Malheur Experiment Station
Oregon State University
Information for Sustainable Agriculture

Potato Variety Trials 2003

Eric P. Eldredge, Clinton C. Shock, and Lamont D. Saunders
Malheur Experiment Station
Oregon State University
Ontario, OR

Introduction

Potatoes are grown under contract in Malheur County for potato processors to produce frozen products for the food service industry. There is very little production for fresh pack or open market, and very few growers have potato storage buildings on their farms. There is also no production of varieties for making potato chips. There is no potato seed production in Malheur County because high populations of aphids result in virus infection in the tubers. The varieties grown are mainly 'Shepody', 'Ranger Russet' and 'Russet Burbank'. Harvest begins in July, providing potatoes to processing plants directly from the field. Yields are limited by "early die" syndrome, causing early senescence of the vines. Early die is caused by a complex of soil pathogens, including bacteria, nematodes, and fungi, and is worse when rotations between potato crops are shorter.

Small acreages of some advanced selections or new varieties are contracted by processors each year to study the feasibility of expanding the use of the new varieties. To displace an existing processing variety, a new potato variety needs to have several outstanding characteristics. The yield should be at least as high as the yield of Russet Burbank. The tubers need to have low reducing sugars for light, uniform fry color, and high specific gravity. A new variety should be resistant to tuber defects or deformities caused by disease, water stress, or heat. It should begin tuber bulking early if it is a variety for early harvest. Or, if it is a late-harvest variety, it should be resistant to early die.

Potato variety development trials at Malheur Experiment Station in 2003 included a trial of 9 selected strains of Umatilla Russet, an 8-Hill trial of 54 long russet clones from the USDA Agricultural Research Service (ARS) potato breeding program at Aberdeen, Idaho; the Oregon Preliminary Yield Trial with 99 entries; the Oregon Statewide Trial with 28 entries; the Western Regional Early Harvest Trial with 19 entries; and the Western Regional Late Harvest Trial with 17 entries. Through these trials and active cooperation with other scientists in Idaho, Oregon, and Washington, promising new lines are bred, evaluated, and eventually released as new varieties.

Materials and Methods

The six potato variety trials were grown under sprinkler irrigation on Owyhee silt loam, where winter wheat was the previous crop. The wheat stubble was flailed and the field was irrigated and disked. A soil test taken September 9, 2002 showed 18 ppm NO3, 18 ppm P, 306 ppm K, organic matter 2.2 percent, and pH 7.6. Fall fertilizer was broadcast to apply 21 lb N/acre, 100 lb P2O5/acre, 60 lb K2O/acre, 60 lb S/acre, 30 lb Mg/acre, 4 lb Zn/acre, 2 lb Cu/acre, 1 lb Mn/acre, and 1 lb B/acre. The field was ripped, Telone II was injected at 25 gal/acre, and the field was bedded on 36-inch row spacing.

Seed of all varieties was hand cut into approximately 2-oz seed pieces and treated with Tops-MZ + Gaucho dust 1-2 weeks before planting and placed in storage at approximately 90 percent relative humidity and 45°F to suberize. On April 4, 2003, Roundup was applied at 1 qt/acre to control winter annual weeds and volunteer wheat. The Western Regional Early Harvest Trial was planted on April 10, 2003, the Preliminary Yield Trial was planted on April 17, and the other trials were planted on April 18. The 8-Hill Trial was unreplicated, the Preliminary Yield Trial had two replicates, and the Umatilla Strain, Statewide, Western Regional Early Harvest, and Western Regional Late Harvest trials each had four replicates.

Potatoes were planted in single row plots using a two-row cup planter with seed spacing 9 inches in the row, with rows 36 inches apart. Red potatoes were planted between each pair of plots to serve as markers to separate the plots at harvest. After planting, hills were formed over the rows with a Lilliston rolling cultivator. Prowl at 1 lb/acre plus Dual at 2 lb/acre was applied on May 1 and was incorporated by a total of 0.42 inch of rain May 3-5. Matrix herbicide was applied at 1.25 oz/acre on May 28 and was incorporated with a 1.5-inch sprinkler irrigation on May 29

Fungicide applications to help control early blight and prevent late blight infection started with an aerial application of Ridomil Gold and Bravo at 1.5 pint/acre on June 7, which was repeated on June 25. Bravo fungicide plus liquid sulfur was applied by aerial applicator on July 2, and again on August 8. Sulfur dust was applied by aerial applicator on July 20 at 40 lb S/acre to prevent mite infestation and powdery mildew infection.

Petiole tests were taken every 2 weeks from June 12, and fertilizer was injected into the sprinkler line during irrigation to supply the crop nutrient needs. A total of 103 lb N/acre, 50 lb P2O5/acre, 21 lb K2O/acre, 53 lb SO4/acre, 40 lb S/acre, 0.5 lb Mg/acre, 0.55 lb Mn/acre, 0.32 lb Cu/acre, 0.1 lb Fe/acre, and 0.02 lb B/acre were applied. The sprinkler system was operated 22 times, from May 29 to September 23, with scheduling based on potato evapotranspiration (ET), which was calculated based on measurements made by a U.S. Bureau of Reclamation AgriMet weather station at the Malheur Experiment Station. The soil water potential was monitored with 6 Watermark soil moisture sensors (Irrometer Co. Inc., Riverside, CA) logged every 8 hours by a Hansen AM400 (M. K. Hansen Co., East Wenatchee, WA). The AM400 unit was read frequently through the summer to predict crop water needs, with the objective to apply an irrigation just before the average soil moisture in the potato root zone at the seedpiece depth reached -60 kPa. Water applied was measured by recording the sprinkler set duration at 55 psi

Vines were flailed in the early harvest trial on August 19, and in the late harvest trials on October 2. The vines of most varieties had died by the date of the last irrigation on September 23. Western Regional Early Harvest Trial potatoes were lifted August 20 with a two-row digger that laid the tubers back onto the soil in each row. Visual evaluations included observations of desirable traits, such as a high yield of large, smooth, uniformly shaped and sized, oblong to long, attractively russetted tubers, with shallow eyes evenly distributed over the tuber length. Notes were also made of tuber defects such as growth cracks, knobs, curved or irregularly shaped tubers, pointed ends, stem-end decay, stolons that remained attached, folded bud ends, rough skin due to excessive russetting, pigmented eyes, or any other defect, and a note to keep or discard the clone based on the overall appearance of the tubers.

Tubers were placed into burlap sacks and hauled to a barn where they were kept under tarps until grading. After grading, a 20-tuber sample from each plot in the Western Regional Early Harvest Trial was evaluated for tuber quality traits for processing. Specific gravity was measured using the weight-in-air, weight-in-water method, and 10 tubers per plot were cut lengthwise and examined for internal defects. Center slices from 10 tubers were fried for 3.5 min in 375°F soybean oil. Percent light reflectance was measured on the stem and bud ends of each slice using a model 577 Photovolt Reflectance Meter (Seradyn, Inc., Indianapolis, IN), with a green tristimulus filter, calibrated to read 0 percent light reflectance on the black standard cup and 73.6 percent light reflectance on the white porcelain standard plate.

The potatoes in the Preliminary Yield Trial were dug on October 7, and the potatoes in the Statewide Trial on October 8. Western Regional Late Harvest and 8-Hill Trial tubers were dug on October 14, and the Umatilla Strain Trial tubers were dug on October 15. At each harvest, the potatoes in each plot were visually evaluated. Tubers were graded and a 20-tuber sample from each plot was placed into storage. The storage was kept near 90 percent relative humidity and the temperature was gradually reduced to 45°F. Tubers were removed from storage November 3 through 13 and evaluated for tuber quality traits, specific gravity, and fry color as described above.

Results and Discussion

At the Malheur Experiment Station in 2003, spring weather was cool and wet, followed by prolonged heat and a record high temperature on July 22 of 110°F. The extreme heat stressed the potato plants, causing reduced yields and early senescence. Dry weather prevented late blight from developing in 2003. No powdery mildew or mite problems were observed in the field.

Precipitation for May 1 through September 30 was 2.38 inches, the crop ET for the late-harvest trials totaled 30.34 inches, and the trials received 31.19 inches of irrigation plus precipitation, or 103 percent of crop ET (Fig. 1). The step increases in the irrigation plus rainfall curve show the 22 sprinkler irrigations applied during the growing season.

The trend of soil moisture during the growing season is shown in Figure 2. The data were not recorded frequently enough to show the individual irrigations, and the sensors did not always respond to an irrigation. Although the irrigation plus rainfall was in excess of the AgriMet ET prediction through the growing season, sensor data show that average root zone soil water potential became drier than -60 kPa at least three times during the hottest part of the season

Soil water potential at the seedpiece depth was allowed to become drier than -60 kPa at the end of the growing season, after the vines died on the early maturing varieties, by applying frequent sprinkler irrigations of short duration, as shown in Figure 1. This was necessary to avoid swollen lenticels and the associated potential for rotting the tubers of the early senescing varieties, while continuing to apply the ET requirement for the late maturing varieties in shallow moisture increments

Umatilla Strain Trial


This was the first year of a Umatilla Strain Trial, which was conducted at this location (MES) and also at the Hermiston Agricultural Research and Extension Center (HAREC). Umatilla Russet was released jointly by the Oregon, Idaho, and Washington Agricultural Experiment Stations and the USDA ARS in 1998, and over the years some plants had been selected in the field that appeared to be superior strains. Nine of these strains were compared to Russet Burbank and Umatilla Russet (Table 1). Four of the strains had adequate yield, produced a high percent of U.S. No. 1 tubers and had acceptable processing quality. Based on the data from MES and HAREC trials, UM407, UM418, UM432, and OURS311 were advanced to the 2004 Statewide Trial.

8-Hill Trial


Eight hills were grown of each of 54 clones selected for long, russeted tubers from the Aberdeen ARS potato breeding program, including 11 clones with the LB suffix that were bred for resistance to late blight. The 54 clones were evaluated for tuber type, yield, grade, and processing quality (Table 2). Several of the clones had high yields, produced a high percent of U.S. No. 1 tubers, and had good processing quality. The clone 'A96112-20' yielded a total of 905 cwt/acre, with 90 percent U.S. No. 1 grade tubers, specific gravity of 1.0978 g/cm3, and an average fry strip light reflectance of 49.5 percent, which was acceptable for processing, with 0 percent sugar ends. The clone 'A96783-109LB' yielded 828 cwt/acre total, with 91 percent U.S. No. 1 grade, with specific gravity 1.1092, and fry strip light reflectance of 45.3 percent. The clone 'A99123-1' yielded 751 cwt/acre total, with 97 percent U.S. No. 1 grade, with specific gravity 1.0887, fry strip light reflectance of 49.1 percent and 0 percent sugar ends. The clone 'A99133-6' produced a total yield of 769 cwt, with 99 percent U.S. No. 1, specific gravity 1.1038, average fry strip light reflectance 54.4, and 0 percent sugar ends.

Preliminary Yield Trial


In the Preliminary Yield Trial, 94 numbered clones were compared to Russet Burbank, Ranger Russet, Shepody, 'Norkotah', and 'Umatilla Russet' (Table 3). The Oregon potato variety selection committee kept 12 clones to advance to the Statewide Trial for 2004. The clones that were advanced were: 'AO9006-4', 'AO94007-1', 'AO96047-2', 'AO96073-2', 'AO96162-1', 'AO98114-2', 'AO98141-2', 'AO99002-4', 'AO99002-7', 'AO99024-8', 'AO99060-5', and 'AO99099-3', and are marked with an asterisk in the entry list. These clones yielded well across the four locations (Hermiston, Klamath Falls, and Powell Butte data are not shown in this report), had low incidence of undesirable characteristics, had high percent U.S. No. 1 grade tubers, and if selected as promising clones for processing, had high specific gravity and light fry color.

Oregon Statewide Trial


In the Oregon Statewide Trial, five clones were retained by the variety selection committee, 'AO96160-3', 'AO96141-3', 'AO96205-3’, 'AO98133-2' and 'AO98133-4' will be maintained in the Statewide Trial in 2004 (Table 4). The clone 'AO96160-3' will be recommended for advancement to the Western Regional Trials for 2004, and 'AO96141-3' will be discarded unless there is interest in it from the other states.

At this location in 2003, AO96160-3 produced total yield of 452 cwt/acre, with 89 percent U.S. No. 1, specific gravity of 1.093 g/cm3, and fry strip light reflectance of 52.2 percent, with no sugar ends. AO96141-3 produced total yield of 497 cwt/acre, with 75 percent U.S. No. 1, specific gravity of 1.091 g/cm3, and fry strip light reflectance of 51.4 percent, and 3 percent sugar ends. AO96205-3 produced total yield of 534 cwt/acre, with 83 percent U.S. No. 1, specific gravity of 1.097 g/cm3, and fry strip light reflectance of 47.9 percent with no sugar ends. AO98133-2 produced total yield of 395 cwt/acre, with 94 percent U.S. No. 1, specific gravity of 1.098, and fry strip light reflectance of 51.6 percent, with 3 percent sugar ends. AO98133-4 produced total yield of 380 cwt/acre, with 83 percent U.S. No. 1, specific gravity of 1.095, and fry strip light reflectance of 44.5 percent, with 8 percent sugar ends. Russet Burbank had 63 percent sugar ends, far more than any other variety.

Western Regional Early Harvest Trial


In the Western Regional Early Harvest Trial, 'A91814-5' with 641 cwt/acre total yield, 'A92294-6' with 608 cwt/acre total yield, Shepody with 603 cwt/acre, and Russet Burbank with 602 cwt/acre, were among the highest in total yields (Table 5). All of those clones except Russet Burbank had acceptable specific gravity and fry color. In production of marketable tubers (the total of U.S. No.1 plus U.S. No. 2 grades), Shepody with 574 cwt/acre, and Russet Burbank with 522 cwt/acre, were among the highest.

Western Regional Late Harvest Trial


In the Western Regional Late Harvest Trial, among the highest for total yield were, ‘A91814-5’ with 719 cwt/acre, ‘A9305-10’ with 714 cwt/acre, ‘A92294-6’ with 713 cwt/acre, Ranger Russet with 629 cwt/acre, ‘A93157-6LS’ with 627 cwt/acre, and Russet Burbank with 570 cwt/acre (Table 6). Among the highest for marketable yield, A9305-10 yielded 678 cwt/acre marketable yield, Ranger Russet produced 610 cwt/acre marketable yield, and A91814-5 yielded 576 cwt/acre marketable yield. Russet Burbank produced 279 cwt/acre U.S. No. 2 tubers, and A92294-6 produced 217 cwt/acre U.S. No. 2 tubers, which were significantly more than other clones in this trial The clone A91814-5 produced 143 cwt/acre undersized tubers under 4 oz, significantly more than the other clones.


Figure 1. Evapotranspiration (ET) and sprinkler irrigation applied (plus rain) to potato variety trials, Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.



Figure 2. Soil moisture data for sprinkler-irrigated potato variety trials, Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

Table 1. Umatilla Strain Trial: yield, grade, and processing quality of Umatilla Russet strains grown at the Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

 

 

U.S. No. 1

 

 

 

 

 

 

 

Average

Percent

Clone or Strain

Total

yield

Percent

No. 1

Total

>12

oz

4-6

oz

6-12

oz

U.S.No. 2

Market-

able

<4 oz

Rot

Length/

width

Specific

gravity

fry color, light

reflectance

sugar

ends

 

cwt/acre

%

oz

ratio

g cm-3

%

%

Russet Burbank

640.9

55.6

355.3

83.1

200.0

72.2

214.0

569.2

64.1

7.6

2.31

1.069

35.24

45.00

Umatilla Russet

660.1

72.1

474.4

175.8

231.1

67.5

141.3

615.7

40.8

3.6

1.95

1.082

44.66

0.00

*UM407

627.7

75.6

468.2

184.9

224.3

59.0

115.0

583.2

41.6

2.9

1.96

1.085

45.53

0.00

*UM418

590.2

81.8

480.6

159.5

248.2

72.9

67.8

548.4

41.1

0.7

1.88

1.086

47.20

0.00

*UM432

533.0

78.6

421.1

139.5

234.6

47.1

75.1

496.2

29.8

7.0

1.98

1.090

46.37

0.00

UM433

644.3

70.8

459.8

170.6

216.5

72.6

144.2

603.9

40.3

0.0

2.06

1.089

45.86

2.50

UM436

618.9

77.7

478.0

140.8

275.5

61.7

100.8

578.8

39.3

0.8

1.86

1.085

45.25

0.00

UM446

626.0

65.0

407.8

135.9

200.7

71.2

173.9

581.6

43.8

0.6

1.96

1.084

45.05

2.50

OURS307

633.0

63.1

400.5

151.7

192.4

56.4

192.6

593.2

39.3

0.5

2.05

1.090

44.49

5.00

*OURS311

632.3

79.5

502.8

159.9

267.6

75.2

89.9

592.7

37.8

1.8

1.89

1.084

48.17

0.00

OURS313

643.5

59.6

382.7

112.6

196.9

73.2

187.7

570.3

70.3

2.9

1.89

1.089

45.99

7.50

mean

622.7

70.9

439.2

146.7

226.2

66.3

136.6

575.8

44.4

2.6

1.98

1.085

44.89

5.68

LSD (0.05)

NS

7.5

NS

NS

53.3

NS

53.0

NS

15.5

NS

0.06

0.005

2.94

10.12
*Advanced to the 2004 Statewide Trial, based on the data from Malheur Experiment Station and Hermiston Agriculture Research and Extension Center.

Table 2. Yield, grade, and processing quality of 54 early selections in an unreplicated 8-Hill Trial, Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

 

 

U.S. No. 1

 

 

 

 

 

 

Average

 

 

Variety

Total

yield

Percent

No. 1

Total

>12

oz

4-12

oz

U.S.

No. 2

Marketable

<4 oz

Cull

Length/

width

Specific

gravity

fry color, light

reflectance

Sugar

ends

 

cwt/acre

%

-----------------------------cwt/acre-------------------------------

ratio

g cm-3

%

%

A95061-67LB

715