A planting of 59 selections of crabapples was rated for apple-and-thorn skeletonizer (ATS) damage and Japanese beetle (JB) adult feeding on August 9, 1996, at the Secrest Arboretum, Wooster, Ohio. Significant differences in crabapples with ATS damage were observed. Seven cultivars had 10% skeletonization or less while 21 cultivars had 50% leaf skeletonization, which was deemed unacceptable. JB adult feeding was less severe than ATS in 1996. Thirteen cultivars sustained very little skeletonization, while 12 cultivars had more than 50% of the leaves skeletonized.
In 1984, 45 cultivars of crabapple were established with three replicates in a completely randomized plot at the Secrest Arboretum, Wooster, Ohio. In 1991, an additional 14 cultivars were added to the plot, with 'Golden Raindrops' losing one replicate. By 1996, one replicate each of 'Red Jewel' and M. zumi 'Calocarpa' was lost. The trees in this plot were evaluated in 1994 and 1995 for growth habits and disease incidence (Chatfield et al., 1996; Draper et al.,1996). In 1996, the disease ratings were again taken, and severe skeletonizing damage was noted. This damage was caused by a caterpillar, the apple-and-thorn skeletonizer (ATS), Choreutis pariana (Clerck) [Lepidoptera: Choreutidae], and Japanese beetles (JB), Popillia japonica Newman [Coleoptera: Scarabaeidae]. Some cultivars appeared to be attacked preferentially, so an evaluation of the skeletonizing damage by ATS and JB was performed and is herein presented.
The 59 cultivars of crabapples were evaluated for leaf skeletonization damage on August 9, 1996, by a single evaluator (DJS). ATS larvae fold individual leaves together with silk webbing. Within this webbing and leaf protection, the ATS larvae skeletonize the leaves by feeding only on the upper leaf surface. Japanese beetle adults generally land on upper leaves of trees and skeletonize the leaves by eating upper, middle, and lower tissues between larger veins.
Because of the types of feeding and difficulty in reaching upper parts of the trees, two rating systems of skeletonizing were used. For ATS, a branch on the southwestern portion of the tree was selected, and the first 10 leaves were rated. A rating of 0 to 10 was recorded where 0 = no webbing or skeletonized leaves observed and 10 = all 10 leaves webbed or skeletonized.
For JB, a visual rating of JB skeletonizing was given after walking around each tree, observing damage. A rating of 0 to 5 was recorded where 0 = no JB skeletonizing noted and 5 = almost every leaf skeletonized by JB. Rating data were analyzed using ANOVA followed with LSD mean separation at p = 0.01 (MSTAT, Michigan State University).
Significant differences between crabapple selections were detected for ATS damage (df = 58, F = 5.82, p < 0.001) and for jb skeletonizing (df = 58, f = 4.54, p < 0.001). for ats damage, 'bob white,' 'david,' 'indian summer,' 'red jewel,' 'snowdrift,' 'white cascade,' and 'golden raindrops' had the least damage (10% or fewer leaves skeletonized). 'candied apple,' 'centurion,' 'dolgo,' M. floribunda, 'Molten Lava,' 'Ormiston Roy,' 'Professor Sprenger,' 'Profusion,' 'Radiant,' 'Red Barron,' 'Red Jade,' 'Red Splendor,' 'Ruby Luster,' 'Selkirk,' 'Sentinel,' 'Silver Moon,' 'Sinai Fire,' 'Camelot,' 'Prairie Maid,' 'Louisa,' 'Narrangansett,' and 'Pink Satin' sustained 50% or more leaves attacked by ATS. This level of activity was deemed aesthetically unacceptable.
For JB damage, M. baccata 'Jackii,' 'Jewelberry,' 'Profusion,' 'Red Jade,' 'Red Jewel,' 'Silver Moon,' 'Sugar Tyme,' M. zumi 'Calocarpa,' 'Sinai Fire,' 'Glen Mills,' 'Louisa,' 'Canary,' and 'Gold-en Raindrops' had rating averages of 1.0 or less. Unacceptable damage was found on 'Liset,' 'Radiant,' 'Red Splendor,' 'Royalty,' M. sargentii, 'Velvet Pillar,' 'Camelot,' and 'Candymint' which had ratings of 3.0 or more. (See Table 1. for data.)
It should be noted that the severity of damage from apple-and-thorn skeletonizer at Secrest Aboretum appears to be unusual with respect to other sites. In addition, this data is for one year only. For these reasons, the significance of this pest as a major problem on crabapples in general is questionable.
Chatfield, J.A., E.A. Draper, K.C. Cochran, P.W. Bristol, and C.E. Tubesing. 1996. Aesthetic evaluation of crabapples at Secrest Arboretum in Wooster, Ohio: 19941995. The Ohio State University and Ohio Agricultural Research and Development Center, Special Circular 152. pp. 12-21.
Draper, E.A., J.A. Chatfield, K.C. Cochran, P.W. Bristol, and C.E. Tubesing. 1996. Evaluation of crabapples for apple scab at Secrest Arboretum in Wooster, Ohio: 1995. Ibid. 152. pp. 22-26.
| Table 1. Summaries of Apple-and-Thorn Skeletonizer (ATS) and Japanese Beetle (JB) Adult Damage to 59 Cultivars of Crabapples at Secrest Arboretum, Wooster, Ohio, August 9, 1996. | |||||
|---|---|---|---|---|---|
| Crabapple | # Replicates | Average ATS±SDa | (LSD separation) | Average JB±SDb | (LSD separation) |
| Adams | 3 | 1.67±1.15 | JKLM | 2.33±0.58 | CDE |
| M. baccata Jackii | 3 | 2.67±0.58 | GHIJKLM | 0.33±0.58 | F |
| Beverly | 3 | 3.33±1.15 | FGHIJKLM | 2.33±0.58 | CDE |
| Bob White | 3 | 0.67±0.58 | M | 2.33±0.58 | CDE |
| Candied Apple | 3 | 5.00±2.65 | DEFGHIJ | 2.00±0.00 | CDE |
| Centurian | 3 | 5.67±3.21 | CDEFGH | 2.33±1.15 | CDE |
| David | 3 | 1.00±0.00 | LM | 2.00±0.00 | CDE |
| Dolgo | 3 | 5.00±1.00 | DEFGHIJ | 2.00±0.00 | CDE |
| Donald Wyman | 3 | 4.67±2.31 | EFGHIJK | 2.67±0.58 | BCD |
| M. floribunda | 3 | 5.00±0.00 | DEFGHIJ | 1.67±0.58 | DE |
| M. halliana Parkmanii | 3 | 3.67±0.58 | FGHIJKLM | 2.00±0.00 | CDE |
| Harvest Gold | 3 | 2.33±0.58 | HIJKLM | 1.67±0.58 | DE |
| Henningi | 3 | 4.33±3.51 | EFGHIJKL | 2.00±0.00 | CDE |
| Hopa | 3 | 3.33±0.58 | FGHIJKLM | 2.00±1.00 | CDE |
| Indian Magic | 3 | 1.33±0.58 | KLM | 1.67±0.58 | DE |
| Indian Summer | 3 | 1.00±0.00 | LM | 2.00±0.00 | CDE |
| Jewelberry | 3 | 4.00±3.61 | FGHIJKLM | 1.00±0.00 | EF |
| Liset | 3 | 2.33±0.58 | HIJKLM | 4.00±0.00 | AB |
| Mary Potter | 3 | 2.00±0.00 | IJKLM | 2.00±1.00 | CDE |
| Molten Lava | 3 | 7.67±2.08 | ABCDE | 2.00±0.00 | CDE |
| Ormiston Roy | 3 | 5.00±2.65 | DEFGHIJ | 1.67±0.58 | DE |
| Prairifire | 3 | 3.33±1.53 | FGHIJKLM | 2.00±0.00 | CDE |
| Professor Sprenger | 3 | 5.33±3.06 | DEFGHI | 2.00±0.00 | CDE |
| Profusion | 3 | 5.67±2.08 | CDEFGH | 1.33±0.58 | EF |
| Radiant | 3 | 6.00±1.00 | CDEFG | 4.33±0.58 | A |
| Ralph Shay | 3 | 4.33±0.58 | EFGHIJKL | 2.33±0.58 | CDE |
| Red Barron | 3 | 5.00±2.65 | DEFGHIJ | 2.67±0.58 | BCD |
| Red Jade | 3 | 8.33±1.15 | ABCD | 1.00±0.00 | EF |
| Red Jewel | 2 | 1.00±0.00 | LM | 1.00±0.00 | EF |
| Red Splendor | 3 | 6.00±2.65 | CDEFG | 3.00±1.00 | ABCD |
| Robinson | 3 | 1.33±0.58 | KLM | 2.33±0.58 | CDE |
| Royalty | 3 | 2.00±1.73 | IJKLM | 3.33±0.58 | ABC |
| Ruby Luster | 3 | 5.33±0.58 | DEFGHI | 2.67±1.53 | BCD |
| M. sargentii | 3 | 1.67±0.58 | JKLM | 3.00±0.00 | ABCD |
| Selkirk | 3 | 6.33±1.53 | BCDEF | 2.33±0.58 | CDE |
| Sentinel | 3 | 5.67±2.52 | CDEFGH | 1.67±0.58 | DE |
| Silver Moon | 3 | 6.00±2.00 | CDEFG | 1.33±0.58 | EF |
| Snowdrift | 3 | 1.00±1.00 | LM | 1.67±0.58 | DE |
| Strawberry Parfait | 3 | 1.67±1.15 | JKLM | 1.67±0.58 | DE |
| Sugar Tyme | 3 | 3.00±1.00 | FGHIJKLM | 1.33±0.58 | EF |
| Velvet Pillar | 3 | 1.33±0.58 | KLM | 3.67±0.58 | AB |
| White Angel | 3 | 4.33±2.08 | EFGHIJKL | 2.00±0.00 | CDE |
| White Cascade | 3 | 1.00±0.00 | LM | 1.67±0.58 | DE |
| Winter Gold | 3 | 4.00±1.73 | FGHIJKLM | 1.67±0.58 | DE |
| M. zumi Calocarpa | 2 | 2.50±0.71 | GHIJKLM | 1.00±0.00 | EF |
| Sinai Firec | 3 | 9.67±0.58 | AB | 1.00±0.00 | EF |
| Lancelot | 3 | 1.33±0.58 | KLM | 1.67±0.58 | DE |
| Adirondack | 3 | 3.67±1.53 | FGHIJKLM | 1.67±1.15 | DE |
| Camelot | 3 | 6.00±2.65 | CDEFG | 3.00±1.00 | ABCD |
| Prairie Maid | 3 | 7.67±3.21 | ABCDE | 2.67±1.15 | BCD |
| Glen Mills | 3 | 4.33±3.06 | EFGHIJKL | 1.00±0.00 | EF |
| Louisa | 3 | 10.00±0.0 | A | 1.00±0.00 | EF |
| Candymint | 3 | 3.67±2.52 | FGHIJKLM | 3.00±1.00 | ABCD |
| Narrangansett | 3 | 9.00±1.00 | ABC | 1.67±0.58 | DE |
| Silver Drift | 3 | 4.00±1.00 | FGHIJKLM | 1.67±0.58 | DE |
| Purple Prince | 3 | 2.33±1.15 | HIJKLM | 2.67±1.15 | BCD |
| Pink Satin | 3 | 8.33±0.58 | ABCD | 1.67±0.58 | DE |
| Canary | 3 | 3.33±0.58 | FGHIJKLM | 1.33±0.58 | EF |
| Golden Raindrops | 2 | 0.50±0.71 | M | 1.00±0.00 | EF |
| LSD value (p=0.01)d | 3.65 | 1.34 | |||
| a Average based on number of leaves with ATS damage, out of 10. | |||||
| b Average based on visual rating of 0 to 5 where 0 = no JB skeletonizing and 5 = every leaf skeletonized. | |||||
| c Following 14 cultivars were established in 1991. | |||||
| d Means sharing the same LSD letters are not significantly different from each other. | |||||