clxxiv PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



called by growers the Black Mildew. It is a fungous disease very common 

 all over Europe, and though it may be checked by Bordeaux mixture, no 

 actual remedy is known. It was considered to be greatly stimulated and 

 encouraged by growing the plants too closely together without sufficient 

 air and light, or in too humid an atmosphere. It is advised to dry the 

 plants oft', letting all the leaves fall (which should be collected and burnt), 

 and then induce them to make altogether fresh growth. 



Grubs on Cherry-tree Leaves. — Mrs. Knight, Lower Hartlip, reported 

 considerable damage done by small black grubs of which she enclosed 

 specimens. 



Mr. Saunders said : " The grubs are those of one of the sawflies 

 (Eriocampa limacina). They are commonly known as ' Slug-worms,' I 

 suppose because they are neither slugs nor worms ; they certainly, however, 

 resemble the former. Powdered Hellebore dusted over the leaves is very 

 efficacious, but it is a very poisonous article to use, and finely powdered 

 freshly slaked lime is just as good ; spraying with 1 paraffin emulsion ' is very 

 effective, and so is a solution of soft soap, and quassia extract. Which- 

 ever of these remedies is used, it should be repeated after an interval of a 

 day, as the grubs have the power of casting off the slimy matter with which 

 they are covered, consequently the insecticide is thrown off too, and 

 another application should be made before the insect's fresh coat is fully 

 developed, and the power of throwing it off regained. Spraying with 

 Paris-green, lib. mixed with 180 gallons of water, is very useful, as it 

 renders the leaves poisonous ; the mixture should be kept well stirred, as the 

 Paris-green quickly settles to the bottom on account of its weight. As it 

 is a violent poison, care must be taken in using this remedy. When the 

 grubs are full-grown they fall to the ground, and bury themselves some 

 two or perhaps three inches below the surface, each forming a papery 

 cocoon round itself, within which it turns into a chrysalis. If the surface 

 soil is skimmed off so as to remove the cocoons, and is then burnt, 

 buried deeply, or thrown where poultry can pick it over, the trees should 

 be free from the pest next season, unless they are infested by the parent 

 sawflies, which may have been bred in a neighbour's garden or orchard. If 

 there was some co-operation between gardeners in the matter of destroy- 

 ing insect pests, many might soon be stamped out, for several years at 

 least." 



Scientific Committee, September 15, 1908. 

 Mr. A. D. Michael, F.L.S., in the Chair, and six members present. 



Silver-leaf Disease. — With reference to the report in the minutes of 

 the last meeting, Mr. Gaut wrote as follows : "I notice a slight error. 

 It is this, ' Silver-leaf was due to a lack of nitrogen in the soil.' It 

 should have been ' Silver-leaf was due to the presence of too much 

 nitrogen in the soil.' Mr. Bland, the owner of the affected fruit trees, 

 before he wrote to me, sent some leaves to the Board of Agriculture, who 

 sent them on to Mr. Massee. The following is a copy of the report : — 

 'Copy A, 8300.— Diseased Plum trees. — The disease is generally known 



