50 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



seedlings ever imported or likely to be. Prohibition is the only 

 eilicient means of prevention, as the disease can not be detected in 

 tlie shipment by any system of inspection. 



One of the most discouraging features of reforestation is the 

 prevalence in the forest nursery of damping-ofT and other seedling 

 diseases wliich may sometimes destroy the entire annual output of 

 a nursery, especially of coniferous seedlings. One of the commonest 

 of these diseases, popularly called "blight," has been controlled at 

 the Forest Service nursery at Ilalsey, Nebr., by slight and perfectly 

 practicable changes in the management of water supply and shade. 

 Damping-oflF of eucalyptus seedlings, a source in the past of great 

 loss, proves- to be preventable by selecting the proper soil for planting. 



Data collected in the forest-disease survey indicate that in America 

 timber decay and tree disease are second only to forest fires as causes 

 of loss. In theory it is easy to remove diseased trees in the forest 

 when cuttings are made, leaving only healthy individuals for seed 

 trees, and so continually improve the health of the forest; but in 

 practice so many questions of economy and differing local conditions 

 are involved that many difficulties must be overcome. A great 

 deal of attention will be given to working out this problem. 



Cotton and truck-crop diseases.— The wilt-resistant varieties 

 of cotton and cowpeas which the Department has been breeding and 

 disseminating for several years have been brought to a higher stand- 

 ard than ever before, but wilt and root-knot have been spreading 

 faster than the improved varieties have come into use, so that many 

 thousands of acres continue to be destroyed each year. The prob- 

 lem now is to reach the farmers with the new seed and methods. For 

 this purpose a special campaign of education is being inaugurated, 

 to develop breeders of the new cotton and cowpeas and to demon- 

 strate the effectiveness of the improved varieties. 



A rust-resistant asparagus has finally been secured, and the stock 

 is being propagated with all possible dispatch. 



New prominence has come to the potato wilt, a disease laiown for 

 some years, by the discovery that it is very widespread and injurious 

 in an inconspicuous form, causing premature ripening, as well as 

 dry-rot in storage. It must be more widely understood, and pre- 

 ventive measures, such as longer rotations, must be adopted. 



Black-leg, another new potato disease, is increasing through the 

 use of infected seed, especially in eastern trucking districts. Internal 

 brown-spot is common. The present varieties of potatoes are some- 

 what limited in their climatic adaptations, and the diseases that affect 

 them emphasize the importance of a broadly planned line of breeding 

 to develop new potatoes possessing disease resistance and stronger 

 local adaptation through bringing from South America or elsewhere 

 new strains for hybridization. Potatoes for the warmer States are 

 especially needed. 



