Response of canola to simulated diamondback moth (Lepidoptera: Plutellidae) defoliation at different growth stages

2000 ◽  
Vol 80 (3) ◽  
pp. 639-646 ◽  
Author(s):  
Suresh Ramachandran ◽  
G. David Buntin ◽  
John N. All
Keyword(s):  
Diamondback Moth ◽  
Maximum Yield ◽  
Field Trials ◽  
Crop Growth ◽  
Growth Stages ◽  
Economic Injury Level ◽  
Leaf Stage ◽  
Filling Stage ◽  
Crop Development ◽  
Economic Injury

In field trials conducted during 1995–1998, canola cultivar "Falcon" was subjected to different levels of simulated insect defoliation at four stages of crop growth. Plants were 0, 33, 67 and 100% defoliated at rosette and flowering stages during the 1995–1996 season as well as 2–4 leaf stage during the 1996–1997 and 1997–1998 seasons. Plants were 0, 50 and 100% defoliated at pod filling stage during all seasons. Over all seasons, defoliation did not consistently affect the number of plants per unit area, plant height, 1000 seed weight, and oil content of seeds for most of the defoliation treatments. However, defoliation at the 2–4 leaf and rosette stages made plants more susceptible to cold injury. Generally, canola could withstand a higher level of defoliation as crop development progressed. Maximum yield reductions occurred for defoliations at the 2–4 leaf stage followed by the rosette and flowering stages of the crop. No significant yield losses were recorded for defoliations at the pod filling stage. Results suggest that canola is most sensitive to defoliation in its early stages of growth. Greater amounts of defoliation can be tolerated as crop development progresses. The relationships between defoliation and yield loss were used to establish diamondback moth economic injury levels for canola at different crop growth stages. Key words: Canola, Brassica napus, oilseed rape, simulated defoliation, economic injury level

scholarly journals Integrating Economics in the Critical Period for Weed Control Concept in Corn

Weed Science ◽  
2014 ◽  
Vol 62 (4) ◽  
pp. 608-618 ◽  
Author(s):  
Martina Keller ◽  
Geoffroy Gantoli ◽  
Jens Möhring ◽  
Christoph Gutjahr ◽  
Roland Gerhards ◽  
...  
Keyword(s):  
Weed Control ◽  
Critical Period ◽  
Logistic Models ◽  
Crop Growth ◽  
Growth Stages ◽  
Corn Yield ◽  
Leaf Stage ◽  
Weed Interference ◽  
Free Interval ◽  
Crop Growth Stages

The effect of weed interference on corn yield and the critical period for weed control (CPWC) were determined in Germany and Benin. Treatments with weed control starting at different crop growth stages and continuously kept weed-free until harvest represented the “weed-infested interval.” Treatments that were kept weed-free from sowing until different crop growth stages represented the “weed-free interval.” Michaelis–Menten, Gompertz, logistic and log–logistic models were employed to model the weed interference on yield. Cross-validation revealed that the log–logistic model fitted the weed-infested interval data equally well as the logistic and slightly better than the Gompertz model fitted the weed-free interval. For Benin, economic calculations considered yield revenue and cost increase due to mechanical weeding operations. Weeding once at the ten-leaf stage of corn resulted already profitable in three out of four cases. One additional weeding operation may optimize and assure profit. Economic calculations for Germany determined a CPWC starting earlier than the four-leaf stage, challenging the decade-long propagated CPWC for corn. Differences between Germany and Benin are probably due to the higher yields and high costs in Germany. This study provides a straightforward method to implement economic data in the determination of the CPWC for chemical and nonchemical weed control strategies.

scholarly journals Pest status of the leafhopper Empoasca dolichi Paoli on groundnut (Arachis hypogaea L.) in the Zaria area of northern Nigeria

2010 ◽  
Vol 41 (No. 4) ◽  
pp. 158-164 ◽  
Author(s):  
E.A. Egwurube ◽  
O. Ogunlana M ◽  
C. Dike M ◽  
I. Onu
Keyword(s):  
Arachis Hypogaea ◽  
Growth Stages ◽  
Northern Nigeria ◽  
Economic Injury Level ◽  
Pest Status ◽  
Growing Seasons ◽  
Economic Injury ◽  
One Year ◽  
Empoasca Dolichi ◽  
Different Growth Stages

Population studies and tests on the relationship between density and damage were conducted in 1999 to 2001 to determine the pest status of <I>Empoasca dolichi</I> on groundnut (<I>Arachis hypogaea </I>L.) in the Zaria area of northern Nigeria. Analyses showed that <I>Empoasca</I> numbers varied significantly from one year to another, and within each year the numbers of leafhoppers observed at the different growth stages of the plant were significantly different (<I>P</I> = 0.01). There was an inverse and highly significant relationship between the mean kernel yield and the <I>Empoasca </I>damage at the different growth stages of the plant. When natural population densities were plotted against economic injury level (EIL), the densities did not reach the EIL throughout the groundnut growing seasons. The insect was thus not an economic pest on groundnut in Zaria during the period of the study.

scholarly journals Establishing Defoliation Thresholds for Insect Pest of Peanut in Mississippi

2019 ◽  
Vol 46 (1) ◽  
pp. 1-7 ◽  
Author(s):  
C. C. Abbott ◽  
J. M. Sarver ◽  
J. Gore ◽  
D. Cook ◽  
A. Catchot ◽  
...  
Keyword(s):  
Photosynthetic Capacity ◽  
Plant Biomass ◽  
Insect Pest ◽  
Canopy Height ◽  
Growth Stages ◽  
Economic Injury Level ◽  
Pod Yield ◽  
Economic Injury ◽  
Plant Emergence ◽  
The Impact

ABSTRACT Defoliation of peanut by foliage-feeding insects reduces photosynthetic capacity, and in turn, may reduce pod yield, particularly when canopy loss occurs at critical growth stages, i.e., 40 or 80 d after full plant emergence (DAE). The objective of this research was to determine the impact of peanut defoliation levels of 0, 20, 40, 60, 80, and 100%, at 40 or 80 DAE on canopy height and width, plant biomass, pod grade and yield, and economic injury level. Research was conducted in Stoneville and Starkville MS in 2015 and 2016. The experimental design was a six (defoliation level) by two (defoliation timing) factorial arranged in a randomized complete block. Up to four wk after defoliation, canopy height, canopy width, and plant biomass were negatively correlated with defoliation level regardless of defoliation timing (40 and 80 DAE). Neither defoliation level nor timing had an effect on peanut grade or maturity. Similarly, defoliation at 40 DAE did not affect pod yield but when damage occurred 80 DAE, pod yield was reduced 18.6 kg/ha for every 1% increase in defoliation. Considering average crop value and insect control costs, the economic injury for peanut defoliation at 80 DAE is 5% defoliation. These data indicate that control of canopy-feeding insects is only economically viable when defoliation exceeds 5% defoliation at 80 DAE.

Reducing the risks of in-crop nitrogen fertilizer applications in spring wheat and canola

2008 ◽  
Vol 88 (5) ◽  
pp. 907-919 ◽  
Author(s):  
G. P. Lafond ◽  
S. A. Brandt ◽  
B. Irvine ◽  
W. E. May ◽  
C. B. Holzapfel
Keyword(s):  
Ammonium Nitrate ◽  
Spring Wheat ◽  
Crop Production ◽  
Field Trials ◽  
Climatic Conditions ◽  
Growth Stages ◽  
Potential Yield ◽  
Canadian Prairies ◽  
Leaf Stage ◽  
Urea Ammonium Nitrate

Nitrogen is the most limiting nutrient in crop production on the Canadian prairies. There is great interest in managing it more effectively for environmental and economic reasons. Our objective was to study the effectiveness of using different proportions of recommended nitrogen rates at seeding with the balance at different crop growth stages to minimize the risks of potential yield losses from in-crop nitrogen applications in spring wheat and canola. The field trials with wheat were conducted at three locations from 2003 to 2006 and at two locations for canola from 2004 to 2006. The treatments consisted of applying 100, 67, 50, 33 or 0% of the targeted N rate at seeding using urea in mid-row bands and the balance in-crop at the 1.5, 3.5 or 5.5 leaf stages in spring wheat and at the 5-6 leaf stage, bolting or start of flowering stage in canola using surface dribble band of liquid urea-ammonium nitrate. With spring wheat, applying 33% of the recommended N rate at seeding with the balance in-crop resulted in similar yields to when all the nitrogen was applied at seeding in one study while, in the other, some yield loss was observed at the 3.5 leaf stage. This indicates that a higher proportion, such as 50%, would be more appropriate. With canola, a minimum of 50% of the recommended nitrogen rate was required at seeding and the in-crop application at or before the bolting phase to give yields equivalent to when all fertilizer was applied at seeding. Consequently, applying 50% or more of the recommended N at seeding enhances the opportunity for in-crop applications of nitrogen in spring wheat and canola to better match the soil and climatic conditions. Key words: Canola, wheat, split applications, liquid urea-ammonium nitrate, grain yield, grain protein

Response of Diploid Watermelon to Imazosulfuron POST

2010 ◽  
Vol 24 (2) ◽  
pp. 127-129 ◽  
Author(s):  
Peter J. Dittmar ◽  
Katherine M. Jennings ◽  
David W. Monks
Keyword(s):  
Fruit Quality ◽  
Field Trials ◽  
Growth Stages ◽  
Leaf Stage ◽  
Crop Injury

Field trials were conducted to evaluate imazosulfuron applied POST at 0.1, 0.2, 0.3, and 0.4 kg/ha to watermelon at the two- to four-leaf stage or to vines 30.5 cm long. At 7 d after treatment (DAT), crop injury to watermelon increased linearly for both growth stages as rate increased. The least injury to watermelon observed 7 DAT was 19 and 15%, respectively, for the two- to four-leaf and 30.5-cm growth stages treated with 0.01 kg/ha imazosulfuron. The 0.4 kg/ha imazosulfuron treatment caused the greatest watermelon injury (approximately 30%) at both application timings. Yield of watermelon treated with 0.1 and 0.2 kg/ha imazosulfuron applied at the two- to four-leaf and 30.5-cm stages were similar to the nontreated check (all plots were maintained weed-free). For both application timings, yield decreased linearly as imazosulfuron rate increased. The application of imazosulfuron to watermelon at the 30.5-cm stage averaged across rates resulted in less injury at 15 DAT (16%) and greater yield (92,869 kg/ha) than watermelon treated at two- to four-leaf stage averaged across rates (29%, 83,560 kg/ha). Internal fruit quality was not affected by imazosulfuron.

Growth and yield of barley in relation to grasshopper feeding damage

2008 ◽  
Vol 88 (1) ◽  
pp. 219-227 ◽  
Author(s):  
Sultan H. Begna ◽  
Dennis J. Fielding
Keyword(s):  
Surface Area ◽  
Dry Matter ◽  
Growth And Yield ◽  
Plant Responses ◽  
Feeding Damage ◽  
Economic Injury Level ◽  
Hordeum Vulgare L ◽  
Leaf Stage ◽  
Economic Injury ◽  
Below Ground

Grasshoppers are common pests of barley (Hordeum vulgare L.) in subarctic Alaska and cause substantial crop loss during outbreaks, but there is little information about the growth response of barley to grasshopper feeding damage. In two growth chamber experiments, we studied the effect of four densities (0, 1, 2, and 3 pot-1, equivalent to 0, 25, 50 and 75 grasshoppers m-2) of grasshoppers (Melanoplus sanguinipes F.) on the above-and below-ground growth of barley (eight plants per pot). Plants were exposed to grasshoppers beginning in the 3rd to 4th leaf stage (exp. 1) and in 1st to 2nd leaf stage (exp. 2). Plants were harvested and growth variables were measured shortly after anthesis and at maturity. Generally, the reduction in above-ground dry matter, at the highest density was 29 and 47% for exp. 1 and exp. 2, respectively. Effects of grasshoppers on below-ground growth (dry matter and surface area of roots) was less consistent than on above-ground variables; however, at the highest grasshopper density in exp. 2, dry matter and surface area of roots were reduced by about 40–53%.Grain yield (pooled over experiments) decreased by 19 and 36% for grasshopper densities of 2 and 3 pot-1, respectively. Most of the yield loss was accounted for by reduced seed weights, while protein content per seed remained nearly constant. The proportion of total above-ground dry matter represented in harvested grain and root:shoot ratios were not affected by grasshopper feeding. These results provide greater understanding of plant responses to insect feeding damage and will lead to more accurate estimates of economic injury levels. Key words: Cropyield loss, economic injury level, harvest index, Insecta

Reevaluating the Economic Injury Level for Brown Stink Bug (Hemiptera: Pentatomidae) at Various Growth Stages of Maize

2020 ◽  
Vol 113 (5) ◽  
pp. 2250-2258
Author(s):  
Tim B Bryant ◽  
Seth J Dorman ◽  
Dominic D Reisig ◽  
DeShae Dillard ◽  
Roger Schürch ◽  
...  
Keyword(s):  
Grain Yield ◽  
Growth Stage ◽  
Early Stage ◽  
Growth Stages ◽  
Stink Bug ◽  
Infestation Level ◽  
Economic Injury Level ◽  
Euschistus Servus ◽  
Economic Injury ◽  
Late Stages

Abstract Economic yield loss and reduction in grain quality from brown stink bug, Euschistus servus (Say), feeding injury in early and late stages of maize, Zea mays (Poales: Poaceae, Linnaeus), development was assessed in Virginia and North Carolina in 2018 and 2019. Varying levels of stink bug infestations were introduced to seedling maize (V2—early stage), and a range of late-stages of maize, including 1) the last stage of vegetative development (V12/V14), 2) prior to tasseling, 3) at tasseling (VT), and 4) across all tested late growth stages. Euschistus servus infestation levels included 33, 67, and 100% of maize seedlings, and 25, 50, 100, and 200% of plants during later stages. Infestations were maintained on seedling maize for 7 d, and 8 or 16 d in reproductive stages. Infestation level in seedling maize had an impact on grain yield. Infestation level and growth stage both had an impact on grain yield in reproductive maize. The percentage of discolored kernels was also affected by infestation level, but not growth stage. Regression analysis between grain yield and infestation level indicated that the average economic injury level is 7% in seedling maize (7 bugs/100 plants) and 12% (12 bugs/100 plants) from the last vegetative stages (V12/V14) through pollination (VT). The economic injury level in the late vegetative stages is only applicable when infestations are present for an extended period of time (16 d), emphasizing the need for continued scouting of maize throughout the season to make informed management decisions.

WEATHER AT DIFFERENT GROWTH STAGES, MULTIPLE PRACTICES AND RISK EXPOSURES: PANEL DATA EVIDENCE FROM ETHIOPIA

2020 ◽  
Vol 11 (02) ◽  
pp. 2050009
Author(s):  
HAILEMARIAM TEKLEWOLD ◽  
ALEMU MEKONNEN
Keyword(s):  
Agricultural Practices ◽  
Weather Conditions ◽  
Crop Growth ◽  
Growth Stages ◽  
Production Risk ◽  
Heterogeneous Effects ◽  
Crop Development ◽  
Crop Growth Stages ◽  
Variable Weather ◽  
Risk Reducing

This study investigates the effects of combinations of climate smart agricultural practices on risk exposure and cost of risk. We do this by examining the different risk components — mean, variance, skewness, and kurtosis — in a multinomial treatment effects framework by controlling weather variables for key stages of crop growth. We found that adoption of combinations of practices is widely viewed as a risk-reducing insurance strategy that can increase farmers’ resilience to production risk. The hypothesis of equality of weather parameters across crop development stages is also rejected. The heterogeneous effects of weather across crop growth stages have important implications for climate change adaptation to maximize quasi-option value. For a country that has the vision to build a climate-resilient economy, this knowledge is valuable to identify a combination of climate smart practices that minimizes production risk under variable weather conditions.

scholarly journals Economic Injury Levels for Flea Beetles (Phyllotreta spp.; Coleoptera: Chrysomelidae) in Spring Oilseed Rape (Brassica napus; Brassicales: Brassicaceae)

2019 ◽  
Vol 113 (2) ◽  
pp. 808-813 ◽  
Author(s):  
Ola Lundin
Keyword(s):  
Brassica Napus ◽  
Oilseed Rape ◽  
Field Experiments ◽  
Flea Beetle ◽  
Crop Growth ◽  
The European Union ◽  
Economic Injury Level ◽  
Flea Beetles ◽  
Crop Injury ◽  
Economic Injury

Abstract Flea beetles (Phyllotreta spp.) are major insect pests in spring oilseed rape (SOSR; Brassica napus L.). Prohibited use of three neonicotinoid insecticides in the European Union means that there are currently no insecticide seed treatment options available. Insecticide spraying remains as a control option, but there is a need to estimate the economic threshold for crop injury. As a first step to this end, economic injury levels were determined for flea beetles in SOSR. Data from 16 field experiments were used to quantify the relationship between flea beetle crop injury and SOSR yield, and additional data from paired sprayed and unsprayed plots in 12 commercial SOSR fields were used to determine the reduction in crop injury from a pyrethroid spray. There was a strong linear negative effect of flea beetle injury with 19 kg/ha yield loss per percent crop injury to seedlings and a pyrethroid spray reduced crop injury by 39%. These results gave an economic injury level of 11% defoliation of SOSR seedlings under average oilseed rape prices and insecticide use costs in 2017. This is considerably lower than previously used nominal thresholds of 25–30% injury to cotyledons. Increased yields and increasingly cheaper pyrethroids might be the reason for the lower levels of crop injury that warrant chemical control. The economic injury levels presented here can be used to construct economic thresholds that preferably should also take into account crop growth stage, crop growth rate, and anticipated flea beetle activity.

scholarly journals 452 Stand Reduction and Foliage Damage Reduce Yield of Onion for Dehydration

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 471E-472
Author(s):  
George H. Clough
Keyword(s):  
Growth Stage ◽  
Leaf Growth ◽  
Field Trials ◽  
Growth Stages ◽  
Leaf Stage ◽  
Plant Growth Stages ◽  
The Impact ◽  
Stage Yield ◽  
Different Growth Stages ◽  
Production Characteristics

Field trials were conducted at Hermiston, Ore., from 1995 through 1998 to determine the impact of stand loss and plant damage at different growth stages on yield of onions grown for dehydration. The experiment was a complete factorial with four replications. Stand reduction (0%, 20%, 40%, 60%, 80%) and foliage damage (0%, 25%, 50%, 75%, or 100%) treatments were applied at 3-, 6-, 9-, and 12-leaf onion growth stages. All average onion production characteristics decreased linearly as stand reduction increased (plant population decreased) at all plant growth stages except average bulb weight which increased as stand was reduced. Bulb weight was not changed by up to 100% foliage removal at the three-leaf stage of growth. At the 6- and 12-leaf stages, bulb weight was reduced when >50% of the foliage was removed. The most severe response occurred at the nine-leaf stage when bulb weights were reduced the most. At the three-leaf stage, yield was not affected by foliage damage. At the six-leaf growth stage, yield was reduced by 75% or more foliage loss, but at the 9- and 12-leaf stages, >50% foliage removal reduced expected yields. As with bulb weight, the impact of foliage removal on yield was most severe at the nine-leaf growth stage.

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