Laferriere, Louise, Caitilyn Allen and John P Helgeson. "Bacterial Wilt Resistance From Solanum
Commersonii: Strain Specificity and Systemic Colonization By Ralstonia Solanacearum."
[Vol. 76, No. 6, 376]
S. commersonii is a potential source of bacterial wilt resistance in potatoes. We have obtained resistant BC1 and BC2 lines from
a resistant S. tuberosum + S. commersonii somatic hybrid. In order to test the possibility that resistant plants are
merely tolerating higher bacterial populations, we investigated systemic colonization in the stems of the S. tuberosum parents, the S.
commersonii fusion parent, the somatic hybrid and the BC1 lines. When plants were diseased, bacterial populations in the
stem were invariably high. No line tolerated high populations of bacteria in their stems, regardless of resistance level. Resistance is strain
specific. Of the twelve strains of R. Solanacearum tested, two race 1/biovar 1 strains overcame S. commersonii resistance.
S. commersonii expressed resistance to the remaining genetically diverse strains, including three other race 1/biovar 1 strains.
Lamont, William, Michael Orzolek, Lew Otjen and Terry Simpson. "Production of Potatoes Using
Plastic Mulches, Drip Irrigation and Row Covers." [Vol. 76, No. 6, 376]
Seed pieces of two varieties of potatoes, NY1O1 and Dark Red Norland were hand-planted 8 inches apart on raised beds covered with
three colors of plastic mulch-red, silver, black or no mulch on April 22, 1998 at the Horticulture Research Farm, Rock Springs, PA. Prior to
making the beds and applying the plastic mulch and drip irrigation tape, 640 lbs/A of 10-10-10 was broadcast on the field. Spacing between
the mulched beds was 6 feet. Drip irrigation was used with all treatments and the potatoes were fertigated throughout the season. Typar, a
floating row cover material, was applied on April 22nd to half of each treatment. Standard pest management practices were utilized
throughout the growing season. Dark Red Norland and NY1O1 were dug on August 5 and 24, respectively. Although, there was a clearly
observable increase in growth of the potato plants there was no significant effect of row cover on yield of either variety. All mulches
significantly increased yields compared to bare ground. Only yields of Dark Red Norland showed a statistical significant difference between
mulch color with silver and red being higher than black. Silver mulch resulted in highest yields for both varieties of potatoes.
Landeo, Juan A and Manuel Gastelo. "Heritability of Horizontal Resistance to Late Blight in Breeding
Population B At The International Potato Center." [Vol. 76, No. 6, 376]
Population B is a potato breeding population under improvement for horizontal resistance to late blight in absence of major genes
(R genes) for vertical resistance. Other important agronomic and quality traits for table and industry use, resistance/tolerance to other
important biotic stresses and, adaptation to major agro-ecological zones in developing countries are also taken into account. Genetic
variability for horizontal resistance to late blight is under continuous monitoring to ensure progress from selection through recombination
cycles. During 1998, progenies of a random sample of resistant clones from cycle 1 (B3C1), obtained by NC design I (D-I) and Line x
tester (LxT), were evaluated for late blight resistance and total tuber yield. Filed designs RCB and simple lattice with two 2 replications and
30 individual plot sizes were used respectively. Three independent estimates of heritability include PO-regression for the area under
the disease progress curve AUDPC, taken as a parameter for resistance, resulted in very close values (h²=0.48,
h²=0.53, h²=0.40) indicating consistency of these estimates. It also indicates that the additive genetic
variance is still important and large enough to ensure further progress from selection. Implications in population breeding will be
discussed.
Leiby, James and Scott Kenney. "Variable Packing Costs."
[Vol. 76, No. 6, 377]
Based on small-scale survey, costs of packing tablestock potatoes for packers of a range of volumes are estimated. These costs are
developed for various potato packs from a computer model of different sized packing operations. We consider packing costs for three
different size classes of packers--small, 66,000 cwt. to 99,000 cwt./year; medium, 99,001 cwt. to 200,000 cwt./year, and large 200,001
cwt./year and above, and 4 different packs: 5# and 10# paper, and 5# and 10# poly bags, including bailed and unbailed packs. Costs
are considered for equipment operation, raw materials, labor, fuel and power. Ownership costs are not considered in this analysis. Per
cwt. costs are highest for the mid-sized packers because of greater per-unit labor costs than smaller scale operations, and higher bag
costs more than the larger sized operations. Further the use of computerized weigher-baggers reduces both the potato overage and
labor costs for the larger sized operations.
Leiby, James and Steven Belvea. "The Weekly Costs of Potato Storage."
[Vol. 76, No. 6, 377]
Estimates of week-to-week storage costs for tablestock and processing potatoes as well as cold storage costs are performed. With
such numbers the profitability of the time in storage can be calculated and delivery contracts may more adequately reflect the costs to
growers. The costs presented include only the costs that depend on the time that the potatoes are in storage and ignore completely
ownership costs of the storage, including the capital (interest depreciation, etc.) costs of the building, maintenance, taxes, building
insurance, etc. since these costs should not affect the decision of how long to store. Shrink and loss, and interest costs together make up
the two-thirds of these week-to-week costs. Shrink and loss as well as electricity costs vary through the storage season, and the costs
of interest and shrink and loss depend on the market value of the crop. Sensitivity analysis of the assumptions of the models is
performed.
Lozoya-Saldana, Hector and A Hernandez-Vilchis. "Three Year Evaluation of International
Potato Clones For Resistance to Late Blight in the Toluca Valley, Mexico." [Vol. 76, No. 6, 377]
Toluca Valley is the place of choice to test genetic resistance to the late blight (Phytophthora infestans) for several reasons:
a) it is the natural environment for the two mating types of the fungus, b) and consequently, all known pathogenic races are present every
year, c) a number of wild Solanum species host the pathogen, and d) these highlands have the ideal climate for development of
the disease. In 1998, 103 out of 330 clones from previous years and 415 genotypes from 4089 new entries were selected for further
evaluations. Selection in 1998 was based on less than 40% foliar infection and more than 800 g tuber/plant, although in 1996-97 such
criteria were not considered. Several outstanding new materials had only about 10% foliar infection at the end of the cycle. The clones
were from Wisconsin (Madison and Sturgeon Bay), Idaho, Washington State, Ithaca, the Netherlands, the National University of Mexico, and
Ireland. Cultivars from the Genotype x Environment program were also included, although not for selection purposes.
Lozoya-Saldana, Hector and A Hernandez-Vilchis. "Fungicide Trials With Registered and Section
18 Compounds for Control of Late Blight in 1997-98 in Toluca, Mexico." [Vol. 76, No. 6, 377]
In 1997 Toluca was included as one of 13 locations where seven protective fungicide programs of combined registered and section
18 products applied as weekly foliar sprays were evaluated for control of late blight (Inglis, D.A. et.al., Am J Potato Res 75:279, 1998). The
trial was repeated in Toluca in 1998. Susceptible cultivar Alfa was included in the two years of testing. As usual, a greater variability
of physiological races of the pathogen were present, and the control plots with no chemical control were 80 to 90% infected before the end
of the season. All programs reduced the incidence of the pathogen, and no significant differences in foliar infection levels were detected
among treatments. There were differences, though, when any program was compared to the control with no fungicides. Effectiveness of
treatments to control the disease fluctuated between 71% and 94% in 1997, and 63% and 89% in 1998. Considering the value of the
harvested tubers and the cost of the programs, the decision of which program to adopt may be based on yield. Programs including
section 18 compounds outperformed registered products.
Ludy, RL and ML Powelson. "Distribution of Tubers With Late Blight Within A Potato
Hill."
[Vol. 76, No. 6, 378]
Potato cultivars Atlantic, Katahdin, Kennebec, Red La Soda, Russet Burbank, Sebago, and Shepody were planted in the field at
Corvallis, OR in June 1998. Foliar symptoms of late blight first appeared throughout plots on 28 Aug. At this time the plant canopy was
sprayed once with Dithane to slow the progress of the epidemic. Tubers were harvested weekly beginning 3 Sept. and placement of each
tuber within a hill was established by measuring stolon length and depth. Tubers were assessed for symptoms of late blight. Tubers
without symptoms were surface sterilized and incubated at 18 C for 1 wk and then evaluated. At the first harvest, the average incidence of
tuber blight was 3% when foliar symptoms averaged 9%. Another 6% of the tubers developed symptoms after incubation. Proportion of
diseased tubers increased to 19% by the 3rd harvest when foliar symptoms average 64%. Another 4% of the tubers developed symptoms
after incubation. Cumulative incidence of tuber blight ranged from a high of 29% for Red La Soda to a low of 9% for Russet Burbank.
Differences among cultivars were not significant for percent tuber blight at harvest and after incubation, as variability was high. Statistical
comparisons on stolon length and depth of blighted versus healthy tubers from the same hill did not reveal any differences. Overall,
however, proportion of diseased tubers increased as stolon length (p=0.06) and depth (p=0.09) decreased. Percent of tubers with late
blight were 33, 28, 22, 21, 9, 6 and 25% for stolon lengths of <2.5, 3-4.5, 5-6.5, 7-8.5, 9-10.5, 11-12.5, 13 cm, respectively. Percent of
tubers with late blight were 42, 33, 23, 18, 22 and 25% for tuber stolon depths of <4.5, 5-6.5, 7-8.5, 9-10.5, 11-12.5, 13 cm, respectively.
Lulai, Edward C and Thomas P Freeman. "Relationships Between the Deposition of Suberin
Polyphenolic and Polyaliphatic Domains During Tuber (Solanum tuberosum L.) Wound-Healing." [Vol. 76,
No. 6, 378]
Suberin is a protective biopolymer that is deposited on phellem cell walls of potato tubers during growth and wound-healing. Although
suberin is known to be composed of complex polyphenolic and polyaliphatic domains, little is known about the biochemistry initiating and
integrating the accumulation of these two domains. Earlier, we demonstrated the importance of these two domains by showing that
deposition of the polyphenolic domain alone conferred resistance to infection by bacterial pathogens causing soft rot. However, resistance
to fungal pathogens causing dry rot did not appear until after suberin polyaliphatic deposition. We have histochemically monitored the
deposition of the two suberin domains during tuber wound-healing and we have adapted a simple method to chromatographically
fingerprint suberin aliphatic accumulations in native periderm and developing wound periderm. These results, together with corresponding
inhibitors studies and previous research, show that suberin phenolic disposition is histochemically detectable in wound-healing cell walls
well in advance of suberin aliphatic deposition. However, unincorporated suberin aliphatic material is chromatographically detectable within
the periderm before it begins to accumulate in suberizing cell walls. Several inhibitors of suberin polyphenolic deposition were tested and
the results indicate that suberin polyaliphatic disposition is coupled to the preceding polyphenolic deposition. These results are important
in determining how suberization processes are initiated and integrated in potato tuber to prevent disease.
McBeath, Jenifer Huang, William Kirk and Brendan Niemira. "Biological Control of Late
Blight Infested Seed Pieces by Trichoderma Atroviride." [Vol. 76, No. 6, 378]
Phytophthora infestans is an extremely aggressive plant pathogen. Under high relative humidity and with a temperature range
of 4 to 25 C, P. infestans can cause severe late blight disease on potato plants and tubers. Increasing evidence indicates that
seed-borne late blight, especially on healthy seed pieces which become infested during pre-cutting, plays a significant role in disease
establishment and disemination. Management of late blight relies on complete and repeated coverage of foliage with fungicides. No
effective seed piece treatment is presently available. Trichoderma atroviride is a versatile, aggressive hyperparasite that can
parasitize a wide spectrum of pathogenic fungi, including P. infestans. It has a temperature range of 4 to 33 C and prefers high humidity.
Treatments of seed pieces with T. atroviride after the freshly cut surfaces are inoculated with large numbers of P. infestans
in one pole and treatment of T. atroviride in another, late blight disease development in discs, as indicated by necrosis of
cells, was more suppressed than in those without T. atroviride treatments, although no direct contact between T. atroviride
and P. infestans was observed. A direct correlation was found between intensity of disease suppression and T. Atroviride
population. Hyperparasitism and induced resistance seemed to be two of the mechanisms involved in the late blight suppression.
Mohammed, A, D Douches, W Pett, E Grafius, J Coombs, Liswidowati, W Li and MA Madkour.
"Evaluation of Potato Tuber Moth Resistance in Tubers of BT-CRY5 Transgenic Potato Lines."
[Vol. 76, No. 6, 379]
The potato tuber moth, Phthorimaea operculella (Zellar) is the most destructive pest of cultivated potato in tropical and
subtropical countries. The codon-modified Bt-cry5 gene, transformed and expressed in potato, should provide host plant resistance
to Lepidoptera and Coleoptera pests. The purpose of this study was to evaluate the efficacy of the Bt-cry5 transgene to control the
potato tuber moth in tuber tissues. Tuber bioassays using eleven to twelve-month-old stored and newly harvested tubers of Bt-cry5-
Atlantic lines which shown a mortality range from 47.1% to 67.6%. Spunta, an economically important potato cultivar in Egypt, was previously
transformed with three different Bt-cry5 gene constructs. Potato tuber moth mortality was 100% in the lines that were transformed
with Bt-cry5 gene controlled by the CaMV35S promoter (pBIML1 vector). The transgenic line expressing Bt-cry5 under the
control of the patatin promoter (pBML12 vector) showed the lowest tuber moth mortality (25.6% and 31.1%). The Bt-cry5 transgenic
lines with high tuber expression of Bt have value as host plant resistance in an integrated pest management system to control potato tuber
moth.
Morgan, Gaylon D, Tim R Connell, Ann E MacGuidwin and William G. Schmitt. "Pest Distribution
Within Production Potato Fields." [Vol. 76, No. 6, 379]
The spatial distribution and movement of pest into or within production potato fields provide important information for strategic pest
management. The aggregated distribution and low mobility of nematodes, Verticillium, and Early Blight provide optimum opportunity
for localized management. Localized management benefits producers by increasing economic efficiency and reducing pesticide use. The
objective of this research is determining the spatial distribution of pests within potato production fields.
Morgan, Gaylon D, Tim R Connell and William G Schmitt. "Estimation of Weed Distribution
And Potential For Variable Rate Management." [Vol. 76, No. 6, 379]
Environmental concerns regarding pesticide use and issues of economic efficiency have promoted the use of precision agriculture in
many realms of agriculture, including weed science. Weed management is a major concern in potato production due to limitation in
labeled herbicides, harvesting complications, and yield loss. The objectives of this research were to determine the weed distribution in a
potato production field, the affect of grid size on the estimation of weed distribution, and the influence of weed density and distribution on
potato yields.
Murphy, Agnes, Henry De Jong and Kenneth Proudfoot. "F87084: A Fertile, Adapted Clone With
Multiple Disease Resistances. [Vol. 76, No. 6, 379]
Genetic plant resistance is one strategy for minimizing the effects of disease. Sources of resistance to most pathogens are known to
exist among various wild and cultivated potatoes. Classical breeding programs have striven to transfer these sources into cultivars for many
years. Disease resistance is one of many attributes including adaptation, consumer quality and appearance that must be combined in a
new cultivar before it is accepted and grown on any scale. F87084 has resistance to several pathogens which can be traced back to
diverse germplasm sources. The development of this adapted, fertile germplasm selection will be used to demonstrate the assembly of
many desirable traits that is possible through traditional breeding methods.
Naess, SK, SM Wielgus, JM Bradeen, GT Haberlach and JP Helgeson. "Introgressing Late
Blight Resistance From Solanum Bulbocastanum into Potato. [Vol. 76, No. 6, 379]
Although resistance to late blight does not exist in potato cultivars currently grown in the U.S., it has been captured from the wild
diploid Solanum bulbocastanum by somatic hybridization between a tetraploid potato and S. bulbocastanum. This resistance
has been passed on through 3 backcross generations to potato. Homeologous recombination between the genomes of potato and S.
bulbocastanum is essential for the eventual successful introgression of resistance and the efficient reconstitution of the
recurrent parent. Three to one segregation ratios of dominant S. bulbocastanum specific RAPD markers in several BC2 populations
as well as the presence of both alleles of codominant S. bulbocastanum specific RFLP markers in BC1 progeny of the somatic
hybrids provide evidence that some homeologous pairing between genomes does in fact occur in the hexaploid somatic hybrids.
Niemira, Brendan A, William W Kirk, Jeffery M Stein, Robert Schafer and Roger Brook. "Chlorine
Dioxide Treatment of Potato Disease Complexes (Phytophthora infestans, Fusarium Sambucinum, Erwinia Carotovora): In Vitro and In Vivo
Efficacy." [Vol. 76, No. 6, 380]
Chlorine dioxide was tested for efficacy against late blight (P. infestans), fusarium dry rot (F. sambucinum) and soft rot
(E. carotovora)under in vivo (potato tuber) and in vitro (selective media) conditions. Chlorine dioxide (150 ppm) was applied to
whole tubers and wounded tubers inoculated with the pathogens singly and in combinations. Treated tubers were stored under disease
conducive conditions in controlled environment chambers. While wounding led to greater overall disease development, chlorine dioxide was
not effective in either whole or wounded tubers against any pathogen/pathogen complex tested. Pathogen/pathogen complex response to
in vitro treatment with chlorine dioxide will be discussed.
Novy, Richard and Craig Longtine. "Introgression of Virus Resistance From Solarium etuberosum
to Cultivated Potato." [Vol. 76, No. 6, 380]
An increased incidence of potato leafroll virus (PLRV) and Potato Virus Y (PVY) has been observed in seed and commercial fields in
recent years. The expansion of these virus diseases are thought to result from an increased use of fungicides for late blight control and the
spraying of insecticides for the control of other insects such as Colorado potato beetle. Both production practices can "flare"
aphid numbers, thereby increasing the transmission of PVY and PLRV which are vectored by aphids. Solanum etuberosum
(PI# 245939) has been identified as being immune to PVY and PVX, and highly resistant to PLRV. Tetraploid potato hybrids with
S. etuberosum in their pedigree have been screened for resistance to PVY and PLRV, and have displayed high levels of heritable
resistance to both viruses. S. etuberosum hybrids displayed 1/4 to 1/3 the PVY titer of the susceptible cultivar Atlantic, and
approximately half the titer of moderately resistant Katahdin when assayed over a two year period using ELISA. Five of six S.
etuberosum hybrids challenged with PLRV infected aphids were as resistant or more resistant than the PLRV-resistant cultivar
Cascade. The results from field and greenhouse evaluations of these hybrids for virus resistance will be presented. At this time, third
generation progeny of S. etuberosum and S. tuberosum have been obtained, and selections from this generation will be made
in 1999.
Olsen, Nora, Robert Thornton, Andre Baritelle and Gary Hyde. "The Effects of Storage on
Physiological and Physical Characteristics of Seed Tubers." [Vol. 76, No. 6, 380]
Seed tuber storage conditions can influence seed physiological age, sprouting capacity, biochemical status and tissue physical
properties. The influence of storage temperatures (pre-storage, 3 C, 7 C and 9 C) and controlled atmosphere (CA) conditions (7 C, 2% 02,
10% CO 2) were evaluated relative to the physiology and mechanical tissue properties of potato seed tubers (cv. Shepody).
Typical model prediction ascribes lower tissue toughness to greater tissue turgor. In this study, tubers prior to storage (dormant) actually
had high relative tissue turgor (wave speed) as well as high tissue toughness. Stored tubers generally responded to the model assertion
with greater tissue toughness corresponding to lower relative tissue hydration levels. The pre-storage tubers may be exhibiting
characteristics of stronger cell walls as indicated by the mechanical properties and independent of tissue turgor. Tissue toughness was
lower at the bud compared to the stem end only for pre-storage tubers and tubers stored at 9 C. No differences between bud and stem
end were evident in tubers from 3 C, 7 C and CA storage. Tubers stored at 3 C had the lowest tissue toughness value. Measurements of
tissue mechanical properties indicated changes occurred due to storage conditions and seed tuber aging. Tubers removed from CA
storage had similar physiological (sugar and starch content) and physical properties as tubers from 3 C storage yet had a greater capacity
for rapid sprouting indicated by more advanced sprouting upon removal from storage. A trend for tubers with a lower sugar content to have a
higher tissue toughness was observed with the pre-storage tubers and 9 C stored tubers compared to the other storage treatments. Tuber
sugar composition may be more of an indicator of how the tubers were stored and therefore correspond or coincide with the tissue physical
properties.
Oltmans, Shannon M and Richard G Novy. "Development of Cold Chipping Potato Cultivars By
The Use of Wild Species." [Vol. 76, No. 6, 380]
Potatoes used for chips are typically stored at temperatures ranging from 10 15 C. Storing tubers at lower temperatures (3-
4 C) would decrease the incidence of storage disease such as silver scurf, and reduce tuber shrinkage and sprouting,. However,
at these lower temperatures, there is an accumulation of reducing sugars (i.e., glucose and fructose) that result in commercially
unacceptable chips. Progress has been made by potato breeders in the development of cultivars that resist the accumulation of reducing
sugars at storage temperatures of 6-8 C. However, there are currently no potato cultivars that can be chipped from long term storage at
<6 C. Maximization of the benefits of cold storage could be realized if storage temperatures for chipping potatoes could be lowered to below 6 C.
Plant material with cold-chipping characteristics was found in haploid x wild species families provided by the USDA/ARS National
Cooperative Enhancement Project. In 1997, tubers of 142 potato hybrids were harvested from a single site and stored at 3 C for 15 weeks
and 1) directly chipped, or 2) chipped following 2 weeks reconditioning at 18 C. Of the 142 hybrids evaluated, 12% and 80% from direct
and reconditioning, respectively, were acceptable to marginal for chip color based on industry standards. In 1998, the hybrids were grown
at two sites, and harvested tubers were again evaluated for chipping characteristics following storage at 3 C for 15 weeks. Hybrids have
been identified that chipped acceptably in both 1997 and 1998. Tubers of S . raphanifolium hybrids displayed the best chip color.
The haploid x wild species hybrids and wild species clones were crossed with adapted potato cultivars and selections in 1998. Twenty-three
plants from three families tuberized and were harvested. These putative tetraploids will be planted in the field in 1999 and evaluated
for their agronomic characteristics and their ability to chip from long-term storage at 3 C.
Platt, HW (Bud) and F Daayf. "Canadian Populations of Phytophthora infestans in 1998."
[Vol. 76, No. 6, 381]
About 340 potato samples suspected of having late blight were collected from the ten Canadian provinces in 1998. Phytophthora
infestans was isolated from 81% of these samples. In comparison with 1997, there were 151 more samples received, 160 more late
blight-infected ones, and five more provinces were represented in 1998. This study was conducted to determine the different changes in
P. infestans populations across Canada Assessments included pathogen isolate mating type, level of resistance to metalaxyl, and
glucose phosphate isomerase (Gpi) patterns. A2 was the only mating type found in all provinces for which samples were tested except for
two provinces; for samples from British Columbia 20% of the isolates were Al while from Quebec one Al isolate was found. Metalaxyl
resistance variations within the Canadian populations based on the relative growth of isolates on three metalaxyl concentrations
(1, 10, and 100 ug/mI) will be presented. Generally, the results demonstrated a decrease in resistance to metalaxyl of the A2 mating type
populations. Finally, results of Gpi-allozyme patterns found in these populations will be described but in summary the US-8 pattern was
the most common found across the country. Conclusions will also be presented regarding the general shifts in the Canadian populations of
P. infestans during the last few years and the implications that these findings may have on the potato industry.
Platt, HW (Bud) and F Daayf. "In Vitro Responses of Canadian Phytophthora infestans Isolates
to Common Late Blight Fungicides." [Vol. 76, No. 6, 381]
Thirty isolates of Phytophthora infestans collected from five Canadian provinces in 1997, from both potato and tomato plants, were
tested for their relative growth on culture media with or without fungicide amendments. Rye agar culture medium was amended (or not) with
one of the following fungicides: Acrobat, Dithane, Curzate, Bravo and Tattoo-C, at four different concentrations: 0.5, 1, 2.5, and 5 ug/ml. Relative
growth of isolates was compared with each fungicide-amended medium on the basis of the isolates’ province of origin, mating type,
Glucose-phosphate isomerase (Gpi) allozyme pattern, and host or origin. Bravo and Tattoo-C were able to repress growth of P.
infestans isolates at all concentrations for almost all isolates tested. Isolates from Manitoba were the most resistant to Dithane and
Acrobat, while there was no significant difference between provinces in terms or resistance to Curzate. Al mating type isolates were more
resistant to Curzate than A2 ones but there was no significant difference between mating types in terms of growth in rye agar amended with
Acrobat. For Dithane, Al isolates were more resistant than A2 isolates at both 0.5 and lug/ml but Al was less resistant than A2 at 5 ug/mi.
Among Gpi-allozyme genotypes, US-11 was the most resistant to Curzate, while UN-4 and US-8 were the most resistant to Dithane. No
significant differences were recorded between genotypes with Acrobat.
Riebe, Jennifer. "Aphid Management in PLRV and CPB Resistant NewLeaf Plus Potatoes:
Insecticide-Free Production in the Pacific Northwest." [Vol. 76, No. 6, 381]
NatureMark’s NewLeaf Plus Russet Burbank potatoes are genetically modified for resistance to the Colorado potato beetle
(CPB) and potato leafroll virus (PLRV), which is vectored most commonly by the green peach aphid (GPA). Without the need for intensive
insecticides to limit virus spread, it is anticipated that beneficial insects alone may maintain pests at acceptable levels. NewLeaf Plus
potatoes were grown commercially at 11 sited in ID, OR, and WA in 1998. None of the fields were treated for aphids or CPB. Beneficial
insects appeared to be responsible for lower mite populations in NewLeaf Plus fields. Growers recognized an average chemical savings
of $95.45/acre in the Columbia Basin of OR and WA, and $40.71/acre in Idaho.
Rivera-Peña, Antonio, I Sanchez-Valdez, G Garza-Falcon and LJ Yepes-Padilla. "Paz Blanca: A New
Variety of Potato Resistant to Late Blight and Good Chipping Quality." [Vol. 76, No. 6, 382]
PAZ BLANCA (77-70-91) is an oval white potato selected from a cross between WIS-BR-63-65 and JUANITA made in 1977 and will be
released by the INIFAP-CIRCE-CE-VALLE DE TOLUCA in 1999. It is a medium late variety, with uniformly sized tubers. The smooth skin has
shallow eyes well distributed on the tuber and it has cream flesh. PAZ BLANCA produces medium to high yield, comparable to ALPHA.
The tuber is very similar to Alpha in appearance. Specific gravity averages 1.075. It has processing and fresh markets potential. Its internal
quality is a little better than ALPHA. It is resistant to late blight under natural attack in the field by a complex population of races of
Phytophthora infestans. The new variety have been tested in regional trials in four localities in Mexico from 1993 to 1997. PAZ BLANCA
as an alternative of an innovative technology to the farmers will be discussed.
Rojas-Cifuentes, GA and RG Novy. "RAPD Heteroduplex Formation in Potato And Its Impact on
Genetic Distance Estimates." [Vol. 76, No. 6, 382]
RAPDs have many positive attributes for inclusion in a breeding program, and have been used extensively for genetic analysis in
agricultural crops. Typically having a dominant mode of inheritance, codominant RAPDs have been reported in several plant species as
well. Codominant RAPDs are typically found at the same chromosomal site and have high sequence homology to one another, however,
they differ by the insertion, deletion or substitution of base pairs. During the polymerase chain reaction, the DNA strand of one codominant
marker can reanneal with the DNA strand of the other "allele" to form a heteroduplex molecule. These hybrid DNA molecules
migrate more slowly during electrophoresis than the codominant markers. Subsequently, heteroduplex can be scored as unique markers
when they are actually artifacts of the RAPD procedure. Heteroduplex formation between codominant RAPDs can, therefore be a confounding
factor in the use RAPDs. In order to assess the frequency of RAPDs heteroduplex formation in potato, the DNA of 38 haploid potato clones
was amplified using RAPD primers. The DNA of individuals lacking a RAPD allele were then intermixed in equal parts andre-amplified to
determine if the missing marker could be recreated; evidence that it is a heteroduplex artifact. Based on this assay, 25 of 62 (40%) RAPDs at
this time have been identified as heteroduplex artifacts. Using (1) all the RAPDs (including heteroduplexes) identified in the haploids and (2)
only nonheteroduplex RAPDs, genetic distance estimates were calculated for the 38 potato haploids. The two datasets of genetic distance
estimates were used in constructing dendrograms that allow for direct comparisons of relationships among the analyzed clones in each of
the two datasets. Correlation coefficients were also calculated between the two genetic distance matrices in order to assess the impact
heteroduplexes have on genetic distance estimates.
Ronald, Andrew and MK Pritchard. "Effect of Desiccation on Yield, Process Quality, And Late Blight Tuber
Rot Development in Manitoba Grown Russet Burbank Potatoes." [Vol. 76, No. 6, 382]
Vine killing is practiced in most production areas to increase harvest efficiency and reduce the potential for tuber infection by late
blight at harvest. With yields already limited by a short growing season, Manitoba growers have been reluctant to adopt this practice. In a
two year study, Russet Burbank potatoes were desiccated with diquat to determine the effect of vine killing on yield and processing quality
over three harvest dates. The incidence of late blight on tubers in storage was measured to evaluate the effectiveness of diquat in reducing
tuber infection during harvest. Compared to the untreated control, yield was reduced by desiccation with the largest reduction in total yield
observed in the early September harvest; 23.7% in 1997, 16.8% in 1998. By the late September harvest, however, the effect of vine killing in
reducing total yield was less apparent; 8.9% in 1997, 4.2% in 1998. Skin-set was significantly higher in the desiccated treatment for all
harvest dates in 1997 but only in the early September harvest in 1998. Glucose and sucrose concentrations were similar in tubers from
the desiccated and untreated plots in both years of the study. Specific gravity was lower in the vine killed treatment for all harvest dates in
1997 but only in the early and mid September harvests in 1998. The incidence of tuber rot in the early September harvest in 1998 was
5% lower in the desiccated treatment as compared to the control. Results from this study indicate that vine killing with diquat for a mid
to late September harvest can be done in Manitoba with minimal effects on tuber yield and processing quality.
Salaiz, Thomas A and Bradley M Krohn. "Development of Low Black Spot Bruise Ranger Russet
Via Antisense Inhibition of Polyphenol Oxidase." [Vol. 76, No. 6, 383]
Polyphenol Oxidase (PPO) catalyzes the blackening reaction in potato tubers which are susceptible to black spot bruise. Three
different binary gene constructs, designed to generate tuber-specific antisense inhibition of PPO, were independently transformed into
Ranger Russet via Agrobacterium-mediated transformation. Transgenic lines ranging from intermediate reductions to complete
elimination of PPO activity were identified by assay of greenhouse mini-tubers. The same low PPO lines were evaluated for reduction in
black spot bruise susceptibility in 1998 field trials at Parma, ID, and Hancock, WI. In "bruise barrel" tumbling assays of mature
field-grown tubers, samples were bruised and peeled, or bruised, stored at 8 C, and peeled. Several lines from two of the three gene
constructs demonstrated virtually complete elimination of black spot bruises, both before cold storage, and after 4 months of cold storage.
All three gene constructs produced lines with a range of intermediate levels of reduction in black spot bruises. All lines with a complete
elimination of black spot bruises demonstrated a statistically-significant reduction in twenty-four hour abrasive peel ratings, in which peeled
transgenic tubers remained nearly white. Currently, low bruise Ranger Russet lines which show preliminarily acceptable plant and tuber
typeness, have been advanced to 1999 agronomic field trials to select for commercial candidates.
Sanchez-Lopez, Vladimir and Hector Lozoya-Saldana. "Virus Incidence on International Potato Clones
in The Toluca Valley, Mexico." [Vol. 76, No. 6, 383]
In recent years, thousands of potato clones have been introduced to the Toluca Valley for evaluation of field resistance to potato
late blight (Phytophthora infestans). This situation represents a potential risk of importing pathogenic agents with the planting
material, in particular, viruses. In the International Cooperative Program for Potato Late Blight (PICTIPAPA) evaluation plots in Metepec,
Mexico, leaves from 348 clones that have been in the valley for one to three years were sampled 75 days after planting in the 1998 growing
cycle. After harvest, tubers from 227 selected clones from the same group were also taken to run ELISA on both leaves and tubers
to detect the presence of seven viruses. From all the samples, 17% were positive for virus X (PVX); 1% for virus Y (PVY); 3% for virus
S (PVS), and 1.4% for leaf roll (PLRV). Virus M (PVM), virus A (PVA), and Andean Latent (APLV) were not detected. A direct relationship was
found between viral incidence and the number of growing cycles that the genotypes have been naturally exposed to the fungus in the field
(20,36, and 60% of the sampled clones evaluated for the first, second, and third year respectively were positive for at least one virus).
We conclude that the plants acquired the viruses directly in the field.
Shock, Clinton C, Erik BG Feibert, Eric P Eldredge and Lamont D Saunders. "The Response of
Umatilla Russet to Nitrogen Fertilizer Rates And Irrigation Deficits." [Vol. 76, No. 6, 383]
Umatilla Russet was compared with Russet Burbank, Shepody, and Ranger Russet for yield, grade, and processing quality response
to four applied N rates under sprinkler irrigation in 1992, 1993, and 1994, and to four N rates under furrow irrigation in 1994, 1995, and 1996,
and to four levels of sprinkler irrigation in 1992, 1993 and 1994. The varieties did not differ in average yield response to N rate, but specific
gravity was reduced with increasing N rate. In the sprinkler irrigated N rate study, averaging over the three years at the optimum N rate each
year, Shepody and Umatilla Russet had the highest yield of US #1 tubers. Russet Burbank and Umatilla Russet had the highest total yield.
In the furrow irrigated N rate study Ranger Russet had the highest yield of US #1 tubers and large #1 tubers, followed by Umatilla Russet.
Shepody and Umatilla Russet had the highest stem end fry color. Deficit sprinkler irrigation decreased US #1 yield in all four varieties. Deficit
irrigation did not reduce total yield of Russet Burbank, and severe irrigation deficit increased yield of US #2 tubers only in Russet Burbank.
Specific gravity of Shepody was reduced by irrigation deficits, but remained stable in Russet Burbank and increased in Umatilla Russet. In
the non-stressed check treatments, averaged over three years, Umatilla Russet had the highest total yield, the highest yield of US #1 tubers,
and yield of large US #1 tubers as high as Shepody. In these trials, with optimum to adverse irrigation and N levels, Umatilla Russet
demonstrated good stability in tuber yield, grade, and processing quality compared to the other varieties.
Sieczka, Maria T, Charles R Brown, Edyta Gawronska, Kazimierz M Swiezynski, Hanna Zarzycka and Ewa
Zimnoch-Guzowska. Identification of Potatoes Resistant to New Strains of Late Blight (Phytophthora infestans).
[Vol. 76, No. 6, 384]
Resistance to Phytophthora infestans has been evaluated in Polish and foreign cultivars reported to be resistant, and in
diploid and tetraploid advanced selections obtained at Mlochow (in the breeding program for P. infestans resistance). In addition,
segregation for P. infestans resistance was evaluated in three diploid and three tetraploid seedling families originated from parents
differing in resistance level. In laboratory tests, two highly pathogenic strains of P. infestans were used: US 8 (A-2) and MP 322 (A-I),
isolated in the U.S. and Poland, respectively. They exhibit similar pathogenicity to the evaluated potato genotypes. All material was parallely
evaluated under high natural infection pressure. Among cultivars the highest level of foliar resistance was found in the Polish cv. Meduza and
in the foreign cv. Cruza 148. Cv. Meduza was also resistant in tubers. Preliminary data indicates that among diploid and tetraploid
selections/seedlings some were superior to cvs in both foliage and tuber resistance. Among them genotypes have been found with
satisfactory tuber quality and, quite significantly, maturity earlier than the most resistant cultivars: Meduza and Cruza 148.
Singh, U, C Trevors, S DeBoer and JD Janse. "A Procedure For The Detection of Erwinia
chrysanthemi in Potatoes." [Vol. 76, No. 6, 384]
Erwinia chrysanthemi which is responsible for bacterial soft rot in potato is a quarantine organism for which specific and sensitive
detection methods are required. In this study, both serological and DNA based techniques were used to develop detection systems for this
bacterium. Monoclonal and polyclonal antisera were raised to this organism using glutaraldehyde treated cells as the antigen and a
DAS-ELISA was developed. Using this ELISA, all potato strains of E. chrysanthemi originating from temperate regions of the world
gave a strong positive reaction whereas non potato strains were not specific in their reaction. Heterologous bacteria were all negative in
ELISA using the monoclonal antibody to E. chrysanthemi. Using published sequences, a PCR assay was developed for the detection
of this bacteria All strains of E. chrysanthemi regardless of origin gave a positive reaction whereas none of the heterologous bacteria
were positive. A comparison of the two methods showed that the sensitivity of ELISA was 106while that
of the PCR was 1O6 cells per ml.
Sowokinos, Joe, Sanjay Gupta and Irene Shea. "Purification and Characterization of Isozymes of UDP-GLC Pyrophosphorylase
(UGPase) Unique to Potatoes Demonstrating Resistance to Cold-Induced Sweetening." [Vol. 76, No. 6, 384]
Cold temperature (4 C) accelerates starch breakdown hi stored potato tubers and renders them unacceptable for the production of chips
or fries. it is imperative that genes be identified which could confer resistance to cold-induced sweetening. The enzyme UGPase catalyzes
the first step common to the sweetening pathway in potato tubers via the formation of UDP-Glc. Previous research has indicated that the
polymorphism of UGPase seen at the allelic level bore a relationship to the polymorphism seen at the phenotypic level relating to a
clone’s ability to sweeten in the cold (Sowokinos et at., 1997, Plant Physiol. 113:511-517). The major isozyme of UGPase
(UGP3) found in the cold-sensitive (CS) cultivar Norchip has been previously purified and characterized (Sowokinos et. a!. 1993, Plant
PhysioL 101:1073-1080). In this study sixteen potato clones, differing in their ability to sweeten in the cold, were screened for isozymes of
UGPase. Native-activity gels detected two new isozymes (UGP4 and UGP5) that were present only in cold-resistant (CR) potatoes. These
isozymes were purified to near homogeneity from the CR cultivar Snowden. A subunit mass of 53 kD was found using denaturing gel
electrophoresis. The deduced amino acid sequence yielded key differences between CS and CR polypeptides which led to proteins differing
in charge. Differences in the kinetic properties between the isozymes from CS and CR clones will be discussed. This study is supported,
in part, by USDA/Specific Cooperative Agreement # 58-5442-6-124.
Stein, Jeffery M, William W Kirk, Robert L Schafer and Brendan A Niemira. "The Role of Select
Fungicides Within A Potato Late Blight (Phytophthora infestans) Control Program; Antisporulation And Tuber Blight Aspects."
[Vol. 76, No. 6, 384]
Late blight (P. infestans) control programs in which two of the standard chlorothalonil applications were replaced with novel
fungicides or mixtures were examined under field conditions for foliar disease control, antisporulation capacity, and tuber loss reduction.
The novel fungicide applications were targeted specifically at pathogen inoculation and/or crop desiccation events. All of the fungicide
programs reduced foliar disease significantly in comparison to the untreated control, but not the season long chlorothalonil control. None
of the fungicide programs significantly reduced the number of sporangia produced per cm2 lesion
area The late season dimethomorph/mancozeb program had significantly higher marketable tuber number per plant and yield than the
untreated and chlorothalonil controls. The early season cymoxanil/mancozeb program had a significantly reduced level of season
long tuber loss than both the untreated and chlorothalonil controls. Further relationships between fungicide programs, foliar disease levels,
and tuber loss will be discussed.
Sterrett, SB, MR Henninger and KG Haynes. "Relationship of Internal Heat Necrosis to Specific
Gravity." [Vol. 76, No. 6, 385]
Most high specific gravity potato chipping cultivars grown in the mid-Atlantic states are susceptible to internal heat necrosis (IHN), a
physiological disorder of the tuber parenchyma tissue. The purpose of this study was to investigate the relationship between susceptibility
to IHN and specific gravity. Twelve clones from 33 segregating tetraploid families were evaluated for both incidence and severity of IHN and
specific gravity in replicated field plots in VA in 1994 and 1997. There was a highly significant correlation between incidence and severity of
IHN in 1994 (r=-0.90, P<0.01) and 1997 (r=-O.89, P<0.01). The correlation between severity of IHN and specific gravity was low in
1994 (r=0.07, P=0.05) and in 1997 (r=O.002, P=0.95). Although the incidence and severity of IHN was greater in families with Atlantic as
a parent, there was no correlation between incidence or severity of IHN and specific gravity in most of the families. This suggests that the
increased susceptibility to IHN in segregating families with Atlantic as a parent is due to some factor other than high specific gravity.
Tek, Ahmet L, John P Helgeson and Jiming Jiang. "Molecular Cytogenetic Characterization of Solanum
Brevidens Chromatin Introgressed into Potato." [Vol. 76, No. 6, 385]
Eight BC3 plants together with their parents derived from a single somatic hybrid between potato
and Solanum brevidens were investigated using genomic in situ hybridization (GISH) and restriction fragment length
polymorphism (RFLP) analysis. The somatic hybrid A206 had 24 S. brevidens chromosomes and 48 potato chromosomes as expected.
One of the two BC1parents contained 11 S. brevidens chromosomes and the other
BC1 parent had 11 complete S. brevidens chromosomes and a potato S. brevidens
translocation chromosome. Two BC² parents analyzed had three and four complete S. brevidens
chromosomes, respectively. Among the eight BC³progeny, two possessed a translocation chromosome,
five contained a single complete S. brevidens chromosome and one plant had one translocation chromosome and one complete
S. brevidens chromosome. We demonstrated that it should be possible to isolate a complete set of 12 addition or substitution lines.
The potato S. brevidens translocation chromosomes probably originated from genetic recombination. This recombination
potential between potato and S. brevidens chromosomes provides the basis for introgression of useful genes from S. brevidens into potato.
Thill, Christian A, EB Radcliffe and DW Ragsdale. "Breeding For Potato Leafhopper Resistance Using
Wild Solanum Species." [Vol. 76, No. 6, 385]
Potato cultivars and germplasm developed with resistant to potato leafhopper (PLH) are important; substantial yield losses result
when PLH is not controlled. Moreover, chemical control of PLH causes green peach aphid (GPA) outbreaks amid GPA spread potato virus
Y (PVY) and potato leafroll virus (PLRV). Resistance to PLH is found among the wild relatives of potato. In previous work, we evaluated
120 accessions from 32 Solanum species and found resistance to segregate between species and significantly among
species’ accessions. Subsequently, twelve species from 31 accessions were evaluated to identify individual genotypes (fine
screening) within accessions conferring resistance. Resistance was assessed by counting the number of PLH adults and nymphs
following vacuum-suction sampling of individual genotypes. Three species, S. berthaultii (P.1. 208881, 320257, 473331, 498105),
S. megistacroloburn (310936), and S. polytrichon (184770) had the best resistance against both PLH nymphs and adults.
All genotypes within accessions of these species had greater than 5x the resistance of susceptible cultivars Russet Burbank and 15x
that of Cascade. Our future objectives are to transfer PLH resistance to cultivated potatoes using S. tuberosum haploids and 2n
gametes and determine the basis of PLH resistance.
Thill, Christian A, EB Radcliffe, DW Ragsdale, RE Hanneman, Jr. and JB Bamberg. "The
Identification of Aphid Resistant 4X Potato Germplasm For Use in Breeding." [Vol. 76, No. 6, 385]
PLRV reduces market tuber yield by diminishing internal tuber quality through expression of net necrosis. PVY reduces plant productivity
and yield. Spread of PLRV by aphids that colonize potatoes is persistent, while PVY spread is nonpersistent during aphid probing while
feeding. High aphid populations in Minnesota since 1995 and yield losses of 35% in 1998 have been reported. We evaluated 100 4x
parental clones (complex interspecific hybrids) and 348 new progeny (4x-complex interspecific clones crossed to cultivars) for resistance to
aphids. Resistance segregated in the 4x population and ranged from 77 to 7600 aphids per plot (5 compound leaves from each of 4 plants).
Twenty-one 4x clones had better aphid resistance than Russet Burbank (740). These will be used in crosses to develop new hybrid
progenies. Existing new hybrid progenies had aphids ranging from 4-1700 per plant and 39% had better resistance than Russet Burbank.
The best families were Atlantic x MN85345 (92% of the progeny were aphid-resistant), Snowden x MN85348 (45%), W1005 x MN85348
(50%), MN85348 x Ranger Russet (80%), and MN85477 x Ranger Russet (67%). Progenies are being evaluated for resistance to PLRV and
PVY using ELISA. The best clones will be increased and evaluated for horticultural and processing characteristics.
Varrieur, John M, Rebecca J Cutright and Richard E Veilleux. "Selection Pressures Inherent in
The Monoploid Derivation-Mechanisms, Androgenesis And Gynogenesis." [Vol. 76, No. 6, 386]
Monoploid potato is free of deleterious alleles and can be used to develop homozygous lines through chromosome doubling. Three
studies were conducted to analyze monoploid populations derived from Solanum phureja clones PP5 and 1-3 to observe selection
inherent in either androgenesis or gynogenesis. S. phureja PP5 clones from both derivations were planted from tubers in 10 cm pots
in April 1998 and transplanted to the field in May 1998 in a completely randomized design of 1-plant plots with 21 clones in 3 replications.
Mean squares due to derivation for 7 traits were evaluated using the mean squares for genotypes within derivation as error. Significant
differences between derivations were found for shoot and tuber number with androgenic exceeding gynogenic for both (3.3 vs. 2.0 shoots
and 6.7 vs. 1.8 tubers per plant, respectively). Androgenic and gynogenic monoploids (74 total) from both parental lines were planted from
cuttings in 10 cm pots in Dec. 1998 in a randomized complete block of 1-plant plots in 3 replications in the greenhouse under 16 h day length.
Preliminary results indicated no significant differences between derivations for 3 traits: vigor, height and stem number. Flow cytometry
of 9 androgenic and 10 gynogenic plantlets derived from 1-3 revealed no significant difference for DNA content per nucleus between
derivations.
Wahab, Jazeem, Doug Waterer and Terry Hogg. "Optimizing Fertility Levels And Plant Populations
For Potato Grown Under Short Growing Seasons." [Vol. 76, No. 6, 386]
Cultivar specific agronomic practices suited for Saskatchewan’s short, cool growing season are being developed for
"seed" and "consumption" (processing and fresh market) grade potato. This study examined factorial combinations
of nitrogen and phosphorus and seed piece spacing for Russet Norkotah (mid-season, fresh market), Shepody (mid-season french fry), and
Ranger Russet (very-late, french fry) potato. Fertility levels were 50-200 kg N/ha and 60- 120 kg P2O
5N/ha with 15 or 30 cm in-row seed spacing. Ranger Russet produced lower "seed" and
"consumption" grade tuber yields than Russet Norkotah or Shepody. Yield responses to nitrogen and phosphorus levels were
similar for the two market classes and interactions between the test factors were limited. Optimum yields for Russet Norkotah and Ranger
Russet were obtained with 150 kg N/ha Shepody yields increased through to the highest nitrogen level tested (200 kg N/ha). Applying
120 kg P205/ha produced little advantage over 60 kg
P205/ha The 15 cm seed piece spacing significantly outyielded the
30cm spacing, irrespective of the fertility level. Fertility and seed piece spacing effects on yield components, tuber specific gravity, and related
economic implications are discussed.
Walters-Felcher, Kimberly, Wenbin Li and Dave Douches. "Molecular Characterization And
Disease Reaction of Transgenic Potato Plants Carrying A Fungal Glucose Oxidase Gene."
[Vol. 76, No. 6, 386]
Late blight, (Phytophthora infestans) is one of the most devastating diseases of potato worldwide and the development of
cultivars resistant to this disease is an important objective for many potato breeders. Current emphasis is on utilization of horizontal
resistance rather than vertical resistance conferred by specific R genes. Our research was undertaken to determine if enhanced resistance
to late blight could be obtained by combining natural resistance and engineered resistance conferred by the fungal transgene glucose
oxidase. This gene was selected due to its reported effect against multiple pathogens including P. infestans, Erwinia carotovora,
Alternaria solani, and Fusarium sambucinum. Late blight susceptible cultivars Atlantic, Snowdon and Spunta and partially
resistant cultivars Zarevo and Libertas were transformed with the glucose oxidase gene under the control of the Gelvin Super Promoter.
Putative transgenic lines were verified and copy number determined via Southern blotting. Copy number rang from 1 to 7. Lines containing
the glucose oxidase transgene were evaluated for reaction to P. infestans in growth chambers and/or inoculated field studies.
Results from both types of studies revealed no significant effect of the transgene in either susceptible or partially resistant cultivars. Lines
for which tubers were available were tested for reaction to Erwinia carotovora (soft rot) and Fusarium sambucinum (dry rot).
All transgenic lines tested were significantly better than non-transgenic controls for lesion diameter and depth when inoculated with
E. carotovora. Four transgenic lines (SGO-1, SGO-2, SGO-14, and SGO-26) and two transgenic lines (SGO-3, and SGO-26) were
significantly better than the non-transgenic control for lesion diameter and depth respectively when inoculated with F. sambucinum.
Our results indicate that glucose oxidase will not be an effective component of a combined resistance strategy to develop late blight
resistance in potatoes but may be useful in a similar strategy for developing soft rot resistance.
Weingartner, DP and KG Haynes. "Inheritance of Resistance to Corky
Ringspot."
[Vol. 76, No. 6, 387]
Corky ringspot (CRS) in potato tubers is caused by tobacco rattle virus which in Florida is transmitted by trichodorid nematodes,
principally Paratrichodorus minor. External tuber symptoms range from prominent concentric rings of alternating living and
necrotic tissue to small necrotic flecks. The internal tuber symptom is necrosis. Twenty crosses between CRS susceptible and resistant
parents were made using a design H mating scheme. Twenty-five progeny from each cross were planted in 1997 in a randomized
complete block design with three replications in a trichodorid infested field in Hastings, FL. Incidence and severity of CRS were recorded
at harvest. Approximately 14% of the tubers showed internal symptoms but only 4% of the tubers showed external symptoms of CRS.
Additive variance was approximately twice as great as dominance variance for both incidence and severity of CRS. Because the inheritance
of resistance to CRS is controlled by no more than one or two genes breeding for resistance should be a relatively direct process.
Wright, Ryan. "The Profitability of Growing Soybeans in Rotation With Potatoes in
Maine."
[Vol. 76, No. 6, 387]
This research examines the profitability of growing soybeans as a crop in rotation with potatoes in Maine, and how this crop affects the
profit level of the entire farm operation. One goal of the Maine Potato industry is finding more profitable crop rotations. However, maximizing
the profit of a farm cannot look only at the primary crop produced (potatoes); it must examine the profitability of the entire cropping system.
Enterprise budgets are constructed separating the costs of soybean production on a per acre basis for a hypothetical farm. The budgets
include any rotational benefits soybeans offer potato production. Information from the American Society of Agricultural Engineers 1997
Standards, local data, and budgets from other states are used to calculate variable costs of production. The Agricultural Research Service
office in Orono, Maine conducted field trials in Newport and Presque Isle, Maine. Data gathered from these trials are used to examine the
rotational effects of including soybeans in a potato rotation. Sensitivity analysis is conducted on the estimated revenues and variable costs
of production determining a range of profitable production conditions.
Yencho, GC, SP Kowalski, GG Kennedy and LL Sanford. "Leptine Glycoalkaloids And Colorado
Potato Beetle Resistance in F2 Solanum tuberosum x S. Chacoense Progenies."
[Vol. 76, No. 6, 387]
S. chacoense (chc) is resistant to the Colorado potato beetle. Resistance has been associated with the presence of leptine
glycoalkaloids. Seven tetraploid, P2S. tuberosum x S. chacoense families of 33 sibs each were evaluated for production of
leptines land II, leptinines I and II, and a-solanine and a-chaconine, and screened for resistance to CPB in laboratory and field defoliation
experiments. Resistance was correlated with the concentrations of foliar glycoalkaloids on a family and individual basis. Leptine
concentrations ranged from undetectable to a high of 18.0 mg/g DW. All of the progeny produced solanine and chaconine. Family 9623,
which had the highest mean leptine concentration had the lowest mean leaf disk feeding and CPB defoliation levels. Family 9616, ranked
as the lowest glycoalkaloid producer, ranked as one of the most susceptible families. Regression analyses of the traits solanine + chaconine,
leptine I and II, and leptinine I and II foliar concentrations versus leaf disk consumption and field defoliation revealed that only increased foliar
levels of leptines resulted in decreased CPB feeding. The linear regression models for leptines versus leaf disk consumption and field
defoliation were highly significant (p<0.0001) accounting for 17% and 26% of the variation in consumption and defoliation, respectively.
Results are discussed within the context of breeding for resistance to CPB.
Zlesak, David C and CA Thill. "The Identification of Late Blight Resistance in 1, 2, and 4EBN Wild
Solanum Species For Use in Breeding." [Vol. 76, No. 6, 388]
Resistance to Phytophthora infestans (US8, A2) was evaluated in 1928 seedling genotypes from 51 accessions across 13
Solanum species. Species evaluated were 2x 1EBN S. bulbocastanum, S. cardiophyllum, S. commersonii, S. pinnatisectum,
and S. trifidum; 2x 2EBN S. berthaultii, S. microdontum, S. stoloniferum, and S. verrucosum; 4x 2EBN S. fendleri;
6x 4EBN S. guerreroense; and 2x ? EBN S. megistacrololbum and S. polyadenium. Infection proceeded after placing
seedlings (2 replications of 24 seedlings per accession) between inoculated rows of cv. Norchip and by direct spray inoculation 12 days
after placement. Resistance was determined using the CIP scale (1=0% to 9=100% infection) then converted to AUDPC scores.
Resistance was found to segregate between species and AUDPC ranged from 555 (S. cph) to 1932 (5. mga). The most resistant
species were S. cph (555), S. bIb (649), S. pld (1075), and S. pnt (1178). S. bib and S. cph had
the greatest variability among accessions, while S. pld and S. pnt had the least. Moreover, resistance segregated
within accessions i.e. S. bIb: P.1. 243512 (35-1075), P.1. 243345 (315-1312), and P.1. 342505 (110-1072). The most resistant
accession was S. bIb 243512; 36 of 48 genotypes had no more than 25% plant defoliation. Ninety-five resistant seedlings were
selected 56 (1EBN), 27 (2EBN), and 12 (IEBN) for use in breeding. Selected seedlings (2EBN) will be crossed to haploid-species hybrids
and cultivars; (IEBN) will be somatically doubled prior to crossing to haploid-species hybrids.
Zvomuya, Francis, Carl Rosen and Mike Thornton. "Response of Superior And NewLeaf Superior
Potato Clones to Nitrogen." [Vol. 76, No. 6, 388]
During genetic transformation of potatoes, single plants are selected from tissue culture and then clonally propagated. Backcrossing to
the standard clone is not performed due to the heterozygous nature of potatoes. Therefore, in addition to the genetic transformation for the
selected trait, chances of obtaining differences in other traits are high. NewLeaf Superior potato has been shown in previous field trials to
be more vigorous than the standard clone. The objective of this study was to determine the effect of nitrogen fertilizer on yield and quality of
standard and NewLeaf Superior potato clones. A two year field study was conducted at the Sand Plain Research Farm in Becker, Minn. on
a Hubbard loamy sand. Four N rates were tested: 25, 100,200, and 300 lb N/A in a split plot design replicated four times. Significant N rate
by genotype interactions for total tuber yield were obtained each year. Yield was optimized at 100-200 lb N/A for the NewLeaf clone in contrast
to 200-300 lb N/A for the standard clone. Nitrogen rates higher than 200 lb N/A depressed yield of the NewLeaf clone. Differences in N
response were likely due to increased vine growth and a delay in maturity of the NewLeaf clone compared to the standard type.
|