scholarly journals Association of Solar Irradiance and Days of Precipitation with Incidence of Potato Late Blight in the Semiarid Environment of the Columbia Basin

Plant Disease ◽  
2009 ◽  
Vol 93 (3) ◽  
pp. 272-280 ◽  
Author(s):  
Dennis A. Johnson ◽  
Thomas F. Cummings ◽  
Rita Abi Ghanem ◽  
J. Richard Alldredge
Keyword(s):  
Late Blight ◽  
Solar Irradiance ◽  
Meteorological Data ◽  
Potato Late Blight ◽  
Multiple Regression Model ◽  
Columbia Basin ◽  
South Central ◽  
Commercial Potato ◽  
First Occurrence ◽  
Rainy Days

The effects of cumulative solar irradiance and rainfall on incidence of potato late blight (caused by Phytophthora infestans) in the Columbia Basin of south-central Washington and north-central Oregon were investigated using meteorological data collected near Othello, WA from 1990 through 2007 and Prosser, WA from 1990 through 2006. An association between solar irradiance and seasonal differences in late blight epidemics has not been quantitatively determined. Incidence of late blight in the Columbia Basin significantly increased as cumulative solar irradiance decreased during 1 April to 31 July and 1 June to 31 July at both Othello and Prosser. Incidence of late blight also increased as number of rainy days increased during 1 April to 31 July at Othello and Prosser and from 1 June to 31 July at Prosser. Coefficients of determination for significant models on late bight incidence ranged from 0.28 to 0.43 for cumulative solar irradiance and 0.27 to 0.38 for number of rainy days. Late blight incidence significantly increased as day of the year for first occurrence of late blight decreased in the Columbia Basin. A multiple regression model that included cumulative solar irradiance from 1 June to 31 July at Prosser and day of year for first occurrence of late blight as independent variables accounted for 58% of the variation for late blight incidence (adjusted R2 = 0.58), and a model that included number of cloudy days without rain combined with number of rainy days accounted for 62% of the variation for late blight incidence. This is the first report demonstrating a quantitative association of solar irradiance and incidence of late blight in commercial potato fields.

scholarly journals Ametoctradin: a new fungicide for potato late blight control

2016 ◽  
Vol 83 (0) ◽  
Author(s):  
Jesus Guerino Töfoli ◽  
Ricardo José Domingues ◽  
Walter Jacobelis Jr. ◽  
Marina Pacheco Lombardi Tortolo
Keyword(s):  
Late Blight ◽  
Block Design ◽  
Potato Late Blight ◽  
Significant Control ◽  
Progress Curve ◽  
Randomized Block Design ◽  
Commercial Potato ◽  
Crop Development ◽  
Potato Crops ◽  
Application Volume

ABSTRACT: Late blight (Phytophthora infestans ) is among the most important and destructive diseases in potato cultivation. Aiming to evaluate the efficacy of the new fungicide ametoctradin, mixed with dimethomorph and metiram, an experiment was carried out in commercial potato crops (Ágata cultivar) in Pilar do Sul, São Paulo state, Brazil, during the growing season in 2013. A randomized block design was used, with 4 replications, on plots of 15 m2. Applications were carried out using a backpack sprayer with a spray-bar under 3 bar of constant pressure. The application volume varied from 300 L to 600 L.ha-1 based on crop development. The variables evaluated were leaf severity (0 to 100%), area under the disease progress curve, and yield. Ametoctradin + dimethomorph (1.25 L.ha-1) provided significant control of late blight, exceeding benthiavalicarb + fluazinam, dimethomorph + metiram, dimethomorph + pyraclostrobin, cymoxanil + mancozeb, metalaxyl-M + mancozeb, ametoctradin + metiram, and pyraclostrobin + metiram, although similar to ametoctradin + dimethomorph (1.00 L.ha-1), fluopicolide + propamocarb, and fenamidone + propamocarb. Ametoctradin + metiram resulted in moderate control, which was always similar to the standard. Ametoctradin and its associations represent a new alternative for the management of potato late blight.

SIMBLIGHT1 ? a new model to predict first occurrence of potato late blight

EPPO Bulletin ◽  
2007 ◽  
Vol 37 (2) ◽  
pp. 339-343 ◽  
Author(s):  
Benno Kleinhenz ◽  
Kristina Falke ◽  
Joachim Kakau ◽  
Dietmar Rossberg
Keyword(s):  
Late Blight ◽  
Potato Late Blight ◽  
New Model ◽  
First Occurrence

scholarly journals The Effects of Host Diversity and Other Management Components on Epidemics of Potato Late Blight in the Humid Highland Tropics

2001 ◽  
Vol 91 (10) ◽  
pp. 993-1000 ◽  
Author(s):  
K. A. Garrett ◽  
R. J. Nelson ◽  
C. C. Mundt ◽  
G. Chacón ◽  
R. E. Jaramillo ◽  
...  
Keyword(s):  
Late Blight ◽  
Potato Production ◽  
Potato Late Blight ◽  
Planting Density ◽  
Susceptible Host ◽  
Host Diversity ◽  
Progress Curve ◽  
Commercial Potato ◽  
Diversity Effect ◽  
Diversity Effects

A field study at three highland sites near Quito, Ecuador, was conducted to determine whether host-diversity effects on potato late blight would be as important as recently found in studies conducted in temperate areas. We compared three potato mixtures and use of mixtures in combination with different planting densities and two fungicide regimes. Treatment comparisons were made by absolute and relative measures of host-diversity effects and incorporating a truncated area under the disease progress curve as a means of standardizing comparisons across sites. Potato-faba intercrops consisting of only 10% potato provided an estimate of the effects of dilution of susceptible host tissue. Host-diversity effects were very different across study sites, with a large host-diversity effect for reduced disease only at the site most distant from commercial potato production. Planting density had little influence on host-diversity effects or on late blight in single-genotype stands. Fungicide use in combination with potato mixtures enhanced a host-diversity effect for reduced late blight. Potato-faba intercrops produced only a small decrease in potato late blight. Effects of host diversity on yield were variable, with the greatest increase in yield for mixtures treated with fungicides at the site most distant from commercial potato production. The effects of host diversity on late blight severity may be less consistent in the tropical highlands than in the temperate zone, but can contribute to integrated disease management.

scholarly journals Cost of Fungicides Used to Manage Potato Late Blight in the Columbia Basin: 1996 to 1998

Plant Disease ◽  
2000 ◽  
Vol 84 (4) ◽  
pp. 399-402 ◽  
Author(s):  
Dennis A. Johnson ◽  
Thomas F. Cummings ◽  
Philip B. Hamm
Keyword(s):  
Late Blight ◽  
Management Practices ◽  
Potato Late Blight ◽  
Columbia Basin ◽  
Total Cost ◽  
Late Season ◽  
The North ◽  
The Cost ◽  
Mean Cost ◽  
Tuber Rot

The cost of managing potato late blight with fungicides in the Columbia Basin of Washington and Oregon in 1996 to 1998 was documented and compared with the cost of managing the epidemic in 1995. Mean number of fungicide applications on late-season potatoes from 1996 to 1998 ranged from 5.3 to 8.8 in the north Columbia Basin of Washington and 8.5 to 12.3 in the southern basin of Washington and Oregon. Mean cost per hectare of fungicides and application on late-season potatoes in 1998 was $316 per hectare ($128 per acre) in Washington's north basin and $472 per hectare ($191 per acre) in Washington's south basin. Even though the price of most fungicides had increased since 1995, total cost of control per hectare over the season was less during 1996 to 1998 than in 1995 because of altered management practices. These included fewer fungicide applications, a shift toward lower cost fungicides, substitution of aerial application by chemigation, and a reduction in the number of fields chemically desiccated before harvest. Total cost of managing late blight and tuber rot loss was $22.3 million in 1998, whereas it was $30 million in 1995. The 1998 cost included $19.8 million for fungicide applications and materials, $1.1 million for canopy desiccation, and $1.4 million loss due to tuber rot in storage.

scholarly journals Effect of Host Plant Resistance and Reduced Rates and Frequencies of Fungicide Application to Control Potato Late Blight

Plant Disease ◽  
2001 ◽  
Vol 85 (10) ◽  
pp. 1113-1118 ◽  
Author(s):  
W. W. Kirk ◽  
K. J. Felcher ◽  
D. S. Douches ◽  
J. Coombs ◽  
J. M. Stein ◽  
...  
Keyword(s):  
Late Blight ◽  
Field Experiments ◽  
Potato Late Blight ◽  
Application Rate ◽  
Effective Control ◽  
Michigan State University ◽  
State University ◽  
Breeding Lines ◽  
Application Rates ◽  
Commercial Potato

Field experiments were conducted during 1998 to 2000 to determine the response of commercial potato cultivars and advanced breeding lines (ABL) differing in susceptibility to foliar late blight (caused by Phytophthora infestans) to reduced rates and frequencies of residual, contact fungicide applications. When environmental conditions were most favorable for the development of late blight, the lowest application rate of the fungicides chlorothalonil or fluazinam (33% of the manufacturers' recommended application rate [MRAR]) gave unsatisfactory control of potato late blight. Under conditions moderately conducive for late blight development, effective control was achieved with 33 to 66% MRAR with either fungicide. The Michigan State University advanced selection, MSG274-3, was the least susceptible ABL tested and, during 1998 to 2000, late blight was effectively managed using reduced rates of fungicides. Application rates of chlorothalonil (33 to 100% MRAR) significantly reduced late blight in the cultivar Snowden (5-day application interval) compared with the nontreated control; whereas, late blight was not effectively controlled in Snowden even at 100% MRAR of chlorothalonil at either 10- or 15-day application intervals in 1999 or 2000. The ABL MSG274-3 was the least susceptible of all cultivars and ABL used in this study, and required minimal chemical protection against late blight. The study demonstrates that ABL with reduced susceptibility to late blight can be managed with reduced fungicide rates and longer application intervals, thus offering more economical control of this disease.

scholarly journals Expansion of Potato Late Blight Forecasting Models for the Columbia Basin of Washington and Oregon

Plant Disease ◽  
1998 ◽  
Vol 82 (6) ◽  
pp. 642-645 ◽  
Author(s):  
Dennis A. Johnson ◽  
J. Richard Alldredge ◽  
Philip B. Hamm
Keyword(s):  
Late Blight ◽  
Disease Outbreaks ◽  
Disease Status ◽  
Growing Season ◽  
Potato Late Blight ◽  
Columbia Basin ◽  
Indicator Variable ◽  
Forecasting Models ◽  
Forecasting System ◽  
Using Data

A regional potato late blight forecasting system for irrigated potatoes in the semiarid environment of the Columbia Basin was expanded by developing specific forecasting models for four vicinities throughout the Basin. Relationships between weather and outbreaks of late blight at the locations over a 27-year period were examined using logistic regression analysis. The response variable was a year either with or without a late blight outbreak. An indicator variable representing the occurrence of an outbreak during the preceding year (Yp) and number of days of rain during April and May (Ram) correctly classified the disease status (presence or absence of late blight) of 89, 82, 78, and 78% of the years at Prosser, Washington, Hermiston, Oregon, and Hanford and Othello, Washington, respectively. The percentage of years with disease outbreaks correctly classified was 93, 85, 79, and 79% at the four respective locations. All years with late blight outbreaks and 96% of the total years were correctly classified using data from at least one of the four locations. These predictors are particularly important early in the growing season and can be used to make area forecasts. A second set of predictors, Yp and number of days of rain in July and August (Rja), for Hermiston and Hanford, and a third set, Yp, Ram, and Rja, for Prosser and Othello were found effective for making additional late blight forecasts later in the growing season.

scholarly journals Occurrence of Late Blight Caused by Phytophthora infestans on Potato and Tomato in Alaska

Plant Disease ◽  
2007 ◽  
Vol 91 (5) ◽  
pp. 634-634 ◽  
Author(s):  
L. M. Winton ◽  
R. H. Leiner ◽  
A. L. Krohn ◽  
K. L. Deahl
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Economic Impact ◽  
Mating Type ◽  
Plant Pathogens ◽  
The State ◽  
Mitochondrial Haplotype ◽  
South Central ◽  
Commercial Potato ◽  
Allozyme Loci

Phytophthora infestans, causal agent of late blight, was included in a list of plant pathogens found in Alaska in 1934 (1). No notes of symptoms, extent of disease, or dates were recorded. The only reference to the location was given as Wrangell, a town in southeast Alaska with subsistence gardening. Neither P. infestans nor late blight was noted again in the state for another 59 years. Late blight first appeared in Alaska's major potato-growing region in south-central Alaska's Matanuska Valley in 1995. Subsequent outbreaks have been sporadic, occurring only in 1998, 2005, and 2006. Each of these outbreaks was identified from rapidly enlarging brown foliar lesions with branched sporangiophores and lemon-shaped sporangia (~25 × 30 μm). The 1995 and 1998 potato late blight outbreaks in Alaska were not sampled extensively nor have they previously been formally reported. We recovered single isolates of P. infestans from symptomatic potato foliage in the 1995 and 1998 outbreaks. In 2005, symptomatic foliage was collected from individual potato plants in 10 commercial fields and from tomato plants in greenhouses at two locations. Sporulating stem and leaf tissue were used to inoculate semiselective rye medium and 147 isolates from potato and six from tomato were recovered. The isolates from the 1995, 1998, and 2005 outbreaks were analyzed to determine genotype at the allozyme loci GPI and PEP (3), mitochondrial haplotype (4), mating type, and metalaxyl sensitivity (2). The 1998 and 2005 outbreaks were similar because both were caused by the relatively aggressive US-11 allozyme genotype and had significant economic impact for commercial potato growers. All 153 isolates from potato and tomato in 2005 displayed the same allozyme pattern as the US-11 genotype, possessed the IIB mitochondrial haplotype, and were mating type A1. Of the 16 isolates tested, all were determined to be metalaxyl resistant because isolates grown on 5 and 100 μg/ml metalaxyl exhibited growth greater than 40% of the unamended control. The 1995 outbreak was caused by the relatively rare US-7 genotype and started so late during the season that economic impact was minimal. Similarly, the 2006 outbreak was noted from only one commercial potato field at the time of harvest in September 2006. However, the genotype of the 2006 isolate has not been determined because the patch was destroyed before adequate samples could be collected. Because the disease occurs so sporadically in Alaska, fungicides are not routinely in use, but it is unlikely that the pathogen has persisted locally between outbreaks. The source of P. infestans is unknown for each of the occurrences in Alaska. However, possible routes include seed potatoes for home gardens or commercial farms, tomato transplants, and retail vegetables shipped to Alaska from out of state. While potato is Alaska's main vegetable crop, there are less than 405 ha (1,000 acres) of potatoes planted in the state, with the majority planted in the Matanuska Valley. To our knowledge, this is the first formal report of P. infestans on both tomato and commercial potato in Alaska. References: (1) E. K. Cash. Plant Dis. Rep. 20:121, 1936. (2) D. E. L. Cooke et al. Plant Pathol. 52:181, 2003. (3) S. B. Goodwin et al. Plant Dis. 79:1181, 1995. (4) G. W. Griffith and D. S. Shaw. Appl. Environ. Microbiol. 64:4007, 1998.

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