I have grown plants of Illusion since the early 70's at two different locations in northern Ohio. I have found it to have beautiful red, very double, and relatively large flowers. It is also a continual bloomer, blackspot- and mildew-free (without spraying), and relatively hardy (here in a normal zone 5b winter, -10 to -15 degrees F, only the tips show any winter injury). A very important point, in northern Ohio, is that the Japanese Beetles ignore it! Illusion occupies the premier location in my front yard - it surrounds the lamp post.
In Modern Roses 10 Illusion is described as a Kordesii (the second parent has never been disclosed) shrub that was hybridized in 1961 by Kordes. "Flowers blood-red to cinnabar, dbl., large blooms in large clusters; fragrant; foliage leathery, glossy, light green; vigorous growth." In Wilhelm Kordes book, Roses, Reinhold Publishing Corporation, page 195 (1964) Illusion is described as having flowers that are large, full, well-formed with wild rose fragrance. The blooms are about 3 inches across and appear in clusters of up to 8 individual florets. The time of flowering is early, and the habit of growth is upright with good branching. He recommends it as a pillar, hedge, and/or specimen shrub. It can reach a height of 10 feet. It is free flowering and resistant to disease. In the 1965 Rose Annual of the British National Rose Society, Wilhelm Kordes wrote an article titled "The History of Rosa kordesii, Wulff". In the article he states: "We brought out Illusion in 1961. It is a really rich deep blood red, very free flowering and an upright grower, with the scent of the dog rose." Roy Genders in his book, The Rose, A Complete Handbook, Bobbs-Merrill Company publisher, page 440, (1965) stated the following about Illusion: "A most arresting climber with its huge trusses of fragrant flowers of exotic cinnabar-red which are borne all along the stems to a height of 8 - 9 ft."
The University of Minnesota Agricultural Experiment Station published, in 1995, a 92-page report Roses for the North (item number ESMR-6594-SKID, cost $11.95 plus $3.50 shipping and handling, Minnesota Extension Service, 415 Coffey Hall, 1420 Eckles Ave, Saint Paul, MN 55108-6068). Illusion was one of the roses evaluated. For bloom pattern Illusion is reported to have heavy June bloom, slight July rebloom, and moderate August/September rebloom. For comparison this is the same bloom pattern reported for Dortmund, Henry Kelsey, and William Baffin. For winter injury Illusion was found to have dieback to the snow line, to the ground, and to the snow line for the winters of 1988-89, 1989-90, and 1990-91 respectively (remember the tests were done in zone 4a where the minimum winter temperatures are in the range of - 25 and -30 degrees F). This was the same as reported for Dortmund, Alchymist, Bonica, and for the hybrid rugosa, Hunter. In the section on diseases, Illusion did not exhibit any blackspot, powdery mildew, leaf spots, or rust during the two years of the study. Unfortunately in the section on insect observations, none of the Kordesiis were listed.
Illusion does set hips. The seeds are relatively easy to germinate. I am very impressed with the seedlings that I have grown. All of the flowers have been double, and all but one (a pink) have been a rich red. Since the oldest seedlings are only two years old, it is too soon to know what type (climber, shrub, etc.) they will be. I am now trying to cross Illusion and William Baffin with the hope of obtaining a climber with the hardiness of William Baffin and the flower of Illusion. I would suggest that crosses of Illusion with red hybrid teas be made in an attempt to increase the fragrance and/or hardiness and/or disease resistance and/or the insect resistance of the red hybrid tea class. It is not often one can hope for four possible improvements from one cross!
I purchased both of my plants from Pickering Nurseries, 670 Kingston Road, Pickering, Ontario L1V 1A6 (they do ship to the USA).