Acuna, Ivette, Barry Jacobsen, Dennis Corsini and Joseph Pavek. "Thaxtomin-A Low Susceptibility
Seedling and Tuber Scab Resistance." [Vol. 76, No. 6, 363]
Thaxtomin A (TA) produced by pathogenic Streptomyces scabies strains is one of the major factors involved in common scab
development. Previously, we reported the use of TA to select common scab resistant germplasm. We will report on results from two
experiments: 1) TA and non-TA select seedlings and 2) Results from a field trial of TA selected clones from 1997. True potato seed (TPS)
from self-crosses of Ranger (very susceptible), Nooksack (moderately resistant) and crosses of Ranger by Nooksack were germinated on
agar containing 0 to 1uM of TA for 7 days at 20 C. Seedlings were evaluated using an index rating of radical necrosis on a 1 to 5 scale (1=no
necrosis, 5=complete radical necrosis). Seedlings with scores of 1 and 2 are rescued from 1uM TA. Random seedlings were rescued from
0uM TA. These seedlings were multiplied in tissue culture and plants were transplanted to miniplots with scab infested field soil. At harvest,
90 days after transplanting, tubers were evaluated for scab symptoms using a scale of 0 to 6 (0-no scab, 6=>90% scabby surface).
Evaluated tubers showed scores in the range of 0.0 to 2.7. Higher percentage of plants (50%) from TA selected seedlings had tuber scores
lower or similar to Nooksack (moderate resistant) compared to plants from non TA selections (29%), (P<0.5). Minitubers
of TA selected seedlings previously tested (1997) in miniplot field soil from selfcrosses of Ranger, Nooksack and Atlantic (susceptible)
were planted in scab infested soil field conditions as a second year trial (1998). Tuber scores from these plots ranged between 1 and 6.
These plants produced tubers with scab scores lower than Ranger (6.0), being mainly similar to or lower than Nooksack (2.6),
(P<0.5). We identified two Ranger progenies with scores of 0.5 and 1.8. We concluded that Thaxtomin A is a useful took for selection
of scab resistant germplasm.
Araji, AA, Acuna Ivette, Barry Jacobsen, Dennis Corsini and Joseph Pavek. "Thaxtomin-A Low
Susceptibility Seedling and Tuber Scab Resistance." [Vol. 76, No. 6, 363]
Thaxtomin A (TA) produced by pathogenic Streptomyces scabies strains is one of the major factors involved in common scab
development. Previously, we reported the use of TA to select common scab resistant germplasm. We will report on results from two
experiments: 1) TA and non-TA select seedlings and 2) Results from a field trial of TA selected clones from 1997. True potato seed
(TPS) from self-crosses of Ranger (very susceptible), Nooksack (moderately resistant) and crosses of Ranger by Nooksack were
germinated on agar containing 0 or 1pM of TA for 7 days at 20 C. Seedlings were evaluated using an index rating of radical necrosis on a
1 to 5 scale (l=no necrosis, 5=complete radical necrosis). Seedlings with scores of 1 and 2 were rescued from 1pM TA. Random
seedlings were rescued from OpM TA. These seedlings were multiplied in tissue culture and plants were transplanted to miniplots
with scab infested field soil. At harvest, 90 days after transplanting, tubers were evaluated for scab symptoms using a scale of 0 to 6
(0=no scab, 6=>90% scabby surface). Evaluated tubers showed scores in the range of 0.0 to 2.7. Higher percentage of plants (50%) from
TA selected seedlings hail tuber scores lower or similar to Nooksack (moderate resistant) compared to plants from non TA selections (29%),
(P<0.05). Minitubers of TA selected seedlings previously tested (1997) in miniplot field soil from self crosses of Ranger,
Nooksack and Atlantic (susceptible) were planted in scab infested soil field conditions as a second year trial (1998). Tuber scores from
these plots ranged between 1 and 6. These plants produced tubers with scab scores lower than Ranger (6.0), being mainly similar to or
lower than Nooksack (2.6), (P<0.05). We identified two Ranger progenies with scores of 1.0 and 1.8 and two Atlantic progenies
with scores of 0.5 and 1.8. We conclude that Thaxtomin A is a useful tool for selection of scab resistant germplasm.<0.05).
We identified two Ranger progenies with scores of 1.0 and 1.8 and two Atlantic progenies with scores of 0.5 and 1.8. We conclude that
Thaxtomin A is a useful tool for selection of scab resistant germplasm.
Araji, AA "The Benefit of Public Investments in Potato Research." [Vol. 76, No. 6, 363]
Agricultural research in the U.S. has evolved into a decentralized federal/state system. The state agricultural experiment stations have
responded with considerable flexibility to changing circumstances and developed appropriate technologies. The economic benefit of
investment in agricultural research has been evaluated for all agricultural commodities, except potato. Potato is an important agricultural
commodity with farm value of over $2.6 billion and processed value of over $4.1 billion. Idaho accounts for over 32% of the fall potato
production and over 29% of all potatoes processed in the U.S.. This study analyzes the benefit of potato research in Idaho. A database to
evaluate the economic, environmental, and social benefits of potato research is developed. It is classified by (1) research area, (2) type of
research, and (3) focus of research. The research includes (1) farm production research, and (2) post-harvest research. The type of research
includes (1) maintenance research, (2) applied research, and (3) basic research. The research focus includes (1) economic focus and
(2) environment focus. The results show a very high return to investment and reduction in chemical use with significant environmental
benefits.
Bamberg, John B and AH del Rio. "Vulnerability of Alleles in the US Potato Genebank Extrapolated
From RAPDs." [Vol. 76, No. 6, 363]
Crop genebanks wish to preserve genes for breeding use, so genebank managers must be concerned with preserving low frequency
alleles that are vulnerable to accidental loss from the genebank. Mathematical models and recommendations that follow from hypothetical
vulnerable alleles have been made. This work was undertaken to measure the actual prevalence of such alleles in the US Potato Genebank
by extrapolation from RAPD markers. Two out crossing species were selected, Solanum jamesii Torr. (2n=2x=24) and Solanum
sucrense Hawkes (2n=4x=48). RAPD banded-plant frequencies for a total of 85 marker loci within each of 15 populations were
assessed using 29 plants per population. For both species, about 10% of within-population bands were vulnerable (frequency considering
just the particular population in question. However, about half of these were fixed (therefore invulnerable) in at least one other population.
The highest within-population frequency for bands not fixed in any population was, with one exception, always. So, while many RAPD alleles
are vulnerable within populations, these are nearly always fixed or nearly fixed (invulnerable) in another population. This indicates that the
most effective strategy for conserving all alleles is to apportion available resources among many separate Mendelian populations rather
than to select a representative few for rigorous attention.
Berlanger, Ingrid E, ML Powelson and KB Johnson. "Verticillium Wilt Suppression With a
Broccoli Green Manure." [Vol. 76, No. 6, 364]
A field study was conducted in 1997 and 1998 to determine the effect of a broccoli green manure on Verticillium wilt of potato in
the Williamette Valley of Oregon. Broccoli was grown in field plots artificially infested with Verticillium dahliae. Following the
incorporation of the broccoli green manure (4.63 kg/rn2) to a depth of 15 cm in August, the soil organic
matter content was unaffected; soil populations of V. dahliae, however, were significantly less (p < 0.05) in broccoli amended
soil than in fallowed soil in both 1997 and 1998. Disease severity in cultivar Russet Norkotah, measured as AUSPC (area under the
senescence progress curve), was reduced by 40% in broccoli amended compared to fallowed soil in 1998 (p < 0.05). Mean total
tuber yield was 9.6% higher in broccoli amended plots than in fallowed plots, however, the difference was not significant. Small volumes
(0.5 L) of a field soil artificially infested with V. dahliae were amended with a broccoli green manure at rates of 0,0.28,0.56, 1.12, or
2.24 kg/L soil and incubated at 25 C for 19 days. The log transformed mean soil populations of V. dahliae were negatively correlated
(r=-0.73) with the amount of biomass incorporated. Soils naturally infested with V. dahliae were collected from Idaho and Washington
potato fields, amended with a broccoli green manure (1.12 kg/L soil), and incubated at 25 C for 17 days. Soil populations of V. dahliae
in greenhouse experiments were 50 to 80% less in broccoli amended soils compared to non-amended soils in 3 of 4 trials. This effect
occurred in both a Delco loam and a Quincy fine sandy loam soil.
Bisognin, DA, DS Douches, K Jastzrebski and W Kirk. "Progeny Evaluation of Potato Late Blight
Resistant Clones." [Vol. 76, No. 6, 364]
Potato breeding has refocused on late blight (LB) - Phytophthora infestans -resistant breeding, because of the increased
aggressiveness and frequency of new races. Since most of the LB resistant sources are late in maturity and poor in tuber quality, it is
very important to know how LB resistance sources combine with susceptible adapted germplasm. The objectives of this study were
1) to evaluate the value of different LB resistant clones associated with tuber quality (chip-processing or tablestock), and 2) to develop
a selection procedure capable of identifying superior individuals in early stages of selection for varietal development. We made crosses
among 8 clones (B0718-3, Bertita, Bzura, Greta, Libertas, Stobrawa, Tollocan and Zarevo) with reported LB resistance and a sample of
susceptible ones to produce 95 families (4,750 seedlings). In 1997, a phenotypic selection in single hill resulted in 408 (8.6%) clones that
were evaluated for chip-quality, tuber appearance and specific gravity. A random sample of tubers from each 8-hill plot were used to evaluate
the clones again in 1998. Also, the clones were evaluated for their LB reaction in greenhouse and in the field trials using LB isolates of the
US-8 genotype. Based on either the percentage of selected clones or mean progeny performance (P<0.05%) the best parents for tuber
quality were Zarevo, Tollocan, and Greta. Overall, 12% and 21% of the clones based on single and 8-hill plot data, respectively, were
considered potential clones for chip-processing and over 90% of the clones for tablestock. Correlation analysis between single and 8-hill
data was high for tuber appearance (r=0.77) and specific gravity (r=0.92) indicating that selection could be done in both stages. The LB
parents that resulted in highest percentage of selected clones were Tollocan, Zarevo, B0718-3, and Greta. Combining LB resistance with
tuber quality, 6% were considered potential clones for chip-processing and 28% for tablestock. In conclusion, the LB resistant parents
differ in their ability to transmit tuber quality characteristics and LB resistance that can be combined in the offspring and superior clones for
tuber appearance and specific gravity can be identified in single hill plots.
Bohl, William H and Stephen L Love. "Effect of Planting Depth on Yield and Agronomic Characteristics
of Three Potato Varieties." [Vol. 76, No. 6, 364]
Potato seed pieces were planted 8, 15, or 23 cm deep measured from the top of the hill to assess planting depth effects on yield and
agronomic characteristics of three potato varieties. Russet Burbank and Frontier Russet were planted in field studies 1995 through 1997
with Shepody being included in 1996 and 1997. Five single-cut seed pieces of each variety were hand-planted with cut side down in each
of five replications. Seed pieces weighed 57-71 gin. The number of days to reach 100 percent emergence averaged over years was
significantly longer for each increase in planting depth for all varieties tested. Planting at 23 cm compared with planting at 8 or 15 cm
significantly reduced total yield of Russet Burbank and Frontier Russet, but total yield was not affected in Shepody. U.S. No. Russet
Burbank yield was not affected by planting depth. Planting Frontier Russet 23 cm significantly reduced U.S. No. 1 yield compared
with 8 or 15 cm. Shepody U.S. No. 1 yield was significantly decreased when planted 8 cm deep compared with 15 cm. Planting Russet
Burbank and Frontier Russet at 23 cm compared with 8 or 15 cm significantly increased the distance to the uppermost tuber Planting
Shepody at 15 or 23 cm compared with 8 cm significantly increased distance to the uppermost tuber. Each increase in planting depth
significantly increased the distance to the lowermost tuber in all varieties. The 23 cm planting depth did not significantly decrease green
tuber yield, measured in 1996 and 1997, compared with 15 cm in these three varieties. Planting at 8 cm significantly increased green tuber
yield in Frontier Russet and Shepody compared with 15 or 23 cm.
Boluarte, Tatiana and Richard E Veilleux. "Molecular Markers Linked to Anther Culture Response
and Leptine Content in Three Backcross Families Derived From Solanum phureja and S. chacoense."
[Vol. 76, No. 6, 365]
BARD 1-3, a clone of S. phureja and 80-1, a clone of S. chacoense shows high and low anther culture response (ACR),
respectively. The same clones have 0 and high leptine content (LC) in their foliage, respectively. An F1
hybrid (CP2) was intermediate for both traits, but self-incompatible. Two backcross (BC) families: PBCp (1-3 x CP2 —78 individuals)
and CBC (CP2 x 80-1 —54 individuals) were phenotypicaliy characterized for ACR. High and low selections were used for bulk
segregant analysis (BSA). PBCp and its reciprocal PBCc (CP2 x 1-3) were screened for LC. High and low leptine genotypes were again
selected for BSA. A total of 160 RAPD primers was screened in these bulks. A band amplified by OPQ1O primer was found to be linked
in repulsion to ACR in PBCp. Another band amplified by OPW14 primer was found to be linked in coupling to ACR. Two primers OPQ2
and OPW1O amplified bands linked in coupling to LC in both the PBCp and PBCc families. Analysis of individual genotypes verified linkage
of the markers to the traits.
Bradeen, James M, S Kristine Ness, Susan M Wielgus, Geraldine T Haberlach and John P
Helgeson. "Late Blight Resistance From Solanum bulbocastanum~ Towards Fine Mapping and BAC Clone Isolation."
[Vol. 76, No. 6, 365]
Late blight remains a disease of major importance to potato production worldwide. Although no U.S. cultivars are adequately resistant,
the wild diploid Solanum bulbocastanum is highly resistant even under extreme disease pressures. However, S. bulbocastanum
is sexually incompatible with potato. Late blight resistant hexaploid potato + S. bulbocastanum somatic hybrids, backcrosses of
somatic hybrids to potato, and a S. bulbocastanum diploid population are the subjects of continued mapping efforts using RFLPs,
RAPDs, and AFLPs. Markers linked to late blight resistance were used to identify BAC clones from a library constructed from S.
bulbocastanum. Further characterization of these clones is ongoing. Among our goals are contig development (i.e. alignment of
overlapping BAC clones) for regions near late blight resistance and development of markers better adapted to large scale breeding
efforts.
Brown, CR, H Mojtahedi and GS Santo. "Genetic Analysis of Resistance to Races 1 and 2 of
Meloidogyne chitwoodi Derived From the Mexican Wild Species Solanum Hougasii."
[Vol. 76, No. 6, 365]
An accession of Solanum hougasii, a wild tuber-bearing potato species native to Mexico was found to be resistant to races 1 and
2 of Meloidogyne chitwoodi. A resistant selection was selfed and the progeny possessed the same combined resistance uniformly.
A selected resistant seedling from the selfed progeny was crossed to cultivated tetraploid potato to form a F1
hybrid, and this was backcrossed to cultivated tetraploid potato to form a BC1 population in which
resistance to the two races segregated. Progeny of the BC1 were tested in inoculation experiments
with four replicates for each progeny genotype for each race of nematode. Resistance was evaluated on the basis of extracted egg counts
from the entire root system of pot grown plants. Considering resistance to each race separately, for race 1, non-host status was exhibited
by approximately half of the BC1. About one-third of the progeny showed nonhost status to race 2. Egg
production among progeny which showed non-host status for both races, was higher with race 2 than with race 1. Analysis of
co-segregation established that genetic control for the two races appears to be independently segregating. This provides evidence of an
independent genetic control in Solanum spp. for resistance to race 2 of M. chitwoodi. These results contribute to our knowledge
base of a series of genes for resistance to M. chitwoodi, identified in Mexican wild species, which may have phytogenetic significance.
Cheng, Hsiang-Tai, Stephanie Peavey and Alan S Kezis. "Regional Differences in Consumer Potato
Purchasing Decision." [Vol. 76, No. 6, 366]
This study analyzes the potato purchasing behaviors of consumers in Massachusetts and North Carolina with the goal of identifying
effective ways of enhancing marketing strategies within different marketing areas. In-personal surveys were conducted, and gathered
information on respondents’ socio-economic characteristics, potato purchasing habits and factors that influence their purchasing
decision. Significant regional differences were found in potato purchasing habits and opinions about the importance of particular
attributes, such as origin of the potatoes and guarantee of product satisfaction. The results of this study clarify the importance of certain
product attributes among different groups of consumers and can be used to help marketers tailor merchandising activities accordingly.
Coltman, Robert R and TLGerman. "Variety-Specific Effects of Seed Generation on Potato
Yields." [Vol. 76, No. 6, 366]
Most certified seed potatoes originate from pathogen-free tissue-culture stocks and are propagated only a limited number of times
under field conditions to reduce the risk of pathogen entry and disease development. Surveys of potato growers have suggested that the
productivity of seed lots declines significantly with years in the field, irrespective of disease levels. This report presents results of a statistical
analysis of six site-years of data that reveals significant influences of field generation (FG) on potato crop productivity in the absence of
significant disease pressure. These influences appear to be variety specific. Elite-foundation quality seed lots of Red Norland Superior and
Atlantic ranging from 2 to 7 years of propagation in the field were planted in replicated field trials at the UW Elite Foundation Seed Potato
Farm and at the UW Hancock Agricultural Research Station in 1994, 1995 & 1996. Orthogonal contrasts were used to identify best-fit
polynomials of yield responses, with data statistically blocked by site-year. No overall effect of FG on yields of Red Norland was found.
Superior yields decreased linearly from FG2 levels in later generations, although the magnitude of this decline was only about 1.7% per year.
The best-fit cubic polynomial for Atlantic yield response indicated that yield declines of 3.8%, 3.0%, 1.5% and O% resulted from a single
additional year of propagation of FG2, FG3, FG4 and FG5 seed lots, respectively. The highly significant recovery of yield potential (2.3%)
for FG6 Atlantic seed lots is enigmatic, but it demonstrates that it is possible to have a positive interaction between successive cycles of field
propagation and seed vigor.
Coombs, Joseph, David Douches, Wenbin Li, Edward Grafius and Walter Pett. "Field Evaluation
of Potato Resistance Mechanisms For Control of Colorado Potato Beetle." [Vol. 76, No. 6, 366]
The Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), is the leading insect pest of potato in
northern latitudes. Host plant resistance is an important tool in an integrated pest management program for controlling insect pests.
During the 1998 season, a field study was conducted to compare natural and engineered host plant resistance mechanisms of potato for
control of Colorado potato beetle. Twenty-seven different lines representing six different host plant resistance mechanisms (glandular
trichomes, leptine glycoalkaloids, Bt-cry3A, Bt-cry5, Bt-cry5+glandular trichomes, and Bt-cry5+leptines) were evaluated in a
choice situation under natural Colorado potato beetle pressure at the Montcalm Research Farm in Entrican, Michigan. Greenhouse-grown
tissue-culture plantlets were transplanted to the field between rows of a susceptible guard cv. Snowden in a randomized complete block
design consisting of four replications often plants each. No insecticides were applied to the field for the duration of the experiment.
Observations were recorded weekly on each individual plant for a visual estimation of percent defoliation by Colorado potato beetle, the
number of egg masses, eggs per mass, and the number of first, second, third, fourth instar larvae, and adults. The Bt-cry3A
transgenics and high leptine expressing lines were most effective for controlling defoliation by Colorado potato beetle adults and larvae.
Although one Bt-cry5 transgenic had significantly lower defoliation than the other Bt-cry5 lines, in general the Bt-cry5
lines were not as effective as the Bt-cry3A transgenics. The glandular trichome and Bt-cry5+glandular trichome lines proved
to be ineffective in this choice field situation. Based on these results, the Bt-cry3A transgenic and high leptine lines are effective
resistance mechanisms that could be incorporated in a resistance management program for control of Colorado potato beetle.
Copp, Leslie J, Robert W Blenkinsop, Alejandro G Marangoni and Rickey Y Yada. "The
Relationship Between Respiration And Color Chip During the Long-Term Storage of Potato Tubers."
[Vol. 76, No. 6, 366]
Commercial processing potatoes, both sprout inhibited and untreated, were evaluated for respiration rate and chip color during storage
under commercial conditions (12 C, —95% humidity, hi darkness) following three growing seasons. While absolute respiration rates
varied depending upon growing season and treatment, all cultivars and treatments studied during the 1995, 1996 and 1997 storage seasons
showed similar relative respiration profiles. The initial stage following curing and sprout inhibition treatment (if applied) showed essentially
constant respiration rates for a period of time varying from 2 to 15 weeks, depending upon growing season, treatment and cultivar. This was
followed by a stage which showed an increase in respiration rates. In some cases the respiration rates eventually stabilized, or decreased.
There was an apparent correlation between increases in respiration rates and decreases in chip color, though the statistical significance
varied between cultivars and seasons. Qualitative analysis of the data showed the point at which respiration rates began to increase
coincided with a precipitous decline in chip color. Monitoring respiration rates may provide a nondestructive, in situ method for
determining the maximum storage life of tubers destined for potato chip production.
Davis, JR, OC Huisman, DO Everson, LH Sorensen and AT Schneider. "Control of Verticillium
Wilt of the Russet Burbank Potato With Corn and Barley." [Vol. 76, No. 6, 367]
A 6-year field study to determine the effects of green manure crops on Verticillium wilt of potato was initiated in 1992 and
concluded in 1997. This study showed Verticillium wilt, caused by Verticillium dahliae, to be controlled when preceded by two
consecutive years of green manures of either Jubilee sweet corn or Jubilee super-sweet corn. When potato had been grown for two
consecutive years in 1994 to 1995, following two years of green manures, the beneficial effects from green manures were minimal.
Following green manure treatments of either sweet corn or barley in 1996, control of Verticillium wilt was restored in 1997 when potato was
again grown in the same plots. This control occurred even though the inoculum densities (ID) of V. dahliae had increased by 2 to 4
fold. Results provide additional evidence that Verticillium wilt of potato may be controlled without reducing the inoculum density
of Verticillium dahliae. With this control, yields were significantly increased by 22%, 31%, and 29% for total yields, U.S. l’s, and
tubers >280 g, respectively. Results of this study emphasize that V. dahliae may be controlled without a pesticide to reduce
inoculum density.
Davis, JR, OC Huisman, DT Westennann, DO Everson, AT Schneider and LH Sorensen.
"Increased Yield and Quality of Russet Burbank With Sudangrass and Associations With Soil Nutrients."
[Vol. 76, No. 6, 367]
A 3-yr field study investigating the effect of green manure incorporation on Verticillium wilt showed wilt reduction, increased inoculum
densities (ID) of Fusarium equiseti and increases of U.S. #1 tubers >280 g by 29-43% as sudangrass was added to soil. Three
lines of evidence indicated that increased yields with sudangrass were independent of Verticillium dahliae infection. Although
V. dahliae infections of potato roots and stems were highly correlated with wilt incidence, these infections were not correlated with
yield and quality. Yield responses were most closely related to N, Mn, and K resulting from added sudangrass. A greenhouse study
comparing rates of sudangrass corroborated a direct effect between quantities of sudangrass, increased populations of equiseti,
and yield that was independent of V. dahliae infection. The direct effect of sudangrass rates on potato quality was further confirmed
with an additional 3-yr field study comparing green manures of sudangrass, barley, sweet corn, Austrian winter pea, and fallow treatments.
Sudangrass showed significant increases of U.S. #1 tubers and tubers>280 g. These increases again exceeded benefits from
Verticillium wilt suppression. As with earlier work, benefits to potato quality were associated with Mn from the sudangrass
green manure.
del Rio, Alfonso H and John B Bamberg. "Association of Eco-Geographical Variables With Patterns of
Genetic Variation in Native Wild US Potato Populations Determined by RAPD Markers." [Vol. 76, No. 6, 367]
Strategies to maximize capture of genetic variation are essential in germplasm conservation. Sampling diversity would become more
efficient if collecting explorations had clearly defined target areas. This research investigated whether eco-geographical structure has a
significant association with patterns of genetic variation in wild potato populations. This study used 96 populations collected from the
southwestern US: 43 populations of Solanum fendleri (2n=2x=48) and 53 of S. jamesii (2n=2x=24). These species
represent two of the most predominant breeding systems among Solanum species. RAPD markers were used to assess genetic
variation through: (1) estimation of genetic differences and (2) estimation of genetic diversity. Results from 2,282 pair wise comparisons
suggest that patterns of genetic differentiation are not explained by differences in eco-geographical variables. Remarkably, physical
separation, a parameter very often used for collecting germplasm, did not predict genetic differentiation very well. The assessment of
genetic diversity revealed that eco-geographical variables significantly predicted genetic diversity in S. fendleri populations. In contrast,
genetic diversity had no significant association with eco-geographic components for the diploid species S. jamesii. This study reveals
how genetic variation relates to geographical and environmental variables at sites of origin. Such information could help to enhance efficiency
in collecting strategies.
Dong, Fenggao, Junqi Song and Jiming Jiang. "Development of Chromosome-Specific
Cytogenetic DNA Markers in Potatoes." [Vol. 76, No. 6, 368]
Potato chromosomes are small and similar in size, making it impractical to identify the 12 different chromosomes by conventional
somatic chromosome karyotyping, pachytene chromosome analysis and chromosome banding. A bacterial artificial chromosome (BAC)
library was constructed from a diploid species Solanum bulbocastanum. DNA of 24,576 clones from this library were placed on 16
nylon filters and hybridized with potato DNA markers with known chromosomal locations based on restriction fragment length polymorphism
(RFLP) mapping. BAC clones with positive hybridizations to the RFLP probes were selected and their DNA were hybridized onto potato
chromosomes by fluorescence in situ hybridization (FISH). Such BAC clones generated distinctive and consistent FISH signals on
both somatic metaphase chromosomes and meiotic pachytene chromosomes, which can serve as convenient and reliable cytogenetic
markers for chromosome identification in potatoes. Cytological mapping of marker-tagged BAC clones can also integrate the cytogenetic
chromosome numbering system with the one in genetic mapping. So far, 12 such markers have been isolated and tested, with one for
each potato chromosome.
Englehart, Kathryn M and Michael E Vayda. "A Multiplex PCR System For Simultaneous
Detection of Three Potato Viruses." [Vol. 76, No. 6, 368]
A multiplex PCR assay for three potato viruses was developed to augment ELISA screening of nuclear seed. Assays for Potato Virus
X (PVX), Potato Virus Y (PVY) and Potato Leaf Roll Virus (PLRV) were developed independently and then optimized for simultaneous use in
a single reaction. Efficacy of this technique was first assessed using samples known to contain, or be free of, the target viruses. In order to
test the sensitivity and reliability of this assay, we applied the multiplex approach to screen potato leaf samples taken early and in the middle
of the 1998 field season, and tubers from the same plants were tested upon harvest. This work was conducted at the Aroostook Farm in
Presque Isle, ME. All materials tested by multiplex PCR assay were also screened by standard ELISA assay using Agdia kits. Our results to
date indicate that the PCR multiplex assay can reliably and effectively detect viruses in singly- or multiple-infected plant tissues early in the
field season.
Errampalli, Deena, Walter Arsenault, J Brian Sanderson and Tony Sturz. "Response of Four
Different Potato Cultivars to Black Scurf of Potatoes." [Vol. 76, No. 6, 368]
Rhizoctonia solani, the causal agent of black scurf of potato is found wherever potatoes are grown. This pathogen attacks potato at
more than one stage in potato development and black scurf usually results in a decline in tuber quality. A field experiment was conducted
to demonstrate the relationship between stem canker and black scurf stages, and yield in four potato cultivars, Kennebec, Shepody,
Superior and Russet Burbank. Significantly higher disease incidence was observed on the R. solani inoculated treatments
(18%) than non-inoculated treatments (10%). Relationships between black scurf, and total and marketable yields were observed. Black
scurf disease progression in storage was assessed by comparing the disease incidence at harvest and after three months in storage.
Significantly higher disease incidence was seen on tubers after storage (27%) than at harvest (14%). The effect of seed piece treatments
on R. solani and yield will also be discussed.
Estrada, Nelson, R Pineda, A Rodriguez and Sonia Tinjaca. "Crossability Between Solanum
Stoloniferum and Solanum Palustre, Two Wild Potato Species." [Vol. 76, No. 6, 368]
Solanum stoloniferum Schltdl, 2n-4x=48, was crossed to Solanum palustre Schltdl, 2n-2x=24 obtaining valuable and productive
Fl hybrids. The first crosses were made on 1984 in Andean environmental conditions at 2600 m.o.s.l., near Bogota. A few of the hybrids
appeared as tetraploids, being more tuber productive and showing acceptable cooking quality. In fact, two of them have been released
as commercial varieties: JASPE in Bolivia (clone CCC84-75-16) and MOR1TA (clone CCC 84-630-1). The parents of both clones were sto
P1. 160225 and pls P1218228. More recently 10 additional cross combinations have been made utilizing 5 different sto and two different
pls P1 accessions, getting about 700 seeds and some hybrids showing fairly good tuber types (3-4 cm). S. stoloniferum is considered
to be an allopolyploid species and its genomic differentiation and low homeologous pairing has been often postulated to explain its
cytological and Crossability results. The purpose of these crosses was to get genetic materials more resistant to some virus diseases and
to late blight.
Estrada, Nelson and Sonia Tinjaca. "Crossability Between Solanum Palustre and Solanum
Etuberosum, Two Non-Tuber Bearing Potato Species." [Vol. 76, No. 6, 369]
Solanum palustre Schltdl (2n-2x=24) previously named S. brevidens was crossed successfully to Solanum
etuberosum Phil, obtaining viable seeds and thrifty seedlings under the Andean conditions of Colombia and Bolivia (3000 m.o.s.l). On
1998, were planted 28 seeds obtaining after germination 17 seedlings which at maturity were able to produce from 2 to six small tubers
(5 to 8 mm), but no flowers. These clones were planted in February 1999 supplying them with extra daylight hours trying to induce flowering
and to make possible crosses to diploid cultivated clones of the Solanum phureja species. Both pls and etb species have genetic
potential to transfer onto cultivated potatoes resistance to important virus diseases. S. palustre in addition, has been reported
as resistant to some bacterial diseases, as well as to late blight (field resistance) and to light frosts.
Ewing, Elmer E, Ivan Simko, Christine D Smart, Mendeth W Bonierbale, Eduardo SG Mizubuti, Gregory D May
and William E Fry. "An R-Gene From Solanum berthaultii For Resistance to Phytophthora infestans Maps to
Qznmiosome 10." [Vol. 76, No. 6, 369]
A backcross population [Solanum tuberosum x S. berthaultii) x S. tuberosum segregated for resistance to
Phytophthora infestans, indicating the presence of an R-gene. The R-gene segregated from the S. berthaultiiparent and
mapped 4.8 cM from the RFLP marker TG63 on chromosome 10. Other resistance genes have been reported in this region, including
Ph-2, an R-gene from tomato. The tester clone was an isolate of the US-8 clonal lineage of P. infestans. This isolate is
compatible to R-genes 1, 2, 3, 4, 5, 7, and 10 and incompatible with R-genes 6, 8, 9, and 11. It is incompatible
with Ph-1 and Ph-2 from tomato. Genotypes incompatible to US-8 were also incompatible when inoculated with an isolate of
US-7 (compatible to Ph-I and Ph-2). From comparison with the location of the five other R-genes that have been mapped, the
R-gene from S. berthaultii was not R-t, R-2, R-3, R-6, or R-7. Based upon compatibility, it does not appear to be
R-4, R-5, R-10, Ph-I, or Ph-2.
Glass, Jenny Rebecca, KB Johnson and ML Powelson. "Barriers to Potato Tuber Infection by
Phytophthora infestans." [Vol. 76, No. 6, 369]
An understanding of how P. infestans inoculum travels from potato foliage to infect developing tubers is crucial to the development
of late blight management strategies. Our studies investigated if physical barriers, plastic mulches or deeper soil layers, could protect tubers
from disease. In the plastic mulching trial, Red la Soda tubers were planted in a randomized block with factorial treatments of stem and
hill barriers. A PVC pipe surrounding the plant stem separated the stem area from the rest of the hill and the plots were mulched with black
plastic and/or spray foam to prevent water containing spores from penetrating into these areas. Using foam to block movement of water down
the stem had little effect on the percentage of diseased tubers (P =0.1697) while plastic along the hill significantly reduced
(P= 0.0001) the percentage of infection. On average, the percentage of infected tubers in the plots covered with black plastic was
31.8% ± 3.6% as compared to 56.1% ± 3.6% in plots without the black plastic mulch covering the hill. In the hilling regime trial, three potato
cultivars, Russet Burbank, Red la Soda and Shepody, were planted in a split-plot design with three hilling treatments. The low, medium and
high hilling regimes, established by running a hilling machine over plots 0, 1 or 2 times, hart cross-sectional areas of 263.2 ± 22.7,
494.0 ± 18.9, 662.1 ± 32.9 cm2, respectively. Both hill (P=0.0005) and cultivar (P=0.0001)
were shown to have an effect on the percentage of diseased tubers. On average, Red La Soda had 47% ± 3% of the tubers infected,
Shepody 39% ± 3% and Russet Burbank 15% ± 3%. The low hill regime resulted in 40.3% ± 2.6% diseased tubers as compared to the
middle (30.1% ± 2.6%) and high hills (31.0% ± 2.6%). Although tuber infection appears difficult to suppress in a favorable environment, this
research may provide direction for the development of management strategies that target this important stage of disease. Chromosome
pairing occurs, but univalents are also present. It displays field resistance to late blight equivalent to its wild species’ parent.
Haploid x S. berthaultii hybrids exhibited moderate to high resistance to late blight and good agronomic characteristics. Colorado
potato beetle resistance was tested among Tuberosum haploid species hybrids of S. bukasovii, S. chacoense, S. raphanifolium, S.
sparsipilum, S. tarijense, and S. tuberosum ssp. andigena. Twenty-one families, one backcross, 9 PIs, 11 haploids, and
7 cultivars were tested in a 7x7 lattice using Norland as a spreader. S. bukasovii, S. raphanifolium, and S. sparsipilum
families displayed low levels of insect resistance. S. tarijense families exhibited moderate resistance and S. chacoense
families showed high resistance. Information such us this will help to continue to lay a firm foundation for utilization of wild species for
enhancement and pre-breeding for the 21st century.
Goth, RW and EW Goins. "The Schultz Potato Virus Collection."
[Vol. 76, No. 6, 371]
The Schultz Potato Virus Collection, containing 17 distinct pathogens, some of which occur as strains, are maintained on Aroostook
Farm, Presque Isle, Maine, and at Beltsville, Maryland. The collection, initiated in 1916, is maintained in cages to prevent contamination
and insure against loss of the original virus. The collection was maintained by E.S. Schultz until his retirement in 1954, R.E. Webb
1954-1960, W.B. Raymer,1960-1967, and R.W. Goth 1968-date. Each virus culture is maintained in tuber progeny and plants. Two seedlings,
one designated S 41956 (immune to PVX) and another of cv Green Mountain (virus X-free) are used to maintain the viruses without PVX.
Since the discovery of Potato virus 5, in 1951, some entries are maintained in the cv Saco, which is immune to viruses PVA, PVS, and PVX.
Each potato variety or seedling containing a virus culture is grown under 2 separate cages in the field. Four plants are grown in each cage.
Since 1989 ELISA and nucleic acid tests for PSTVd have been used to test all plants for PVA, PVM, PVS, PVX, PVY, PLRV, and PSTV. Tubers
harvested from these cages are used for replanting and distribution to other investigators. In addition to serving as Type cultures, material
from this collection has been used to study physical properties, strain variations, serological properties, virus-vector relationships, genetics
and the development of disease-resistant cultivars.
Halseth, Donald E, WL Hymes and Randy L MacLaury. "Benefits of Pre-Warming and Pre-Cutting
Seed of Long Dormancy Clones." [Vol. 76, No. 6, 371]
Many new clones from the Cornell potato breeding program have relatively long tuber dormancy. NYIO1, Andover, Pike, NY1O3 and
Allegany have tuber dormancies of 2.2,6.1,6 .3, 8.5 and 10.8 weeks longer than Atlantic, respectively. As seed of all of our breeding and
extension yield trials are warmed and cut one to two months in advance of planting, tuber dormancy is not considered a problem. However,
as many NYS growers cut and plant within a day or two, tuber dormancy may have an impact on stand and yield. Several seed handling
experiments have been conducted to assess the level of significance that tuber dormancy may impose on yields. In one experiment Allegany
seed was subjected to three treatments: (CEHW) cut early and held warm at 15.6 C for 4 weeks; (CPHW) held warm at 15.6 C for 4 weeks
and cut at planting; and (CPHC) held cold at 4.4 C, then warmed two days at 15.6 C and cut at planting. This trial was conducted on grower
farms in Steuben and Wyoming counties and averaged total yield increases of 30% and 18% for the CEHW and CPHW treatments,
respectively. In three years of trials at our research farm, the CEHW treatment produced a 15% and 19% increase in total and marketable
yields, respectively, for Allegany. In a similar trial with Allegany, Atlantic Superior and NY1O3, the CEHW treatment increased marketable yields
by 15%, 29%, 11% and 14%, respectively. Tuber set, tuber weight and specific gravity of these four clones were not significantly affected by
seed handling treatments. Note that Atlantic and Superior, with shorter tuber dormancy, also benefited from seed pre-warming and
pre-cutting.
Hanneman, Robert E, Jr. "Techniques to Transfer Germplasm From 2X(1EBN) Mexican Species
to 2X(2EBN) Material Via Hybridization." [Vol. 76, No. 6, 371]
The 2x(1EBN) Mexican species are a rich genetic resource exhibiting extreme resistance to viruses, insects, fungi and nematodes.
This group of species is unable to hybridize with other 2EBN diploid species and 2x(2EBN) Tuberosum haploids because of EBN. To use
these species efficiently, means must be found to routinely create hybrids between 2x(1EBN) and 2x(2EBN) species and haploids. A hybrid
has been created between a Tuberosum haploid and the Mexican species S. pinnatisectum using embryo rescue and second
pollination techniques. Hybrids have also been generated using S. verrucosum as a bridging species. In addition, the S.
verrucosum -2x(1EBN) Mexican species hybrids have been successfully crossed with 2x(2EBN) S. phureja, S. chacoense and a
Tuberosum haploid. An efficient and effective means has been found to open the 2x(1EBN) genepool to exploitation for potato improvement
using common hybridization techniques coupled with knowledge of 2n gametes and Endosperm Balance Number (EBN).
Hanneman, RE, Jr and M Ramon. "Evaluation and Pre-Breeding With New Sources of
Resistance to Colorado Potato Beetle and Late Blight." [Vol. 76, No. 6, 371]
As apart of the joint National Cooperative Enhancement Project, enhancement materials are evaluated for resistance to early blight,
late blight, Colorado potato beetle in unsprayed plots and for early dying in an infected plot at the UW Agricultural Research Station at
Hancock, Wisconsin. These tests augment routine evaluations for yield, chipping, specific gravity, adaptation, etc. A summary of 1998
field evaluation on over 1000 selections for early blight, Colorado potato beetle and early dying will be reported. A unique haploid x S.
pinnatisectum hybrid was evaluated. It exhibits low blight, respectively. Although each species is extremely difficult to cross directly with
potato, we have obtained fertile somatic hybrids for use in breeding programs. In each case, we have also demonstrated that the disease
resistance of the wild species can be recovered in sexual progeny of the hybrid crossed with potato breeding lines. With S.
brevidens - derived materials, we have obtained evidence for introgression of wild species DNA into the potato genome. With S.
bulbocastanum - derived materials we have obtained full resistance to late blight even in third backcross progeny. These results
indicate that these lines, which we will provide to breeders on request, can provide a number of resistances that could be highly
economically useful. During the next year we will cross key hybrids with potato breeding lines to preserve useful genotypes in progeny.
However, at the present time we can still provide the fertile hybrids to breeders so that they can make the crosses with lines of their choice.
Haynes, KG, BJ Christ, DP Weingartner, DS Douches, CA Thill, G Secor, WE Fry and DH
Lambert. "Foliar Resistance to Late Blight in Potato Clones Evaluated in National Trials in 1997."
[Vol 76, No. 6, 370]
With the emergence of new and more aggressive strains of Phytophthora infestans an evaluation of potato clones for resistance
to late blight is necessary. Twenty-two potato clones (10 cultivars, 12 selections) were evaluated in 1997 for late blight resistance at seven
U.S. locations. The US-8 strain of P. infestans was present. Percent infected foliage was recorded at approximately weekly intervals
following the onset of disease. Area under the disease progress curve (AUDPC) was calculated. The nonparametric stability statistics mean
absolute rank differences and variances of the ranks were analyzed for phenotypic stability. Both of these statistics were significant,
indicating the importance of genotype x environment interaction on the rankings of these clones across locations. The most late blight
resistant clones were AWn86514-2, B0692-4, B0718-3 and B0767-2. The most susceptible clones were B1004-8, NorDorina, Krantz, and
Libertas.
Haynes, KG, DP Weingartner, DS Douches, CA Thill, G Secor, WE Fry, DH Lambert, BJ Christ and R Voss. "Foliar Resistance to Late Blight in Potato Clones Evaluated in National Trials in 1998."
[Vol. 76, No. 6, 370]
With the emergence of new and more aggressive strains of Phytophthora infestans an evaluation of potato clones for resistance
to late blight is necessary. Thirty-five potato clones (12 cultivars, 14 selections, 9 differentials) were evaluated in 1998 for late blight
resistance at eight US. locations. The US-8 or US-1 strains of P. infestans were present. Percent infected foliage was recorded at
approximately weekly intervals following the onset of disease. Area under the disease progress curve (AUDPC) was calculated The
nonparametric stability statistics mean absolute rank differences and variances of the ranks were analyzed for phenotypic stability. Both of
these statistics were significant, indicating the importance of genotype x environment interaction on the rankings of these clones across
locations. The most late blight resistant clones were AWn86514-2, B0692-4, and B0718-3. These clones are important breeding materials
for resistance to P. infestans. AUDPC was minimal in the differentials LBR8 and LBR
9.
Heckman, JR, MR Henninger and RW Goth. "Scab on Potatoes in Relation to Source of
Nitrogen and Manganese Fertilization." [Vol. 76, No. 6, 370]
In 1998, a field experiment to investigate the influence of MnSO4 and N source on incidence of
scab (streptomyces scabies) of potato (Solanum tuberosum) was conducted on a pH 7.0 Holmdel sandy loam soil (fine-loamy,
mixed, mesic Aquic Hapludult) near Adolphia, NJ. Soybean (Glycine max) previously grown in this field exhibited Mn deficiency
symptoms. Mn was measured at 4.0 mg/kg using the Mehlich-3 extractant soil test method. The potato cv was Green Mountain. The
treatments were seed tuber inoculation with mixed isolates of Streptomyces scabies and uninoculated. Nitrogen was applied at
168 kg N/ha as either Ca(N031)2 or (NH
4) 2 S04, and Mn was applied in the
row at 0 or 22.4 kg Mn/ha as MnSO4. Inoculation of seed tubers significantly increased the percentage of
scabby tubers at harvest, 64% for the inoculated seed pieces vs 3% uninoculated. Neither the application of MnSO
4 nor the source of the N fertilizer affected the incidence of common scab. The percentage of scabby tubers was 30%
for applied Mn and 37% without. For N source, percentage of scabby tubers was 32% with Ca(N03)
2 and 34% with (NH4) 2
SO4.
Helgeson, John P, Kristine Naess, James M Bradeen, Susan M Wielgus and Geraldine T Haberlach.
"Availability of Somatic Hybrids Between Potato and Wild Solanum Species For Obtaining New Disease Resistant Breeding
Lines." [Vol. 76, No. 6, 370]
Wild IEBN Solanum species such as S. brevidens, S. commersonii, and S. bulbocastanum carry genes for
resistances to potato leaf roll virus (PLRV), bacterial wilt and late blight, respectively. Although each species is extremely difficult to cross
directly with potato, we have obtained fertile somatic hybrids for use in breeding programs. In each case, we have also demonstrated
that the disease resistance of the wild species can be recovered in sexual progeny of the hybrid crossed with potato breeding lines. With
S. brevidens - derived materials we have obtained full resistance to late blight even in third backcross progeny. These results indicate
that these lines, which we will provide to breeders on request, can provide a number of resistances that could be highly economically useful
genotypes in progeny. However, at the present time we can still provide the fertile hybrids to breeders so that they can make the crosses
with lines of their choice.
Honeycutt, C Wayne, Georgette M Trusty and David B Torrey. "Foliar versus Soil N Application
to Potato: 15N Recovery, Growth, Yield, and Quality Relations." [Vol. 76, No. 6, 372]
Only about 30-50% of N fertilizer applied to soil at planting is recovered by potato (Solanum tuberosum L.) under rainfed
conditions in Maine. This unrecovered N represents a significant loss in profitability and a potential environmental concern. A field study
was conducted in Newport, ME with cv. Atlantic to determine the most efficient method of supplying N to potato (i.e., foliar application, soil
application, or some combination of both) and to determine if recommended N fertilization rates can be reduced through foliar application.
Recovery of soil-applied 15N depleted ammonium sulfate ranged from 37 to 57%. Uptake of foliar
15N enriched urea ranged from 56 to 69%. Tuber yield ranged from 28 to 38 Mg
ha-1 when N was soil-applied, but only 21 to 31 Mg ha-1 when
foliar-applied. Greater root growth was observed for soil-applied N (228 kg root dry weight ha-1)
compared to foliar N (177 kg root dry weight ha’). Lower yield with foliar N may reflect the importance of soil-applied fertilizers for
promoting root growth and thus water uptake. Although N use efficiency was greatest with foliar N, the observed yield penalty indicates
foliar application is not a viable alternative to soil application of N to potato.
Ingerson-Mahar, Joe and MR Henninger. "Surveying Wireworms to Predict Damage in White
Potatoes in New Jersey." [Vol. 76, No. 6, 372]
Within the past 6 years, wireworms, particularly Melanotus communis (Gyllenhal), have become a problem in field corn
(Zea mays) and potatoes (Solanum tuberosum) in the Salem and Cumberland County area of southern New Jersey. Bait
trapping, using a mixture of corn and wheat seed to attract wireworms, has become an effective way of determining whether wireworms are
present in fields and how many prior to planting. Studying wireworms numbers in corn fields preceding potatoes has provided cultural
recommendations to farmers to help lessen wireworm injury. Avoid planting potatoes in fields that have received dairy manure and have a
history of continuous corn. Change the crop rotations to reduce or eliminate corn and small grains between plantings of potatoes.
Inglis, DA, BM Gundersen, RLLudy and ML Powelson. "Preventive Versus Curative Applications
of Potato Seed Piece Fungicides For Management of Seedborne Phytophthora infestans."
[Vol. 76, No. 6, 372]
Healthy and blighted potato tubers were cut into 2 oz seedpieces, treated with selected fungicides (Tops MZ @ 1 lb/cwt; Curzate
M-8 @ 10,000 ppm ai.; mancozeb @ 1 lb/ cwt; Tops SD @ 0.5 lb/cwt), and planted in the field at Mount Vernon and greenhouse at Corvallis.
Healthy seed pieces were inoculated following fungicide treatment whereas blighted seed pieces were inoculated 7-10 days prior to
treatment using US-11 on White Rose and US-8 on Russet Burbank at the respective locations. At Mount Vernon, emergence of inoculated
vs. blighted seed pieces was 97 vs. 20, 99 vs. 22, and 97 vs. 8% for Tops MZ, Curzate M-8, and mancozeb, respectively. In contrast,
emergence of inoculated vs. blighted seedpieces was 14 vs. 2, and 5 vs. 1% for Tops SD and the nontreated control, respectively.
Similarly at Corvallis, treatment of inoculated vs. blighted seedpieces resulted in 85 vs. 18, 65 vs. 14 and 55 vs. 6, and 11 vs.
2 and 1 vs. 2% emergence for the five respective treatments. Preventive application of a fungicide without activity against
P. infestans as well as curative applications of fungicides with or without activity against P. infestans to seed pieces
resulted in decreased emergence, lower area under the emergence progress curve and increased seed piece decay of emerged plants.
Seedpiece fungicides with activity against P. infestans need to be applied preventively rather than curatively for control of seedborne
inoculum.
James, Steven R "A Comparison of Two Winter Testing Schemes For Certifying Seed Potato
Lots." [Vol. 76, No. 6, 372]
Greenhouse and outdoor winter testing schemes for certifying seed potato lots were compared between 1995 and 1998. Samples
taken from seed lots produced during the 1995, 1996, and 1997 growing seasons were obtained from central Oregon growers and divided
into two size ranges. The 2-3 ounce (57-85g) tubers were planted at Oceanside, California (outdoor site), and the 4-6 ounce (1 13-170g)
tubers were planted at Corvallis, Oregon (greenhouse site) and rated for viral infection by certifying agencies in Idaho and Oregon,
respectively. The percentage of plants visually observed to be infected with Potato Virus Y (PVY) or Potato Leafroll Virus (PLRV) was nearly
identical at each testing location in 1995-96 and 1996-97. In 1997-98, PVY infection was detected in the same lots at both winter testing sites,
however, the percentage of infected plants varied inconsistently. Emergence averaged 73 percent at Oceanside and 96 percent at Corvallis
over the three seasons the study was conducted.
James, Steven R, Dan C Bane, Alvin R Mosley, Kenneth A Rykbost and Clinton C Shock.
"A World Wide Web Database For Potato Breeding Selections. [Vol. 76, No. 6, 373]
A database of potato variety trial results from testing sites in the western United States was developed. Database records contain plant
and tuber characteristics, yield, grade, tuber internal and external defects, French fry color and quality, and disease evaluations. Included in
the database are breeding selections tested in Oregon advanced statewide variety trials from 1987 to present, western regional variety trials
from 1991 to present, and tristate variety trials from 1997 to present. Variety trial data was placed in a Microsoft Access database and
published on the World Wide Web using Active Server Pages. Web users can generate custom reports by selecting the breeding selection,
testing site(s), year(s) tested, trial(s), and data desired. Plant and tuber photographs, descriptions and disease reactions for each breeding
selection can also be accessed. Database information can be retrieved at: http://oregonstate.edu/potatoes/potlinks.htm
Johnson, Alexander, AT, A Raymond Miller and Richard E Veilleux. "Agronomic, Leptine and
Fertility Analysis of a Potato Somatic Hybrid and First Generation Progeny. [Vol. 76, No. 6, 373]
A somatic hybrid (SH2) was produced by protoplast fusion between Solanum phureja monoplold 13-14 203 (2n=lx=l2) and a
monoploid CP2-103, derived from an F1 hybrid between S. chacoense and S. phureja, to
transfer leptines, a feeding deterrent of the Colorado potato beetle (Leptinotarsa decemlineata Say), to cultivated potato. 5H2
(2n=6x=72) was pollinated with both S. phureja clone 66AP11-53 (2n=2x=24) and S. andigena clone 8-1 (2n=4x=48) to yield
SH2P and SH2A progeny, respectively. A replicated field trial consisting of 9 clones (SH2, 4 SH2P progeny, 2 SH2A progeny and cvs.
Katahdin and Atlantic) was conducted in 1998. The two cultivars had the greatest total tuber yield (1.7 kg per plant) but did not differ
significantly from one of the SH2P progeny. Tuber number per plant was similar for the two cultivars, SH2 and 4 of its progeny. The
cultivars had the highest average tuber weight (152 g per tuber). However, 3 SH2P progeny exceeded the average tuber weight of SH2
(20 g per tuber). SH2 produced 7,256 pg mg-1 dry weight of acetylleptinidine (ALD). SH2 progeny
produced ALD ranging from 995-4,740 pg mg-1 dry weight for SH2P progeny to 1,996-3,034 pg
mg-1 dry weight for SH2A progeny. SH2P and SH2A progeny displayed increased fertility relative to
SH2 and were crossed as both male and female parents to cv. Atlantic.
Joyce, PJ, KF McCue, WR Belknap, DL Corsini, SL Love, H Groza and BD Bowen.
"Glycoalkaloid Levels in a Genetically Modified Lenape. [Vol. 76, No. 6, 373]
Microtuber discs were used in the transformation of the variety Lenape by Agrobacterium-mediated gene transfer. The new
transgenic lines contained an antisense solanidine glucose-ADP glucosyltransferase (SGT) transgene, with the intention of inhibiting the
biosynthesis of tuber glycoalkaloids. Thirteen transgenic lines of the variety Lenape were evaluated and characterized in replicated trials
at two locations, Rhinelander and Aberdeen. In Aberdeen tubers from three transgenic lines had significantly lower glycoalkaloid levels
than tubers of the variety Lenape. Glycoalkaloid concentrations of the transgenic lines ranged from 24.6 milligrams glycoalkaloids per
100 grams tuber fresh weight (mg/1OO g FW) to 15.7 mg/100 g FW with Lenape at 22.2 mg/100 g FW. In Rhinelander, similar reductions
were measured, but they were not statistically significant. Western analysis revealed lower levels of glycoalkaloids correlated with lower
levels of the SGT protein. Northern analysis confirmed the presence of the antisense SGT RNA in the transgenic plants. Northern
and Western analyses are consistent with the hypothesis that the antisense SGT gene inhibited the biosynthesis of the glycoalkaloids.
Kelling, KA and PE Speth. "Responsiveness of Russet Burbank to ACA Rate.
[Vol. 76, No. 6, 373]
Agricultural Crop Additive (ACA) is zinc ammonium acetate, contains 15% N and 17% Zn, and in some situations, has been shown to
increase root growth, stress tolerance, and crop yield. Yield responses with agronomic crops have been mixed; however, few experiments
have been conducted with horticultural crops. We evaluated the use of several ACA rates (48 to 288 mL/ha) applied with the banded fertilizer
at planting in each of 4 years on a Plainfield loamy sand (Typic Udipsamments, sandy, mixed, mesic), using a RCB design with six
replications. A different set of plots was used in each year. In each of the years, at least one ASA rate (96 mL/ha in 1994, 48, 96, and 288
mL/ha in 1996; 192 mL/ha in 1997, and 288 mL/ha in 1998) increased total yield above a 0 ACA control (Pr _ 0.10). Averaged over the 4
years, all rates increased total yield significantly or nearly significantly. Grade and size parameters showed some tendencies toward
improvement with ACA, but results were very inconsistent. Early-season growth (vegetation weight, root weight, tuber number, tuber weight)
did not show any consistent effect of the ACA additions, nor did mid-season leaflet and petiole nutrient analysis. While data from these
experiments show general potato yield benefits from using ACA, no clear mode of action was identifiable.
Kelling, KA and PE Speth. "Effect of Harvest Date on Optimum N Rate For Norland.
[Vol. 76, No. 6, 374]
Previous research at Wisconsin showed that the optimum nitrogen rate for the variety Norland, when grown for full season on sandy
soils, was very high (270 to 335 kg/ha). However, this red variety is often harvested early in an attempt to capture part of the early-season
new potato market. This research attempted to identify the optimum N rate x harvest date relationship for Norland by applying various rates
of N (0 to 270 kg/ha in 67 kg/ha increments) and harvesting the potato at three times (mid-July, mid-August, or mid-September). In all 3
years, the potato had senescence by 25 to 30 August, irrespective of N rate. Plots were laid out in split plots with harvest date as the main
plot and N rate as the subplots in a RCB with four replications on a Plainfield loamy sand (Typic Udipsamments, sandy, mixed, mesic). In
2 of the 3 years of the study, the N rate x harvest date interaction time was significant for total yield, size, grade, and yield of US#1 170 to 370
g tubers. As expected, yield and quality were maximized with a lower N rate for the earliest harvest (135 kg N/ha), but required about 200 kg
N/ha for the later two harvest dates. It is likely the data may have separated even more had we been able to keep the crop growing for the full
season. Data from this experiment confirm that lower N rates may be used for early-harvested potato.
Kianian, Penny MA and Richard G Novy. "The Development of Codominant Sequence Tagged
Site Markers From RAPD Heteroduplexes. [Vol. 76, No. 6, 374]
Random amplified polymorphic DNA (RAPD) markers have been used extensively in the plant sciences for genetic analyses. RAPDs
typically have a dominant mode of inheritance, however, the occurrence of codominant RAPDs has been reported in a number of plant
species. These codominant RAPDs result from the amplification of "allelic" DNA segments that differ by the insertion, deletion,
or substitution of base pairs between their primer annealing sites. During PCR amplification, the DNA strands of each codominant
marker may reanneal to form two homoduplexes and two heteroduplexes. The migration of hybrid heteroduplex molecules during
non-denaturing electrophoresis differs from the homoduplex bands from which they originate. While confounding in genetic analyses,
RAPD heteroduplexes also provide a means of identifying codominant RAPDs. Once identified, codominant RAPDs can be cloned arid
sequenced, and primers specific for their amplification designed—effectively converting a codominant RAPD to a sequence tagged
site (STS) marker. We report on the identification and cloning of two codominant RAPDs that were identified based on their formation of a
heteroduplex band. The two codominant RAPDs were sequenced and found to have 83% homology with one another. The major difference
between the two Hands was a deletion of 26 bp within the smaller fragment. These RAPDs were converted to STS markers following the
design of 20-mer primers specific for their amplification at higher annealing temperatures. This research provides a new approach in the
development of codominant molecular markers similar to SSR’s, but without their difficulty in identification and development. The
development of additional STS markers using this approach is ongoing.
Kirk, William W, Jeffery M Stein, Robert L Schafer and Brendan A Niemira. "Efficacy of Azoxystrobin
Against Potato Late Blight. [Vol. 76, No. 6, 374]
Azoxystrobin (Quadris®, Zeneca), a novel fungicide from the strobilurin class, was tested over three years in field trials inoculated
with Phytophthora infestans and in controlled environment studies. Dose response studies conducted in the field confirmed
functional application rates between 0.225 and 0.337 kg a.i./ha. when azoxystrobin was applied prophylactically. Studies in which
azoxystrobin was applied after test plots had been inoculated showed that azoxystrobin suppressed late blight up to 72 hours after
inoculation but not after late blight became established. Controlled environment studies to establish the duration of efficacy of azoxystrobin
will be reported.
Kirk, William W, David Douches, Brendan A Niemira and Jeffery M Stein. "Combining Varietal
Resistance With Managed Fungicide Applications For The Control of Potato Late Blight." [Vol. 76, No. 6, 375]
Durable resistance was defined as production systems that utilized potato cultivars with reduced susceptibility to late blight in
combination with managed fungicide applications. Experiments to control late blight using fungicides in combination with heritable host
resistance using reduced amounts of fungicide (combinations of extended intervals and reduced dose rates) and with lower amounts of
active ingredient fungicides were continued from trials conducted in 1997. Reduced levels of fungicide applications resulted in less foliar
disease when combined with varietal resistance. The novel fungicide Fluazinam was effective at 33% of recommended rates on all varieties
tested. The conventional fungicide Bravo WS was effective at 33% of recommended rates on the moderately susceptible cultivars. Both
fungicides were effective at 67% of recommended rate on all varieties. Reducing the application rate of Bravo WS 6SC from 100 to 67 and
33% (7 day interval) caused increases in foliar disease. In varieties less susceptible to late blight, the magnitude of the difference was
negatively correlated and little response to fungicide application was noted. MSG274-3, was the least susceptible variety in a separate
trial.
Kiru, Stefan and NJ Vavilov. "Solanum Andigenum. Juz. et Buk. As Basic Material For High Starch Potato
Breeding." [Vol. 76, No. 6, 375]
A cultivated South American tetraploid specie Solanum andigenum is a highly polymorphic and a rich source of valuable
genetic, agronomic and breeding traits. A high starch content in potato tubers is one of these traits. During the period of 1994-1998,35
potato genotypes - sources of high starch content were distinguished after a progeny evaluation of 406 samples from, which include 96
forms - varieties of Solanum andigenum, from various South American countries. A high fertility of S. andigenum makes it
possible to use this specie in different combinations of crosses with many potato species and cultural varieties. A character of inheritance
of high starch content and general combining ability were also determinated in the progenies derived from self-pollination and crossing with
cultural varieties and wild species. On testing of Fl and back crossing progenies high starch content genotypes with high inheritance
coefficient were selected. Among them there were Peruvian forms: herrerae, rayancachense, ccompis and ccompetillo, Columbians
ones: caiceda and tocanum, and tungurahuense from Ecuador. On crosses between above mentioned forms with
S. chacoense, f. shikki, f. gibberillosum and S. demissum up to 55% of seedlings with starch content more than 25% were
observed. Also above-mentioned S. andigenum forms were crossed with high content cultural varieties Bison, Saturna, Hertha, Milda
and Ogonjok. In this case, about 46% of seedlings had the same high starch content. As the result of our investigations several selected
clones will be integrated into further breeding programs on development of high starch content potato highbreds and varieties.
Kline, Wesley, Melvin Henninger and Stephen Johnston. "Hybrid Sudangrass to Control Nematodes
Before Planting Potatoes." [Vol. 76, No. 6, 375]
Hybrid sudangrass (cv. Trudan 8) has been shown to suppress nematodes in some areas when the plant material is incorporated
into the soil. New York research demonstrated that mowing once during the growing season stimulated tillering, prevented development of
woody stems, and promoted deep root growth. An experiment was established to compare the cultivar Trudan 8 to small grain stubble in
suppressing lesion nematodes (Pratylenchus penetrans). Plots were arranged in a randomized complete block design with
six replications. Sudangrass (25 lbs/A) was no tilled into pre-irrigated soil in July 1997. Plots were topdressed with 50 lbs/A nitrogen and
one-half of each sudangrass plot was cut to 8-10 inches in August 1997. All plots were mowed, moldboard plowed and the soil sealed with
a cultipacker in October 1997. The potato cultivar Superior was planted in spring 1998 and harvested August 1998. Soil samples were
collected three times during the study to determine what effect the sudangrass had on nematode populations. Forage samples were
collected from the cut and uncut subplots to determine fresh and dry weights. There was no statistical difference in either fresh
(22.4 tons/A cut and 22.5 tons/A uncut) or dry (3.9 tons/A cut and 4.0 tons/A uncut) forage yields. There were more lesion nematodes in
the sudangrass plots (90.6/250cc of soil) versus (65.6/250 cc of soil) the stubble when the three sampling dates were averaged. The
nematode population did increase with each sampling date, but did not reach damaging levels (>100/250 cc of soil) until potato
harvest. Potato yields and grades were similar for both treatments with 298 cwt/A in the sudangrass plots and 317 cwt/A grain stubble.
Kuhl, JC, RE Hanneman, Jr and MJ Havey. "Resistance to Phytophthora infestans in Diploid
Solanum Species of Mexico and South America." [Vol. 76, No. 6, 376]
Two diploid Solanum species from central Mexico and eight diploid species from northwestern South America were evaluated.
Replicated detached leaf assays using the Phytophthora infestans isolate MSU 96 (US-8 A2) were used to score infected leaf area
on a scale of 0 to 9. Visual identification of hypersensitive reactions were based on morphological characteristics of the disease reaction.
For genetic characterization of a resistant S. pinnatisectum, a resistant F1 interspecific hybrid was
backcrossed to the susceptible S. cardiophyllum subsp. cardiophyllum parent. According to the segregation data, few loci
contribute to resistance in this S. pinnatisectum accession, which comes from a region of complex and diverse P. infestans
populations in Central Mexico. Additional sources of resistance were identified in the distantly related diploid species from the Advanced
Rotata (Hawkes) of northwestern South America Hypersensitive reactions were also identified, concentrated in specific accessions of some
of these South American species. This resistance comes from species of a region traditionally not associated with the pathogen P.
infestans.