scholarly journals The Roles of Three Fungicides in the Epidemiology of Potato Late Blight

Plant Disease ◽  
2001 ◽  
Vol 85 (9) ◽  
pp. 1006-1012 ◽  
Author(s):  
H. Mayton ◽  
G. A. Forbes ◽  
E. S. G. Mizubuti ◽  
W. E. Fry
Keyword(s):  
Growth Rate ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Environmental Conditions ◽  
Suppressive Effect ◽  
Disease Progress ◽  
Lesion Growth ◽  
Epidemic Development ◽  
Chamber Studies ◽  
Growth Chamber Studies

Three fungicides were tested in the field for efficacy on late blight caused by Phytophthora infestans. The effects of these fungicides on epidemic development, lesion growth rate and sporulation were measured. No fungicide completely arrested epidemic development under the environmental conditions of these experiments. However, the fungicide mixture, propamocarb hydrochloride plus chlorothalonil, had the most suppressive effect of the fungicides tested. The mechanism of effect included suppression of disease progress and lesion expansion. Growth chamber studies demonstrated that 24°C compared to 10 or 16°C limited cymoxanil efficacy.

scholarly journals Effect of Temperature on Growth and Sporulation of US-22, US-23, and US-24 Clonal Lineages of Phytophthora infestans and Implications for Late Blight Epidemiology

2015 ◽  
Vol 105 (4) ◽  
pp. 449-459 ◽  
Author(s):  
Anna C. Seidl Johnson ◽  
Kenneth E. Frost ◽  
Douglas I. Rouse ◽  
Amanda J. Gevens
Keyword(s):  
Growth Rate ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Growth Rates ◽  
Weather Data ◽  
Effect Of Temperature ◽  
Clonal Lineage ◽  
Tomato Production ◽  
The Us ◽  
Lesion Growth

Epidemics of late blight, caused by Phytophthora infestans (Mont.) de Bary, have been studied by plant pathologists and regarded with great concern by potato and tomato growers since the Irish potato famine in the 1840s. P. infestans populations have continued to evolve, with unique clonal lineages arising which differ in pathogen fitness and pathogenicity, potentially impacting epidemiology. In 2012 and 2013, the US-23 clonal lineage predominated late blight epidemics in most U.S. potato and tomato production regions, including Wisconsin. This lineage was unknown prior to 2009. For isolates of three recently identified clonal lineages of P. infestans (US-22, US-23, and US-24), sporulation rates were experimentally determined on potato and tomato foliage and the effect of temperature on lesion growth rate on tomato was investigated. The US-22 and US-23 isolates had greater lesion growth rates on tomato than US-24 isolates. Sporulation rates for all isolates were greater on potato than tomato, and the US-23 isolates had greater sporulation rates on both tomato and potato than the US-22 and US-24 isolates. Experimentally determined correlates of fitness were input to the LATEBLIGHT model and epidemics were simulated using archived Wisconsin weather data from four growing seasons (2009 to 2012) to investigate the effect of isolates of these new lineages on late blight epidemiology. The fast lesion growth rates of US-22 and US-23 isolates resulted in severe epidemics in all years tested, particularly in 2011. The greater sporulation rates of P. infestans on potato resulted in simulated epidemics that progressed faster than epidemics simulated for tomato; the high sporulation rates of US-23 isolates resulted in simulated epidemics more severe than simulated epidemics of isolates of the US-22 and US-24 isolates and EC-1 clonal lineages on potato and tomato. Additionally, US-23 isolates consistently caused severe simulated epidemics when lesion growth rate and sporulation were input into the model singly or together. Sporangial size of the US-23 isolates was significantly smaller than that of US-22 and US-24 isolates, which may result in more efficient release of sporangia from the tomato or potato canopy. Our experimentally determined correlates of fitness and the simulated epidemics resulting from their incorporation into the LATEBLIGHT model suggest that US-23 isolates of P. infestans may have the greatest fitness among currently prevalent lineages and may be the most likely lineage to persist in the P. infestans population. The US-23 clonal lineage has been documented as the most prevalent lineage in recent years, indicating its overall fitness. In our work, US-23 had the highest epidemic potential among current genotypes. Given that epidemic potential is a component of fitness, this may, in part, explain the current predominance of the US-23 lineage.

Control of Kochia in Sugarbeets With Benzadox

Weed Science ◽  
1970 ◽  
Vol 18 (1) ◽  
pp. 183-185 ◽  
Author(s):  
D. M. Weatherspoon ◽  
E. E. Schweizer
Keyword(s):  
Acetic Acid ◽  
Beta Vulgaris ◽  
Temperature Regime ◽  
Environmental Conditions ◽  
Growth Chamber ◽  
Kochia Scoparia ◽  
Simulated Rain ◽  
Chamber Studies ◽  
Growth Chamber Studies

Benzadox [(benzamidooxy)acetic acid] applied at 1, 2, 3, and 4 lb/A as a postemergence treatment controlled kochia [Kochia scoparia(L.) Schrad.] selectively in sugarbeets (Beta vulgarisL.). Control increased as the rate of benzadox increased, but some kochia survived at the 4-lb/A rate. Competition from these plants reduced the yields of sugarbeet roots and sucrose. Where surviving kochia plants were removed by hand 7 weeks after emergence, all sugarbeets treated with benzadox yielded as well as the hand-weeded checks. In growth chamber studies, the activity of benzadox was increased by temperature and decreased by simulated rain which occurred within 4 hr following application. Under a temperature regime of 70 F day and 40 F night, if simulated rain was delayed for 8 hr, the control of kochia was identical to that obtained where no simulated rain followed treatment. The growth chamber studies confirmed our results with the performance of benzadox under different environmental conditions in the field.

Growth, Reproductive Potential, and Control Strategies for Deeproot Sedge (Cyperus entrerianus)

2012 ◽  
Vol 26 (1) ◽  
pp. 122-129 ◽  
Author(s):  
Charles T. Bryson ◽  
Richard Carter
Keyword(s):  
Growth Rate ◽  
Field Study ◽  
Control Strategies ◽  
Reproductive Potential ◽  
Field Studies ◽  
Growth Chamber ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
And Control ◽  
Achene Production

Greenhouse, growth chamber, and field studies were conducted at Stoneville, MS, in 2000 to 2008, to determine the growth rate, reproductive and overwintering potential, and control of deeproot sedge. In growth chamber studies, deeproot sedge growth rate (ht) and plant dry wt were greatest at 25/35 C (night/day temperatures), when compared with regimes of 5/15, 15/25, and 20/30 C. Based on the average number of scales (fruiting sites per spikelet), spikelets per inflorescence, and culms per plant, deeproot sedge reproductive potential was 2.6-, 6.2-, and 17.4-fold greater than Surinam, green, and knob sedges, respectively. A single deeproot sedge plant produced an average of 85,500 achenes annually. Mowing at 15-cm ht weekly prevented achene production but did not kill deeproot sedge plants. The average number of inflorescences produced on mowed plants was 1.2 to 4 times greater in 2- and 1-yr-old deeproot sedge plants, respectively, when compared with unmowed plants. Mature deeproot sedge achenes were produced between monthly mowings. In a 3-yr field study, glyphosate, glufosinate, hexazinone, and MSMA provided more than 85% control of deeproot sedge, and above the soil, live deeproot sedge plant dry wt was reduced by 50, 64, 68, 72, 86, and 93% by dicamba, halosulfuron-methyl, MSMA, hexazinone, glufosinate, and glyphosate, respectively. All (100%) deeproot sedge plants 1 yr old or older overwintered at Stoneville, MS, at 33°N latitude.

scholarly journals Potential Effects of Diurnal Temperature Oscillations on Potato Late Blight with Special Reference to Climate Change

2015 ◽  
Vol 105 (2) ◽  
pp. 230-238 ◽  
Author(s):  
S. K. Shakya ◽  
E. M. Goss ◽  
N. S. Dufault ◽  
A. H. C. van Bruggen
Keyword(s):  
Climate Change ◽  
Growth Rate ◽  
Late Blight ◽  
Global Climate Change ◽  
Global Climate ◽  
Potato Late Blight ◽  
Disease Development ◽  
Diurnal Temperature ◽  
Temperature Oscillations ◽  
Lesion Growth

Global climate change will have effects on diurnal temperature oscillations as well as on average temperatures. Studies on potato late blight (Phytophthora infestans) development have not considered daily temperature oscillations. We hypothesize that growth and development rates of P. infestans would be less influenced by change in average temperature as the magnitude of fluctuations in daily temperatures increases. We investigated the effects of seven constant (10, 12, 15, 17, 20, 23, and 27°C) and diurnally oscillating (±5 and ±10°C) temperatures around the same means on number of lesions, incubation period, latent period, radial lesion growth rate, and sporulation intensity on detached potato leaves inoculated with two P. infestans isolates from clonal lineages US-8 and US-23. A four-parameter thermodynamic model was used to describe relationships between temperature and disease development measurements. Incubation and latency progression accelerated with increasing oscillations at low mean temperatures but slowed down with increasing oscillations at high mean temperatures (P < 0.005), as hypothesized. Infection efficiency, lesion growth rate, and sporulation increased under small temperature oscillations compared with constant temperatures but decreased when temperature oscillations were large. Thus, diurnal amplitude in temperature should be considered in models of potato late blight, particularly when predicting effects of global climate change on disease development.

scholarly journals Can Weed Hosts Increase Aggressiveness of Phytophthora infestans on Potato?

2012 ◽  
Vol 102 (4) ◽  
pp. 429-433 ◽  
Author(s):  
L. Grönberg ◽  
B. Andersson ◽  
J. Yuen
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Genotypic Variation ◽  
Latency Period ◽  
Potato Production ◽  
Potato Late Blight ◽  
Hairy Nightshade ◽  
Weed Hosts ◽  
Lesion Growth ◽  
Sporulation Capacity

Potato late blight, caused by Phytophthora infestans, is a major disease in potato production throughout the world. In southern Sweden, hairy nightshade (Solanum physalifolium), an alternative non-crop host to the pathogen, is an increasing weed problem. Single-lesion leaves infected by P. infestans were collected from potato and hairy nightshade to determine phenotypic and genotypic population differentiation of P. infestans between the two hosts. Genotypic variation was estimated using microsatellites as markers. The results showed no genotypic differentiation in the samples between the two hosts. Aggressiveness tests were performed using the sampled isolates to cross-inoculate potato and hairy nightshade. The proportion of infected leaves, latency period, lesion growth rate, and sporulation capacity were measured. For isolates from hairy nightshade, the odds of infection were higher on both hosts combined. When tested on potato leaves, isolates from hairy nightshade showed a significantly shorter latency period and higher sporulation capacity compared with isolates from potato. This indicates that an alternative host can filter populations of P. infestans toward a higher aggressiveness, which could lead to increasing problems in controlling potato late blight.

scholarly journals In vitro and in vivo effect of poplar bud (Populi gemma) Extracts on late blight (Phytophthora infestans)

2014 ◽  
Vol 6 (1) ◽  
pp. 5-12
Author(s):  
János Bálint ◽  
Botond Turóczi ◽  
István Máthé ◽  
Klára Benedek ◽  
Károly-Attila Szabó ◽  
...  
Keyword(s):  
Growth Rate ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Environmentally Friendly ◽  
Populus Nigra ◽  
Field Conditions ◽  
Black Poplar

Abstract The effect of populin extract from black poplar (Populus nigra) on late blight was assessed under laboratory and field conditions. The growth rate of hyphae was found to be significantly lower after 1v/v% populin application, and no hyphae growth was detected under 3 and 6v/v% populin application. Populin also reduced the light blight severity on potato leaves under field conditions. From our results, we have concluded that populin extract can be considered as a new and environmentally-friendly alternative for the control of late blight under field conditions.

scholarly journals The Effectiveness of Induced Defense Responses in a Susceptible Potato Genotype Depends on the Growth Rate of Phytophthora infestans

2019 ◽  
Vol 32 (1) ◽  
pp. 76-85 ◽  
Author(s):  
Cécile Thomas ◽  
Romain Mabon ◽  
Didier Andrivon ◽  
Florence Val
Keyword(s):  
Growth Rate ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Induced Defense ◽  
Plant Immunity ◽  
Defense Responses ◽  
Alternative Methods ◽  
Gene Expressions

Phytophthora infestans causes the devastating potato late blight disease, which is widely controlled with fungicides. However, the debate about chemical control is fueling a promotion toward alternative methods. In this context, the enhancement of natural plant immunity could be a strategy for more sustainable protection. We previously demonstrated that a concentrated culture filtrate (CCF) of P. infestans primes defense reactions in potato. They are genotype-dependent and metabolites produced decrease pathogen growth in vitro but not in vivo on tubers. Induced potato defenses are assumed to affect P. infestans life history traits depending on strains. This assumption was studied in vivo through induced leaflets on a susceptible genotype inoculated with four P. infestans strains differing for lesion growth rate. This study combines both defenses mechanistic analysis and ecological observations. Defense-gene expressions were thus assessed by quantitative reverse transcription-polymerase chain reaction; pathogen development was simultaneously evaluated by measuring necrosis, quantifying mycelial DNA, and counting sporangia. The results showed that CCF pretreatment reduced the pathogenicity differences between slow- and fast-growing strains. Moreover, after elicitation, PR-1, PR-4, PAL, POX, and THT induction was strain-dependent. These results suggest that P. infestans could develop different strategies to overcome plant defenses and should be considered in biocontrol and epidemic management of late blight.

scholarly journals IDENTIFICATION OF SOURCES OF RESISTANCE AND BIOCHEMICAL MANAGEMENT OF LATE BLIGHT OF POTATO (PHYTOPHTHORA INFESTANS)

2019 ◽  
Vol 3 (3) ◽  
pp. 141-150
Author(s):  
Syed Atif Hasan Naqvi ◽  
Abdul Rehman Sajid ◽  
Ateeq Ur Rehman ◽  
Ummad ud Din Umar ◽  
Hameed Ullah Khan Sherwani ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Disease Incidence ◽  
Block Design ◽  
Sources Of Resistance ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Potato Germplasm ◽  
Progress Curve ◽  
Late Blight Of Potato

A bulk of potato varieties were screened against historical Phytophthora infestans causing the late blight of potato. Almost the potato germplasm showed a varying response against the devastating pathogen at Okara and Sahiwal. Field trails were consisted of screening of germplasm, area under disease progress curve and chemical management of the disease by using the various fungicides. Randomized complete block design was used for the research at both locations. Out of 68 genotypes/ varieties 16 were susceptible, 20 moderately resistant, five highly susceptible and 27 as moderately susceptible. Maximum disease incidence was recorded on Desiree and Cardinal (90%) followed by Santee (83.33%). The maximum mean disease severity 9.48 was noted on Cardinal, followed by Desiree 9.11 and Karoda 9.0 with the area under disease progress curve 28.55, 27.33 and 26.00 respectively. The results showed that 5gm/ L was the best dose against the suppression and control of the potato late blight under the field conditions. Azoxystrobin which is a new chemistry fungicide found to be the best chemical treatment against the late blight of potato followed by the copper oxychloride-based fungicides Cobox which also showed best response. Aliette, Antracol, Tebuconazole and Mancozed were also played a role to minimize the disease yet their higher concentration was even not so effective to combat the disease. Mancozeb was not found to be effective to control the disease as compared to the other three fungicides. The abrupt climate change is also facilitating the occurring of disease in all areas of the world.

scholarly journals First record of tomato late blight in Basrah province (Short Notes)

2019 ◽  
Vol 31 (2) ◽  
pp. 65-67
Author(s):  
Labeed A. Al-Saad ◽  
Aqeel A. Al-Yousuf ◽  
Mohamed M. Mezaal
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Environmental Conditions ◽  
Geographical Area ◽  
First Record ◽  
Late Blight Disease ◽  
Blight Disease

PlaTomato production in Al-Zubair district, Basrah province, Iraq was affected by late blight disease that was not recorded before in this geographical area. The symptoms were firstly appeared in December 2018 in several farms of Al-Zubair district. The infection was spread widely at January 2019 according to the environmental conditions that fitted the development infection. The pathogen was identified morphologically as Phytophthora infestans.

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