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MANAGING POWDERY MILDEW IN PUMPKIN WITH RESISTANT VARIETIES

Margaret Tuttle McGrath and Jane F. Davey
Department of Plant Pathology, Cornell University
Long Island Horticultural Research and Extension Center
3059 Sound Avenue, Riverhead, NY 11901-1098. mtm3@cornell.edu
and
Bob Precheur, Mac Riedel, Andy Wyenandt, Jim Jasinski, and Celeste Welty
Dept. of Horticulture and Crop Science, Departments of Plant Pathology Southwest Extension IPM, and Entomology, Ohio State University, Columbus, OH 43210-1087
and
Timothy E. Elkner
Penn State Cooperative Extension
1383 Arcadia Rd., Rm. 1, Lancaster, PA 17601-3184
and
Walter R. Stevenson and R. Vaughan James
Plant Pathology Department, University of Wisconsin
1630 Linded Drive, Madison, WI 53706-1520
and
Mark Hutton and David Handley
University of Maine Cooperative Extension
P.O. Box 179, Highmoor Farm, Monmouth, Maine 04259

Powdery mildew is a common disease of pumpkin, as well as other cucurbit crops, which reduces yield when not adequately managed. The characteristic white, powdery fungal growth is readily recognizable on foliage. Infected leaves usually wither and die. Premature loss of leaves can result in reduced market quality because fruit ripening prematurely before achieving full color and handles may be shriveled or rotten. Size and/or number of fruit can be reduced when powdery mildew is severe. Severe disease can also lead to imperfections on fruit rind such as speckling and oedema. In addition, powdery mildew infection predisposes plants to other diseases, in particular, gummy stem blight/black rot.

Resistant varieties are becoming an increasingly important tool for managing powdery mildew in pumpkin as the number of resistant varieties available to growers increases and as fungicide resistance continues to challenge effective chemical control. The first powdery mildew resistant (PMR) pumpkins, Merlin and Magic Lantern, were commercialized in 1998 and the next, Mystic Plus, in 2000. Recently, several new PMR varieties of pumpkin, as well as winter squash, have been released each year. Effectively managing powdery mildew with fungicides necessitates products able to provide control on the underside of leaves through systemic, translaminar or volatile activity. Unfortunately, all such materials have been at risk for resistance development. Strains of the powdery mildew fungus resistant to QoI fungicides (FRAC Group 11; aka strobilurins; Amistar, Quadris, Cabrio, and Flint) are believed to now occur throughout the US. Resistance to MBC fungicides (aka benzimidazoles; Topsin M and Benlate) are likely still widespread in the US. They were common on Long Island in 2004. QoI and MBC resistances are qualitative, thus resistant strains are fully insensitive to these fungicides. Resistance to the DMI (demethylation inhibiting) fungicides (Bayleton, Nova, and Procure) is quantitative; pathogen strains exhibit a range in fungicide sensitivity depending on the number of genetic changes they possess that affect the fungicide’s ability to function. Moderately resistant strains likely are common in the US now. These are fully insensitive to Bayleton and have reduced sensitivity to low rates of Nova and Procure.

PMR pumpkin varieties vary in their susceptibility to powdery mildew depending on the number of genes for resistance they possess. The major gene for resistance in PMR varieties was obtained from a wild cucurbit at the Cornell Department of Plant Breeding. Varieties with this resistant gene from both parents (homozygous) usually develop less powdery mildew than those with resistance from one parent (heterozygous). In catalogues these are often, but not always, described as resistant and tolerant, respectively. The degree of powdery mildew suppression in PMR pumpkins and squashes usually is not as great as that in PMR melons and cucumbers. Some heterozygous PMR pumpkin varieties exhibit suppression of powdery mildew development for a few weeks, but become as severely affected as a variety without resistance by the end of the season. However, although leaves become severely affected by powdery mildew on these PMR varieties, they typically have less mildew on fruit handles than susceptible varieties. Also, initial disease suppression results in leaves dieing later and consequently more fruit with good color and solid handles at harvest. In addition to the major PMR gene, there are modifying genes with small affects that could account for the variation in susceptibility observed among PMR varieties. The resistance in PMR pumpkins and winter squash is not race-specific as it is in melons. However, the powdery mildew fungus has the potential to evolve the ability to overcome this specific major resistance gene in PMR pumpkins and squash. Such a new strain of the pathogen would be called a race.

To obtain information growers need on relative tolerance and yield to select PMR varieties most suitable for their operation, evaluations have been conducted in ME, NY, OH, PA, and WI over the past 3 years. Pumpkins were either transplanted or direct-seeded into black plastic mulch or bareground in June. Cultural practices recommended for each area were followed. Fungicides for powdery mildew were applied to achieve an integrated management program except in WI. Powdery mildew developed naturally. Severity was assessed repeatedly. Other diseases were also assessed in some locations. Fruit number, weight and quality were determined. References to full reports on the individual studies are listed at the end.

Among the 39 PMR varieties and experimental lines evaluated, powdery mildew was least severe on Gold Dust, Bumpkin, Touch of Autumn, Hobbit, Magician, Gladiator, and experimental lines from pumpkin breeding programs at Outstanding Seed Company, Harris Moran Seed Company, Cornell University and University of New Hampshire. Relative to varieties without PMR genes, percent control achieved with PMR pumpkins ranged tremendously – from 0% (eg no control) to 100% (complete control) (Table 1).

Variation was detected in susceptibility to other diseases among the varieties and experimental lines evaluated. Super Herc (HMX 3692), Gold Gem, Gold Medal, and Pro Gold 510 were highly susceptible to anthracnose while Wee-B-Little was highly resistant in the Ohio State pumpkin variety trial in 2003. Magic Lantern and Merlin were shown in another project to be more susceptible to bacterial wilt than the susceptible varieties Harvest Moon and Howden (*). Research is underway to determine if this occurs with other resistant varieties.
* http://vegetablemdonline.ppath.cornell.edu/NewsArticles/Cuc_AttrBeetle.htm

Average fruit weight of the PMR varieties and experimental lines evaluated ranged from 0.5 to 26.5 (Table 2). Additional information about yield can be found in the full reports on these experiments (web sites listed below). Some reports also have descriptions of horticultural characteristics and photographs. Harris Moran pumpkins generally had good color and appearance. In the NY 2004 experiment, fruit of 03RPX764 was the most popular among growers and others who selected their top 3, Scarecrow was second, and Sorcerer was third. Other pumpkins receiving high ratings were Howden, Magic Lantern, Magician, and HMX 2689.

An integrated program, consisting of a reduced fungicide program applied to a PMR variety, is recommended for managing powdery mildew in pumpkin to improve control and to minimize chance of selection of pathogen races able to overcome the genetic resistance in the plant or the action of fungicides. Fewer fungicide applications are needed with a PMR variety because powdery mildew often starts to develop later in PMR than susceptible varieties and the spray interval can be increased from 7 to 14 days without affecting control. Routine scouting is needed when growing PMR varieties not only to determine when powdery mildew has started to develop, and thus fungicide treatment is warranted, but also to detect other diseases. Some fungicides used for powdery mildew on susceptible varieties have broad-spectrum activity and thus will control additional diseases that may consequently not be detected when growing susceptible varieties.

For more information on these experiments, see the following on-line reports:
NY http://www.longislandhort.cornell.edu/vegpath/2005/PMRPkin.pdf
OH http://vegnet.osu.edu/library/res05/pumpk05.pdf
http://vegnet.osu.edu/library/libr.htm#rr
PA http://capitalhort.cas.psu.edu/Research.html
WI http://www.plantpath.wisc.edu/wivegdis/index.htm

For photographs of the fruit of pumpkins evaluated go to:
OH http://vegnet.osu.edu/library/pumpic05.htm
Abbott & Cobb: http://abbottcobb.com/pumpkin/
Harris Moran: http://www.harrismoran.com/products/default.htm
Rupp Seeds: http://www.ruppseeds.com/divVegetable/default.htm
Sieger’s Seeds: http://www.siegers.com/shop/browse_species.asp?species_id=pump

Table 1: Percent control of powdery mildew on leaves achieved in pumpkin varieties and experimental lines with resistance to powdery mildew relative to varieties lacking resistance in experiments conducted in ME, NY, OH, PA, and WI in 2003, 2004 and 2005 listed in order of overall performance.

Pumpkin Variety or Experimental Line

Sourcez

PM Reactiony

Percent Control of Powdery Mildewx

2005

2004

2003

OH-1w

OH-2w

NY

WI

OH

NY

PA-1v

PA-2v

WI

OH

WI

ME

XP6899

OS

PMRR

--

--

100

--

--

--

--

--

--

--

--

--

XP6888

OS

PMRR

--

--

100

--

--

--

--

--

--

--

--

--

NH1788

NH

PMRR

--

--

100

--

--

--

--

--

--

--

--

--

NH1799

NH

PMR

--

98

100

--

--

--

--

--

--

--

--

--

HMX 5684

HM

PMRR

--

98

--

93

--

--

--

--

--

--

--

--

HMX 4684

HM

PMR

--

98

--

91

--

--

--

--

--

--

--

--

NY01-605A

NY

PMRR

--

--

100

--

--

88

--

--

--

--

--

--

Gold Dust

RU

PMR

--

--

--

91

--

--

98

92

--

--

--

--

Bumpkin

MY

PMR

--

--

100

--

--

--

90

84

--

--

--

--

HMX 5681

HM

PMR

--

--

--

83

--

--

98

92

--

--

--

--

HMX 5683

HM

PMR

--

88

--

93

--

--

--

--

--

--

--

--

HMX 5680

HM

PMR

--

--

--

85

--

--

90

84

--

--

--

--

Touch of Autumn

RU

PMR

--

--

100

81

81

84

--

--

--

--

77

--

NY01-609

NY

PMRR

--

--

100

--

--

67

--

--

--

--

--

--

NH1755A

NH

PMR

--

--

--

--

--

82

--

--

--

--

--

--

Hobbit

SD

PMR

--

--

100

--

--

62

--

--

--

--

--

--

Magician (HMX 0683)

HM

PMRR

--

98

100

--

--

60

90

96

51

33

97

--

Gladiator (HMX 2689)

HM

PMRR

--

99

100

--

71

81

--

--

62

33

94

--

Gold Bullion

RU

PMR

--

--

100

--

48

73

74

74

--

--

88

--

Munchkin

HM

PMS

--

--

--

--

--

--

71

79

--

--

--

--

Merlin

HM

PMR

--

--

89

--

--

58

--

--

--

--

--

80

NH1771A

NH

PMR

--

--

--

--

--

72

--

--

--

--

--

--

Magic Lantern

HM

PMR

--

84

94

--

--

26

62

80

32

--

90

80

Mystic Plus

HM

PMR

--

--

--

--

--

--

--

--

--

--

--

80

03RPX763

RU

PMR

--

--

100

--

18

69

--

--

--

--

--

--

03RPX764

RU

PMR

53

--

100

--

23

68

--

--

--

--

--

--

Iron Man (HMX 2690)

HM

PMR

82

88

--

--

--

--

79

54

26

24

60

--

RPX 03515

RU

PMR

--

--

--

--

45

67

--

--

--

--

--

--

Scarecrow (MSX6009)

MY

PMRR

--

--

--

--

--

27

60

66

--

--

--

--

HMX 4682

HM

PMR

--

100

--

--

51

--

--

--

0

--

--

--

Harvest Princess

MY

PMR

--

--

--

--

--

--

75

16

--

--

--

--

Aladdin

HM

PMR

86

0

--

--

--

--

20

70

32

--

--

--

MSX 6078

MY

PMR

--

--

--

--

--

--

42

38

--

--

--

--

HMX 3694

HM

PMR

--

--

--

--

53

--

--

--

24

--

--

--

Harvest Time

AC

PMR

--

--

--

--

37

--

--

--

--

--

--

--

MSX 6074

MY

PMR

--

--

--

--

--

--

13

58

--

--

--

--

Super Herc

  (HMX 3692)

HM

PMR

--

--

--

--

45

--

--

--

35

6

51

--

RPX 03516

RU

PMR

--

--

--

--

29

63

--

--

--

12

--

--

Wee-B-Little

RU

PMS

--

--

--

--

--

--

--

--

--

24

--

--

King Midas

SI

PMS

--

--

--

--

18

--

--

--

--

--

--

--

Phat Jack

SI

PMS

--

--

--

--

18

--

--

--

--

--

--

--

Pro Gold 510

AC

PMS

--

--

--

--

12

--

--

--

--

--

--

--

Oktoberfest

SI

PMS

--

--

--

--

9

--

--

--

--

--

--

--

Apprentice

HM

PMS

--

--

--

--

--

--

13

0

--

--

--

--

RPX 1002

RU

PMS

--

--

--

--

7

--

12

0

--

6

--

--

Mother Lode

RU

PMS

--

--

--

--

--

--

--

--

--

--

--

25

Sorcerer

HM

PMS

--

--

0

--

--

14

--

--

--

--

0

30

Racer

JO

PMS

--

--

--

--

--

--

--

--

--

--

--

25

RPX 1003

RU

PMS

--

--

--

--

1

--

13

0

--

--

--

--

RPX 1006

RU

PMS

--

--

--

--

0

--

0

17

--

0

--

--

Howden

HM

PMS

--

--

0

0

--

0

--

--

0

--

20

20

Howdy Doody

SE

PMS

--

--

--

--

--

--

--

--

--

--

--

20

Gold Medal

RU

PMS

0

--

--

--

1

--

0

0

--

--

0

0

Golden Condor

MY

PMR

--

--

--

--

--

--

0

0

--

--

--

--

20 Karat Gold

  (RPX 760)

RU

PMR

--

0

0

0

--

--

--

--

--

--

--

--

Autumn King

RU

PMS

--

--

--

--

0

--

0

0

--

--

--

0

Gold Gem

RU

PMS

0

--

--

--

0

--

0

0

--

0

--

0

Gold Standard

RU

PMS

--

--

--

--

0

--

--

--

--

--

--

--

Harvest King

MY

PMS

--

--

--

--

--

--

0

0

--

--

--

--

Lil Pump-Ke-Mon

HM

PMS

--

0

--

--

--

--

--

--

--

--

--

--

Gold Rush

RU

PMS

--

--

--

--

--

--

--

--

--

--

--

0

Trojan

SE

PMS

--

--

--

--

--

--

--

--

--

--

--

0

Gold Strike

RU

PMS

--

--

--

--

--

--

--

--

--

--

--

0

Rocket

JO

PMS

--

--

--

--

--

--

--

--

--

--

--

0

Rock Star

JO

PMS

--

--

--

--

--

--

--

--

--

--

--

0

Aspen

SE

PMS

--

--

--

--

--

--

--

--

--

--

--

0

Phantom

SE

PMS

--

--

--

--

--

--

--

--

--

--

--

0

Pick-A-Pie

RU

PMS

--

--

--

--

0

--

--

--

--

--

--

--

z AC=Abbott & Cobb, HM=Harris Moran Seed Co, MY=Meyer Seed International, NH=Brent Loy, plant breeder, University of New Hampshire, NY= Molly Jahn, plant breeder, Cornell University, JO=Johnny's Selected Seeds, SE=Seedway, SI=Siegers Seed Company, SD=Seeds by Design, RU= Rupp Seeds, and OS=Outstanding Seed Co.

y PMRR=homozygous resistant to powdery mildew, PMR=heterozygous resistant, PMS=powdery mildew susceptible.

x Percent control of powdery mildew was calculated by taking the average of all powdery mildew susceptible varieties in each separate trial and using that value as the susceptible control.  Percent control by each variety relative to the susceptible control was then determined. Negative values are reported as '0'.  Severity values were used from assessments done near the end of the experiment (25 Aug – 10 Sept).  ‘—‘ indicates not tested.

w OH-1=replicated variety trial, OH-2=unreplicated demonstration trial.

v PA-1=Lancaster County, PA-2=Westmoreland County.

Table 2: Average mature fruit weight of pumpkin varieties and experimental lines evaluated in experiments conducted in ME, NY, OH, PA, and WI in 2003, 2004 and 2005.   Entries are listed alphabetically.

Pumpkin Variety or Experimental Line

Sourcez

PM Ratingy

Average Fruit Weight (lbs)

2005

2004

2003

ME

OH-1x

OH-2x

NY

PA

WI

OH

NY

PA-1w

PA-2w

WI

OH

WI

ME

03RPX763

RU

PMR

--

--

--

10.5

13.0

--

16.0

13.7

--

--

--

--

--

--

03RPX764

RU

PMR

--

--

--

11.2

14.4

--

18.0

15.2

--

--

--

--

--

--

Aladdin

HM

PMR

21.5

18.0

--

--

--

--

--

--

24.5

27.0

22.9

--

--

--

Appalachian

HM

PMS

--

--

--

--

--

--

--

--

--

--

--

--

--

22.8

Apprentice

HM

PMS

--

--

--

--

--

--

--

--

1.1

1.1

--

--

--

--

Autumn King

RU

PMS

25.2

--

--

--

15.9

--

24.0

--

24.3

26.0

--

--

--

25.8

Aspen

SE

PMS

--

--

--

--

--

--

--

--

--

--

--

--

--

19.5

Big Rock

JO

PMS

19.8

--

--

--

--

--

--

--

--

--

--

--

--

23.3

Bumpkin

MY

PMR

--

--

--

0.6

0.5

--

--

--

0.7

0.8

--

--

--

--

Chrisma PMR

JO

PMR

13.1

--

--

--

--

--

--

--

--

--

--

--

--

--

Expert

JO

PMS

21.0

--

--

--

--

--

--

--

--

--

--

--

--

--

Gladiator (HMX 2689)

HM

PMRR

18.2

--

15.7

9.9

13.7

--

15.0

12.6

--

--

15.6

19.0

17.1

--

Gold Bullion

RU

PMR

--

--

--

9.0

10.7

--

14.0

12.0

17.9

18.0

--

--

14.2

--

Gold Dust

RU

PMR

--

--

--

--

0.6

0.6

--

--

0.6

0.7

--

--

--

--

Gold Gem

RU

PMS

18.6

16.0

--

--

15.5

--

22.0

--

19.8

23.0

--

21.0

--

26.8

Gold Medal

RU

PMS

27.6

22.0

--

--

16.4

--

20.0

--

23.4

31.0

--

--

25.0

29.0

Gold Rush

RU

PMS

--

--

--

--

--

--

--

--

--

--

--

--

--

30.6

Gold Standard

RU

PMS

--

--

--

--

--

--

16.0

--

--

--

--

--

--

--

Gold Strike

SE

PMS

19.7

--

--

--

--

--

--

--

--

--

--

--

--

32.0

Golden Condor

MY

PMR

--

--

--

--

--

--

--

--

23.6

29.0

--

--

--

--

Harvest King

MY

PMS

--

--

--

--

--

--

--

--

23.2

25.0

--

--

--

--

Harvest Princess

MY

PMR

--

--

--

--

--

--

--

--

2.1

2.0

--

--

--

--

Harvest Time

AC

PMR

--

--

--

--

21.4

--

23.0

--

--

--

--

--

--

--

HMX 3694

HM

PMR

--

--

--

--

--

--

4.0

--

--

--

4.2

--

--

--

HMX 4682

HM

PMR

--

--

2.4

--

--

--

2.0

--

--

--

2.3

--

--

--

HMX 4684

HM

PMR

--

--

3.2

--

--

3.2

 --

 --

 --

 --

--

 --

 --

--

HMX 5680

HM

PMR

--

--

10.6

--

--

12.3

 --

 --

 --

 --

--

 --

 --

--

HMX 5681

HM

PMR

--

--

9.7

--

--

15.2

 --

 --

 --

 --

--

 --

 --

--

HMX 5683

HM

PMR

--

--

3.8

--

--

4.3

 --

 --

 --

 --

--

 --

 --

--

HMX 5684

HM

PMRR

--

--

4.4

--

--

4.0

 --

 --

 --

 --

--

 --

 --

--

Hobbit

SD

PMR

--

--

--

4.5

--

--

--

5.7

--

--

--

--

--

--

Howden

HM

PMS

--

--

--

10.0

--

11.1

--

15.3

--

--

23.7

--

18.5

23.2

Iron Man (HMX 2690)

HM

PMR

4.0

3.4

4.0

--

3.2

--

--

--

4.0

4.4

4.1

3.5

3.8

--

King Midas

SI

PMS

19.7

--

--

--

--

--

20.0

--

--

--

--

--

--

--

Lil Pump-Ke-Mon

HM

PMS

--

--

1.2

--

--

--

 --

 --

 --

 --

 --

 --

 --

--

Magic Lantern

HM

PMR

13.2

--

--

7.3

11.0

--

--

11.8

18.7

18.0

15.4

--

10.8

20.2

Magician (HMX 0683)

HM

PMRR

9.5

--

--

6.4

9.8

--

--

11.1

13.7

14.0

14.9

15.0

11.3

--

Merlin

HM

PMR

14.6

--

--

7.6

--

--

--

9.6

--

--

--

--

--

16.7

Mother Lode

RU

PMS

--

--

--

--

--

--

--

--

--

--

--

--

--

20.5

Mystic Plus

HM

PMR

5.6

--

--

--

--

--

--

--

--

--

--

--

--

5.9

MSX 6074

MY

PMR

--

--

--

--

--

--

--

--

11.8

21.0

--

--

--

--

MSX 6078

MY

PMR

--

--

--

--

--

--

--

--

11.9

16.0

--

--

--

--

Munchkin

HM

PMS

--

--

--

--

--

--

--

--

0.5

0.6

--

--

--

--

New Rocket

JO

PMS

14.5

--

--

--

--

--

--

--

--

--

--

--

--

--

NH1755A

NH

PMR

--

--

--

--

--

--

--

4.3

--

--

--

--

--

--

NH1771A

NH

PMR

--

--

--

--

--

--

--

9.1

--

--

--

--

--

--

NH1788

NH

PMRR

--

--

--

2.9

--

--

 --

 --

 --

 --

 --

 --

 --

--

NH1799

NH

PMR

--

--

--

10.7

--

--

 --

 --

 --

 --

 --

 --

 --

--

NY01-605A

NY

PMRR

--

--

--

2.6

--

--

--

3.3

--

--

--

--

--

--

NY01-609

NY

PMRR

--

--

--

6.3

--

--

--

9.8

--

--

--

--

--

--

Oktoberfest

SI

PMS

16.7

--

--

--

--

--

18.0

--

--

--

--

--

--

--

Phat Jack

SI

PMS

--

--

--

--

--

--

26.0

--

--

--

--

--

--

--

Phantom

SE

PMS

21.8

--

--

--

--

--

--

--

--

--

--

--

--

21.0

Pick-A-Pie

RU

PMS

--

--

--

--

--

--

9.0

--

--

--

--

--

--

--

Prankster (RPX089)

RU

PMR

--

--

--

--

2.6

--

--

--

--

--

--

--

--

--

Pro Gold 510

AC

PMS

--

18.0

--

--

15.9

--

19.0

--

--

--

--

--

--

--

Racer

JO

PMS

10.6

--

--

--

--

--

--

--

--

--

--

--

--

11.7

Rock Star

JO

PMS

22.3

--

--

--

--

--

--

--

--

--

--

--

--

28.8

Rocket

JO

PMS

11.8

--

--

--

--

--

--

--

--

--

--

--

--

17.9

RPX 03515

RU

PMR

--

--

--

--

--

--

16.0

11.4

--

--

--

13.0

--

--

RPX 03516

RU

PMR

--

--

--

--

--

--

13.0

13.0

--

--

--

12.0

--

--

RPX 1002

RU

PMS

--

--

--

--

--

--

20.0

--

24.2

25.0

--

18.0

--

--

RPX 1003

RU

PMS

--

--

--

--

--

--

21.0

--

21.7

27.0

--

--

--

--

RPX 1006

RU

PMS

--

--

--

--

--

--

17.0

--

17.8

18.0

--

15.0

--

--

20 Karat Gold (RPX 760)

RU

PMR

--

--

13.0

10.5

12.2

15.7

--

--

--

--

--

--

--

--

Scarecrow (MSX6009)

MY

PMRR

--

--

--

--

--

--

--

13.3

17.7

17.0

--

--

--

--

Sorcerer

HM

PMS

--

--

--

7.8

--

--

--

11.7

--

--

--

--

12.3

17.0

Super Herc (HMX 3692)

HM

PMR

--

18.0

--

--

18.2

--

23.0

--

--

--

19.7

23.0

20.0

--

Touch of Autumn

RU

PMR

--

--

--

1.6

--

2.7

2.0

2.0

--

--

--

--

2.7

--

Trojan

SE

PMS

25.7

--

--

--

--

--

--

--

--

--

--

--

--

31.3

Wee-B-Little

RU

PMS

--

--

--

--

--

--

--

--

--

--

--

0.5

--

--

XP6899

OS

PMRR

--

--

--

6.6

--

--

--

--

--

--

--

--

--

--

XP6888

OS

PMRR

--

--

--

5.0

--

--

--

--

--

--

--

--

--

--

z AC=Abbott & Cobb, HM=Harris Moran Seed Co, MY=Meyer Seed International, NH=Brent Loy, plant breeder, University of New Hampshire, NY= Molly Jahn, plant breeder, Cornell University, JO=Johnny's Selected Seeds, SE=Seedway, SI=Siegers Seed Company, SD=Seeds by Design, RU= Rupp Seeds, and OS=Outstanding Seed Co.

y PMRR=homozygous resistant to powdery mildew, PMR=heterozygous resistant, PMS=powdery mildew susceptible.

x OH-1 = replicated variety trial, OH-2 = unreplicated demonstration trial.

w PA-1=Lancaster County, PA-2=Westmoreland County.