88 THE KANSAS CHERRY. 



the under side of the leaves, causing them to curl up so as to cover the 

 lice, and thus making it difficult to hit them with a spray after they 

 have become well established. Since these insects suck their food 

 they cannot be poisoned, but must be killed by contact of the in- 

 secticide with their bodies. 



Remedy. — In fighting these insects close watch should be kept for their first 

 appearance, so that they may be sprayed at once and not allowed to become es- 

 tablished. The treatment should be repeated as circumstances require. Kero- 

 sene emulsion diluted from twelve to fifteen times is commonly recommended for 

 plant-lice. If the leaves are curled so that the spray cannot reach the inset, dip 

 the infested twigs in whale-oil soap and tobacco tea, or in kerosene emulsion pre- 

 pared as follows: Dissolve one-half pound of either common salt or whale-oil 

 soap in one gallon of soft water. Heat the mixture, and, when boiling hot, re- 

 move it from near the fire and add it to two gallons of kerosene. The whole is 

 now thoroughly mixed by pumping continuously through a small force-pump for 

 from five to fifteen minutes. Mix until the ingredients form a creamy mass that 

 becomes thick when cool and from which the oil does not separate. When using 

 on foliage dilute with from ten to fifteen parts of water : when used as a winter 

 treatment, it may be applied as strong as one part of the mixture to four parts of 

 water. In diluting the stock emulsion, first use three or four parts of boiling 

 water, and then dilute to the required strength. Soak off with paper any free 

 oil that appears on the surface, as it will work injury if applied to the plant. 

 This emulsion is used to kill insects that have sucking mouth-parts ; it is not a 

 poison, but kills by contact. The emulsion causes rubber valves to swell and 

 clog the tubes in which they work. Where rubber balls are used for valves they 

 should be replaced with glass or marble balls when using the pumps for kerosene 

 emulsion. The mixture may be poured into shallow pans, and the twigs bent 

 over and dipped into it. 



BL.\CK-KNOT OF THE CHERRY. {Pl<>ivri(/htia iiiorbosa Schw.) 



The black-knot of the cherry is distinctly an American disease, and 

 is recognized at a glance by tlie rough, wart-like swellings which 

 cover the branches and sometimes even appear on the trunks of the 

 trees. 



Where the fungus is not checked whole orchards soon become af- 

 fected, and are a serious menace to every healthy tree in the vicinity. 

 The fungus was described about seventy years ago by the mycologist 

 Schweinitz, who thought, however, as many do still, that the trouble 

 was due to insects, from the fact that there is often found the larva of 

 insects imbedded in the galls. But since the very careful and sys- 

 tematic study of the black-knot by Dr. W. G. Farlow in 1886, there is 

 no reason to doubt that it is caused by a parasitic fungus, the spores 

 of which, after ripening, become detached from the knots and are 

 carried by the wind or by insects to healthy trees, where in some 

 manner they penetrate to the cambium layer, where they take root 

 and grow, producing galls similar to the one from which they became 

 detached. 



Preventives and Bemedies. — As the galls are found on the native cherry 

 growing wild in fence-corners and abandoned places, they should be sought out 



