477 



Wormstekigheid bij Appel en Peer. [Worminess in Apples and 

 Pears.] — Verslag. & Meded. Plantenziektenk. Dienst, Wageningen, 

 no. 20, April 1921, 18 pp., 2 plates. [Received 3rd August 1921.] 



In Holland the fruit of apples and pears is infested by the moths, 

 Cydia (Carpocapsa) pomonella and Argyresthia conjugella, the sawflies, 

 Hoplocampa testudinea and H. brevis, and the pear gall-midge, Con- 

 tarinia pyrivora. The life-history of these pests is briefly described. 



Apples are attacked by H. testudinea in June and July, by C. pomo- 

 nella from July to September, and about the end of the latter period 

 by A. conjugella. 



Pears are attacked by C. pyrivora in May, by H. brevis in June and 

 July, and by C. pomonella from July to September. 



Measures against C. pomonella include the use of band-traps, spray- 

 ing with Paris green or lead arsenate, collecting infested fruits, shelter- 

 traps in store-rooms, and the provision of nesting places for tits in 

 orchards. 



Against H. testudinea and H. brevis an arsenical spray and the 

 collection of infested fruits are useful. 



C. pyrivora can be destroyed at the cost of the entire pear crop by 

 removing all the fruits or by destroying the blossoms with a suitable 

 spray. Instead of this the immediate, careful collection of all fruits 

 that are infested or thought to be so may be useful if scrupulously 

 carried out. 



No definite remedy exists for A. conjugella. The destruction of 

 the caterpillars must be aimed at. Fallen fruit may be examined, 

 young fruit sprayed with an arsenical solution before the eggs hatch, 

 and the ground dug over so as to bury the pupae to a depth that 

 prevents the emergence of the moths. 



VAN Slogteren (E.). Aaltjes-Ziekten in Bolgewassen. [Nematode 

 Diseases in Bulb Plants.] — Plantenziektenk. Dienst, Wageningen, 

 Vlugschr. 26, March 1921, 8 pp. [Received 3rd August 1921.] 



This circular reviews existing data on the infestation of bulbous 

 plants by Nematodes — of which Tylenchus dipsaci, Kiihn [devastatrix, 

 Kiihn) is the economically important species — and on the remedies 

 available [R.A.E., A, vih, 441]. 



Rondknop bij Zwarte-Bessenstruiken. [" Round Buds " on Black 

 Currants.] — Plantenziektenk. Dienst, Wageningen, Vlugschr. 28, 

 February 1921, 3 pp., 1 fig. [Received 3rd August 1921.] 



Outbreaks of " big bud " on one-year-old twigs of black currant 

 are due to infestation by mites [Eriophyes ribis]. These appear about 

 March and infest all parts of the bush without doing any harm until 

 June, when they collect on the young buds, into which they penetrate 

 at the end of July, entering between the scales. They remain in this 

 position until the following year. Eggs are first seen in August and 

 are found up to the following July. This contemporaneous occurrence 

 of eggs and mites makes remedial measures difficult, as continuous 

 treatment is too costly in practice and may harm the plants. Once 

 established, the pest spreads bj^ its own efforts and by wind-carriage. 

 At present the best results are obtained by removing and burning all 

 affected buds during the winter. It is advisable also to remove the 

 apparently healthy buds above and below an infested one. If this 

 practice is carried out regularly, the infestation will gradually decrease. 



