1220 RESISTANT PI^NTS 



vitality and resistance it is not possible to use control methods based on 

 the starvation principle. 



In some experiments carried out on land infested with the larvae 

 of Lachnosterrta, grasses were transplanted the roots of which had first been 

 steeped in a solution of arsenite of soda; the mortality of the larvae amounted 

 in four days to 22.2 %. Under the same conditions the use of arsenate of 

 lead gives negative results. If roots of young maize plants are poisoned 

 with corrosive subUmate, the mortaUty of the larvae reaches 50 %. 



Excellent results are obtained by protecting the seeds by treatment with 

 creosote ; this substance keeps the larvae off. 



947 - Resistance of [Different Varieties [of Wheat to Mayestiola detractor in 



America. — Haseman L,. in journal of Economic Entoniolo'^y, Vol. 9, No. 2, pp. 291-294. 

 Concord, N. H., 1916. 



The destructive cecidomyiid " Hessian fly " {Mayetiola destructor 

 Say) has caused ver}^ extensive injurj^ to wheat almost throughout the great 

 Mississippi valley. 



The opinion generally held by farmers is that all varieties of wheat are 

 not equally susceptible to attack, and that some types remain practically 

 immune. 



In order to ascertain the truth of this opinion, and also to arrive even- 

 tually at a selection of highly resistant t3''pes, a series of experiments was 

 undertaken on a wery large number of wheat varieties. In these researches 

 there were ascertained the percentage of infected plants, the relative num- 

 ber of larvae, etc. ; analyses were also made of the composition of the plant 

 organs and sap, and observations on the manner in which development 

 takes place, in order to fix and estabUsh possible correlations. In the present 

 work there are set out the results of a first year of research. These results 

 do not yet possess the value of definitive conclusions, but the^- are none 

 the less interesting, as they confirm the fact that the various types 

 behave variously as regards the attack of Mayetiola destructor. 



3 varieties of wheat were vised : " Fultz ", " Fulcaster " and an indigen- 

 ous type regarded as very resistant. 



Sowing was carried out on the 24th October, 1914. On the loth May, 

 1915 the following observations were made : 



Maximum Average 



number number 



% of infected of larvae of larvae 



Varieties of \\'heat plants per plant per plant 



"Fultz" 5^ 18 2.72 



" Fulcaster" 66 8 1.46 



Indigenous used £is control. ... 54 12 1.7 



As regards this experiment, " Fulcaster " presents marked tendencies 

 to immunity if compared with "Fultz". Furthermore, the results also 

 prove that an indigenous type believed to be highly resistant may in real- 

 ity be as badly attaked as some selected types. 



