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The "Joui-nal of Afjricultiiral Jiesenreh'' of loth August, 1919 

 publislied l)y the Secretary of Agriculture, Washiuoton, lias under 

 the title " Derris a-<< an Insecticide " an exhaustive article on the 

 subject, and some of its tests and conclusions are "iveu below. 



But first, to prepare the ground, the writer may be ])ermitted 

 to give his own experience in the use of tuba-root in the course 

 of his cultural work. 



A believer in the orthodox standard sprays and emulsions found 

 in text-books, the writer had only once casually tried tuba-root 

 and that without -any notable result. He gave it no further thouglit 

 until, in the presence of the wholesale and persistent destruction of 

 his beau-plots under the attacks of " Afjroniijza pJiaseoU" he was 

 persuaded to give tuba a thorough and well controlled trial. 



" Agromyza phaseoli/' a fly, deposits its eggs under the skin 

 of the stem of the beans, a very few days after germination of 

 the seeds ; the larvae feed on the tender tissues of the stems just 

 below the first pair of leaves: the skin a week or so after germin- 

 ation, turns from green to brown and on pressing with the fingers, 

 it is found to ])C hollow: the leaves fade and drop, and on splitting 

 open the little stem, the small yellow larvae are found iml)edded in 

 the destroyed tissue. 



Every plot was attacked and such is the virulence of this pest 

 that it. is quite an exception for one plant in 20 to survive. Among 

 tlie many remedies employed against the pest were the following: — 



8tee[)ing the seeds in a 5% solution of corrosive sublimate, 

 liubbing the young stems with lime and ]30wdered sulphur. The 

 application of to^bacco dus't. Rubbing the seeds in sifted earth 

 sprinkled over with " neem-oil " and putting some of this earth in 

 each hole at the time of sowing. 



The last device, alone, proved, to some extent, effective — about 

 30% of the plants being saved. 



A trial of tul)a was then made on a field of 8 l)eds, G6 feet 

 long, with 1056 seeds of Lima Bean (Small Sieva) on the 28th 

 October 1919. Ten ounces of tuba-root were well ])ounded in a 

 wooden mortar, the juice thoroughly expressed, and the fibre ex- 

 hausted in 2'0 gallons of water. 



Tuba-water was then applied to eacli young plant at the rate 

 of a cigarette tin full to 1 plants, morning and evening. This was 

 continued for 15 days, until the plants were sufficiently established 

 to ]ye past all danger, which is only present during the fii'st stage 

 of their existence, when the stem is quite tender. 



()]dy 10 seeds failed to germinate and of the 1040 plants that 

 came up, not one has since died. And to-day, the plot is showing 

 the most vigorous growth, a livi)ig testimony to the pofency of the 

 tuba-root as a plant-insect killer. 



