University of Arizona 301 



grows most rapidly during the summer season. In the introduc- 

 tion garden vines have grown 50 feet in a season. This is the most 

 rapid growing of our herbaceous climbers and with its dense foliage 

 is excellent for shade for poultry yards and fences, sheds, and even 

 for houses. It is much planted in parts of Japan as a covering for 

 homes, and for the forage, which is relished by animals. It is best 

 suited for growing in Arizona below altitudes of 2,500 feet, prefer- 

 ably in rich, well irrigated soils. It blossoms about September 15, 

 and with an early frost will hardly mature seed. The leaves and 

 stems of the season's growth are killed with minimum temperatures 

 of 29 degrees F., and the older woody stems, which ordinarily live 

 over, are killed with temperatures of 6 degrees F. This plant should 

 have value as forage for growing along irrigation ditches or in areas 

 not readily accessible to cultivation. 



PLANT DISEASE STUDIES 



For the most part, the plant diseases that have been destructive 

 during the recent growing season are the ones that were predomi- 

 nant during the previous year. These include tomato wilt, which 

 has been serious in many sections, cotton sore shin disease, cotton 

 root-rot, alfalfa root-rot, fruit tree root-rot, melon wilt, and crown 

 gall. Besides these, a serious disease of the common pepper has 

 appeared at Tubac and in the Rillito Valley near Tucson. When 

 nearly mature the plants cease growth, gradually turn yellow and 

 begin to die from the roots with a full crop of peppers. In a num- 

 ber of respects the disease resembles tomato wilt. Practically all 

 the plants within an affected area are killed. A study is being made 

 of this disease. A careful rotation of crops will help both in this 

 disease and in tomato wilt. 



A serious canker disease of cottonwood and poplar trees caused 

 by Cytospora chrysospenna* has been found in a number of localities 

 in Arizona. These include Flagstaff, Williams, Prescott, Douglas, 

 Nogales, Continental, and Tucson. This disease attacks both na- 

 tive and introduced poplars, but is most destructive to introduced 

 species, including the Carolina poplar and the Lombardy poplar. 

 A considerable number of these trees have died in Flagstaff from 

 this cause. The disease may be recognized by the presence of 

 sunken, dead areas on the bark of the larger limbs of trees. The 

 inner bark of these areas is blackish and has a pronounced odor. 

 Later, small reddish, pustule-like fruiting bodies appear on the sur- 

 face of dead areas of bark. On old bark these reddish bodies can 



*Lone:. W. H. Journal of Agric. Research, XIII, 6, 1918. 



