397 



ScHULTZ (E. S.) & FoLSOM (D.). Transmission of the Mosaic Disease of 

 Irish Potatoes. — .//. Agric. Res., Washington^ B.C., xix, no. 7, 

 1st July 1920, pp. 315-337, 8 plates. 



The following is a portion of the author's summary of tliis paper : — • 

 Transmission of potato mosaic by means of tubers, grafting, plant 

 juice, and Apliids {Myzus persicae, Sulz.) was effected under various 

 conditions, including those essentially of the field with insects con- 

 trolled. Infection was obtained with intervarietal transfer of juice. 



Transmission was attempted, but without success so far as could be 

 ascertained in the same season, by means of flea-beetles {Epitrix, 

 cucumeris, Harris), and Colorado potato beetles {Leptinotarsa decem- 

 lineata, Say). Preliminary observations indicate that infection docs 

 not result from growth in soil that produced mosaic potato plants 

 the previous season. 



It appears impossible either for infected plants to recover or, so 

 long as diseased stock is not far off and insect carriers exist, to assm'e 

 the maintenance of health of susceptible varieties by roguing plots 

 or by selecting hills, tubers, or seed pieces. 



Isolation of j)lants by means of insect cages, as well as eUmination 

 of insects in the greenhouse, have mamtained stocks disease-free, 

 indicating that control of Aphids and possibly of some other kmds 

 •of insects as well, is the most important means of checking the spread 

 of potato mosaic among susceptible varieties. 



Matsumoto (S.). Budogaichu ni kwansuru Kenkyu. [Studies on 

 Injurious Insects of the Vine.] — Rinji-Hol'oku [Supplementary 

 Report], Prefectaral Agric. Expt. Sta., Ohayama, no. 21, 30th 

 April, 1920, 28 pp., 3 plates. 



This deals with three insect pests of the grape vine. The Aleurodid, 

 Jleurodes loonabae, Kuvv., was originally described as attacking 

 Taonaha japonica. It infests the upper surface of the vine leaf, which 

 becomes rolled up and sooner or later falls. It also attacks the grapes. 

 As observed in confinement, there are three generations a year ; the 

 winter is passed on Taonaha leaves as larvae, which become adult in 

 May or June ; these enter the vineyard and lay eggs, giving rise to 

 another generation in .\ugust that again oviposits on the vine foliage ; 

 the next brood becomes adult from the middle of September to the 

 beginning of October and oviposits on Taonaba leaves near the vine- 

 yard. In the field, though a great many of the insects infest the vine- 

 yard, few seem to remain and breed on Taonaha throughout the year. 

 The burning of infested fohage of Taonaba near the vineyards is 

 therefore the surest method of preserving vines from attack. Kerosene 

 emulsion with or without insect powder is also efficacious. 



A leaf- hopper, Zz/gina apicalis, Mats., does considerable damage to 

 both fohage and fruit. In breeding experiments it has been found 

 to have three generations a year and to hibernate in the adult stage. 

 Vineyards become infested in the niiddle of April, and the eggs are 

 laid singly in the tissue of the leaf- veins ; they hatch at the beginning 

 of June and become adult at the end of that month. The adults 

 of the second generation appear in the middle of August and of the 

 •third in the middle of September. In the field, however, both nymphs 



