DISEASES OF FRUIT TEEES. 25 



mentioned above. The range in size of the spores may be extended 

 from 60 to 70 by 2 to 2.5 fi to 30 to 75 by 2 to 3 p. 



Specimen collected: Gonzales, 2660. 



Powdery mildew (Podosphaera leucotricha (Ell. and Ev.) Salm.). — 

 Apparently this disease is not common in this territory. The 

 perithecia were abundant on the stems and leaves of the shoots grow- 

 ing from the base of trees. 



Specimen collected: Austin, 1273. 



APRICOT. 



Die-back (Valsa leucostoma (P.) Fr.). — Pustules are formed on the 

 apricot (Prunus armeniaca L.) just beneath the outer bark. At 

 maturity these heaps rupture the bark and are exposed. While it 

 has been reported on several species of the genus Prunus, Kolfs (42) 

 mentions its occurrence also on the apricot. Our specimens show 

 only the Cytospora stage. 



A small orchard of plums, peaches, and apricots at Sound Rock 

 was seriously affected with this disease. The trees were about 8 

 years old. Some had been completely killed, while others were in a 

 badly crippled condition. 



Specimen collected: Round Rock, 2424. 



Shot-hole (Cylindrosporium padi Karst). — The symjDtoms are the 

 same as for the cherry " shot-hole," the foliage becoming perforated 

 with circular openings. 



Bacteria were present in abundance in the dead tissue of the spots, 

 and were apparently responsible for the shot-hole effect. Only a few 

 spores of the fungus were present. 



Specimens collected : Austin, 1441 ; Nursery. 2551. 



DATE PALM. 



Smut {Graphiola phoenicis (Moug.) Poit.). — The smut of the date 

 palm {Phoenix dactylifera L.) is confined to the leaves. It produces 

 small protuberances, the sporocarps, on both surfaces. The entire 

 leaflets or considerable portions from the tips downward may be 

 brown and dead in case of severe infections. The sporocarps are 

 dark gray or black, 0.2 to 0.8 mm. in diameter; when mature they 

 rupture and extrude a mass of pale chocolate-brown spores. (PL 

 VIII, fig. 1.) 



An examination of the herbaria at Washington and at the New 

 York Botanical Garden shows that it has previously been collected 

 in Florida, Georgia, California, and Texas, and in conservatories in 

 various Northern States. It has presumably been introduced from 

 the Mediterranean countries where it is not uncommon (26). 



Specimens collected : Beeville, 1849 ; Victoria, 2525 ; Falfurrias,' 2453. 

 226 



