Research in the Klamath Basin
2007 Annual Report
Brian A. Charlton and Darrin A. Culp
1
Russet production in the Klamath Basin is almost entirely used for fresh market consumption. Russet Norkotah and clonal variants of this variety comprise the majority of russet acreage in the Klamath Basin. Russet Burbank also constitutes a significant percentage of local russet acreage as several packing sheds continue to exclusively pack this variety. Despite this trend, growers are continually looking for alternative varieties that offer improved yields and better pack out with reduced inputs. Since its inception in
1985, the Tri-State Variety Development Program has focused on developing russets for processing and the fresh market. Additional emphasis has focused on developing dualpurpose russets that meet both processing and fresh market criteria. Due to increases in production costs, threats of new as well as continued pressure from endemic pests and diseases, additional breeding efforts have focused on improving genetic resistance.
Climatic constraints in the Klamath Basin result in a relatively short growing season; therefore, new varieties must mature relatively early while still producing acceptable yield and grade.
Every variety attains maximum yield potential at a given plant population and fertility rate per acre. Additionally, this information is needed to assist growers in attaining maximum economic returns. Tri-State cooperators routinely conduct cultural management trials to determine optimum seed spacing and fertility inputs for newly released varieties. With such diverse climatic and growing season conditions throughout the Tri-State area, it is important to conduct cultural management trials in more than one location. Six dual-purpose russet varieties and advanced selections were subjected to various in-row seed spacing at KBREC to determine optimum yield and grade.
The trial included the following varieties and selections: Gem Star Russet,
A95109-1, and A93157-6LS (Idaho) and AO96160-3, AO96164-1, and AO96141-3
(Oregon). The trial was arranged in a split-plot design with 4 replications. Three population densities of 6, 9, and 12 inch comprised the main plots with variety and/or selection as the split plots. Individual plots measured 30 feet in length. The trial location
1
Assistant Professor and Faculty Research Assistant, respectively, Klamath Basin Research and Extension
Center, Klamath Falls, OR.
Acknowledgements: Partial financial support for this program from the Oregon Potato Commission; the
Cooperative State Research, Extension, and Education Service (CSREES); and the USDA Agricultural
Research Service (ARS) is gratefully recognized.
Reference to a product or company is for specific information only and does not endorse or recommend that product or company to the exclusion of others that may be suitable.
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Klamath Basin Research and Extension Center
Effects of Plant Population on Yield and Grade of Advanced Tri-State Potato Selections, 2007 Page 25

Research in the Klamath Basin
2007 Annual Report was planted to teff grass for hay the previous year and treated with glyphosate in the fall of 2006. Gypsum was applied at a rate of 2000 lbs/acre on April 11. Field preparation following the gypsum application included two passes with an off-set disc, roto-tilling, and moldboard plowing to break and bury sod. The area was fumigated with Telone
TM
II
(dichloropropene, Dow AgroSciences) at 15 gal/acre (gpa) and Vapam (sodium methyldithiocarbamate, AMVAC) at 25 gpa on April 26, 2007 followed by a finishing harrow and packer on May 7. Dry fertilizer was broadcast pre-plant followed by liquid fertilizer at row bedding for a total of 165 lb Nitrogen (N), 80 lb Phosphate (P
2
O
5
), 100 lb
Potash (K
2
0) and 140 lb Sulfur (S) on May 9 and 10.
Seed for all trials was hand cut to approximately 1.5-2.0 oz/seed piece on May 9,
10 and 11, treated with Tops MZ (thiophamate-methyl, mancozeb, Bayer CropScience), and suberized for 2 weeks at 55
0
F and approximately 95 percent relative humidity. The trial was planted using 2-row planter on May 23. The insecticide Admire Pro
(imidacloprid, Bayer CropScience) at 5-6 fl. oz. / acre and the fungicide Quadris
(azoxystrobin, Syngenta) at 6-8 fluid oz. / acre were applied in furrow over the seed piece.
Potato Hills were bedded up and leveled off with a rolling cultivator and bar, then sprayed with the pre-emergence herbicides of Dual II Magnum (s-metalachlor, Syngenta) at 1.3 pt./ acre and Prowl H2O (pendimethalin, BASF) at 1.5 pt./ acre. Following application, the herbicides were incorporated with .43 inches of irrigation. Matrix
(rimsulfuron, Dupont) was applied post-emergence at 1 oz. / acre on July 5 and incorporated with .25 inches of irrigation. A total of 19.7 inches of water was applied during the growing season with sprinklers arranged in a 40- by 48-ft. pattern and naturally occurring precipitation.
Plant stands were monitored on June13 and 27. On July 26 the fungicide Ridomil
Gold Bravo (mefenoxam/chlorothalinil, Syngenta) and the insecticide Leverage
(imidacloprid, cyfluthrin, Bayer CropScience) was applied aerially. Another application of Ridomil Gold was applied on August 10 at labeled rates. Vine kill took place on
September 10 with rolling followed by a Reglone (diquat dibromide, Syngenta) application at 1.5 pt. /acre with a ground sprayer.
Tubers were harvested using a one-row digger-bagger on October 10. All tubers from each plot were stored at 55
0
F until grading from November 5. Using the USDA potato grade standards, each plot was graded into U.S. No. 1s, No. 2s, B’s and culls. B size is any tuber under 4 oz. U.S. No. 1s were separated by weight to 4- to 8-oz, 8- to 12oz, and over 12-oz groupings. Subsamples of approximately 10 lbs from the 8- to 12 oz. fraction were used to determine specific gravity by the weight-in-air, weight-in-water method. Ten tubers from the over 12-oz group were selected at random to determine percent internal defects. Potatoes were cut lengthwise and inspected for hollow-heart, brown center, vascular discoloration, internal brown spot, stem end discoloration, and corky ring spot.
Potatoes were downgraded to No. 2s or culls if growth cracks, knobs, or misshapen tubers were severe enough according to USDA grade standards. Yields for
U.S. No. 1s were not adjusted to account for external blemishes such as Rhizoctonia or silver scurf or internal defects such as hollow heart, brown center, and others.
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Klamath Basin Research and Extension Center
Effects of Plant Population on Yield and Grade of Advanced Tri-State Potato Selections, 2007 Page 26

Research in the Klamath Basin
2007 Annual Report
Data collected from grading was analyzed using SAS for Linear Models 9.1 (SAS
Institute Inc.) software. Least significant differences (LSDs) were calculated based on the student’s t test at the 5 percent probability level. Only a portion of the data obtained is reported here.
Emergence data (not shown) were collected 21 and 35 days after planting. All entries had achieved at least 90 percent emergence and final stands exceeded 95 percent in all treatments. A high incidence of hollow heart was observed in GemStar (26 percent) and 6LS (25 percent); data not shown. Seed spacing did not affect the incidence of hollow heart in either of these two varieties which suggests other factors (environmental, genetic, etc) are largely responsible for this tendency. Although hollow heart is usually more prominent in larger sized tubers, both these varieties exhibited problems in smaller tuber sizes (8-12 oz).
Yield, grade, and tuber size distribution data are presented in Table 1. AO96164-
1 produced significantly higher total yield than all other entries. However, this selection and AO96141-3 produced significantly lower US No. 1 yield than all other entries.
AO96164-1 and AO96141-3 also had significantly higher US No. 2 yield than all other entries which suggesting these varieties are not well suited for fresh market production in the Klamath Basin. A95109-1 had the highest US No. 1 yield among the other entries; however, the difference was not significant. This selection appears well suited for fresh market production in the Klamath Basin due to favorable yields and few internal and external defects.
A significant difference was observed among seed spacing. A linear trend was observed with higher total and US No. 1 yield at denser populations and gradually decreasing with increased spacing. Interestingly, US No. 1 yield for 6 and 9 inch spacing were not significantly different but were for total yield. AO96160-3 and A95109-1 produced significantly higher US No. 1 yield at the 6 inch spacing while all other entries showed no differences between 6 and 9 inch. Seed spacing had no significant difference on yield of tubers over 12 oz.
AO96141-3 and AO96164-1 will not be evaluated in future cultural management trials due to poor tuber appearance for the fresh market. GemStar Russet has performed well in yield trials at KBREC and has excellent tuber appearance; however, erratic problems with hollow heart make it a risky choice in the Klamath Basin. In addition, this variety masks PVY symptoms which present multiple challenges for raising clean certified seed. Therefore, it is likely this variety will not gain commercial acceptance on a large scale. AO96160-3 has nice tuber appearance, although not quite as attractive as
Russet Norkotah, and may find a niche in the Klamath Basin. This selection will be further evaluated in seed spacing trials in 2008. 6LS also has performed quite well in the
Klamath Basin, exhibiting excellent tuber appearance and yield. Like GemStar, this variety has shown a propensity to develop hollow heart. Commercial experience in the region has also demonstrated this propensity; therefore, if large-scale acceptance is to occur, additional management studies are needed to lower this risk. A95109-1 appears the best suited among all entries for commercial acceptance in the Klamath Basin. Tuber
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Klamath Basin Research and Extension Center
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Research in the Klamath Basin
2007 Annual Report appearance is excellent, yield and grade is very comparable to Russet Norkotah (standard fresh market variety in the region), and few internal and external defects are observed.
This selection will also be further evaluated in seed spacing trials in 2008.
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Klamath Basin Research and Extension Center
Effects of Plant Population on Yield and Grade of Advanced Tri-State Potato Selections, 2007 Page 28

Research in the Klamath Basin
2007 Annual Report
Table 1. Effect of seed spacing on yield, grade, and tuber size distribution of Gem Star, AO96160-3, A95109-1, 6LS,
AO96141-3 and AO96164-1 grown at the Klamath Basin Research and Extension Center.
Variety Trt.
1
Yield U.S. No. 1s
4-8 oz 8-12 oz > 12 oz Total
Yield
< 4 oz No. 2's culls Total
Gem Star 1
2
3
90
45
47
132
96
78
150
215
151 cwt/acre
372
357
275
39
16
16
50
65
35
9
20
23
470
458
349
AO96160-3
A95109-1
6LS
AO96141-3
AO96164-1
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
175
121
114
130
108
96
128
102
95
107
82
60
208
142
126
142
142
110
182
114
140
144
133
98
136
100
83
92
111
111
112
72
66
130
108
117
113
128
79
43
59
69
68
65
73
428
335
289
442
330
353
386
363
272
311
246
216
342
312
306
40
32
32
42
32
46
79
58
46
89
88
63
104
73
60
50
41
46
37
20
32
30
11
12
70
55
74
130
117
110
17
22
27
18
26
21
10
15
7
21
18
28
34
33
25
547
419
355
550
425
458
482
441
371
504
422
378
597
520
504
Variety Main Effect:
Gem Star
AO96160-3
A95109-1
6LS
AO96141-3
AO96164-1
CV (%)
LSD (0.05)
61
137
112
108
83
158
111
25
102
131
145
125
106
105
51
25
Seed Spacing Main Effect:
1
2
3
CV (%)
LSD (0.05)
140
100
89
119
34
138
116
103
72
NS
103
108
93
37
NS
1/
Treatment seed spacing: 1 = 6 inch, 2 = 9 inch, 3 = 12 inch
172
83
118
107
69
57
143
101
335
351
375
340
258
320
42
53
380
324
285
71
72
23
61
35
40
80
79
156
11
66
50
44
103
13
50
18
46
29
66
119
226
20
61
51
51
50
NS
18
11
22
22
31
22
110
11
18
22
22
53
NS
426
440
478
431
435
540
33
53
525
447
402
66
50
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Klamath Basin Research and Extension Center
Effects of Plant Population on Yield and Grade of Advanced Tri-State Potato Selections, 2007 Page 29