28 A PLANT-DISEASE SURVEY TN TEXAS. 



somewhat grayish when the epidermis has been ruptured by the pro- 

 truding acervuli. 



The twigs may be killed back from the tip or along one side, caus- 

 ing the branches to be angular. Some trees were observed on which 

 the disease had worked well down on the tnnik. 



Specimens collected: (1) On Citrus limonum Risso. — Austin. 1443. (2) On 

 C. aurantium sinensis L. — Beeville, 1846 (doubtful). 



PEACH. 



Crown-gall {Bacterium tumefaciens Erw. Sm, and Townsend). — 

 Just to what extent this trouble is present on the peach {Amygdalus 

 persica L.) is not known. It was observed in two places only. 



Specimens collected: Uvalde. 1939; Round Rock. 



Die-back {Valsa leucostoma (P.) Fr.). — This is the most widely 

 distributed and most serious trouble of the peach. (See also plum 

 and apricot.) The entire tree may be killed or only the smaller 

 branches. Orchards were observed in which nearly all the trees 

 were dead, giving them a ver^' characteristic silvery appearance. The 

 bark is elevated in wartlike nodules covering dark-broAvn or black 

 pustules. These at length are exposed on the surface. Our speci- 

 mens show only the Cytospora stage. 



Specimens collected: San Antonio, 1368, 3170; Kerrville, 1594, 1596; Boeme, 

 1644 : Beeville, 1825 ; Elgin, 1873 ; Bastrop, 2038 ; Lockliart, 2080 ; San Marcos, 

 2122: Seguin, 2288; Round Rock, 2423; Victoria. 2521; Nursery. 2557; Stock- 

 dale. 2625; Gonzales, 2670; Flatouia, 2731; Yoakum, 2756. 



Freckle {CladospoHum' cavpophilum Thm.). — This disease is gen- 

 eral wherever the peach is grown, but was collected only a few times, 

 since the peach crop was almost a complete failure in our territory. 



Specimens collected: Austin, 1440; Beeville, 1838; Elgin, 1892; Georgetown, 

 2362. 



Eust {Tranzschelia punctata (P.) Arth.).— The rust of the peach 

 shows on the upper surface of the leaves as definite, circular, or sub- 

 circular, yellow spots which average about 1 mm. in diameter. The 

 color of the spot on the under surface is the same, but the center of 

 each is occupied by a minute yellowish-brown sorus. 



This rust is abundant on peach foliage in some localities and causes 

 defoliation in the latter part of the growing season. 



Specimens collected: Austin. 202, 210. 454, 468; San Marcos, 2100: Nursery, 

 2560. 



Shot-hole and leaf -spot {Bacterium pnini Erw. Sm.).— This disease 

 is characterized in its typical condition by small, irregular or angular, 

 purplish-brown spots, 2 to 5 mm. in diameter, which are crowded full 

 of bacteria. In some of our collections the spots are less angular and 



226 



