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TROSPECTOR — 



A New Elm for New Hampshire? 



Adapted from an article by A.M. 

 Townsend, LR. Schreiber. W.O. 

 Masters, and S.E. Bentz: U.S. 

 Department of Agriculture. Agri- 

 cultural Research Service, U.S. 

 National Arboretum, Washington, 

 DC 20002. (This article originally 

 appeared in HortSc-ience, Vol. 26 

 (]), January 1991.) 



l-> 1ms are excellent trees. Un- 

 fonunately. both Dutch elm dis- 

 ease, caused by Ceratocystis ulmi. 

 and the elm leal beetle iXan- 

 thogaleruca luteola ) restrict the 

 extensive use of unimproved elms. 

 'Prospector' elm (Ulmus wison- 

 iana) was released because of its 

 insect and disease resistance, vase- 

 shaped crown, intermediate size, 

 and widespread adaptability. 



Origin 

 'Prospector' elm (NA 55398, PI 

 536050) is a seedling selection of 

 Ulmus wilsoniana grown from a 

 seedlot of unknown origin. Two- 

 year-old seedlings were planted 

 about 1965 in Delaware, Ohio, and 

 in 1980. one tree ('Prospector') 

 was selected for more intensive 

 evaluation. It was propagated by 

 softwood coittings and, along with 

 ramets from several other clones, 

 was established in 1982 in nursen' 

 beds in a randomized block, splii- 

 plot design. 



Inoculations were made on 'Pros- 

 pector' and the other elm clones in 

 the beds on May 29, June 28, and 

 July 24. 1984. These inoculations 

 were made with a mixed suspen- 

 sion (1.4 X 10 6 spores/ ml) of ag- 

 gressive and nonaggressive iso- 

 lates of C. ulmi. Comparison of 

 disease symptom expression 4 

 weeks after inoculation showed 

 'Prospector' to have greater re- 

 sistance than Standard Resistant 

 Clone No. 1. CPhe latter clone has 

 proved to be resistant to both 

 aggressive and nonaggressive 

 strains of the fungus in previous 

 studies.) 'Prospector' also has been 

 found to be resistant to the elm 

 leaf beetle. 



Elm yellows is an often-lethal elm 

 disease probably caused by micro- 

 plasma like organisms. Kim species 

 of European or Asian origin are 

 tolerant or immune to this disease. 

 Based on its Asiatic origin and its 

 apparent field resistance when 

 grown among infected American 

 elms at Delaware, Ohio, 'Pros- 

 pector' can be expected to express 

 tolerance to natural infections of 

 elm yellows. 



Description 

 'Prospector' elm has a vase-shaped 

 crown similar to that of the Amer- 

 ican elm, but becomes pendulous 

 at a much lower height. One- 

 year-old rooted cuttings planted at 

 Delaware, Ohio, in April. 1980, 

 showed an average height and 

 crown spread of 7.0 m and 6.4 m, 

 respectively, in September, 1989. 

 Branch angles average 5?> degrees, 

 and range from 28 to 63. The 

 canopy is dense, with large oblong- 

 ovate leaves. Newly expanding 

 leaves are an orange-red, but 

 gradually darken to a yellow-green 

 and finally to a green. The un- 

 derside of mature leaves is a 

 yellow-green; leaf color in the 

 autumn is yellow. Branches, buds, 

 bark, and fruit are typical for the 

 species. 



Adaptability trials in the northern 

 United States have shown 'Pros- 

 pector' to be cold hardy, with no 

 injur\' after three years in St. Paul, 

 Minn. It has also been successfully 

 grown in Maryland. California. Il- 

 linois. Ohio, Oklahoma, Oregon, 

 Tennessee, and Virginia without 

 heat, drought, or cold injur>'. It 

 can be considered to be adaptable 

 in U.S. Department of Agriculture 

 zones 4-7. 



'Prospector' elm should make aii 

 excellent tree for streets, lawns, 

 highways, and parks. Its small to 

 intermediate size makes it useful 

 for planting under power lines. 

 'Prospector' is easily propagated 

 from softwood cuttings, taken in 

 the spring or early summer, dip- 

 ped in 0.8% IBA, and placed under 



intermittent mist in a mbclure of 1 

 peat:l perlite. or a similar medium. 

 Rooting should occur within four 

 weeks. 



Availabilit>' . 

 The U.S. Department of Agri- 

 culture released this cultivar in 

 1990. Several wholesale nursen.'- 

 men are propagating and growing 

 liners of this new cultivar for 

 future sale. Among them are I^ke 

 Countv Nursen,' Exchange, Perry, 

 OH (telephone: 216-2,59-5571); Bur- 

 gaw Creek Nurser\', Burgaw, NC 

 28425; and J. Prank Smith Nurs- 

 ery. Boring. OR 97009 (telephone 

 ,503-663-4128). .^ 



Utilize sales islands 



regularly 



for key sale items. 



Customers begin to 



frequent these sales islands 



to get the seasonal items 



they offer. 



Offer new ideas 



for your customers 



to display hardy mums 



and flowering kale. 



Be sure the planting ideas 



utilize pots you have in 



inventory and 



utilize multiple plants. 



Price plants in multiples that 



relate to planting ideas. 



It is a fact 



that signage can 



increase sales 30-40%. 



Create signs that are clear, 



legible, and visible. 



—Tina Sawtelle 



AUGUST/SEPTEMBER 1991 27 



