duced then will spread rapidly to other Ribes. About, the 

 first week in July the second or late summer stage begins to 

 appear on the infected Ribes. This stage is recognized by . 

 the dark brownish or dark orange colored columns or horn- 

 like structures on the under side of the leaves. The spores 

 produced at this time, known as "telia" are the ones that 

 infect the pine. They can not travel as far on the wind 

 and remain alive, as the spores produced on the pine, so the 

 radius of infection is reduced or limited to a distance which 

 makes economic control possible. 



While the spores from the pine may be carried for great 

 distances by the wind, possibly ten to fifteen miles or more, 

 they may also be carried by other agencies such as insects, 

 animals or man. They will retain their vitality for several 

 weeks and grow wherever they happen to fall on currant 

 or gooseberry leaves. 



The spores from the Ribes leaves, however, are more 

 delicate and apparently of less vitality. They do not seem 

 to be able to thrive if carried for more than at most a third 

 of a mile and usually the distance is less than three hundred 

 yards. This accounts for the difference in distance between 

 the spread of the rust from the trees to the bushes, and from 

 the bushes back to the pine, as has been clearly demonstrat- 

 ed by carefully planned and scientifically conducted experi- 

 ments. 



Hence, wherever the currant and gooseberry bushes have 

 been removed from the vicinity of the pine, the further 

 spread of the disease is absolutely stopped. The low cost 

 of efficient eradication averaging from 24 cents to 35 

 cents per acre over large areas, makes this insurance well 

 worth while, and the owner may feel sure of a commercial 

 stand of white pine, in so far as the damage from blister 

 rust is concerned. 



Some people still believe that the blister rust is not a ser- 

 ious menace to the growing of white pine, but their judg- 

 ment is not in accordance with the facts at hand, and is 

 usually based on insufficient or inconclusive evidence. 



It is not at all necessary to become unduly alarmed 

 about the present mature crop of white pine, but it is good 

 business policy to remove all Ribes from areas where young 

 pine is now growing or where it is to be grown for the fu- 

 ture. The State Forester in every state is ready and willing 

 to cooperate with the private owner in this work and to offer 

 all possible aid and assistance. 



The White Pine (Pinus strobus, L.) is the only native 

 species in the East that is susceptible to the disease, but 



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