Show I Black Currant Nurse o of Rust Acts as Advance Guard in Spreading p Disease Among the White Pines Prepared by the United Stat States 1 Department nt of or Agriculture The European black currant Is Is' isa n a p public nuisance be because ause It acts as an nn pa a guard In spreading the white whitepine I pine blister bUster rust a disease of ot foreign I I origin which is destructive to all nil o of I lour our American white or leafed five pines says s 's Samuel IJ B. Detwiler chief b rust blister specialist of ot the bS S States tates Department of ot Agriculture Two Host Plants The blister rust requires two Ivo distinctly distinctly distinctly dis dis- different kinds kinds' of ot host plants for f or completing its life cycle The spores that Infect the pines are produced pro pro- uce on the leaves of or currant or gooseberry hushes bushes and transmitted to the tile pines through the air nil In turn the currants aril and gooseberries become infected from the spores produced on the pines all species of currant currant cur cur- rant and gooseberry plants take the he disease to some extent the European black bind c currant Is so susceptible that a asin a asin I sin jle Ile spot on one leaf may mily completely complete complete- I ly Iy spread the disease to to the entire t plant t's ts well as ns to other near near-by j plants of III the sante same species Thus the scattered wind-blown wind spores which may travel hundreds ds of miles and not 1 establish the fire rust on en 1 other species of I currants ts do Infect the European black and set up new centers of or I tion For this reason the thC European black currant has been called the nurse ant nt of blister rust rustS and out but out outlawed laved by thee the states in which I. I white pines are arc re I important forest foiest I crops White Pines Endangered red The white pines in the the United States that are endangered by buster blister bus blis ter tel rust ha have hae e a n cash timber value alue of approximately o while th the lumber value of this timber Umber is many times greater This does not tale take info into account the value alue of of trees of these species us used d as ornamentals and ami the potentially great value of the young pines for the future timber crops crOll The money money- value of the blackcurrant black blackcurrant currant plantings of the thc country Is t negligible I For Far or these reasons the United States State Department of Agriculture and lit the e concerned hare declared the European Eu ICu- black currant a public nuisance e and ami are ale co operatively co-operatively engaged in T campaign to s systematically ally eliminate e I It from l the country |