Resistance of Pear Cultivars to Natural Fire Blight Infection
R. A. Spotts and
E. A. Mielke (Oregon State University, MidColumbia Agricultural Research and Extension
Center, 3005 Experiment Station Dr., Hood River, OR 97031)
The table below summarizes results of a trial conducted in Oregon in 1994. Between
April 18 and April 21 of that year, when many pear cultivars at the trial site were in
full bloom, weather conditions were highly favorable for natural infection by the fire
blight bacterium, Erwinia amylovora. An antibiotic (streptomycin) spray was
applied, but many trees showed fire blight symptoms by early May. Between early May and
late July, fire blight "strikes" were counted (and infected wood was removed) a
total of seven times. More than 80% of the strikes appeared by May 9. Note: rootstocks
designated numerically are ‘Old Home’ × ‘Farmingdale’ selections.
Table 1. Natural fire blight infection of pear trees
| Cultivar/Rootstock |
Trees infected (%) |
Mean strikes per tree |
| ‘B.P. Morettini’/‘Winter Nelis’ |
0 |
0.0 |
| ‘Bantam’/333 |
0 |
0.0 |
| ‘Bartlett’ (IRP 3-1)/‘Bartlett’ |
0 |
0.0 |
| ‘Bartlett’ (IRP 3-1)/Pyrus betulaefolia |
0 |
0.0 |
| ‘Bileu’/333 |
0 |
0.0 |
| ‘Blanquilla’/97 |
0 |
0.0 |
| ‘Bosc’/18 |
0 |
0.0 |
| ‘Bradford’ (IRP 133-1)/97 |
0 |
0.0 |
| ‘Bronze Beauty Bosc’/333 |
0 |
0.0 |
| ‘Comice’/‘Bartlett’ |
0 |
0.0 |
| ‘Comice’/333 |
0 |
0.0 |
| ‘Crimson Gem’ (‘Comice’)/333 |
0 |
0.0 |
| ‘Dana Hovey’/333 |
0 |
0.0 |
| ‘Dawn’/333 |
0 |
0.0 |
| ‘Gaspard’/333 |
0 |
0.0 |
| ‘Karr Bosc’/333 |
0 |
0.0 |
| ‘Magness’/333 |
0 |
0.0 |
| ‘Magness 3866E’/333 |
0 |
0.0 |
| ‘Maxine’/333 |
0 |
0.0 |
| ‘Missouri 83’/333 |
0 |
0.0 |
| ‘Moonglow’/333 |
0 |
0.0 |
| ‘Mount Adams Bosc’/333 |
0 |
0.0 |
| ‘Passe Crassane’ (IRP 31-1)/97 |
0 |
0.0 |
| ‘Passe Crassane Rouge’(IRP 32-1)/97 |
0 |
0.0 |
| ‘Shinko’/333 |
0 |
0.0 |
| ‘Tsu-Li’ (IRP 166-1)/97 |
0 |
0.0 |
| ‘Waite’/333 |
0 |
0.0 |
| ‘Abate Fetel’/97 |
25 |
1.0 |
| ‘Bartlett’ (IRP 20-1)/‘Bartlett’ |
25 |
1.0 |
| ‘Bartlett’ (IRP 22-1)/‘Bartlett’ |
25 |
1.0 |
| ‘Belmont’/333 |
25 |
1.0 |
| ‘Bosc’/97 |
25 |
1.0 |
| ‘Cal 8-46’/333 |
25 |
1.0 |
| ‘Comice’/97 |
25 |
1.0 |
| ‘Dabney’/333 |
25 |
1.0 |
| ‘French Bartlett’ (IRP 42-1)/‘Bartlett’ |
25 |
1.0 |
| ‘Hoskins’/333 |
25 |
1.0 |
| ‘Lincoln’/‘Bartlett’ |
25 |
1.0 |
| ‘Red Silk’/‘Bartlett’ |
25 |
1.0 |
| ‘Devoe’/333 |
25 |
2.0 |
| ‘Duchesse de Angouleme’/333 |
25 |
2.0 |
| ‘French Bartlett’ (IRP 42-1)/ Pyrus betulaefolia |
25 |
2.0 |
| ‘Hosui’/333 |
25 |
2.0 |
| ‘MCP-1’/97 |
25 |
2.0 |
| ‘Shin Li’/97 |
25 |
2.0 |
| ‘Swiss Bartlett’ (IRP 21-1)/‘Bartlett’ |
25 |
2.0 |
| ‘Bosc’/‘Bartlett’ |
25 |
3.0 |
| ‘Capitol’/333 |
25 |
3.0 |
| ‘Cascade’/333 |
25 |
3.0 |
| ‘Bartlett’ (IRP 22-1)/Pyrus betulaefolia |
25 |
4.0 |
| ‘Red d’Anjou’/333 |
25 |
4.0 |
| ‘Doyenne d’Hiver’/333 |
25 |
7.0 |
| ‘Lacock 6’/333 |
25 |
7.0 |
| ‘D’Anjou (russeted)/333 |
25 |
14.0 |
| ‘Fondante d’Autumn’/333 |
25 |
18.0 |
| ‘Bosc’/40 |
25 |
21.0 |
| ‘Fame’/333 |
25 |
50.0 |
| ‘Comice’/40 |
50 |
1.0 |
| ‘Packham’s Triumph’ (IRP 30-1)/97 |
50 |
1.5 |
| ‘Red Bartlett’/333 |
50 |
1.5 |
| ‘Comice’/‘BA29C’ |
50 |
2.0 |
| ‘Gorham’/333 |
50 |
2.0 |
| ‘Harrow Delight’/333 |
50 |
2.0 |
| ‘Harvest Queen’/333 |
50 |
2.0 |
| ‘Conference’/333 |
50 |
2.5 |
| ‘Pound’/333 |
50 |
2.5 |
| ‘Twentieth Century’/333 |
50 |
2.5 |
| ‘Columbia Red d’Anjou’/333 |
50 |
3.0 |
| ‘Bartlett’ (IRP 20-1)/Pyrus betulaefolia |
50 |
3.5 |
| ‘Red Bartlett’ (Stark’s)/333 |
50 |
4.0 |
| ‘Duchesse de Brissac’/333 |
50 |
4.5 |
| ‘Flemish Beauty’ (IRP 164-1)/97 |
50 |
4.5 |
| ‘Packham’s Triumph’ (IRP 142-1)/97 |
50 |
4.5 |
| ‘Swiss Bartlett’ (IRP 21-1)/ Pyrus betulaefolia |
50 |
4.5 |
| ‘Butirra Precoce Morettini’/333 |
50 |
5.5 |
| ‘Max Red Bartlett’/333 |
50 |
6.0 |
| ‘Scarlett Red Comice’/ Pyrus betulaefolia |
50 |
7.5 |
| ‘Vermont Beauty’/333 |
50 |
10.5 |
| ‘Concorde’/97 |
50 |
11.0 |
| ‘Concorde’/333 |
50 |
12.0 |
| ‘Placer’/333 |
50 |
13.0 |
| ‘Sensation Red Bartlett’/333 |
50 |
18.0 |
| ‘Glou-Morceau’/333 |
50 |
21.0 |
| ‘California’/333 |
50 |
30.5 |
| ‘Olympic’/333 |
75 |
1.0 |
| ‘New Century’/333 |
75 |
2.0 |
| ‘Collins d’Anjou’/333 |
75 |
3.3 |
| ‘Red Angelo’/333 |
75 |
3.3 |
| ‘Rosired Bartlett’/333 |
75 |
3.3 |
| ‘Rubjyat’/333 |
75 |
3.3 |
| ‘Butirra Rosata Morettini’/333 |
75 |
3.7 |
| ‘Stark Super Red’/97 |
75 |
3.7 |
| ‘Autumn Red’/333 |
75 |
5.0 |
| ‘Eldorado’/333 |
75 |
8.0 |
| ‘Canal Red’/333 |
75 |
11.0 |
| ‘Red Spot’/333 |
75 |
15.3 |
| ‘Dr. Jules Guyot’/333 |
75 |
15.7 |
| ‘Best Ever’/97 |
75 |
16.7 |
| ‘Worden Seckel’/333 |
100 |
5.0 |
| ‘Jules d’Airolles’/333 |
100 |
6.7 |
Since the data are from a natural infection assessment, rather than an inoculation
study, there may have been escapes. So if a cultivars is listed as susceptible, that is a
sure thing, but if it has little or no infection, it may be resistant, or it may not be.
Reference: R.A. Spotts (Oregon State University, MidColumbia Agricultural Research and
Extension Center, 3005 Experiment Station Dr., Hood River, OR 97031) and E.A. Mielke,
"Resistance of Pear Cultivars in Oregon to Natural Fire Blight Infection," Fruit
Varieties Journal 53(2), April 1999, 110-115. (American Pomological Society, 103 Tyson
Bldg., University Park, PA 16802.) |
