scholarly journals Use of Phosphonate to Manage Foliar Potato Late Blight in Developing Countries

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1008-1015 ◽  
Author(s):  
Peter Kromann ◽  
Willmer G. Pérez ◽  
Arturo Taipe ◽  
Elmar Schulte-Geldermann ◽  
Buddhi Prakash Sharma ◽  
...  
Keyword(s):  
Developing Countries ◽  
Late Blight ◽  
Significant Relationship ◽  
Field Experiments ◽  
Meta Analysis ◽  
Potato Late Blight ◽  
Application Rate ◽  
Potato Foliage ◽  
Potato Genotype ◽  
The Cost

Twenty phosphonate products found in the agrochemical market in Ecuador and Peru were evaluated in bioassays for the control of foliar potato late blight, caused by Phytophthora infestans. Eight phosphonate products were evaluated in 16 field experiments done in Peru, Ecuador, Kenya, and Nepal. A meta-analysis across locations involving 71 combinations of potato genotype by site and year demonstrated a significant relationship between phosphonate application rate and efficacy for controlling late blight on potato foliage. The meta-analysis revealed that phosphonate rates of approximately 2.5 g a.i./liter provided efficacy similar to that of the conventional contact fungicides mancozeb and chlorothalonil used at similar rates. At rates higher than 2.5 g a.i./liter, the efficacy of phosphonate was superior to the contact fungicides. Overall, late blight control by phosphonate appeared relatively stable in field experiments across locations. An analysis of field experiments and 64 combinations of potato genotype by site and year showed no correlation between the susceptibility level of potato genotypes and efficacy of phosphonates. The cost of both phosphonate compounds and contact fungicides varied greatly among the countries of the field study; however, in Kenya, control with phosphonate was clearly less expensive than with mancozeb.

scholarly journals Rainfall Thresholds as Support for Timing Fungicide Applications in the Control of Potato Late Blight in Ecuador and Peru

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 142-148 ◽  
Author(s):  
Peter Kromann ◽  
Arturo Taipe ◽  
Willmer G. Perez ◽  
Gregory A. Forbes
Keyword(s):  
Developing Countries ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Field Experiments ◽  
Integrated Management ◽  
Management Strategies ◽  
Potato Late Blight ◽  
Rainfall Thresholds ◽  
Resource Poor ◽  
Accumulated Rainfall

Accumulated rainfall thresholds were studied in seven field experiments conducted in Ecuador and Peru for their value in timing applications of fungicide to control potato late blight, caused by Phytophthora infestans. Fungicide regimes based on accumulated rainfall thresholds ranging from 10 to 70 mm were compared with calendar spray schemes of every 5 or 7 days. Very low thresholds of 10 to 20 mm gave similar levels of control and resulted in similar number of sprays as did calendar spraying. However, neither low thresholds nor calendar sprays were effective in protecting susceptible potato genotypes in over half of the experiments. Thresholds of 25 to 50 mm of rainfall led to reduction in the number of sprays needed to protect resistant cultivars but also resulted in high levels of disease on susceptible cultivars. We conclude that timing fungicide sprays based on accumulated rainfall thresholds could be a successful component of integrated management strategies that include cultivars with moderate or high levels of resistance. The simplicity of measuring accumulated rainfall means that the technology can potentially be used by resource-poor farmers in developing countries.

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 Agroeconomic prospects for the use of nitrogen fertilizers for field crops

2021 ◽  
Vol 1 (99) ◽  
pp. 6-16
Author(s):  
G. M. Gospodarenko ◽  
◽  
O. D. Cherno ◽  
A. T. Martynyuk
Keyword(s):  
Ammonium Nitrate ◽  
Economic Efficiency ◽  
Field Experiments ◽  
Application Rate ◽  
Nitrogen Fertilizers ◽  
Net Income ◽  
Field Crops ◽  
Wide Range ◽  
Additional Costs ◽  
The Cost

The issues of recoupment of nitrogen fertilizers are considered, since they determine the need for fertilizers and the agro-economic efficiency of their use. It is shown that the payback of fertilizers is a complex value and not constant in different crops. The increase in yield from fertilizers in kind is taken on the basis of field experiments with fertilizers carried out on podzolized chernozem of the opita field of the Uman NUS. The cost of an increase in the yield from the use of nitrogen fertilizers was determined by the average actual sales prices of products prevailing on the market through various sales channels in the 6th quarter of 2021. Additional costs included: the cost of fertilizers, a margin for their delivery to the farm, the cost of using it on the farm and collecting increase in yield from nitrogen fertilizers. The cost of ammonium nitrate was taken at UAH 24,000 / t with the addition of a margin for their delivery to the farm. The costs of using fertilizers on the farm and collecting an increase in yield were set calculated according to the accepted standards. The difference between the value of the yield increase (PU) and additional costs (AD) gives the net income received from the use of fertilizers. The ratio of the cost of increasing the yield to additional costs shows their payback. On the basis of comparing the indicators of PU and DZ, the boundaries of the economic efficiency of the use of fertilizers were determined: PU> DZ (general expression of the task). We also calculated the minimum required increase in yield from fertilizers and the limits of price increases for nitrogen fertilizers. It has been established that at a price of ammonium nitrate of UAH 24,000 / t and the cost of its use in optimal doses for field crops against the background of a balanced phosphorus-potassium nutrition, the cost of an increase in yield is 3075–47894 UAH/ha. Payback of 1 kg a.c. nitrogen fertilization varies in a wide range – from 3.0 to 217.3 hryvnyas, depending on the crop. The limit of the unprofitable price per unit of the active substance of nitrogen fertilizers at the optimal application rate depends on the crop and is in the range of UAH 76.5–219.0 /ha. With the current disparity in prices for crop products and ammonium nitrate (24,000 UAH/t), its use is profitable, which is explained by the low ability of podzolized chernozem to provide plants with nitrogen, biological requirements of crops for this food element and technologies for their cultivation. Key words: nitrogen fertilizers, agricultural crops, fertilizer recoupment, loss threshold, price increase limit.

scholarly journals Yield and resistance of potato cultivars with colour flesh to potato late blight

2017 ◽  
Vol 63 (No. 7) ◽  
pp. 328-333
Author(s):  
Pazderů Kateřina ◽  
Hamouz Karel
Keyword(s):  
Late Blight ◽  
Field Experiments ◽  
Potato Late Blight ◽  
Russet Burbank ◽  
Weak Dependence ◽  
Potato Cultivars ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Better Than

The resistance to potato late blight (as AUDPC – the area under the disease progress curve) and yield were evaluated in precise field experiments with 13 colour-fleshed potato cultivars. Red Emmalie and Blaue Anneliese were the most profitable cultivars of potatoes with coloured flesh, the overall yield did not differ statistically from the control cv. Agria. Cv. Blaue Anneliese resistance to potato late blight was considerably better than both control cultivars, other 2 cultivars HB Red and Red Emmalie were similar to cv. Agria. Surprisingly, cv. Russet Burbank was found to be more resistant than most cultivars tested. A statistically significant weak dependence (r = 0.36) between the percentage of infestation of plants in the T6 evaluation date (6–8 August in individual years) and the yield was detected, the slightly stronger (r = 0.40) was the correlation between AUDPC values and total yields.

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 FUNGICIDE APPLICATION FREQUENCIES FOR POTATO LATE BLIGHT (Phytophthora infestans) MANAGEMENT IN THE DOMINICAN REPUBLIC

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 888f-889
Author(s):  
Bielinski M. Santos ◽  
James P. Gilreath ◽  
Persio R. Rodriguez
Keyword(s):  
Dominican Republic ◽  
Late Blight ◽  
Potato Late Blight ◽  
Field Trials ◽  
Marketable Yield ◽  
Cost Component ◽  
Fungicide Application ◽  
The Cost ◽  
Application Programs ◽  
Cost Components

Field trials were conducted in Constanza, Dominican Republic to determine the most effective fungicide application programs against potato late blight, and the cost component associated to those programs. Fungicide programs were: a) chlorothalonil (1.0 kg a.i./ha) every 5, 8, 11, 14 or 17 days; b) chlorothalonil rotated with metalaxyl (1.5 kg a.i./ha) every 5, 8, 11, 14 or 17 days; c) mancozeb (1.5 kg a.i./ha) every 8 days (grower standard); and d) a nontreated control. Examined data indicated that the highest `Granola' marketable tuber weights were obtained with the rotation of metalaxyl and chlorothalonil applied every 5, 8 or 11 days (14, 9 or 6 applications/season). This same rotation every 5 or 8 days (14 or 9 applications/season) was the most effective controlling late blight. There was no correlation between disease severity and marketable yield. For the cost components, the fungicide rotation applied every 11 days reduced application costs by 29%, in comparison with applications every 8 days.

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