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© 2009 Plant Management Network.
Accepted for publication 16 August 2009. Published 14 October 2009.


Relative Susceptibility of Selected Apple Cultivars to Cedar Apple Rust and Quince Rust


Alan R. Biggs, Kearneysville Tree Fruit Research and Education Center, West Virginia University, Kearneysville, WV 25443; David A. Rosenberger, Hudson Valley Laboratory, Cornell University, Highland, NY 12528; Keith S. Yoder, Agricultural Research and Extension Center, Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Winchester, VA 22602; Richard K. Kiyomoto, Department of Forestry and Horticulture, Connecticut Agricultural Experiment Station, New Haven, CT 06504; Daniel R. Cooley, Department of Plant, Soil, and Insect Science, University of Massachusetts, Amherst, MA 01003; and Turner B. Sutton, Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695


Corresponding author: Alan R. Biggs. abiggs2@wvu.edu


Biggs, A. R., Rosenberger, D. A., Yoder, K. S., Kiyomoto, R. K., Cooley, D. R., and Sutton, T. B. 2009. Relative susceptibility of selected apple cultivars to cedar apple rust and quince rust. Online. Plant Health Progress doi:10.1094/PHP-2009-1014-01-RS.


Abstract

Incidences of cedar apple rust and quince rust, caused by Gymnosporangium juniperi-virginianae and G. clavipes, were collected over several years from 1995 (23 entries) and 1999 (22 entries) planting groups of new apple cultivars and selections established at multiple locations. Cultivar Golden Delicious was the standard. Incidence of cedar apple rust on leaves and fruit and quince rust on fruit were analyzed. Only two analyses had significant cultivar × location interactions, suggesting differences within the cedar apple rust fungus. Cedar apple rust on fruit did not vary by location. Incidence of quince rust on fruit varied among cultivars by location. Incidences of cedar apple rust and quince rust on fruit were not related.


Introduction

Several rust pathogens cause important diseases of apples (Malus domestica) in the eastern United States and southern Canada. Cedar apple rust, quince rust, and hawthorn rust, caused by Gymnosporangium juniperi-virginianae, G. clavipes, and G. globosum, respectively, are the most important rust pathogens in this region (14). Disease outbreaks can occur under favorable conditions from early bloom through late spring (5). Losses can be severe, especially under periods of prolonged wet weather in areas with high populations of the main alternate host, eastern red cedar (Juniperis virginianae) (Fig. 1).


 

Fig. 1. Cedar apple rust gall with telial horns on eastern red cedar.

 

Susceptibility ranking of various apple cultivars to diseases often depends on observations at single locations made by plant pathologists, plant breeders, growers, and nursery personnel in the field. Several researchers have observed differences among apple cultivars in susceptibility to rust diseases, although there have been no new reports during the past 15 years (1,18,23,24). In 1994, a regional project was initiated to examine the performance of new apple cultivars in replicated trials under a wide range of climatic and edaphic conditions. The project (NE-183), entitled "Multidisciplinary Evaluation of New Apple Cultivars" (currently NECC-1009 "Multidisciplinary Evaluation of New Tree Fruit Cultivars"), began with 26 cooperators in 18 states and two Canadian provinces. A primary objective of the NE-183 project was to evaluate horticultural qualities and pest and pathogen susceptibility of new apple cultivars, strains, and advanced selections with commercial potential and to determine the limitations and positive attributes of these cultivars (6,7,8,10,11,12,13,15,22,25). This study reports relative susceptibility of new apple cultivars and selections to G. juniperi-virginianae and G. clavipes. Images of symptoms of these diseases are presented in Figs. 2 through 8.


 

Fig. 2. Typical lesions of cedar apple rust on leaves of Chinook apple.

 

Fig. 3. Cedar apple rust lesion in late summer on York apple.


 

Fig. 4. Quince rust gall on eastern red cedar.

 


A
 
B

Fig. 5. Severe quince rust infections on fruitlets and fruit pedicels of Delblush (A) and Chinook (B) apple as seen in New York in 2005.


 

Fig. 6. Quince rust lesion at the calyx end of Red Delicious apple.

 

Fig. 7. Sporulating quince rust lesion on Stayman apple in mid-June.



A
 
B

Fig. 8. Multiple quince rust infections on Zestar! apple in mid-June (A) and at harvest (B).


Establishing Plots

Two groups of cultivars and selections (hereafter referred to as cultivars) were established at multiple locations in 1995 (23 entries) and 1999 (22 entries). Golden Delicious was the standard in both groups since it performs well across a wide variety of climates. Single-tree plots were replicated five times in a randomized complete block design. Planting groups from which rust data were collected were located near Asheville, NC (1999), Winchester, VA (1995 and 1999), Kearneysville, WV (1995), Highland, NY (1995 and 1999), Amherst, MA (1999), and New Haven, CT (1995). Data from Massachusetts are not reported herein because of low disease incidence (cedar apple rust Golden Delicious was 0.6% and 0.5% in 2002 and 2004).

1995 group. All 23 cultivars (Table 1) were propagated by Adams County Nursery, Aspers, PA, on M.9 NAKB 337 rootstock in 1993. Pioneer McIntosh served as an additional standard cultivar with known susceptibility to apple scab. Trees were planted in 1995 at 2-m in-row spacing with spacing between rows varying by location. Drive middles were planted with Kentucky-31 fescue (Festuca arundinacea), and a weed-free strip (1 m in 1995; 2 m in the remaining years) was maintained in the tree row with herbicides applied at recommended rates. Trees were headed at planting time and individually staked. Minimal pruning and training was done to allow assessment of natural tree structure, and to allow expression of natural flowering and fruit set tendencies. All flowers or young fruit were removed the first year by hand or by chemical means followed by hand thinning. Fertilizer application, pest management, and orchard floor management were subsequently done according to recommended local standards and based on leaf analyses. Recorded weather data included daily maximum and minimum temperatures, wetting periods, and precipitation during the growing season. Trees were allowed to fruit in their third leaf, 1997, and in subsequent years. Insecticides were applied from 1996 through 2000, as were fixed copper and/or streptomycin to manage fire blight.


Table 1. Cedar apple rust leaf and fruit infection of 23 apple cultivars planted in 1995 at five locations.

Cultivarx Percent leavesv Percent
fruit
w
NC VA WV NY CT VA NY
Creston   33 abz 27 a     32 a    23 b    45 a    0 1
GoldRushy 35 a    23 abc   26 abc 22 b    44 ab   0 5
Shizuka   29 abc 25 ab  28 ab 26 a    36 abc 0 1
Cameo   19 d-g 21 cd    22 bcd  16 cd   35 bc   2 1
Golden Delicious  22 c-f  22 bcd  17 def 18 c    33 cd   1 0
Braeburn   27 bcd  23 abc 21 cd  14 def 33 cd   1 1
Ginger Gold   19 d-g  23 a-d 19 de 15 c-f  31 cde 1 1
Arlet   24 cde 16 e    19 de   15 cde 29 c-f 1 0
Pristiney   18 d-g 17 e    16 def  12 d-g  25 d-h 0 0
Senshu  14 ghi 19 de  8 gh  12 efg 23 e-i 1 1
Fuji Red Sport #2   8 hij 11 f    13 efg 10 gh 26 c-g 2 0
Yataka  17 efg 7 g 11 fg  9 gh 27 c-g 6 0
Honeycrisp  30 abc 10 fg 11 fg 7 h 21 f-j   0 0
Orin  20 d-g 7 g 11 fg 11 fg 20 f-j   0 0
Sunrise  27 a-d 0 h    7 ghi 0 i 15 i-m 0 0
Suncrisp   7 hij 0 h  2 hi 2 i 18 g-k 1 0
Golden Supreme 0 j 0 h  1 hi 0 i 16 h-l 0 0
Pioneer Mac 5 j 0 h  3 hi 0 i  11 j-m 0 0
Fortune  15 fgh 0 h  3 hi 1 i  7 lm 1 0
Sansa 6 ij 0 h 1 i 3 i  8 lm 1 0
Enterprisey 0 j 0 h 1 i 1 i  10 klm 0 0
NY 75414-1y 1 j 0 h   1 hi 0 i   9 klm 0 0
Gala Supreme 0 j 0 h   3 hi 0 i  6 m   0 0

 v Means from 1998 (NC); 1997 and 1998 (VA); 1995, 1996, and 1997 (WV); 1995, 1996, 1997, and 2004 (NY); and 1996, 1997, and 1998 (CT).

 w Means from 2001 (VA); and 1997, 1998, 1999, 2003, and 2004 (NY).

 x Order of apple cultivars (most susceptible to least susceptible) based on the mean ranks for percent leaves across all locations.

 y Cultivars with genetic resistance to the apple scab pathogen, Venturia inaequalis.

 z Letters denote the differences among means according to the Waller Duncan k-ratio t test (P = 0.05).


1999 group. All 22 cultivars (Table 1) were budded in 1997 at Wafler Nursery in Walcott, NY, on M.9 NAKB 337 rootstock. Subsequent orchard establishment, horticultural management, experimental design, and weather monitoring were as described above.

Moderate to high pathogen inoculum levels were encouraged and minimal spray schedules were applied to maintain tree growth and prevent severe defoliation. In New York and Virginia, a protectant fungicide (primarily captan 50W, 1 lb/100 gal dilute) was applied at a reduced rate three times in May or early June to suppress scab. No fungicide was applied in West Virginia or Connecticut. Cedar apple rust inoculum was naturally abundant in Connecticut, New York, and West Virginia and was introduced on cedar galls in Virginia (2).


Diseases Ratings

Field evaluations for the incidence of rust diseases on apple can be difficult because of the similarity of symptoms caused by the various pathogens, although some distinctions can be made based on pathogen signs on particular plant organs and lesion size on various host cultivars. Evaluations only addressed susceptible lesion types and very small putative resistant reactions were not included in disease assessments presented herein because of the potential for confusion with other causal agents (captan injury, frog eye leaf spot, and others) (21). All leaves were rated on 5 to 10 terminal shoots in early to mid-summer after it appeared that all cedar rust lesions had developed. Evaluation dates usually were on or near 7 August in Connecticut, 24-25 June in West Virginia, 25 June to 9 July in Virginia; 2 August in New York, and 15 June in North Carolina. Dependent variables were percent of leaves with pycnial lesions and percent fruit with cedar apple rust, and percent fruit with quince rust. Hawthorn rust on leaves could not be separated from cedar apple rust reliably based on visible signs and symptoms; however, based on assessments of gall incidence on the alternate host, it was determined that the incidence of hawthorn rust was generally low, except for the 1999 planting in New York where hawthorn rust was relatively common on leaves (20).

Rust incidence data were collected at all locations in all years, but for the purposes of determining relative cultivar susceptibility, only data sets that showed a minimum of 10% cedar apple rust leaf infection incidence on the cultivar Golden Delicious were included in the analysis. For the 1995 planting, those data sets included North Carolina (1998); Virginia (1997 and 1998); West Virginia (1995, 1996, and 1997); New York (1995, 1996, 1997, and 2004); and Connecticut (1996, 1997, and 1998). For the 1999 group, those data sets included Virginia (2000-2004, inclusive); and New York (2000, 2001, 2002, 2004). Each variable was analyzed in a mixed model analysis of variance (PROC MIXED, SAS Institute Inc., Cary, NC) in which sources of error were the fixed effects (cultivar and location) and random effects of replicate, year, interaction of replicate and year, and interaction of cultivar and year, where each of these was nested within location. The Waller Duncan k-ratio t-test method was used for mean comparisons. Linear regression was used to examine the relationship between incidences of cedar apple rust and quince rust on fruit (PROC REG, SAS).


Cedar Apple Rust

1995 group - leaves. Across all cultivars and locations, mean disease incidence ranged from 0% (Golden Supreme, Gala Supreme, and Enterprise) in North Carolina to 45.2% for Creston in Connecticut (Table 1). Mean disease incidence of the standard Golden Delicious ranged from 17.1% in West Virginia to 33.2% in Connecticut. Incidence of cedar apple rust on leaves varied significantly among cultivars (P = 0.0001), but did not vary by location (P = 0.63). The cultivar × location interaction was not significant (P = 0.97). Creston, Shizuka, GoldRush, Braeburn, and Cameo were generally the most susceptible, whereas Golden Supreme, Gala Supreme, NY 75414-1, and Enterprise generally exhibited the lowest incidences of leaf rust (Table 1).

1995 group - fruit. Across all cultivars and locations, mean disease incidence ranged from 0% for many cultivars in both Virginia and New York to 6.4% for Yataka in Virginia and 5.3% for GoldRush in New York (Table 1). For the standard Golden Delicious, mean disease incidence ranged from 0.8% in Virginia to 0.2% in New York. Incidence of cedar apple rust on fruit did not vary among cultivars (P = 0.95) or locations (P = 0.82), and the cultivar × location interaction was not significant (P = 0.84). Incidence of cedar apple rust on leaves was not correlated with incidence on fruit (P = 0.42).

1999 group - leaves. Across all cultivars and locations, mean disease incidence ranged from 0% for Sundance, Runkel, NY 79507-19, and NY 79507-49 in Virginia to 44.7% for Pinova in New York (Table 2). For the standard Golden Delicious, mean disease incidence ranged from 15.6% in Virginia to 39.2% in New York. Incidence of cedar apple rust on leaves varied among cultivars (P = 0.0001), locations (P = 0.0089), and for cultivar × location (P = 0.0001). CQR10T17, Scarlet O’Hara, Crimson Crisp, Chinook (Fig. 2), and Princess were very susceptible at both sites, whereas Zestar, Sundance, NY 65707-19, NY 79507-72, and NY 79507-49 generally exhibited the lowest incidences of leaf rust (the latter four are also scab resistant) (Table 2). The incidence of leaf rust on Pinova (44.7%) and NJ 109 (36.3%) was higher relative to other cultivars in New York when compared with Virginia (8.3 and 6.2%, respectively).


Table 2. Cedar apple rust leaf and fruit infection of 22 apple cultivars planted in 1999 at two locations.

Cultivar
or selection
w
Percent leavesu Percent fruitv
VA NY VA NY
CQR10T17x       26 ay      38 b      6 a    26 a
Scarlet O'Hara (Co-op 25)x       20 b      43 a      4 abc    21 b
Chinook (BC 8S-27-51)       16 c      43 a      0 d    11 ef
Princess (CQR12T50)x       15 c      44 a      5 abc    19 bcd
Pinova        8 d      45 a      0 d    10 ef
Crimson Crisp (Co-op 39)x       20 b      36 bc      2 bcd    19 bcd
Golden Delicious       16 c      39 b      5 ab    10 f
Ambrosia       15 c      39 b      2 bcd    15 de
Cripps Pink       14 c       NAz       NA      NA
NJ 109        6 de      36 bc      0 d    16 cd
BC 8S-26-50        5 e      36 bc      2 cd    19 bcd
September Wonder
(Jubilee Fuji)
       1 f      33 c      0d      8 fg
Rogers McIntosh        0 f      15 de      0 d      0 h
Hampshire        0 f      16 de      0 d      2 h
Delblush        NA      13 ef       NA      4 gh
Runkel Hampshire        0 f      17 d      0 d      3 h
NJ 90        0 f      10 f      0 d      3 h
Zestar! (Minnewashta)        0 f        3 h      1 d      1 h
Sundance (Co-op 29)x        0 f        4 gh      0 d      0 h
NY 65707-19x        0 f        7 g      0 d      1 h
NY 79507-72x        0 f        4 gh      0 d      0 h
NY 79507-49x        0 f        2 h      0 d      0 h

 u Means from 2000 to 2004 (VA); and 2000, 2001, 2002, and 2004 (NY).

 v Means from 2002 and 2004 (VA); and 2001, 2002, and 2004 (NY).

 w Order of apple cultivars (most susceptible to least susceptible) based on the mean ranks for percent leaves across all locations.

 x Cultivars with genetic resistance to the apple scab pathogen, Venturia inaequalis.

 y Letters denote the differences among means according to the Waller Duncan k-ratio t test (P = 0.05).

 z NA = cultivar not available.


1999 group - fruit. Across all cultivars and locations, mean disease incidence on fruit ranged from 0% for many cultivars in both Virginia and New York to 25.9% for CQR10T17 in New York (Table 2). Disease incidence was generally low in Virginia; with the highest incidence also observed on CQR10T17 (5.5%). Disease incidence was 0% at both locations for Rogers McIntosh, Sundance, NY 79507-49, and NY 79507-72 (the latter three are scab resistant). For the standard Golden Delicious, mean disease incidence ranged from 5.0% in Virginia to 9.6% in New York. Incidence of cedar apple rust on fruit varied among cultivars (P = 0.01) but not among locations (P = 0.19); the cultivar × location interaction was not significant (P = 0.25). Incidence of cedar apple rust on leaves was not correlated with incidence of cedar apple rust on fruit.


Quince Rust

1995 group. Across all cultivars and locations, mean disease incidence on fruit ranged from 0% for Pioneer Mac in New York to 56.0% for Fortune in Virginia (Table 3). Quince rust incidence was much lower in New York than Virginia. For the standard Golden Delicious, mean disease incidence ranged from 24.0% in Virginia to 3.6% in New York. Incidence of quince rust on fruit varied among cultivars (P = 0.0001) and locations (P = 0.0001), and the cultivar × location interaction was significant (P = 0.0001). Fortune and Cameo were generally the most susceptible in Virginia, whereas Suncrisp, Shizuka, and Golden Supreme were the most susceptible in New York.


Table 3. Quince rust fruit infection (percent fruitv) of 23 and 22 apple cultivars planted in 1995 and 1999 at two locations.

1995 group 1999 group
Cultivarw VA NY Cultivar VA NY
Shizuka    30 bcdy   4 ab Crimson Crisp (Co-op 39)x 19   41
Cameo    40 ab   3 a-g Princess (CQR12T50)y 6 39
Golden Supreme    26 b-f   4 abc NJ 109 5 47
Senshu    28 b-e   3 a-f September Wonder
(Jubilee Fuji)
NAz 35
Fuji Red Sport #2    34 bc   2 b-h Zestar! (Minnewashta) 1 46
Golden Delicious    24 b-g   4 a-d CQR10T17x 18   27
Braeburn    25 b-f   3 a-e Ambrosia 11   28
Sansa    27 b-f   3 a-g BC 8S-26-50 4 36
Creston    36 bc   2 b-h Delblush NA 33
Fortune    56 a   1 d-h NJ 90 3 34
GoldRushx    23 b-g   4 a-d Pinova 13   22
Suncrisp    11 e-h   5 a Golden Delicious 6 28
Yataka    20 c-g   3 a-f NY 79507-72x 0 38
Gala Supreme    28 b-e   1 e-h Scarlet O'Hara (Co-op 25)x 6 25
Arlet    20 c-g   2 c-h NY 79507-49x 6 27
Enterprisex    24 b-g   0 gh NY 65707-19x 7 21
Sunrise    14 d-h   2 b-h Cripps Pink 2 NA
Orin      7 gh   2 b-h Rogers McIntosh 0 31
Honeycrisp    15 d-h   1 e-h Chinook (BC 8S-27-51) 0 28
Pristinex      1 h   2 a-h Runkel 0 16
Pioneer Mac    14 d-h   0 h Sundance (Co-op 29)x 0 7
NY 75414-1x    13 d-h   0 e-h Hampshire NA 18
Ginger Gold    10 fgh   1 fgh                

 v Means from 2000 (VA) and 1999 (NY) for the 1995 group. Means from 2002, 2003, and 2004 (VA) and 2001, 2002, and 2003 (NY) for the 1999 group.

 w The order of apple cultivars is from most susceptible to least susceptible, based on the mean ranks across all locations.

 x Cultivars with genetic resistance to the apple scab pathogen, Venturia inaequalis.

 y Letters denote the differences among means according to the Waller Duncan k-ratio t test (P = 0.05).

 z NA = cultivar not available.


1999 group. Across all cultivars and locations, mean disease incidence on fruit ranged from 0% for several cultivars in Virginia to 46.0 and 46.5% for Zestar and NJ 109, respectively, in New York (Table 3). Quince rust incidence was numerically lower in Virginia than New York – the opposite of the 1995 group. For the standard Golden Delicious, mean disease incidence ranged from 6.0% in Virginia to 28.2% in New York. The cultivar × location interaction term was not significant in this analysis (P = 0.44), nor were the cultivar (P = 0.49) and location (P = 0.17) main effects. The cultivars Crimson Crisp, Princess, and NJ 109 were ranked highest for disease at both locations, whereas the cultivars Runkel and Sundance were ranked lowest.


Resistance to Cedar Apple Rust and Quince Rust Not Related

In the 1995 group, no significant relationships were observed for the incidences of these two diseases from data sets from Virginia (2001) and New York (1998, 1999, and 2003). Likewise, in the 1999 group, no significant relationships were observed for the incidences of these two diseases from data sets from Virginia (2002 and 2004) and New York (2001 and 2002).


Discussion and Recommendations

Cultivars had similar cedar apple rust leaf incidence across locations in the 1999 group, but dissimilar incidence in the 1995 group. Cultivar fruit reactions were similar among locations for both groups. Differential reactions among apple cultivars at different locations were first observed by Bliss (9) and McNew (17) and the presence of distinct pathogenic populations of G. juniperi-virginianae was first demonstrated by Aldwinckle (3) then further elucidated by Korban et al. (16). The existence of physiological populations of G. juniperi-virginianae underscores the need for projects such as NE-183 in which new cultivars can be tested under a wide variety of conditions. The data in the present study suggest that cultivars in Virginia may be ordered differently from those in New York, suggesting the presence of distinct rust races at these locations.

There are no reports on the existence of physiological populations of G. clavipes. One explanation for differences among cultivar susceptibility ranks in New York and Virginia could be different pathogenic populations of G. clavipes in those locations, although the cultivar × location interaction was significant only with the 1995 group. Another explanation could be the coincidence of infection periods with tree phenology. The phenological window for quince rust infection is fairly narrow, with maximum susceptibility occurring between the pink bud and petal fall stages of bud development (14). Later-blooming cultivars may have escaped infections during rain events that occurred when the earliest cultivars were at pink, whereas late-blooming cultivars might have been at greater risk from infection periods that occurred when the early cultivars were at petal fall.

With rust populations exhibiting significant geographic variation in virulence on apple cultivars, it may be tempting to plant cultivars in a particular region that show favorable differential resistance. The work of Korban et al. (16) would caution against this, however, as their study demonstrated a shift in virulence of G. juniperi-virginianae compared to that presented 10 years earlier by Aldwinckle (4). The most reliable cultivars would be those that consistently express resistance at all geographic locations.

The characterization of resistance to G. juniperi-virginianae in apple leaves has been expressed variably by different researchers. Bliss (9) and Niederhouser and Whetzel (19) used five groups: immune (no symptoms); very resistant (flecks only); resistant (pycnial, but no aecia); susceptible (few aecia); and very susceptible (many aecia). Our study would not have separated among the latter three levels of resistance.

Previously, Aldwinckle (2) demonstrated that lower inoculum concentrations could result in qualitative differences in lesions, with lower inoculum concentrations more likely to lead to a resistance response in the host. Although rust data were collected at all locations in all years, for the purposes of determining relative susceptibility, only data sets that showed a minimum of 10% cedar apple rust leaf infection incidence on the cultivar Golden Delicious were included in the analyses in an attempt to avoid mischaracterization of relative susceptibility related to low inoculum levels.

Although there was no relationship between relative susceptibility to either rust pathogen and genetic resistance to the apple scab pathogen, Venturia inaequalis, scab-resistant Sundance, Enterprise, NY 65707-19, NY 75414-1, NY 79507-72, and NY 79507-49 were among the most resistant to cedar apple rust in these plantings. This is an important attribute for early season disease management in areas where cedar apple rust is a problem, and particularly so if one is attempting to grow fruit as certified organic where effective controls are lacking. Sundance was also the least susceptible to quince rust. By contrast, scab-resistant GoldRush, Pristine, Scarlet O’Hara, Princess, Crimson Crisp and CQR10T17 were highly susceptible to cedar apple rust and would require early season fungicide applications for rust management in high inoculum areas in spite of their resistance to scab.

It is doubtful if multiple location evaluations will take place in the future on the scale described herein. The trend in the apple industry is toward "club varieties" where only certain producers are permitted to grow a certain cultivar, in order to have more stability in the market and to control price volatility related to abundant supply. Under this approach to cultivar development and release, there could be large acreages established with significant financial investment prior to our gaining a thorough knowledge of a cultivar’s relative susceptibility to particular diseases and geographic variation related to disease expression.


Acknowledgments

We appreciate the technical support of Catherine Ahlers, Richard Christiana, A. E. Cochran II, Larry Crim, S. W. Kilmer, Frederick Meyer, W. S. Royston, Jr., Keri VanCamp, Isabelle Winfield, and Robert Young. We acknowledge the research support of the USDA-ARS Appalachian Fruit Research Station and the financial support of Virginia Agricultural Council, Virginia Apple Research Program, and USDA-CSREES via Hatch Act funding for Multi-State Research Project NE-183.


Literature Cited

1. Aldwinckle, H. S. 1974. Field susceptibility of 41 cultivars to cedar apple rust and quince rust. Plant Dis. Rep. 58:696-699.

2. Aldwinckle, H. S. 1975. Effect of leaf age and inoculum concentration on the symptoms produced by Gymnosporangium juniperi-virginianae on apple. Ann. Appl. Biol. 80:147-153.

3. Aldwinckle, H. S. 1975. Pathogenic races of Gymnosporangium juniperi-virginianae on apple. Phytopathology 65:958-961.

4. Aldwinckle, H. S., Lamb, R. C., and Gustafson, H. L. 1977. Nature and inheritance of resistance to Gymnosporangium juniperi-virginianae in apple cultivars. Phytopathology 67:259-266.

5. Aldwinckle, H. S., Pearson, R. C., and Seem, R. C. 1980. Infection periods of Gymnosporangium juniperi-virginianae on apple. Phytopathology 70:1070-1073.

6. Biggs, A. R., and Miller, S. S. 2001. Relative susceptibility of selected apple cultivars to Colletotrichum acutatum. Plant Dis. 85:657-660.

7. Biggs, A. R., and Miller, S. S. 2003. Relative susceptibility of selected apple cultivars to Botryosphaeria dothidea. HortScience 38:400-403.

8. Biggs, A. R., and Miller, S. S. 2004. Relative susceptibility of selected apple cultivars to Botryosphaeria obtusa. HortScience 39:303-306.

9. Bliss, D. E. 1933. The pathogenicity and seasonal development of Gymnosporangium in Iowa. Iowa Agric. Exp. Stn. Res. Bull. 166:338-392.

10. Greene, D., Azarenko, A., Barritt, B., Belding, B., Berkett, L., Cline, J., Cowgill, W., Ferree, D., Garcia, E., Greene, G., Hampson, C., McNew, R., Merwin, I., Miller, D., Miller, S., Moran, R., Parker, M., Rosenberger, D., Rom, C., Roper, T., Schupp, J., and Stover, E. 2004. Multidisciplinary evaluation of new apple cultivars: The NE-183 regional project. J. Amer. Pomol. Soc. 58:61-64.

11. Greene, D., Crassweller, R., Hampson, C., NcNew R., Miller, S., Azarenko, A., Barritt, B., Berkett, L., Brown, S., Clements, J., Cowgill, W., Cline, J., Embree, C., Fallahi, E., Fallahi, B., Garcia, E., Greene, G., Lindstrom, T., Merwin, I., Obermiller, J.D., Rosenberger, D., and Stasiak, M. 2007. Multidisciplinary evaluation of new apple cultivars: The NE-183 regional project 1999 planting. J. Amer. Pomol. Soc. 61:78-83.

12. Hogmire, H. W., and Miller, S. S. 2005. Relative susceptibility of new apple cultivars to arthropod pests. HortScience 40:2071-2075.

13. Jones, A. L., Biggs, A. R., Kiyomoto, R. K., McNew, R., Rosenberger, D. A., and Yoder, K. S. 1998. Susceptibility of apple cultivars in the NE-183 project trial to apple scab, 1997. Biol. Cult. Tests Control Plant Dis. 13:35.

14. Jones, A. L., and Aldwinckle, H. S. 1990. Compendium of Apple and Pear Diseases. American Phytopathological Society, St. Paul, MN.

15. Kiyomoto, R. K., Biggs, A. R., McNew, R., Rosenberger, D. A., and Yoder, K. S. 1998. Foliage susceptibility of 23 apple cultivars in the NE-183 project trial to cedar-apple rust, powdery mildew, and leaf spots, 1997. Biol. Cult. Tests Control Plant Dis. 13:36.

16. Korban, S. S., Chen, H., and Ries, S. M. 1987. Interactions of apple cultivars with populations of cedar-apple rust. J. Phytopathol. 119:272-278.

17. McNew, G. L. 1938. Differential reaction of apple varieties to Gymnosporangium juniperi-virginianae. Iowa Agric. Exp. Stn. Res. Bull. 245:113-141.

18. McVay, J. R., Walgenbach, J. F., Sikora, E. J., and Sutton, T. B. 1993. A Grower's Guide to Apple Insects and Diseases in the Southeast. Alabama Cooperative Extension Service, Auburn University, Circular ANR-838.

19. Niederhauser, J. S., and Whetzel, H. H. 1940. Observations on the varietal susceptibility to Gymnosporangium juniperi-virginianae. Phytopathology 30:691-693.

20. Rosenberger, D. A., and Meyer, F. W. 2006. Susceptibility of new apple cultivars to rust diseases in southeastern New York. Phytopathology 96:S100 (Abstr.)

21. Rosenberger, D. A., Engle, C. A., and Meyer, F. W. 1994. Early-season diseases occurring on scab-resistant apple cultivars and advanced selections grown in southeastern New York State. Fruit Var. J. 48:52-53.

22. Rosenberger, D. A., Yoder, K. S., Biggs, A. R., Kiyomoto, R. K., and McNew, R. 1996. Comparative susceptibility of 23 apple cultivars in the NE-183 trial to powdery mildew and cedar apple rust, 1995. Biol. Cult. Tests Control Plant Dis. 11:36.

23. Warner, J. 1990. Field susceptibility of scab-resistant apple cultivars and selections to cedar apple rust, quince rust and hawthorn rust. Fruit Var. J. 44:216-224.

24. Warner, J. 1992. Field susceptibility of 68 apple cultivars to cedar apple rust, quince rust and hawthorn rust. Fruit Var. J. 46:6-10.

25. Yoder, K. S., Biggs, A. R., Kiyomoto, R. K., McNew, R., and Rosenberger, D. A. 1997. Foliage susceptibility of 23 apple cultivars in the NE-183 trial to scab, powdery mildew, cedar apple rust, and leaf spot, 1996. Biol. Cult. Tests Control Plant Dis. 12:42-43.