed for some 

 days after hatching, but often spent this period in travelling 

 from the laying ground in the desert into cultivated aroas. 

 It was therefore necessary to kill them before they could 

 reaih the crops. All the able bodied population of the 

 threatened district were turned out, some to dig trenches, 

 and others to drive the young locusts into the prepared 

 trenches These trenches had to be duu between the 

 desert places where the eggs were laid and the cultivated 

 fields towards which the locusts would be marching. When 

 the locusts had all been driven into a trench the earth was 

 thrown back into it and well trodden down. Advantage was 

 taken of the fact that the young nymphs collect on any 

 raised object to burn them en uiasse, or to spray them 

 with a contact insecticide. 



Many other methods were tried with varying success, 

 but the above mentioned were the most successful. Some 

 idea of the work that was done may be gathered from the 

 statement that over thirteen thousand metric tons of locusts 

 were collected, representing over seven billion individuals, 

 while some twenty-seven billi m eggs were destroyed. It was 

 also estimated that at least many young hoppers were killed. 



The result of this campaign was that no locust swarms 

 reached maturity in Egypt and the damage done was generally 

 small, a very large percentage of the cotton crop of the Delta 

 being saved. The docility of the natives and the system of 

 unpaid labour enabled the campaign to be organized and 

 carried out successfully, and Government supervision is 

 absolutely neces.sary, since the native population if left to 

 themselves, would be unable to deal with a locust invasion. 



It may be mentioned here, that the South American 

 migratory locust (Schistocerca par.inensis) was abundant in 

 Venezuela in 191-5, doing ser ous damage to vegetation there, 

 and threatening to invade Trinidad. The breeding grounds 

 of this locust in a country like Venezuela, where there is 

 a dense tropical growth, are fortunately few and far between, 

 so that there were none of the enormous hordes which occur 

 in Africa or in the Argentine. 



EFFECT OF MANURES ON THE 



COMPOSITION AND QUALITY OF 



ORANGES. 



The Journal of Agricultural Research (Vol. VIII, 

 No. 4) contains an interesting paper on the above 

 subject, dealing with results obtained in California. 

 By way of introduction, tlio author, H. D. Young, 

 says:— 



Of the great amount of work which has been done 

 with fertilizers, only a relatively smali proportion deals with 

 their effects on the quality of the crop. This is especially 

 true of fruits, partly because of the length of time required, 

 and partly because of the contiictiug factors which enter 

 into a long-time ex|ieriiiient. 



The material presented in this pi|)er hastodowithoranges 

 (Citrus 'lurantiuiii). The quality of this crop may otter an 

 easier subject for study than mo-t fruits, as the factors atl'eot- 

 ing it, such as the percentages of sugar and acid, the texture 

 of the fruit as a whole Jts specific gravity), and the propor- 

 tions nf juice and rind, can be accurately measured. 



The follo^ving is a summary of the main results 

 ai-rived at: — 



Nitrogen is the only fertilizer which in this experiment 

 seemed to exercise a specific effect on the composition of 

 oranges. 



Applications of nitrogen to the soil resulted in a slightly 

 lower amount of sugar, a somewhat coarser fruir, and a little 

 le.ss juice in the orange. 



The ettect of nitrogen was the same, whether applied 

 alone, in conibinati' m with either potash or phosphoric acul, 

 or both. 



The effect of nitrogen was greater in 191-5 than in 1914. 

 As the crop was picked about two months later in 191.5, it 

 would indicate that some effect other than delayed matuiity 

 was caused by the nitrogen. 



(Jomparison with fruit from similar trees grown cjutside 

 the fertilizer plots shows a fair agreement of composition 

 and quality. 



The analyses show a higher percentage of nitrogen from 

 all plots receiving it. while no such ettect was obtained with 

 either phosphoric aoid or potash. 



