Circular No. 1 20. issued March 12, 1910. 



United States Department of Agriculture, 



BUREAU OF ENTOMOLOGY. 

 L. O. HOWARD, Entomologist and Chief of Bureau. 



CONTROL OF THE BROWN-ROT AND PLUM CURCULIO 



ON PEACHES. 



By 



W. M. Scott, of the Bureau of Plant Industry, 



and 

 A. L. Quaintance, of the Bureau of Entomology. 



The two most important troubles of the fruit of the peach and other 

 stone fruits are the so-called '"brown-rot" (Sclerotinia fructigi nia (P.) 

 Schrot.) and the plum curculio ( Conotrachelus nenuphar Herbst). The 

 brown-rot is a fungous disease of the flowers, twigs, and fruit, but is 

 especially destructive to the latter as it approaches maturity. Under 

 weather conditions favorable to the fungus from one-half to three- 

 fourths of the crop, or even the entire crop, may be destroyed within 

 a few days. The marketed fruit, moreover, rarely reaches its desti- 

 nation in good condition and is often a disappointment to the grower 

 as well as to the consumer. This destructive disease is well known to 

 peach growers, especially in the Southern States, and requires but 

 little in the way of description. Although young green fruit may 

 become infected, it is the ripening fruit which suffers most. The 

 disease first appears as a small brown spot, which rapidly enlarges, 

 involving in a few da\'s the entire fruit. On the surface of the 

 diseased spots minute tufts of spore-bearing threads appear, giving 

 to the fruit a grayish, moldy appearance. 



The plum curculio, in the course of its feeding and egg laying, 

 punctures the fruit, and is often so abundant that not a single fruit 

 escapes injury. The punctures form a nidus for brown-rot spores, 

 greatly favoring infection. Larvae of the curculio, hatching from the 

 eggs placed beneath the skin of the peach, make their way to the pit, 

 and by their injury cause much of the young fruit to drop. Fruit 

 infested later in the season may ripen prematurely and fall or be badl} 7 

 misshapen. Worminess of peaches in the East is entirely due to the 

 plum curculio, and the injuries of this insect cause, in the aggregate, 

 a loss each year to fruit growers of many thousands of dollars. As 



[Cir. 120] (3) 



