Corn Yield Loss Research Articles

Competition and fecundity of giant ragweed in corn

Abstract A field study was conducted to determine the effects of giant ragweed emergence time and population density on corn grain yield, giant ragweed seed production, and giant ragweed predispersal seed losses. When weeds and crop emerged concurrently, hyperbolic regression of percent corn yield loss on giant ragweed population densities of 1.7, 6.9, and 13.8 weeds per 10 m2 gave a predicted loss rate of 13.6% for the first weed per 10 m2 in the linear response range at low densities and a maximum yield loss of 90% at high weed densities. Crop yield loss response to weed density was linear when giant ragweed emerged 4 wk after corn, and the regression coefficient indicated a yield loss rate of 1% per unit increase in weed density. A larger proportion of the variation in corn yield loss was explained by weed density (r2 = 0.99) than by weed biomass (r2 = 0.81). There was a positive linear relationship between giant ragweed seed production and weed density at each weed emergence time. When giant ragweed e...

Performance of INTERCOM for predicting corn–velvetleaf interference across north-central United States

Abstract Cost-effective weed management requires accurate estimates of yield and the potential yield loss resulting from weed infestations. However, crop yield and the effects of weeds are highly variable across years and locations. Ecophysiological models may be useful for predicting the effects of environment and management on crop and weed growth and competitive ability. Ability of the model INTERCOM to predict corn (Zea mays) growth and yield, velvetleaf (Abutilon theophrasti) interference on corn yield loss, and single-year economic threshold velvetleaf density (Te) was evaluated using 13 data sets collected in four states. Predicted and observed monoculture corn total aboveground biomass and leaf area index were in close agreement for most of the growing season. Predicted and observed weed-free corn yields were in agreement for yields ranging from 8 to 13 Mg ha−1 but were over- and underpredicted under low-yielding and near-optimal production conditions, respectively. Predicted and observed corn yie...

Predicting Subsurface Drainage, Corn Yield, and Nitrate Nitrogen Losses with DRAINMOD‐N

AbstractNitrate N from artificially drained soils of the upper Midwest USA is finding its way to the Mississippi River and then to the Gulf of Mexico. There is some concern that this nitrate N is causing hypoxia in the Gulf of Mexico. The DRAINMOD‐N model was used to evaluate the long‐term effect of N application rate and drain spacing on corn (Zea mays L.) yield and nitrate N losses. Prior to evaluation, the model was calibrated and then validated against long‐term field data from southwestern Minnesota. A 24‐yr simulation showed that climate plays a major role in determining drainage, yield, and nitrate N losses from a moderately well‐drained Normania clay loam (fine‐loamy, mixed, mesic Aquic Hapludoll) soil under continuous corn. April to August rainfall accounted for 82% of the variation in drainage and 66% of the variation in nitrate N losses during the growing season. Corn yield increased significantly when drain spacing was changed from 56 to 28 m but there was much less increase when changing from 28 to 14 m. During the growing season, drain spacing had little effect on nitrate N losses from this soil. Cost‐benefit analysis showed that a 28 m drain spacing was a good design criterion for this soil. For a given drain spacing, an increase in N application rate significantly increased nitrate N losses through drainage. We conclude that efforts to reduce drainage‐associated nitrate N losses from soils with perched water table conditions in the upper Midwest USA should concentrate on identifying N management strategies that increase N use efficiency.

Evaluation of Transgenic, Bt -Containing Corn Hybrids

European corn borer [ECB; Ostrinia nubilalis (Hubner]) is a major economic pest of corn (Zea mays L.) throughout the Corn Belt. Transgenic corn hybrids containing a modified Bacillus thuringiensis (Bt) gene were evaluated at four Corn Belt environments as a novel method of managing ECB. Manual infestation was done to insure the presence of ECB, and Bt-based insecticides were used to control natural infestations. First generation ECB damage, estimated by leaf damage ratings, and second generation ECB damage, estimated by amount of stalk tunneling, were reduced or eliminated with the use of the Bt hybrids. Grain yield, stalk lodging, and test weight of the transgenic hybrids were not affected by first or second generation ECB infestation. Grain yields of six nontransgenic hybrids were not affected by first generation ECB infestation, but second generation ECB infestation damage, even though relatively low in the environments tested, reduced grain yield in these hybrids by 4.0 to 6.6%, slightly increased stalk lodging, and slightly decreased test weight. In the absence of ECB pressure, the transgenic hybrids performed the same as their non-transgenic counterparts. It is clear that the incorporation of the Bt gene into corn hybrids provides a high level of protection against ECB, with little if any effect on agronomic performance.

Loci Controlling Resistance to High Plains Virus and Wheat Streak Mosaic Virus in a B73 × Mo17 Population of Maize

High Plains disease has the potential to cause significant yield loss in susceptible corn (Zea mays L.) and wheat (Triticum aestivum L.) genotypes, especially in the central and western USA. The primary causal agent, High Plains virus (HPV), is vectored by wheat curl mite (WCM; Aceria tossicheila Keifer), which is also the vector of wheat streak mosaic virus (WSMV). In general, the two diseases occur together as a mixed infection in the field. The objective of this research was to characterize the inheritance of HPV and WSMV resistance using B73 (resistant to HPV and WSMV) × Mo17 (moderately susceptible to HPV and WSMV) recombinant inbred lines. A population of 129 recombinant inbred lines scored for 167 molecular markers was used to evaluate resistance to WSMV and to a mixed infection of WSMV and HPV. Loci conferring resistance to systemic movement of WSMV in plants mapped to chromosomes 3, 6, and 10, consistent with the map position of wsm2, wsm1, and wsm3, respectively. Major genes for resistance to systemic spread of HPV in doubly infected plants mapped to chromosomes 3 and 6, coincident or tightly linked with the WSMV resistance loci. Analysis of doubly infected plants revealed that chromosome 6 had a major effect on HPV resistance, consistent with our previous analysis of B73 × W64A and B73 × Wf9 populations. Quantitative trait loci (QTL) affecting resistance to localized symptom development mapped to chromosomes 4 (umc66), 5 (bnl5.40), and 6 (umc85), and accounted for 24% of the phenotypic variation. Localized symptoms may reflect the amount of mite feeding or the extent of virus spread at the point of infection. Identification of cosegregating markers may facilitate selection for HPV and WSMV resistance in corn breeding programs.

Prediction of corn (Zea mays) yield loss from early observations of the relative leaf area and the relative leaf cover of weeds

The relative leaf area of weeds is a good predictor of the outcome of weed-crop competition. However, this variable has not been used in decision-making tools for integrated weed management because leaf area cannot be measured quickly. A powerful image analysis system for measuring leaf cover (the vertical projection of plant canopy on the ground) has been developed and validated. This research was conducted to compare the efficiency of weed relative leaf area and relative leaf cover in predicting corn yield loss. Field studies were conducted in 1996 and 1997 using varying densities of common lambsquarters, barnyardgrass, common lambsquarters plus barnyardgrass, and a natural weed community. Corn grain yield and biomass loss varied with weed infestation type and year. Values of the relative damage coefficient of weeds (q) were smaller in 1997 compared with 1996. For both years, the relative leaf area of weeds was an adequate predictor of corn yield loss (r2varied from 0.61 to 0.92). The precision of the predictions was not influenced by the leaf area sampling period (four- or eight-leaf stage of corn). In general, smaller values ofqandm(predicted maximum yield loss) were obtained as a consequence of using the relative leaf cover of weeds in model fitting. However, percentages of variation explained by the model (from 0.67 to 0.90) were similar to values obtained with the relative leaf area. On the basis of the residual mean squares, neither of the variables could be declared superior to the other in yield loss prediction. The development of weed control decision-making tools using the relative leaf cover of weeds may require improvements prior to being used in weed management systems. Such improvements would include use of appropriate sampling and image-processing techniques, development and validation of empirical models specific to individual situations, and proper identification of the crop growth stage at which leaf cover must be assessed.

Stability of corn (Zea mays)-foxtail (Setariaspp.) interference relationships

Variation in interference relationships have been shown for a number of crop-weed associations and may have an important effect on the implementation of decision support systems for weed management. Multiyear field experiments were conducted at eight locations to determine the stability of corn-foxtail interference relationships across years and locations. Two coefficients (IandA) of a rectangular hyperbola equation were estimated for each data set using nonlinear regression procedures. TheIandAcoefficients represent percent corn yield loss as foxtail density approaches zero and maximum percent corn yield loss, respectively. The coefficientIwas stable across years at two locations and varied across years at four locations. Maximum yield loss (A) varied between years at one location. Both coefficients varied among locations. Although 3 to 4 foxtail plants m−-1row was a conservative estimate of the single-year economic threshold (Tc) of foxtail density, variation inIandAresulted in a large variation inTc. Therefore, the utility of using common coefficient estimates to predict future crop yield loss from foxtail interference between years or among locations within a region is limited.

Corn Yield, Runoff, and Sediment Losses from Manure and Tillage Systems

AbstractOne challenge in land application of manure is to maximize its benefit to crops without harming the environment. Our objective was to evaluate the impact of manure addition on corn yield, and sediment losses in snowmelt and rainfall runoff under moldboard plow (MP) and ridge tillage (RT) systems. Corn (Zea mays L.) grain yield and sediment losses in surface runoff after a one‐time spring application of (16.2 dry Mg ha−1) solid beef (Bos taurus) manure on a 12% slope Forman (fine‐loamy, mixed Udic Argiborolls)‐Buse (fine‐loamy, mixed Udorthentic Haploborolls) complex were measured from 1992 through 1994. In 1993, there was no effect of manure on grain yield irrespective of tillage because of high rainfall. Under average rainfall conditions in 1994, grain yield (10.2 Mg ha−1) in the manure RT treatment was 1.0, 0.9, and 0.7 Mg ha−1 greater than that in no‐manure RT, manure MP, and no‐manure MP treatments, respectively. Snowmelt runoff was not affected by manure application and it transported <0.1 Mg sediment ha−1. Manure reduced rainfall runoff by 10 mm in 1993 and 3.2 mm in 1994, which led to reduction in sediment loss of 2.5 and 0.2 Mg ha−1, respectively. The RT system resulted in lower rainfall runoff compared with the MP system for all 3 yr. Onetime manure application reduced rainfall runoff and associated sediment loss in both tillage systems. However, manure application was more effective in minimizing runoff and sediment losses during intense rainfall in the RT than in the MP system.

Tolerance and velvetleaf (Abutilon theophrasti) suppressive ability of two old and two modern corn (Zea mays) hybrids

Improved crop tolerance and weed suppressive ability are tactics that may reduce the negative effect of weeds on crop yield. Irrigated field experiments were conducted to compare leaf area index (LAI), intercepted photosynthetic photon flux (PPF), and relative tolerance and velvetleaf suppressive ability among two old (circa 1940) and two modern corn hybrids. Each hybrid was grown in monoculture and in mixture with velvetleaf at 1, 4, 16, and 40 plants m−1row. Plants were periodically harvested in monoculture plots to obtain estimates of corn LAI, and PPF interception was measured. Variation in hybrid tolerance to velvetleaf competition for light was evaluated by comparing among hybrids the coefficients of a regression of corn yield loss on velvetleaf density. Velvetleaf seed capsule production in the presence of each hybrid was compared to evaluate variation in velvetleaf suppressive ability among hybrids. Maximum corn yield loss was 32% lower for the two old hybrids, and velvetleaf capsule production was reduced by 62% at low velvetleaf densities in 1995 compared to the modern hybrids. In 1996, yield loss of the modern hybrid 3394 was 74% lower than that of the other three hybrids at low velvetleaf densities, whereas maximum yield loss of the old hybrid 336 was 44% lower at high densities. Velvetleaf capsule production did not vary among hybrids at any velvetleaf density in 1996. Hybrids with greater tolerance and velvetleaf suppressive ability also had greater LAI and PPF interception, suggesting optimized corn LAI and PPF interception may be useful in an integrated weed management program.

Effect of Annual Medic Smother Plants on Weed Control and Yield in Corn

AbstractUsing spring‐seeded smother plants for weed control could reduce the environmental impact of corn (Zea mays L.) production. Research was conducted to determine whether currently available medic (Medicago spp.) cultivars are adapted for use as smother plants in corn. In field experiments in 1992 at Becker and Rosemount, MN, Medicago scutellata (L.) Mill. cv. Sava and Kelson were interseeded with corn at 0, 85, 260, or 775 seeds m−2. In 1993, Sava and Kelson, along with M. polymorpha L. cv. Santiago and M. lupulina L. cv. George, were interseeded with corn at 260 seeds m−2 and N fertilizer was applied at 0, 84 (56 at Rosemount), or 168 kg−1. Land equivalent ratios for corn and medic intercrops grown in 1992 were not > 1, indicating that corn and medics competed strongly for resources. Medics seeded with corn at a rate high enough to consistently suppress weeds (260 seeds m−2) reduced weed dry weight 14 wk after corn emergence by 69% at Becker and by 41% at Rosemount compared with monoculture corn. The same seeding rate reduced corn grain yield in weed‐free plots by 21% at Becker and 15% at Rosemount compared with monoculture yields. In 1993, medic smother plants reduced weed dry weight more when grown in the 0 kg ha−1 N plots than in the 168 kg ha−1 N plots. Corn yield losses, however, were less severe in the 168 kg ha−1 N treatments than with 0 N. Annual medics managed as smother plants in corn effectively reduced weed biomass; however, additional research is needed to identify medic genotypes and smother plant management systems that reduce corn yields less than those we evaluated, and that provide more consistent weed suppression across environments..

Ground Beetle (Coleoptera: Carabidae) Activity Density and Community Composition in Vegetationally Diverse Corn Agroecosystems

-Influences of weeds on activity density (number captured per trap per day), species richness and diversity of carabids (Coleoptera: Carabidae) in reduced tillage corn (Zea mays L.) plantings were examined in a 2-yr field study. Four treatments were examined: corn monoculture, corn with broadleaved weeds, corn with grassy weeds, and corn with a mixture of broadleaved and grassy weeds. Carabids were sampled with pitfall traps every 34 wk from May to September in 1988 and 1989. Neither broadleafed nor grassy weeds significantly influenced carabid activity density in 1988, a year of severe drought. However, in 1989, a year of normal rainfall, activity density was significantly greater in broadleaved weed treatments. Activity density of each of the major carabid species was affected differently by the treatments. Weedy vegetation in corn plantings generally did not have significant effects on carabid species richness, and community similarity was generally high for all treatments. Weeds had a significant negative effect on corn yields; the possible beneficial effects of such vegetation on enhancement of carabid activity density should be compared to the potential negative effect of corn yield loss. These results suggest carabid species respond differently to vegetational diversity, perhaps due to a number of factors, including suitable prey availability and microclimate preferences.

Influence of barnyardgrass (Echinochloa crus-galli) time of emergence and density on corn (Zea mays)

Barnyardgrass is a serious weed problem in cornfields in Ontario. Field experiments were conducted at two locations in 1994 and 1995 to determine the influence of emergence time and barnyardgrass density on corn yield loss, leaf area at 50% silking, and barnyardgrass seed production. Selected barnyardgrass densities up to 200 plants m−1were established within 12.5 cm on either side of the corn row. Barnyardgrass seeds were planted concurrently with corn and at the 3- to 5- or 1- to 2-leaf stage of corn growth in 1994 and 1995, respectively. Barnyardgrass density and seedling emergence relative to corn influenced the magnitude of corn yield loss. Maximum corn grain yield loss ranged from 26 to 35% for early emerging barnyardgrass, and less than 6% yield loss occurred from barnyardgrass seedlings emerging later than the 4-leaf stage of corn growth. Changes in corn leaf area index at 50% silking reflected the level of barnyardgrass competition in corn. Maximum leaf area reduction ranged from 21 to 23%. Barnyardgrass seed production varied with time of seedling emergence and density. Ten barnyardgrass plants emerging up to the 3-leaf stage of corn growth produced 14,400 to 34,600 seeds m−2compared to only 1,200 to 2,800 seeds m−2from plants emerging after the 4-leaf corn stage. The results of this study are essential in the development of an integrated weed management strategy for corn.

Stability of Corn (Zea mays)-Velvetleaf (Abutilon theophrasti) Interference Relationships

The crop-weed interference relationship is a critical component of bioeconomic weed management models. Multi-year field experiments were conducted at five locations to determine the stability of corn-velvetleaf interference relationships across years and locations. Two coefficients (I and A) of a hyperbolic equation were estimated for each data set using nonlinear regression procedures. The I and A coefficients represent percent corn yield loss as velvetleaf density approaches zero, and maximum percent corn yield loss, respectively. The coefficient I was stable across years at two locations, but varied across years at one location. The coefficient A did not vary across years within locations. Both coefficients, however, varied among locations. Results do not support the use of common coefficient estimates for all locations within a region.

Relationships Among Green Foxtail (Setaria viridis) Seedling Development, Growing Degree Days, and Time of Nicosulfuron Application

Success of postemergence weed management often depends upon application timing and weed seedling size. To develop a predictive tool for estimating green foxtail development and optimizing timing of management operations, seedling growth was monitored in fields for two years, as well as in a single greenhouse experiment, and compared with elapsed thermal time (growing degree days, GDD, base 10 C). The relationship between seedling height (mm) and GDD was similar both years and could be described by the following equation: Height = (-0.27 + 0.033 * GDD)2. A comparable equation described seedling growth in a greenhouse. Leaf number was linearly related to GDD. Green foxtail in corn was controlled with nicosulfuron applied at seven intervals between 100 and 450 GDD after corn planting in 1993 and 1994. In 1993 corn yield losses due to green foxtail interference were least when nicosulfuron was applied 200 to 300 GDD after planting, at which time green foxtail height was 50 to 100 mm. In 1994 corn yield losses were minimized if nicosulfuron was applied any time before 300 GDD.

Reducing Imazethapyr Injury to Field Corn (Zea mays) with Naphthalic Anhydride

A field trial was conducted in 1988 and 1989 to confirm the efficacy of naphthalic anhydride (NA) for providing full-season protection of corn from imazethapyr applied at various times and rates. NA applied as a 1% by weight dust to corn seed caused 6% injury 2 weeks after treatment (WAT) in 1989; however, plants recovered within 6 WAT and grain yield was not affected. Imazethapyr applied to corn untreated with NA resulted in greater than 30% injury for all treatments in both years except PRE in 1988. NA reduced phytotoxicity from all imazethapyr applications in 1989 and from PPI, early POST, and 4- to 5-leaf stage (mid-POST) applications in 1988. Despite the safening effect, corn injury was still observed 6 WAT in NA-treated corn for all imazethapyr applications in both years except early POST in 1988. Higher yields were produced from NA-treated than untreated corn with imazethapyr applied PPI in both years, PRE in 1989, early POST in both years, and mid-POST in 1988. Safened corn treated PPI and early POST yielded the same as the safened corn in the control in both years. Imazethapyr applied at the 8- to 10-leaf stage caused total yield loss regardless of NA treatment. Drought conditions may have caused the lower corn injury and yield loss from imazethapyr observed in 1988 compared to 1989.

Review of the biology and control of the Asian corn borer,Ostrinia furnacalis(Lep: Pyralidae)

Abstract The biology and control of the Asian corn borer, Ostrinia furnacalis Guenee, is reviewed. This insect is distributed from China to Australia and the Solomon Islands. In northern parts of its range the moths have one or a few generations per year, but in the tropics, generations are continuous and overlapping. The caterpillars can cause severe yield losses in corn, both by damage to the kernels and by feeding on the tassels, leaves, and stalks. Survival and growth of the caterpillar is highest on the reproductive parts of the plant. Other economic plants attacked include bell pepper, ginger and sorghum. Recently, the Asian corn borer appears to have become an important pest of cotton. A number of wild grasses are also used as hosts. Information on predators and parasites is summarized. Egg parasitoids are relatively effective in some tropical areas, but no significant larval or pupal parasites have been found. In temperate parts of the Asian corn borer's range, larval parasites are more abundant, ...

Yield Loss in Sweet Corn in Response to Defoliation or Infection by Exserohilum turcicum

Abstract Net CO2 assimilation was reduced in sites of infection by Exserohilum turcicum in leaves of Seneca 60 sweet corn before lesions appeared. In leaf tissue adjacent to infected areas, there was an early small increase in CO2 assimilation followed by a gradual decline to nearly 0 net CO2 exchange by 7 days after inoculation. Translocation of photosynthates in to disease lesions from healthy tissue distal to the lesions was observed within 1 h after exposure of 1.2–cm2 areas of the leaf blade to 14CO2. No translocation from lesions to healthy leaf tissue was observed. The effects of defoliation at specific leaf positions on yield of sweet corn plants were accurately simulated by a model in which yield is expressed as a function of healthy leaf area absorption of incident insolation. Removal of leaves from the bottom third of the plants caused no yield loss, whereas removal of leaves above the ear caused significant losses. The model underes, timated the yield loss caused by infection by E. turcicum by approximately 22 %. The observed effects of infection by E. turcicum on photosynthetic efficiency in leaf tissue adjacent to lesions and on translocation of photosynthates into lesion from distal parts of the leaf show that the effect of northern leaf blight on yield is greater than can be accounted for by the direct loss of healthy leaf area through necrosis within disease lesions.

Relationship of Plant Phenology to Corn Yield Loss Resulting from Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Injury, Nitrogen Deficiency, and High Plant Density

Relationships among stresses caused by nitrogen deficiency, high plant population levels, and western corn rootworm (WCR) ( Diabrotica virgifera virgifera LeConte) injury and their effects on phenological development and grain yield of corn ( Zea mays L.) were determined in a 2-yr field study. WCR infestation did not significantly affect silk development in 1984, although yields were 88.8 and 80.6% of those of the control at densities of 600 and 1,200 eggs per 30.5-cm row, respectively. Effects from root injury appeared to be compounded by moisture-stressed conditions in 1985, and asynchrony between tassel and silk development resulted in increased plant barrenness. Grain yields in 1985 were 80.2 and 55.6% of those of undamaged plants at the 600- and 1,200-egg infestation levels. Evidence from plant density by rootworm interaction on silking interval, barrenness, and yields suggests that the corn plant can tolerate a certain amount of root damage when plant densities are low. A significant nitrogen by rootworm interaction on grain yields provided evidence that root injury interferes with nitrogen uptake. The disruption of phenology of the injured corn plants appeared to be the result of decreased plant turgor resulting from WCR feeding.

Seasonal Emergence and Growth ofSorghum almum

Field studies on time of emergence, influence of planting date on growth and reproduction, and winter survival of rhizomes were conducted on sorghum-almum grown in corn and crop-free environments. In 1985, peak emergence of sorghum-almum occurred during early May in crop-free plots and mid-May in corn. In 1986, two peaks of emergence, one in early June and one in late June, were noted in both crop-free and corn plots. Emergence after mid-July was 4% or less of the total emerged in 1985, and no sorghum-almum emerged after mid-July in 1986. In planting date studies, sorghum-almum was seeded alone or in corn at 2-week intervals. Corn competition reduced sorghum-almum shoot, rhizome, and root growth at all planting dates. Maximum sorghum-almum seed production was 43 110 seed/plant when grown without competition but only 1050 seed/plant when grown with corn competition. When grown with corn competition, no seed developed on sorghum-almum seeded 6 or more weeks (mid-June or later) after corn planting. Shoot dry weight of sorghum-almum grown with corn competition was 3 g/plant or less for plants seeded 4 or more weeks (early June or later) after corn planting. Therefore, controlling sorghum-almum in corn through mid-June should prevent seed production and corn yield losses due to sorghum-almum competition. Rhizomes produced by sorghum-almum grown alone or with corn competition did not survive the winter; therefore, in Minnesota, sorghum-almum survival from one growing season to the next depends on seed production.

A Stochastic Dominance Comparison of Reduced Tillage Systems in Corn and Soybean Production under Risk

AbstractReturns per acre of reduced tillage systems including conventional, chisel, till‐plant, and no‐till are examined under general assumptions concerning risk. These returns are calculated using com and soybean experimental plot yields. Stochastic dominance rankings indicate an advantage (second degree) of conventional and chisel over no‐till when soil loss costs are not assigned. Annual per acre soil loss costs of $@@‐@@5–15 shift rankings towards the reduced tillage systems. A $@@‐@@10 per acre cost results from corn yield losses of 0.06% per year (170 bushel per acre yield base) over fifty years with a 5% real discount rate.