144 MISC. PUBLICATION -4 3 4, IT. S. DEPARTMENT OF AGRICULTURE 



Very often it will be necessary to do hand weeding in nursery sowings 

 when the seedlings are just emerging from the soil. The foreman of 

 a weeding crew can often deploy his men over a considerable part of 

 the block in which the weeding is done, and the presence of the men 

 will keep the birds away. This method has a disadvantage in that 

 it may be difficult to supervise the men properly. 



Protection of conifer beds in a North Dakota nursery by setting 

 wind-operated propellers on posts around the nursery proved mod- 

 erately successful. Shiny pieces of tin were nailed to the blade and 

 a noisemaking device was added, consisting of loose pieces of tin tied 

 to a tin vane. The propellers were 16 to 24 inches long, fashioned from 

 scraps of 2 by 4 material. This idea suggests the possibility of a 

 "scarecrow" whose arms could be moved by a wind-operated propeller. 



Screening, although entirely feasible for conifer beds, is impractical 

 in a big deciduous-tree nursery except on a few species which are 

 grown in beds on a small and intensive scale. 



Shooting of the birds should be limited strictly to those species 

 which are not protected by State or Federal law and which are con- 

 sidered in the "pest" category. This would usually include English 

 sparrows, crows, ravens, and starlings. 



PATHOLOGY OF DECIDUOUS SEEDLINGS 19 



Since the comparatively recent establishment of large, Federal, 

 deciduous nurseries, the diseases of broadleaf tree and shrub species 

 have assumed considerable importance in some instances. Previously 

 little consideration had been given to losses caused by damping-off 

 fungi. Leaf diseases occurring on but few species were relatively 

 unimportant in commercial nurseries where undersized seedlings could 

 be readily carried over from year to year. The overwinter storage of 

 large numbers of seedlings has also emphasized the importance of 

 certain pathological troubles, particularly root rots, and the handling 

 of tons of seed in storage has likewise revealed unusual problems. It 

 is evident that considerable time will be required for research before 

 entirely satisfactory remedial measures can be obtained for these 

 different problems. The information presented here summarizes 

 investigations covering five seasons. 



Selection of Nursery Sites 



Pathological problems can sometimes be avoided by careful selec- 

 tion of nursery sites. If time is available, it is advisable to determine 

 the damping-off potentialities of a given soil by greenhouse and other 

 tests. The information obtained can be used in determining the best 

 nurseries for growing susceptible species, or for the elimination of 

 undesirable areas. Careful inspection of prospective sites is always 

 advisable to avoid lands infested with serious root diseases or liable 

 to chlorosis. For example, the cotton root-rot disease of the South- 

 west is caused by the soil-inhabiting fungus Phymatotrichum omni- 

 vorum (Shear) Duggar. It is found only a few miles north of the 

 Red River in Oklahoma but is common in Texas and States further 



19 Discussion of pathology is contributed by Ernest Wright, associate pathologist, Division of Forest 

 Pathology, Bureau of Plant Industry. 



