scholarly journals Latent Infection of Potato Seed Tubers by Phytophthora infestans During Long-Term Cold Storage

Plant Disease ◽  
2009 ◽  
Vol 93 (9) ◽  
pp. 940-946 ◽  
Author(s):  
Dennis A. Johnson ◽  
Thomas F. Cummings
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Pacific Northwest ◽  
Cold Storage ◽  
Latent Infection ◽  
Seed Tuber ◽  
Potato Seed ◽  
Seed Tubers ◽  
Humidity Chamber

Latent infection of potato seed tubers by Phytophthora infestans was determined following inoculation of tubers and typical seed tuber storage conditions in the Pacific Northwest. Severity of late blight increased over 182 to 209 days during two storage seasons at mean temperatures of 4.1 and 4.2°C. From 0 to 44% of inoculated tubers sampled at given intervals were asymptomatic. However, P. infestans sporangia were observed on slices from these tubers when incubated in a humidity chamber at 15°C or late blight symptoms developed in asymptomatic tubers obtained following storage when incubated at 22 to 23°C for 3 weeks. Development of P. infestans sporangia and symptoms of late blight in asymptomatic seed tubers indicated latent infection of tubers by P. infestans during long-term cold storage. Sporulation was observed after 21 to 24 h on symptomatic tubers and 6 to 20 days on asymptomatic tubers that were removed from storage and incubated in a humidity chamber at 15°C. Latent infection of seed tubers and production of viable sporangia of P. infestans were demonstrated after long-term cold storage of infected potato tubers.

scholarly journals Transmission of Phytophthora infestans from Infected Potato Seed Tubers to Emerged Shoots

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 18-23 ◽  
Author(s):  
Dennis A. Johnson
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Fine Sand ◽  
Russet Burbank ◽  
Potato Seed ◽  
Infected Seed ◽  
Seed Tubers ◽  
Moist Environment ◽  
Soil Level ◽  
Spring Planting

Transmission of Phytophthora infestans from infected seed tubers to emerged potato sprouts, infectivity of sporangia deposited on whole tubers before burial in soil, and infectivity of sporangia in a loamy fine sand to leaflets were investigated in the greenhouse under simulated spring planting conditions of the Columbia Basin. Incidence of late-blight-infected shoots from infected seed tubers was significantly greater when foliage was exposed to wet periods in mist chambers (mist for 45 s every 15 min) for either 24 or 48 h than when not exposed to a wet period. Proportion of infected shoots from infected tubers was 0.210 to 0.261 in a moist environment versus 0.013 to 0.052 in a nonmist environment. Development of chlorosis, necrosis, and sporangia occurred on shoots that emerged from infected, symptomatic tubers buried in soil. However, approximately 20% of the infected shoots produced sporangia before stems had visible discoloration of late-blight symptoms. Sporulation was sparse and formed near the soil line on some of the shoots after 24 h in the moist environment. The latent period or time from inoculation to sporulation on young stems of Russet Burbank was 5 to 6 days, which is too long to account for an infection from either sporangia or zoospores at the soil level of shoots during the wet period in this study. Sporangia were infective when placed directly on eyes of whole tubers before planting. Leaflets touching a loamy fine sand infested with sporangia developed typical late-blight lesions beginning at the leaflet tip within 7 days after a 24-h wet period and the infested loamy fine sand was infective when splashed on leaflets.

Determination of optimum tuber planting density in the potato varieties Pentland Squire, Cara, Estima, Maris Piper and King Edward

1992 ◽  
Vol 119 (1) ◽  
pp. 35-44 ◽  
Author(s):  
D. C. E. Wurr ◽  
J. R. Fellows ◽  
E. J. Allen
Keyword(s):  
Complex Analysis ◽  
Seed Tuber ◽  
Tuber Size ◽  
Planting Density ◽  
Potato Seed ◽  
Stem Density ◽  
Seed Tubers ◽  
Net Returns ◽  
Analysis Technique ◽  
The Cost

SummaryThirty-two experiments examining the effects of the weight and within-row spacing of potato seed tubers on graded tuber yields of five varieties were conducted on eight sites from 1980 to 1985. A complex analysis technique was used to combine these data and estimate the optimum tuber planting densities for different ratios of seed cost to small (40–60 mm) and large (60–80 mm) ware value. The same technique could be applied to any other combination of seed cost, ware size and ware value.The optimum tuber planting density decreased with increasing seed-tuber weight. Differences in optimum planting density between varieties were much greater with small (35 g) than with large (105 g) seed tubers and decreased as the cost of seed increased relative to the value of ware. As large ware became worth more than small ware the influence of increasing seed cost on the optimum density was reduced. As the value of large ware increased, net returns increased and the effect of seed cost on net returns was reduced. Mean tuber size decreased with increasing stem density at harvest and at the same stem density was lower in varieties producing more daughter tubers/stem. Changes of mean tuber size (μ) and the spread of yield across size grades (σ) with time were well described by parallel curves in different varieties. It is suggested that in future it may not be necessary to determine optimum tuber planting densities by complex experiments involving several seed-tuber weights and spacings. Instead μ and σ could be estimated from simple experiments and tuber spacings determined by comparison with control varieties.

Seed Borne Late Blight of Potato

2002 ◽  
Vol 3 (1) ◽  
pp. 14 ◽  
Author(s):  
Mary L. Powelson ◽  
Robin Ludy ◽  
Heather Heather ◽  
Debra A. Inglis ◽  
Babette Gundersen ◽  
...  
Keyword(s):  
Late Blight ◽  
Seed Piece ◽  
Transmission Rate ◽  
Seed Transmission ◽  
Management Program ◽  
Healthy Plant ◽  
Potato Seed ◽  
Stand Establishment ◽  
Seed Tubers ◽  
Healthy Seed

Planting of potato seed pieces infected with Phytophthora infestans can lead to the introduction of late blight within a planting. When infected seed pieces are planted, there are three resulting scenarios: (i) a healthy plant emerges, (ii) no plant emerges because of the rapid decay of the seed piece, or (iii) a symptomatic plant emerges. A major factor favoring stand establishment and seed transmission is the severity of seed piece infection. When infection is severe, stand is compromised and transmission rate is low. When infection is mild, the plant emerges before the seed piece decays and, in some instances, the pathogen makes its way from the seed piece to the plant where a stem lesion is formed. Diseased seed tubers are the principle source of late blight inoculum for infection of healthy seed pieces. Treatment of infected or blighted seed tubers with a seed dressing with activity against P. infestans is not a viable tactic because the products are ineffective against established infections. Conversely, treatment of healthy seed pieces provides a high level of protection against late blight spores that are spread during the seed handling and planting operations. Optimum effectiveness is achieved when products are applied immediately following cutting, as none are effective against established infections. Seed treatment reduces the risk of seed transmission of late blight and enhances stand establishment and plant vigor. This tactic should be an important component of an integrated late blight management program. Accepted for publication 16 January 2002. Published 29 January 2002.

Effect of altering the physiological age of potato seed-tubers in the fall on subsequent production in a short-season environment

1992 ◽  
Vol 72 (1) ◽  
pp. 275-287 ◽  
Author(s):  
N. Richard Knowles ◽  
Gabor I. Botar
Keyword(s):  
Plant Growth ◽  
Harvest Index ◽  
Seed Tuber ◽  
Growing Season ◽  
Russet Burbank ◽  
Physiological Age ◽  
Quadratic Model ◽  
Tuber Quality ◽  
Potato Seed ◽  
Seed Tubers

The efficacy of utilizing "controlled seed-tuber aging" as a technique to enhance yield and improve tuber quality in areas with relatively short growing seasons was investigated in a 3-yr study. Prior to planting in the field, five physiological ages of Russet Burbank, Carlton, Norchip and Superior seed-tubers were produced by varying the heat-unit accumulation over a 200-d storage interval. Total yield increases of up to 90% and substantial improvements in tuber grade were achieved by planting aged (600–900 degree-day (dd)) seed-tubers. Plant growth from aged Russet Burbank seed-tubers was modelled to identify the mechanisms by which yield and quality were altered. Growth analysis demonstrated that the age-induced yield increases were due to faster emergence, faster leaf-area establishment, and tuberization earlier in the growing season compared with that from younger seed-tubers. The annual life cycle was thus accelerated, allowing plants from older seed-tubers to utilize the short (120-d) growing season more efficiently than those from younger seed-tubers. This was reflected in a higher harvest index: plants from 739 dd seed-tubers partitioned 63% of their total fresh weight into tubers compared with 48% for those from 66 dd seed-tubers (based on the quadratic model describing the relationship between seed-tuber age and and harvest index at 121 d after planting). The technique appears to be very promising for enhancing yield and/or promoting ’earliness’ of potatoes in regions with short growing seasons.Key words: Solanum tuberosum, seed-tuber age, plant growth, yield

scholarly journals Evaluation of different fungicides applied as seed tuber treatments for the control of potato silver scurf

2005 ◽  
Vol 82 (2) ◽  
pp. 41-48 ◽  
Author(s):  
V. Hervieux ◽  
R. Chabot ◽  
J. Arul ◽  
R.J. Tweddell
Keyword(s):  
Solanum Tuberosum ◽  
Seed Tuber ◽  
Field Trials ◽  
Potato Seed ◽  
Silver Scurf ◽  
Helminthosporium Solani ◽  
Potato Tubers ◽  
Experimental Conditions ◽  
Soil Inoculum ◽  
Seed Tubers

Silver scurf of potatoes (Solanum tuberosum), caused by the fungus Helminthosporium solani, is an important surface-blemishing disease of potato tubers. The objective of the study was to evaluate the efficacy of different fungicides applied to potato seed tubers for control of silver scurf. Field trials were conducted in Québec province in 1998 and 1999. Potato seed tubers infected with H. solani were treated with either talc, fludioxonil, mancozeb, iprodione, thiabendazole, imazalil or azoxystrobin, and planted at three locations in 1998 and two locations in 1999. The results showed that, under our experimental conditions, the fungicides tested, applied as seed treatments, did not significantly influence total and marketable yields as well as silver scurf severity on daughter tubers at harvest and after different storage periods. In addition, this study showed the influence of the experimental locations on silver scurf development and suggests that soil inoculum plays a role in the epidemiology of the disease.

scholarly journals Population Structure of the Late Blight Pathogen Phytophthora infestans in a Potato Germplasm Nursery in Two Consecutive Years

2015 ◽  
Vol 105 (6) ◽  
pp. 771-777 ◽  
Author(s):  
Yuee Tian ◽  
Junliang Yin ◽  
Jieping Sun ◽  
Hongmei Ma ◽  
Yunfang Ma ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Plant Pathogens ◽  
Control Strategies ◽  
Northwestern China ◽  
Potato Seed ◽  
Low Level ◽  
Potato Germplasm

As the causal agent of late blight on potato, Phytophthora infestans is one of the most destructive plant pathogens worldwide and widely known as the Irish potato famine pathogen. Understanding the genetic structure of P. infestans populations is important both for breeding and deployment of resistant varieties and for development of disease control strategies. Here, we investigate the population genetic structure of P. infestans in a potato germplasm nursery in northwestern China. In total, 279 isolates were recovered from 63 potato varieties or lines in 2010 and 2011, and were genotyped by mitochondrial DNA haplotypes and a set of nine simple-sequence repeat markers. Selected isolates were further examined for virulence on a set of differential lines containing each resistance (R) gene (R1 to R11). The overall P. infestans population was characterized as having a low level of genetic diversity and resistance to metalaxyl, and containing a high percentage of individuals that virulent to all 11 R genes. Both A1 and A2 mating types as well as self-fertile P. infestans isolates were present but there was no evidence of sexual reproduction. The low level of genetic differentiation in P. infestans populations is probably due to the action of relatively high levels of migration as supported by analysis of molecular variance (P < 0.01). Migration and asexual reproduction were the predominant mechanisms influencing the P. infestans population structure in the germplasm nursery. Therefore, it is important to ensure the production of pathogen-free potato seed tubers to aid sustainable production of potato in northwestern China.

scholarly journals Factors affecting the development of Phytophthora infestans on a tomato in the open ground

2020 ◽  
pp. 112-115
Author(s):  
I. Yu. Kondratyeva ◽  
L. K. Gurkina
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Air Temperature ◽  
High Resistance ◽  
Factors Affecting ◽  
Open Ground ◽  
Low Humidity ◽  
Source Resistance ◽  
Increasing Temperature

Relevance and methods. For the Non-chernozem zone, the main factor for the active development of late blight is the low air temperature and its sharp fluctuations during the day, contributing to the formation of increased air humidity and drip-liquid moisture on the plants. In the Moscow region, the causative agent of late blight is manifested almost annually. Populations of Phytophthora infestans are represented by the To and T1 races. Epiphytotic development was observed periodically (1977-1979, 1982, 1986, 1996-1999, 2000, 2001, 2003-2004, 2008-2009, 2013, 2014, 2015, 2016, 2017, 2019) and was provided by the virulent T1 race. Observations showed that epiphytotic situations arose in those years when the minimum air temperature was below long-term average values, and relative humidity and precipitation exceeded them. With a deviation from the norm in the direction of increasing temperature, decreasing rainfall and relatively low humidity, years were observed with a depressive (1992, 1994) or moderate development of the disease (1980, 1981, 1983, 1985, 1987-1991, 2002, 2005-2007, 2010-2012, 2018). Results. As a result of breeding work, a Grot tomato-tolerant tomato variety was obtained, on the basis of which varieties with high resistance Grand, Dubok, Gnom, Chelnok, Patris, Geya, Zolushka, Perst, Severyanka, Blagodatny were obtained. In the general collection of VIR as a source resistance to leaf spot pathogens were registered: Geya (v.k. 14839), Slavyanka (v.k. 14840), Patrice (v.k. 14841), Rossiyanka (v.k. 14842), Krepysh (v.k. 14843), Sibiryachka (v.k. 14444) and line 1079-94 (v.k. 14845) donors, in addition to their high resistance to late blight, have excellent economic characteristics.

scholarly journals Genetic Structure of the Phytophthora infestans Population in Morocco

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 173-176 ◽  
Author(s):  
M. Sedegui ◽  
R. B. Carroll ◽  
A. L. Morehart ◽  
T. A. Evans ◽  
S. H. Kim ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Late Blight ◽  
Sexual Reproduction ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Potato Seed ◽  
Mating Types ◽  
Potato Field ◽  
New Genotype

ABSRACT In 1996 to 1998, a late-blight survey was conducted in potato- and tomato-growing regions of Morocco. A total of 149 isolates of Phytophthora infestans were collected and analyzed for the glucose-6-phosphate isomerase (Gpi) and peptidase (Pep) alleles, mating types, and metalaxyl sensitivities. Four genotypes were identified: MO-1 (mating type A1, Gpi 100/100, Pep 92/100), MO-2 (mating type A1, Gpi 86/100, Pep 92/100), MO-3 (mating type A2 Gpi 100/100, Pep 100/100), and MO-4 (mating type A1, Gpi 100/100, Pep 100/100). The potato isolates were MO-1 (1996 & 97), MO-3 (1998), and MO-4 (1998). The frequencies of A1 (MO-4) and A2 (MO-3) mating types in potato fields in 1998 were 26 and 74%, respectively. Potato isolates were pathogenic to both potatoes and tomatoes. The isolates collected from tomatoes in 1997 and 1998 were MO-2. Potato and tomato isolates were insensitive and sensitive to metalaxyl, respectively. The change of genotype population in 1998 was probably caused by migration of a new genotype from Europe associated with importation of potato seed. The detection of A1 and A2 mating types in the same potato field indicates the potential for sexual reproduction of P. infestans in Morocco.

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