THE MONTHLY BULLETIN. 51 



half size when uuitured. and are usually covered with a black smut 

 fungus. This black, sooty fungus, or smut, grows on the honeydew 

 excreted l)y the walnut aphids. On infested leaves the smut fungus 

 also puts in an appearance, and the reader can readily see how the leaf 

 functions are impaired, if the surfaces are covered with smut. Besides 

 the damage caused by the growth of this smut fungus, there is much 

 loss of vitality in the leaves and nuts, through the loss of sap. 



The eggs of the walnut Aphis become shiny black soon after they have 

 been laid, and are deposited on the leaves of the walnut tree, often as 

 early as September. The locations preferred for the deposition of the 

 eggs, according to the writer previously quoted, are on the old scars of 

 the fallen leaves, the surface of the larger limbs near the bases, in the 

 crotches of the smaller limbs, and in the cavities in the bark. The eggs 

 are fastened to the surfaces of the limbs by a gluey substance. 



These eggs do not hatch until early in the spring, at about the time 

 the buds begin to swell. From these eggs the so-called stem mothers 

 hatch, which, on becoming adults, soon reproduce. The aphids of the 

 new generation are born alive and these, in their turn, after becoming 

 full grown, give rise to a new generation of aphids. 



The United States Bureau of Entomology has conducted several 

 experiments, with a view toward controlling this pest. These experi- 

 ments are given in detail in Bulletin 100 of that bureau. The following 

 summary is taken from this publication : 



The winter spraying for the eggs of the walnut Aphis is the easiest to 

 apply, and high trees can be reached by the spraying at this time, 

 without much trouble. Spraying for the aphids in the summer time 

 is difficult, as a thorougli application is almost impossible on account of 

 the thick foliage. The lime-sulphur and the crude oil emulsion sprays 

 are effective when used at this time. The lime-sulphur solution, how- 

 ever, is a better spray to use than the crude oil emulsion. Every limb 

 and twig should be thoroughly covered with the spray. The strength 

 of the commercial lime-sulphur to use is one part to eight parts of water, 

 or one to eleven of water. The late spring is the best time for making 

 the application — that is, just before the buds are beginning to swell. 

 This is especially true if crude oil emulsion is used, as the oil works 

 better soon after it is applied, and as the young plant lice are emerging 

 from the eggs. The crude oil emulsion prepared can be obtained from 

 the several insecticide dealers of the state, as well as the commercial 

 lime-sulphur solution. 



PLANT DISEASES. 



Peach Leaf Curl. 



Peach leaf curl, as indicated by its name, curls the peach leaves, 

 which afterward fall, often with part of the fruit, which has also 

 become infested. A new crop of leaves will appear later, but the dam- 

 age has already been done. 



Spray just liefore the buds are open in the spring, with commercial 

 lime-sulphur solution, 4.5 degrees Baume, 1.030 specific gravity. This 

 spraying will be unnecessary if the trees have already been sprayed 

 with lime-sulphur for the peach twig borer. 



