Corn-growing Areas Research Articles

Entomofauna Associated with Corn Cultivation and Damage Caused by Some Pests According to the Planting Season on the Ecuadorian Coast

Corn (Zea mays L.) is an important cereal for food sovereignty, extensively planted due to its adaptation to various agroecological conditions. Climatic conditions and pests can affect its production. Concerning the latter, natural enemies could be considered in biological control programs. The objective of this study was to estimate the influence of the presence of insects, damage to plants and cobs, and their incidence on corn yield in two planting seasons. During the rainy (February to May) and dry seasons (Jun to October) of the year 2023, in Calceta, Lodana, and Quevedo, three important corn-growing areas on the Ecuadorian coast, corn plots of 1126 m2 were planted. The diversity of phytophagous and natural enemies was estimated. Damage to young plants and cobs was observed, and corn yield was determined. Of the 9073 insects observed, 44.2% and 55.8% constituted phytophagous and natural enemies, respectively. A moderate diversity (Shannon-H Index = 2.474–2.629 and Margalef Index = 2.734–3.110) of insects associated with corn was determined. Yield (range: 6.9 to 15.3 t) was negatively correlated with rainfall and cob damage (p < 0.05). Although precipitation is necessary for planting in rainy season, frequent and intense rains could be affect corn yield.

Management of the Yellow Corn Stem Borer, Sesamia cretica Led. Using Some Pesticides and Their Alternatives and Their Effect on Production Constituents of Yellow Corn Crop Zea mays in Kirkuk Governorate

Our study, the spring cultivar of the yellow corn crop was adopted in the experimental land, the aim of which was to know the best materials used in managing the corn stalk borer insect. Environmentally friendly materials were used (ash - remnants of burnt materials, in addition to table salt). In addition to our use of effective and approved pesticides in the control of stem borer in a field experiment to see the effect of the materials used on insect infestation rates It also had an effect on the killing rate of corn stalk borer larvae achieved by spraying with the experimental materials, in addition to its effect on the height of infected plants compared to the control treatmen Field surveys were conducted to find out the extent of infection with this insect in the center of Kirkuk Governorate. The experiment was repeated for the fall season 2022, with field surveys conducted for the purpose of confirming the economic importance of the insect.t. The results indicated the spread of the corn stalk borer insect in all corn-growing areas, for which tables were prepared regarding the infection rate. In the autumn season 2021 in Kirkuk Governorate. The results indicated that there was a clear effect of the materials used in the treatments, with a relative superiority of the ash and table salt treatments over the pesticide treatments (Diazinon 10% granular and Aktara EC 25).

The Microflora of Maize Grains as a Biological Barrier against the Late Wilt Causal Agent, Magnaporthiopsis maydis

The maize pathogen Magnaporthiopsis maydis causes severe damage to commercial fields in the late growth stages. This late wilt disease has spread since its discovery (the 1980s) and is now common in most corn-growing areas in Israel. In some fields and sensitive plant species, the disease can affect 100% of the plants. The M. maydis pathogen has a hidden endophytic lifecycle (developed inside the plants with no visible symptoms) in resistant corn plants and secondary hosts, such as green foxtail and cotton. As such, it may also be opportunist and attack the host in exceptional cases when conditions encourage it. This work aims to study the pathogen’s interactions with maize endophytes (which may play a part in the plant’s resistance factors). For this purpose, 11 fungal and bacterial endophytes were isolated from six sweet and fodder corn cultivars with varying susceptibility to late wilt disease. Of these, five endophytes (four species of fungi and one species of bacteria) were selected based on their ability to repress the pathogen in a plate confrontation test. The selected isolates were applied in seed inoculation and tested in pots in a growth room with the Prelude maize cultivar (a late wilt-sensitive maize hybrid) infected with the M. maydis pathogen. This assay was accompanied by real-time qPCR that enables tracking the pathogen DNA inside the host roots. After 42 days, two of the endophytes, the Trichoderma asperellum, and Chaetomium subaffine fungi, significantly (p < 0.05) improved the infected plants’ growth indices. The fungal species T. asperellum, Chaetomium cochliodes, Penicillium citrinum, and the bacteria Bacillus subtilis treatments were able to reduce the M. maydis DNA in the host plant’s roots. Studying the maize endophytes’ role in restricting the invasion and devastating impact of M. maydis is an essential initial step towards developing new measures to control the disease. Such an environmentally friendly control interface will be based on strengthening the plants’ microbiome.

Temperature-Dependent Demography of Two Geographically Isolated Populations of Sesamia cretica (Lepidoptera: Noctuidae).

The pink stem borer, Sesamia cretica Lederer is considered as the main insect pest of maize and sugarcane worldwide. Reproductive and life table parameters of two populations of S. cretica were studied at 10 constant temperatures ranging from 12 to 36 (±1)°C, 50 ± 10% RH and a photoperiod of 0:24 (L:D) h for the larval stage and 16:8 (L:D) h for the other stages. At 12°C, no eggs hatched and at 15, 35, and 36°C only the incubation period was completed. The longest (135.81 and 156.49 d) and shortest (49.61 and 52.09 d) female life span were observed at 20 and 32°C for the Varamin and Rey populations, respectively. The highest (181.66 and 180.94 eggs/female) and lowest (13.40 and 32.85 eggs/female) total fecundity of the Varamin and Rey populations were found at 20°C and 34°C, respectively. At the same time, these two populations had the highest intrinsic rate of increase (r) (0.0343 and 0.0349 d-1) at 30 and 27°C, respectively. Similarly, both Varamin and Rey populations had the highest finite rate of increase (λ) at 27°C (1.0349 and 1.0355 d-1, respectively). It was found that the geographical populations of S. cretica were different in terms of the life table parameters at the same temperatures, and this issue can affect the results of forecasting studies. Accordingly, it is suggested that in the major corn-growing areas, a comprehensive study should be performed on different pest populations to address their commonalities and differences for future managing programs.

Applicability of the dual isotopes δ15N and δ18O to identify nitrate in groundwater beneath irrigated cropland

Identification of the nitrate sources that adversely impact groundwater quality is a necessary first step in the control of this major worldwide pollutant. The impact of nitrate leachate from urea-ammonium nitrate (UAN) (50% urea-N, 25% ammonium-N, 25% nitrate-N) fertilizer, whose use has increased dramatically in the last three decades largely because it can be applied through sprinkler irrigation systems to corn in all growth stages, is investigated. The dual isotopes δ15NNO3 and δ18ONO3 were measured in groundwater samples from 39 irrigation wells in two intensively sprinkler-irrigated, corn-growing areas of Nebraska with nitrate-contaminated (N > 10 mg/L) groundwater and documented UAN use to ascertain whether nitrified ammonia and nitrate fertilizers can be distinguished in the High Plains aquifer. The areas, which are highly vulnerable to nitrate leaching and differ only in the composition and thickness of their unsaturated zones, are uniquely suited to provide scientific evidence of the feasibility of identifying nitrate fertilizer leachate in groundwater and thereby add significantly to the small body of existing and inconclusive data. The dual isotope method (DIM) results indicate that the nitrate contamination in 38 wells is mostly nitrified ammonium fertilizer. Most importantly, nitrate fertilizer from UAN was not identified isotopically in groundwater beneath almost all fields with documented heavy UAN use. This could be a potentially valuable finding for fertilizer management or it could convey limitations on the appropriateness of the DIM for nitrate fertilizer source identification in groundwater. Slightly enriched δ15NNO3 values in a few wells coincide with the practice of wintering cattle on corn stubble, which reportedly occurred more frequently in one focus area. The absence of natural soil-N leachates and denitrification in groundwater enabled an apparently reliable identification of manure leachates in both areas.

Evaluation of Calcium Hydroxide-Treated Stover (Second Crop) in Receiving and Growing Diets and Effects on Cattle Performance

Production of ethanol from corn as an alternative fuel source has significantly affected the pricing landscape for corn as an energy source for livestock. As ethanol usage has become more prevalent, corn prices have become more volatile, especially in critical corn-growing areas that have been affected by drought. Consequently, many beef cattle feeders have become interested in alternative energy sources in an effort to control cost of gain. Second Crop (ADM Corp., Decatur, IL) is a process in which calcium hydroxide is added to fibrous crop residues, such as wheat straw and corn stover. When applied to low-quality roughages, calcium hydroxide disrupts the chemical bonds between lignin and hemicellulose, thus improving digestibility of the fiber by ruminal microbes. Treatment of low-quality forage with the Second Crop process could improve the energy value of forages, effectively decreasing reliance on cereal grains as sources of supplemental energy.

Nebraska's groundwater legacy: Nitrate contamination beneath irrigated cropland.

A 31 year record of ∼44,000 nitrate analyses in ∼11,500 irrigation wells was utilized to depict the decadal expansion of groundwater nitrate contamination (N ≥ 10 mg/L) in the irrigated corn-growing areas of eastern and central Nebraska and analyze long-term nitrate concentration trends in 17 management areas (MAs) subject to N fertilizer and budgeting requirements. The 1.3 M contaminated hectares were characterized by irrigation method, soil drainage, and vadose zone thickness and lithology. The areal extent and growth of contaminated groundwater in two predominately sprinkler-irrigated areas was only ∼20% smaller beneath well-drained silt loams with thick clayey-silt unsaturated layers and unsaturated thicknesses >15 m (400,000 ha and 15,000 ha/yr) than beneath well and excessively well-drained soils with very sandy vadose zones (511,000 ha and 18,600 ha/yr). Much slower expansion (3700 ha/yr) occurred in the 220,000 contaminated hectares in the central Platte valley characterized by predominately gravity irrigation on thick, well-drained silt loams above a thin (∼5.3 m), sandy unsaturated zone. The only reversals in long-term concentration trends occurred in two MAs (120,500 ha) within this contaminated area. Concentrations declined 0.14 and 0.20 mg N/L/yr (p < 0.02) to ∼18.3 and 18.8 mg N/L, respectively, during >20 years of management. Average annual concentrations in 10 MAs are increasing (p < 0.05) and indicate that average nitrate concentrations in leachates below the root zone and groundwater concentrations have not yet reached steady state. While management practices likely have slowed increases in groundwater nitrate concentrations, irrigation and nutrient applications must be more effectively controlled to retain nitrate in the root zone.

Genetically Engineered Bt Corn and Range Expansion of the Western Bean Cutworm (Lepidoptera: Noctuidae) in the United States: A Response to Greenpeace Germany

The western bean cutworm, Striacosta albicosta (Smith), is a pest of corn and dry beans in North America. Before the late 1990s, economic infestations of the insect were restricted mostly to the western Great Plains and Idaho. During 1999–2009, it greatly expanded its range and moved across the central and eastern regions of the Corn Belt, eventually reaching northeastern Atlantic coast states. Greenpeace Germany issued a 2010 report claiming that the dramatic range expansion of the western bean cutworm was due entirely to “pest replacement” that resulted from the adoption of genetically engineered Bt corn, which suppressed one pest species and allowed another species—the western bean cutworm, in this case—to take its place. We maintain that the scientific literature does not provide empirical field-collected data to support the Greenpeace Germany claim that Bt corn is the sole factor that influenced the range expansion of the western bean cutworm. We propose broader ecological and agronomic factors to explain why the western bean cutworm has recently expanded its geographic range to include all of the major corn-growing areas in the central and eastern United States. These additional factors may include insect biology, insect and corn phenology synchrony, reduced insecticide use, conservation tillage, soil type, glyphosate-resistant crops, insect genetics, insect pathogens, preexisting insect population densities, and climate change.

Occurrence and spatial and temporal distribution of pesticide residues in groundwater of major corn-growing areas of Greece (1996-1997).

During 1996-1997, residues of selected pesticides were monitored, at 3-month intervals, in 80 wells, including both irrigation and drinking water wells, distributed among the main corn-growing areas (Pieria, Thessaloniki, Serres, Kavala, and Evros) of Greece. Pesticide residues were found in 48% of the wells; however, in most cases residues were very low ranging from LOQs (quantification limits of the analytical methods) to <0.1 microg/L, while in 11% (nine wells) pesticide residues higher than 0.1 microg/L were present. Most of the latter wells were found in Evros and specificallythe Ardas Valley. The frequency of occurrence, in descending order, was atrazine > DEA > alachlor = metolachlor; however, the order of descending concentrations was atrazine > metolachlor > DEA > alachlor. The occurrence and the spatial and temporal distribution patterns of pesticide residues indicate that at the present the situation of groundwater quality is favorable throughout the corn-growing areas of Greece with the exception of the Ardas Valley.

Migration pathways of corn earworm (Lepidoptera: Noctuidae) indicated by tetroon trajectories

The corn earworm moth, Helicoverpa zea (Lepidoptera: Noctuidae), is a nocturnal pest insect that is capable of long-distance flights. Buoyant superpressure balloons (tetroons) with attached transponders were tracked as surrogate markers of moths migrating from three corn-growing regions in Texas. Launches were synchronized with peak emergence of corn earworm moths in June and July 1992. The tetroons were launched at the time (approximately 0.5 h after sunset) of peak take off (ascent of moths into the boundary layer) from the corn-growing areas, and ballasted to drift near the altitude (500–1000 m a.g.l) of the maximum insect flight concentration. Each tetroon was followed by a tracking vehicle or the Argos satellite for maximum distances of 466 km per 9 h night flight, and for one to four successive nights. The endpoints of four of the six tetroons that were tracked for 9 h from Weslaco, Texas were clustered within a 40 km radius circle centered 35 km east of Uvalde, Texas. The prorated (9 h) vector-average of National Weather Service forecast trajectories at the surface and 85.0 kPa geopotential-height estimated mean atmospheric displacements 57% as long as, and 3° clockwise from seven observed 9 h tracks of tetroons. Implications of these findings are discussed relative to the prediction of insect migrations and development of area-wide pest management.

Agricultural impacts of increased alcohol industry demand for corn: the case of Ohio

A mathematical programming model was used to forecast the impacts on Ohio's agricultural sector of a moderate increase in alcohol industry demand for corn. Because converting corn into ethanol yields byproduct feeds that can substitute for soybean meal and other commodities, most of the alcohol industry's demand for corn can be satisfied by switching land from the production of soybeans to the production of corn. For this reason, projected levels of ethanol production do not greatly affect crop or livestock prices. This finding is likely to hold for other corn-growing areas in North America.

RELATION OF CORN MATURITY TO CLIMATIC PARAMETERS

A 3-yr study was conducted in Manitoba to evaluate the influence of several climatic variables on corn maturity. Results indicated that efficiency of heat in maturing corn was lower at the northerly sites than in the corn-growing areas of southern Manitoba. This led to analysis to determine quantitatively the effect of latitude on heat accumulation – maturity relationship of corn. Corn maturity, as measured by kernel moisture, was related to latitude, corn heat units, degree days above 50 F, solar radiation and planting date. The highest contribution to regression was made by a variable involving an interaction between heat accumulation and latitude. Approximately 90% of the variation in kernel moisture was accounted for by the variation in climatic variables.

Dispersion of the European Corn Borer (Lepidoptera: Pyralidae) in Minnesota and South Dakota, 1945 to 1970 1 , 2

The European corn borer first appeared in the southeast corner of Minnesota in 1943. It spread northward throughout Minnesota except the extreme north and northeast, and westward through corn-growing areas in South Dakota. This report reviews the history and some biological characteristics of the dispersion of the insect in the 2 States from 1945 to 1970. There was a high population build-up, or a “population swell” just behind the front of distribution. This phenomenon was shown by populations differing at only a subspecies level. On the basis of the population swells which occurred during the 26-year period, it is suggested that after the initial invasion in 1943, distinctly different populations could have invaded Minnesota in 1952 and again in 1966.

Corn Stunt Virus: Transmission by Three Cicadellid Vectors1

The duration of nymphal instars of Dalbulus maidis (DeLong & Wolcott), D. elimatus (Ball), and Graminella nigrifrons (Forbes) was 18.5, 20.2, and 23.5 days, respectively, at 24±2°C. The life span of adult D. maidis, D. elimatus , and G. nigrifrons was 56.5, 51.5, and 38.2 days, respectively. G. nigrifrons was inefficient in acquisition and transmission of corn stunt virus (CSV) to plants in comparison with both Dalbulus species. D. elimatus was able to acquire CSV during access feeding times of 15 minutes. G. nigrifrons and both species of Dalbulus transmitted virus during 4-hour and 15-minute inoculation access feeding periods, respectively, but not at shorter periods. The minimum incubation period of CSV in colonies of the 3 leafhoppers ranged from 22 to 26 days in G. nigrifrons , 17 to 22 days in D. maidis , and 14 to 15 days in D. elimatus at 24±2°C. The frequency of virus transmission by G. nigrifrons and D. elimatus showed that infective insects of both species transmitted virus to almost every plant they were transferred to at 1-, 2-, and 4-day intervals. Poor and efficient vectors were observed in both species. In spite of its comparative inefficiency in acquisition and transmission of CSV, G. nigrifrons might play an important role in the spread of the virus, since it is abundant throughout the corn-growing areas of North America, and it can survive on a variety of plant hosts.

Corn Production as Affected by Plant Population and Hybrids of Varying Maturity

The environment of the western edge of the North American cornbelt is, on the average, less favorable and more variabIe for corn (Zea mays L. ) production than farther east. Consequently, in this <'fringe, of which northeast Kansas is representative, one year may resemble typical cornbelt conditions while the next may be characterized by drought, high temperatures, and resulting lower yields. Securing information on optimum plant population in this area is important because of high yield fluctuations ofter encountered among locations and years. Data on the response of different hybrids to stand density in such environments are limited. Numerous studies have been conducted to determine the optimum plant population and extent of plant population X hybrid interaction for most major corn-growing areas. Results of older trials, however, may not be applicable now in the western edge of the cornbelt because of increased nitrogen fertilizer use and development of hybrids with higher yield potential. Dungan et v1. (3) and Stringfield (9) have reviewed the literature on the subject. Optimum stands were related to soil productivity, with soil moisture availability and soil fertility probably the most important components. In the western edge of the cornbelt, moisture becomes relati?vely more important in limiting corn yields than farther east. Several researchers (1, 2, 6, 10) have shown that different hybrids may vary in response to stand density. Tolerance to high stand density is related to tolerance of low light intensity (6, 7). Other work has shown that the activity of the light-sensitive enzyme, nitrate reductase, decreases with decreased light intensity (4) and is lower in shadeintolerant hybrids (4, 5 ) . This study was to investigate 1) the optimum plant population for corn production on certain nonirrigated soils in the western fringe of the cornbelt, and 2) the extent of plan population X hybrid interaction, using hybrids of varying maturities.