12 



CIRCULAR NO. 129, BUREAU OF PLANT INDUSTRY. 



writer in 1912 found the disease in a lot of white pmes sent to this 

 country by Buch & Ilermansen in 1909, at which time the trees 

 were a])])arently healthy. 



INEFFICIENCY OF INSPECTION EVEN WHEN REPEATED. 



In earlier publications ' the writer has repeatedly called attention 



to the fact that a single inspection of a lot of 

 white })hi(>s diseased with the blister rust will 

 not result in the complete eradication of the 

 infected trees. The inefficiency of inspection 

 even when repeated, except as a temporary 

 expedient, has become mcreasingly evident 

 from the beginnino; in 1909, when the disease 

 was first discovered liere on ])hies. It has been 

 f(»und by i)ersonal mvestigations that the closest 

 inspection possible wnH not remove all mfected 

 trees in a smgle large lot of trees.^ That is, 

 plainly diseased trees were found in 1910 and 

 1911 in a lot of 10,000 white pines which were 

 m 1909 very closely inspected and from which 

 aU suspicious trees were then removed and 

 destroyed. Moreover, after three personal in- 

 spections in previous years this lot of trees was 

 found in 1912 to have quite a number which 

 bore abundant fruitmg bodies. 



Another parallel case is that of another lot 

 of 10,000 white pines, imported when 3 years 

 old. These were inspected in 1910 by a State 

 (official who knew tlie disease well. About 150 

 were removed and burned at that time, includ- 

 ing every doubtful tree that was found. The 

 Ribes plants in that locality were also pulled 

 up and burned; there were but two, and these 

 showed no signs of the disease. In 1912 re- 

 inspection showed that about 30 of the re- 

 maining trees bore very abundant fruiting 

 bodies of the fungus. Manv of the diseased 



"IG. 4.— White-pine tree about 

 10 years old which has borne 

 blister-rust fruiting bodies in 

 previous years. Note the 

 heavy scales of bark on a stem 

 which at this age should be 

 smooth. 



' Spaulding, Perley. 

 (a) The blister rust of white pine. U.S. Department of Agriculture, Bureau of Plant Industry, Bulletin 



206, 88p., 5fig., 2pl., Iflll. 



(ft) Notes upon Cronartium ribicola. Science, n. s., v. 35, no. S91, p. 146-147, 1912. 



((.) and Field, Ethel C. Two dangeroii.< Imported plant diseases. T'. S. Iieparlmonl of Agri- 

 culture, Farmers' Bullelhi 4^(t, 2<) p., ;5 fig. 

 2 Spaulding, t'erley. Notes upon Cronartium ribicola. Science, n. s., v. 35, no. sm, p. 14(^147, 1912. 



[Cir. l'_'!ll 



