DUTCH ELM DISEASE ON 
     
     PRINCE EDWARD ISLAND 
     
    
   
   
    
     “Dutch e1m disease" - for those of 
     
    

    
     5 who have noted the gradua1 
     
     disappearance of the species in 
     
     eastern Canada, the term invokes 
     
     visions of stream borders 1ined 
     
     with dead e1ms, their trunks 
     
     devoid of bark, b1eached by the 
     
     e1ements 1ike the bones of a 
     
     beached wha1e. What is this 
     
     terrib1e disease, and how has it 
     
     arrived here? 
     
    
   
   
    
     Dutch e1m disease was first 
     
     observed in the Netherlands in, 
     
     1918 and now occurs throughout 
     
     the who1e of Western Europe. It 
     
     was discovered on this continent 
     
     in Ohio, in 1930, apparent1y 
     
     having been introduced in a ship- 
     
     ment of e1m 1095 from Europe. 
     
     The disease had spread to Canada 
     
     by 1944, and is now present at 
     
     epidemic 1eve1s in Manitoba, 
     
     Ontario, Quebec, New Brunswick 
     
     and Nova Scotia. The first 
     
    

    
     infection was found on Prince 
     
     tdward Is1and in 1979. 
     
    
   
   
    
     The disease is caused by a fungus, 
     
     Ceratocystis u1mi, the spores of 
     
     w 1c are transported from 
     
     diseased to hea1thy trees by the 
     
     native e1m bark beet1e, 
     
     Hy1urgopines rufipes. A11 species 
     
     of e1m may be so infected. The 
     
     fungus enters the tree's water- 
     
     conducting vesse1s, as adu1t 
     
     bett1es feed in the upper 
     
    

    
     branches of hea1thy trees. 
     
    

    
     There it produces spores and toxic 
     
     chemica1 byproducts which are 
     
     carried in the sap stream to a11 
     
     parts of the tree. Eventua11y, 
     
     vesse1s are b1ocked, and the 
     
     1eaves wi1t from 1ack of water. 
     
    
   
   
    
       
     
    
   
   
    
     -,_ ....__,,_ .. 
     
    
   
   
    
     Ye11owing and sudden wi1ting of 
     
     the 1eaves during Ju1y, on one 
     
    

    
     or more 1imbs in the upper crown, 
     
     is the first obvious_sympton of 
     
     Dutch e1m disease. It is 
     
     .important that surveys be carried 
     
    
   
   
    
     out at this time as natura1 
     
     ye11owing, not associated with the 
     
     disease, common1y begins in ear1y 
     
     August. Diseased 1eaves turn 
     
     brown, dry out and fa11, or they 
     
     may shrive1, become britt1e, and 
     
     remain attached to the twigs for 
     
     many weeks. 
     
    
   
   
    
     F011owing deve1opment of the first 
     
     fo1iar symptoms of Dutch e1m 
     
     disease, affected branched die 
     
     quick1y and the condition extends 
     
     through a11 1arge 1imbs unti1 the 
     
     tree dies. Depending on the 
     
     initia1 condition of the tree, 
     
     and the severity of attack, death 
     
     may occur in from one to three 
     
     years. 
     
    

    
     The first infections on Prince 
     
     Edward Is1and, 1ocated at Conway 
     
     and Northam in centra1 Prince 
     
     County, were confirmed in 
     
    

    
     August, 1979. At that time, an 
     
     attempt was made to contain the 
     
     "hot spots” by removing and 
     
     destroying a11 infected trees, 
     
    

    
     as we11 as other e1ms in their 
     
     immediate vicinity. A11 areas 
     
     of the Province have been 
     
     surveyed for the disease in 
     
    

    
     1980. Though suspects have 
     
    

    
     once again been identified, a 
     
     fina1 ana1ysis must await the 
     
     resu1ts of 1aboratory testing. 
     
    
   
   
    
     Favored for its beauty and vigor, 
     
     American e1m was p1anted exten- 
     
     sive1y a1ong streets of new1y- 
     
     sett1ed towns in the 1ast century. 
     
     Significant popu1ations of our 
     
     native e1m occur in centra1 
     
     Prince County, a1ong with 
     
     scattered sma11 groups e1sewhere 
     
     throughout the Province. Unfor— 
     
     tunate1y, the future surviva1 of 
     
     this species is in jeopardy. 
     
     Un1ess a practica1 means is 
     
    

    
     found to ha1t its spread, Dutch 
     
     e1m disease may very we11 
     
    

    
     resu1t in the eventua1 
     
     disappearance of American e1m 
     
     from the 1andscape of P.E.I. 
     
    
   
   
    
     Jean-Pau1 Arsenau1t 
     
     Forestry Branch 
     
    

    
     P.E.I. Dept. of 
     
     Agricu1ture & Forestry