Dynamic economic thresholds for the management of vegetable leafminer on glasshouse cucumber estimated by simulated defoliation

2020 ◽  
Vol 144 (8) ◽  
pp. 719-731
Author(s):  
Shahzad Iranipour ◽  
Tahereh Alaei ◽  
Roghaiyeh Karimzadeh ◽  
J. P. Michaud
Keyword(s):  
Economic Thresholds ◽  
Glasshouse Cucumber ◽  
Simulated Defoliation

scholarly journals Perception and Use of Economic Thresholds Among Farmers and Agricultural Professionals: A Case Study on Soybean Aphid in Minnesota

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Natalie Hoidal ◽  
Robert L Koch
Keyword(s):  
Soybean Aphid ◽  
Educational Outreach ◽  
Economic Injury Level ◽  
Economic Thresholds ◽  
Foundational Principle ◽  
Economic Injury ◽  
Fundamental Misunderstanding ◽  
The Difference ◽  
Commercial Pesticide ◽  
Agricultural Professionals

Abstract Economic thresholds (ETs) are a foundational principle of integrated pest management but are not always widely accepted by farmers and agricultural professionals. This article reports on a survey of Minnesota farmer and agricultural professional perceptions of the ET for soybean aphid, Aphis glycines Matsumura (Hempitera: Aphididae). We discuss insights for Extension programs on how to frame the importance of thresholds and teach stakeholders to use them effectively. Key takeaways include farmers and agricultural professionals often worry about combined effects of insect, disease, and physiological pressures, whereas effects of interactions with these other stressors are seldom discussed in educational outreach. Across groups, there is a fundamental misunderstanding about the difference between ETs and economic injury level. Many survey participants reported believing in the ET but lacked the time and capacity to fully implement it. Sales agronomists and farmers were the least likely groups to trust the university-determined soybean aphid ET, whereas commercial pesticide applicators and independent consultants were the most likely groups to trust it. Based on these results, we recommend adapting communication about ETs based on the target audience to address common misconceptions and barriers to ET use that are unique to each group.

A, The ESTIMATION OF ECONOMIC THRESHOLDS OF JUNGLE RICE (ECHINOCHLOA COLONA L.) AND FALSE AMARANTH (DIGERA ARVENSIS FORSSK.) IN DIRECT SEEDED RICE

2020 ◽  
Vol 27 (2) ◽  
pp. 507-523
Author(s):  
Amir Ehsan ◽  
Muhammad Ehsan Safdar1 ◽  
Amjed Ali
Keyword(s):  
Block Design ◽  
Dry Weight ◽  
Field Trials ◽  
Research Area ◽  
Growth And Yield ◽  
Rice Grain ◽  
College Of Agriculture ◽  
Competitive Index ◽  
Economic Thresholds ◽  
Direct Seeded

ABSTRACT There is little understanding about ecological interference of weeds in direct-seeded rice. To get estimates of economic thresholds of two weeds in direct seeded rice, two-year field trials were conducted at research area of College of Agriculture, University of Sargodha, Punjab-Pakistan. Treatments included 0, 22, 44, 66 and 88 plants m-2 densities of each of Echinochloa colona and Digera arvensis laid out in randomized complete block design. Augmented densities of E. colona (0, 22, 44, 66 and 88 weed plants m-2) enhanced its plant dry biomass up to 348 and 353%; and relative competitive index maximally to 80 and 77% in years 2015 and 2016, respectively. While the corresponding increases in plant dry weight and relative competitive index of D. arvensis were 367 and 360% and 79 and 82%. The enhancement in N (up to 258 & 257 %), P (up to 220 & 232%) and K (up to 293 & 301%) uptake in years 2015 and 2016, respectively were made by E. Colona whereas the corresponding increases in N, P and K assimilation by D. arvensis were as far as 265 & 257%, 238 & 233% and 305 & 298%, respectively. The declines in growth and yield of rice were observed in response to growing number of both the weeds. Rice grain yield losses ranged between 9.8 to 80% and 28 to 80% by E. Colona and D. arvensis. The economic thresholds of false amaranth and jungle rice were estimated to be 1.6-1.4 plants m-2 and 2.2-2.6 plants m-2, respectively.

scholarly journals Influence of Simulated Defoliation and N Fertilization on Compensatory Growth of Gmelina arborea Seedlings

2020 ◽  
pp. 59-66
Author(s):  
Titus Fondo Ambebe ◽  
Anjah Grace Mendi ◽  
Abubakar Ali Shidiki
Keyword(s):  
Compensatory Growth ◽  
Interactive Effect ◽  
N Fertilization ◽  
Stem Volume ◽  
Total Biomass ◽  
N Availability ◽  
Gmelina Arborea ◽  
Leaf Production ◽  
Increasing Trend ◽  
Simulated Defoliation

To investigate the effect of artificial defoliation and N availability on growth of Gmelina arborea, seedlings were subjected to three artificial defoliation levels (0, 25, 50%) and four N regimes (unfertilized, 1 g N plant-1, 3 g N plant-1, 6 g N plant-1) in a field trial. The results showed that height increment was 24.09% lower in the 50% defoliation than the undefoliated and 25% defoliation treatments which were not significantly different from each other. On average, the 25% and 50% defoliation treatments reduced stem volume increment by 44.34%. Increments of diameter and biomass and leaf production were not reduced by defoliation. In terms of response to N, increments in height and stem volume rose from 8.98 cm and 8.23 mm at unfertilized  to 11.39 cm and 12.13 mm at 3 g N plant-1, respectively, while number of new leaves increased by a margin of 1.51 from unfertilized to  6 g N plant-1. Total biomass increment that was unaffected by defoliation showed an increasing trend from 0.55 g at unfertilized and 1 g N to 0.83 g at 3 g N and 0.94 g at 6 g N plant-1. There was no significant interactive effect of treatments on any parameter, suggesting that the adverse effect of defoliation on growth of G. arborea seedlings may not be alleviated by N fertilization. It is encouraged that a similar study be conducted for a longer duration to ascertain if the responses are sustained or modified.

Yield-Based Economic Thresholds for Grape Berry Moth (Lepidoptera: Tortricidae) in Juice Grapes

2013 ◽  
Vol 106 (2) ◽  
pp. 905-911 ◽  
Author(s):  
Craig R. Roubos ◽  
Keith S. Mason ◽  
Luís A. F. Teixeira ◽  
Rufus Isaacs
Keyword(s):  
Grape Berry ◽  
Economic Thresholds

Trophic interactions between three species of cereal aphid (Hemiptera: Aphididae) and spring wheat (Poaceae): implications for pest management

2007 ◽  
Vol 139 (6) ◽  
pp. 850-863 ◽  
Author(s):  
Samuel M. Migui ◽  
Robert J. Lamb
Keyword(s):  
Spring Wheat ◽  
Trophic Interactions ◽  
Plant Biomass ◽  
Rhopalosiphum Padi ◽  
Aphid Species ◽  
Economic Damage ◽  
Cereal Aphids ◽  
Cereal Aphid ◽  
Economic Thresholds ◽  
Specific Impact

AbstractThe susceptibilities of genetically diverse Canadian spring wheats, Triticum aestivum L. and Triticum durum Desf., to three aphid species, Rhopalosiphum padi (L.), Sitobion avenae (Fabricius), and Schizaphis graminum (Rondani), were investigated. Trophic interactions measured as changes in biomass of aphids and wheat plants were used to quantify levels of resistance, components of resistance, and impact of aphids on yield. Plants in field cages were infested with small numbers of aphids for 21 days at heading. These plants were usually more suitable for the development of S. avenae and S. graminum than of R. padi. Partial resistance, measured as seed production by infested plants as a proportion of that by a control, varied from 11% to 59% for different aphid species and wheat classes when all wheat plants were infested at the same stage. Cultivars within wheat classes responded similarly to each of the aphid species. None of the wheat cultivars showed agriculturally effective levels of antibiosis. The specific impact of each aphid species and wheat class varied from 5 to 15 mg of plant biomass lost for each milligram of biomass gained by the aphids. Canadian Western Red Spring wheat had a lower specific impact and therefore was more tolerant to aphids than the other two classes, but not tolerant enough to avoid economic damage at the aphid densities observed. Plants did not compensate for feeding damage after aphid feeding ceased, based on the higher specific impacts observed for mature plants than for plants that were heading. The interactions between aphids and plants show that current economic thresholds probably underestimate the damage caused by cereal aphids to Canadian spring wheat.

scholarly journals Western Bean Cutworm Survival and the Development of Economic Injury Levels and Economic Thresholds in Field Corn

2013 ◽  
Vol 106 (3) ◽  
pp. 1274-1285 ◽  
Author(s):  
S. Paula-Moraes ◽  
T. E. Hunt ◽  
R. J. Wright ◽  
G. L. Hein ◽  
E. E. Blankenship
Keyword(s):  
Field Corn ◽  
Economic Thresholds ◽  
Western Bean Cutworm ◽  
Economic Injury

Principles of Integrated Pest Management

2020 ◽  
pp. 370-380
Author(s):  
Patricia J. Vittum
Keyword(s):  
Integrated Pest Management ◽  
Pest Management ◽  
Economic Value ◽  
Crop Damage ◽  
Pest Population ◽  
Economic Thresholds ◽  
Activity Setting ◽  
Economic Injury ◽  
A Site ◽  
The Cost

This chapter examines the principles of integrated pest management (IPM). IPM often is defined as a program that, in the context of the environment and the population dynamics of pests, uses many different techniques and strategies in as compatible a manner as possible to maintain pest population levels below those causing economic injury. The concept of IPM was initially developed in traditional agriculture, where the success of a crop was measured in economic yield (quantity and quality of produce). The key to such agricultural IPM programs has always been establishing consistent and reliable “economic thresholds” — pest populations at which the cost of expected crop damage exceeds the cost of implementing control. In turf, the expected economic benefit from reducing a pest population usually is much more difficult to measure than in agriculture. It is difficult, if not impossible, to determine the economic value of suppressing pest insects. As a result, “economic thresholds” in turf IPM usually are more accurately described as “tolerance levels,” or “action thresholds.” In a turf IPM program, the turf manager must determine what pest populations can be tolerated without incurring unacceptable damage. The basic components of an IPM approach include assessing a site, monitoring and predicting pest activity, setting thresholds, managing turf stress, identifying and optimizing management options, and evaluating the results.

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