431 



RiTZEMA Bos (J.). Bestrijding van de Boonenbladluis. [Measures 

 against the Bean Aphis.] — Tijdschr. Plantenziekten, Wageningen, 

 XXV, no. 4, July 1919, pp 129-144. 

 The common bean aphis, Aphis rumicis, L., infests a large number 

 of shrubs and woody plants, of which a list is given. It has been 

 recorded under various synonyms, including Aphis papaveris, F., 

 A. atriplicis, ¥., A. genistae, Scop., and A. euonymi, F. Theoretically, 

 the fifth generation of descendants of one female should number 

 3,270,800 individuals, and the importance of early measures is there- 

 fore apparent. Though there are many methods of destroying this 

 Aphid, they are usually difficult to apply in practice. A preventive 

 recommended by Dr. Feldt of Koenigsberg is based on the fact that a 

 field of beans is first attacked at the edges, the insects subsequently 

 spreading to the centre, when it is too late to do anything except to 

 plough up the field. Such infestation, which occurs in May or .June, 

 starts from the woody plants on which the eggs have remained during 

 the winter. The first signs of the pest in bean fields are noticed at 

 the side removed from the prevalent winds. The plants should either 

 be removed and burnt or sprayed with a spirit-soap solution. Spraying 

 must be repeated if all the Aphids are not killed by the first application. 

 Wherever possible beans should be planted in exposed situations and 

 the rows should be arranged in the direction of the prevalent wind. 

 Early sowing is desirable, and varieties should be chosen that soon 

 form pods low down on the stalk. The seed should be soaked before 

 planting to promote germination. Feldt states that when the rows 

 run from east to west the plants are 50-100 per cent, taller than those 

 in rows running from north to south, and as there is more shadow 

 among the tall plants less fertilisation by insects takes place. Tall 

 plants also interfere with the free passage of wind, so that Aphid injmy 

 is more probable. A space of about 2 feet should be allowed between 

 the rows, but the plants can be close together in a row. Feldt also 

 states that garden peas growing in a field of parsley were not attacked 

 by Aphids, whereas a few yards away a field containing peas only was 

 very heavily infested. Parsley, sununer root crops and potatoes 

 may be planted for this purpose, and a border of potatoes or tomatoes 

 along the edges of a field of beans will protect the crop. The author 

 remarks in this connection that in the Ukraine hemp planted among 

 other crops is found to drive away many insect pests [see this Review, 

 Ser. A, i, pp. 68, 191]. 



ScHOEVERS (T. A. C). Het Spint. [Mite Inji\ry.]--Tijdschr. Planten- 

 ziekten, Wageningen, xxv, no. 4, July 1919, pp. 145-155. 

 During the dry weather in June 1919 mite injury, due to Tetranychus 

 spp., was very much in evidence at Wageningen. Descriptions of the 

 injury and of the life-history of these mites are given. Some injury 

 was also caused by mites of the genus Bryohia. Spraying with 

 a 6-8 per cent, solution of carbolineum is recommended. Dusting 

 with sulphur or the use of a sulphur-soap solution also give good results, 

 and a 0-4 per cent, solution of liver of sulphur was found to be excellent. 

 Sulphur should not be used on gooseberry bushes as it causes defolia- 

 tion. A powerful stream of cold water will wash away the mites, and 

 heavy showers of rain cause a reduction of infestation for this reason. 

 A species of Scymnus is predaceous on these mites. 



