DANGEROUS INTERNATIONAL FOREST TREE DISEASES 93 



Hosts: 



Pinaceae — 



Pinus banksiana Lamb 



P. contorta Dougl. 



P. nigra Arnold (Planted in U.S.) 



P. pinaster Aiton (Planted in U.S.) 



P. ponderosa Laws. 



P. ponderosa var. arizonica (Engelm.) Shaw 



P. pungens Lamb 



P. rigida Mill. 



P. sylvestris L. (Planted in U.S.) 



P. taeda L. 

 Santalaceae — 



Comandra umbellata (L.) Nutt., syn. (C. pallida A. DC.) 



C. livida Richards (Geocaulon lividum (Richards) Kern.) 



Literature : 



Arthur, J. C. Manual of the rusts in the United States and 



Canada. Lafayette: Purdue Res. Found., 438 pp. 1934. 

 Hedgcock, C. G., and Long, W. H. A disease of pines caused by 



Cronartium pyriforme. U.S. Dept. of Agr. Bui. 247, 20 pp. 1915. 

 Mielke, J. L. The comandra blister rust in lodgepole pine. U.S. 



Forest Serv. Intermountain Forest & Range Expt. Sta. Res. Note 



46, 8 pp. 1957. 



Southern Fusiform Rust 



A. F. Verrall 



Forest Service, U.S. Department of Agriculture, 

 Netv Orleans, Louisiana 



Cronartium fusiforme Hedge. & Hunt is a heteroecious long-cycle 

 rust causing perennial stem and branch galls on Pinus and leaf spots 

 on Quercus in Southeastern United States. Bark swellings usually 

 are first evident in early fall following spring infection, but sometimes 

 are not pronounced until second year. Galls are typically spindle 

 shaped, may finally reach a meter or more in length, and on large boles 

 usually become sunken cankers with age. Proximal growth of branch 

 galls is often irregular so that only the distal end may be fusiform. 

 Rate of gall elongation is very variable but averages 75 to 125 mm. 

 per annum. 



Aecial fruiting biennial, bright yellow orange, February to April ; 

 peridium erumpent, cerebroid, moderately thin (1 to 2 cells). Aecio- 

 spores 13-18 X 22-28/x, coarsely verrucose. Following aeciospore 

 infection of oaks, pale green leaf spots develop, quickly followed by 

 bright orange uredial pustules on the under surface in February to 

 May. Uredospores 12-15 X 17-21/x, evenly and sharply echinulate. 

 Telia appear in uredinial spots or, more frequently, independently 

 from February to June ; are brown, average 104 X 2.872/*, with telio- 

 spores averaging 14.7 X 36.4/x. Pycnia appear in October to April : 

 pyenial ooze at first pale orange but soon becomes a black splotch on 

 the bark. Spores are windborne and pine infection occurs through 

 first-year needles. 



This is one of the most serious diseases of Pinus taeda and P. 

 elliottii var. elliottii. Pines of all ages are susceptible, but most 



