DISEASES OF PLANTS. 845 



DISEASES OF PLANTS. 



Notes on plant diseases occurring' in North Carolina, F. L. Stevens and 

 J, G. Hall (North Carolina Sta. Rpt. 1910, pp. 59-72, figs. 5). — Notes are given 

 on a number of plant diseases reported from different parts of North Carolina, 

 most of them being on fruit, field, and garden crops. 



Plant diseases in Virginia in the years 1909 and 1910, H. S. Reed and 

 J. S. CooLEY (Virginia Sta. Rpts. 1909-10, pp. 99-119, figs. 13).— The results of 

 a plant disease survey of the State are given, based upon replies to circulars 

 sent out to about 900 addresses, as well as on the personal observations of 

 the authors. The diseases are grouped according to the host p'ants, and some 

 notes are included on tlae relative distribution and damage. Ja some instances 

 suggestions are given for control. 



Three interesting species of Claviceps, F. L. Stevens and J. G. Hall 

 (North Carolina Sta. Rpt. 1910, pp. 52-55, figs. 8). — Previously noted from 

 another source (E. S. R., 24, p. 448). 



Investigations on the diseases of beets. — 5, On the causes of the damping- 

 off disease of beet seedlings, L. Peteks (Arb. K. Biol. Anst. Land u. Forstw., 

 8 (1911), No. 2, pp. 211-259, figs. 12). — The author discusses the life cycles of, 

 and the various parts of the beet seedlings which are attacked by, the 3 main 

 fungi responsible for the damping-off disease, viz. Pythium debaryanum, 

 Plioma hetw, and Aphanomyccs Iwvis. 



It was found that P. dcbaryanum not only attacks and kills the hypocotyl 

 and upper parts of the roots, but may also cause the death of the main root of 

 young plants and of the side rootlets during the entire vegetative period. P. 

 hctw as a damping-off fungus destroys the lower parts of the hypocotyls and the 

 upper parts of the roots, but does not attack the main root tip or side roots. 

 A. Iwvis attacks the plants very much like P. debaryanum, causing the death 

 of the seedlings. 



Investigations on the diseases of beets. — 6, On the occurrence of the 

 damping-off organisms in the soil, W. Busse, L. Peters, and P. Ulrich (Arb. 

 K. Biol. Anst. Land u. Forstiv., 8 (1911), No. 2, pp. 260-302).— It is claimed 

 that the damping-off disease of sugar beets can occur through organisms which 

 are present in the soil or on the seed when planted. These soil organisms are 

 able to kill the germinating seed and thus materially reduce the stand. The 

 mechanical, physical, and chemical condition of the soil will also influence the 

 stand without the intervention of any organism. 



The greater part of the damping off results from the attacks of Phoma 

 betce, as this organism is generally present on the seed in large numbers. 

 Pythium debaryanum attacks the beet plants immediately after germination 

 and in the earlier developmental stages, while Phoma betcB and Aphanomyces 

 Iwvis attack the plants somewhat latei'. Damp weather favors Pythium and 

 Aphanomyces, while Phoma is more of a dry weather organism. The damping- 

 off disease is especially bad on certain types of soil, viz, heavy encrusting soils, 

 low soils rich in humus, moor soils, limy sands, and sandy soils. 



Cabbage club root in Virginia, H. S. Reed (Virginia Sta. Bui. 191, pp. 12, 

 figs. 5). — An account is given of the occurrence of cabbage club root (Plas- 

 modiophora brassicw) in Virginia, together with observations on the spread of 

 the disease by cultivators, the feet of horses, soil erosion, and through feeding of 

 diseased cabbage to stock. Experiments are also reported on the control of the 

 disease which were begun in 1909 and carried on for 2 years. The experi- 

 ments consisted of soil treatments with lime, acid phosphate, and stable manure, 

 comparisons being made of the yield of cabbage from the different plats. The 



