Corn In Ontario Research Articles

Predicting soil nitrogen availability to grain corn in Ontario, Canada

Predicting the soil-available nitrogen (N) to grain corn over a growing season in humid temperate regions is the key for improving fertilizer N recommendations. The objective of this study was to evaluate a suite of soil-N tests to predict soil N availability to grain corn over two growing seasons at 13 individual sites with long-term history of synthetic N fertilization in Ontario, Canada (13 site-years). At each site, fertilizer N was applied at various rates (0–224 kg N·ha−1) to determine the crop response to N fertilizer, relative yield (RY), and the most economic rate of N (MERN). Across the entire dataset, water-extractable mineral N (WEMN) was the only soil test that strongly correlated to both RY (r = 0.74**) and MERN (r = −0.56*) indicating that in grain corn fields with long-term history of N fertilization, mineral forms of N in soil solution can be used for fertilizer N recommendations in southern and eastern Ontario. We also provide evidence that grouping soils based on clay content could further refine fertilizer-N recommendations for grain corn in Ontario. A multi-year validation of the WEMN test with more field sites and development of a fertilizer recommendation table for this soil test are recommended.

Economic and environmental consequences of nitrogen application rates, timing and methods on corn in Ontario

Large scale adoption of nitrogen (N) management practices, including the 4Rs, could lead to beneficial environmental and economic outcomes, but only if they improve agricultural profit or are driven by policy and legislation. This study uses a spatial economic maximization and environmental simulation model to examine the economic and environmental tradeoffs of adopting three different 4R practices, specifically N rate reduction, timing (sidedress versus at-planting) and placement methods (broadcast versus injection) in Ontario corn production, under alternative annual weather conditions. The study shows that the use of optimized agronomic, based on meeting crop N requirements specific to each fertilizer management practice, rather than historic, N application increases annual average Ontario-wide farm profit from $124 million to $173 million (39.5%), decreases N application from 122 to 97 kt (20.5%), decreases nitrous oxide (N2O) emissions from 3.4 to 2.4 kt (29.4%), decreases ammonia (NH3) volatilization from 12.4 to 1.2 kt (90.3%) and decreases nitrate (NO3−) leaching from 47 to 13 kt (72.3%), over 30-years of weather data. Injection and sidedress appear to be more N use efficient than broadcast, with sidedress becoming increasingly important as N prices and constraints increase. N2O emissions appear to be more difficult to mitigate compared to NH3 emissions and NO3− leaching. Regarding the 4Rs, right placement and right timing play a role under specific spatial conditions, while right rate appears to be the most effective means to mitigate the environmental impacts of corn N application and may be mutually beneficial to farmers and society.

Occurrence and Distribution of Physiological Races of Exserohilum turcicum in Ontario, Canada.

Northern corn leaf blight (NCLB) caused by Exserohilum turcicum is the most common and economically significant fungal leaf disease of corn in Ontario, Canada. During the past 10 years in Ontario, severity and incidence of NCLB have increased, possibly owing to the appearance of new races. Several races have been identified in various parts of the world; however, information on occurrence and distribution of races in Ontario is lacking. In the current study, 677 single conidial isolates of E. turcicum were isolated from 687 symptomatic leaf samples collected between 2012 and 2016. These isolates were evaluated for pathogenicity on six corn differential inbreds (A619, A619Ht1, A619Ht2, A619Ht3, A632Htn1, and H102Htm1) under controlled environmental conditions and then grouped into 17 physiological races (0, 1, 2, 3, M, N, 12, 1M, 1N, 3M, 13M, 12N, 13N, 1MN, 12MN, 13MN, 123MN) based on the reaction of the inbreds to infection (resistant or susceptible). Four races (0, 1M, 1N, and 1MN) were most frequent, with an isolation frequency of 13, 10, 12, and 41%, respectively. Seventy-six percent of the isolates were virulent on more than one Ht resistance gene, with 2.4% (16 isolates) virulent on all five Ht resistance genes used in this study. Further analysis of the distribution of races in four regions over the years revealed that the occurrence and distribution of the races changed with time in Ontario. Overall, the frequency of virulence of the 677 isolates screened on the differentials with resistance genes Ht1, Ht2, Ht3, Htm1, and Htn1 varied from 6 to 81% (Ht1 81%, Ht2 6%, Ht3 12%, Htm1 64%, and Htn1 64%). Virulent isolates produced fewer lesions on the Htm1 differential, and smaller lesions that were slower and having less sporulation on the Htn1 differential, compared with infection of the differentials with Ht1, Ht2, and Ht3 resistance genes. Virulence frequency also changed within the four geographical regions of Ontario, with fewer isolates virulent on all resistance genes in eastern Ontario compared with southern and western Ontario. Isolates from southern Ontario had greater virulence frequency against Ht1 and Htm1, whereas isolates from western Ontario were more frequently virulent on Ht1 and Htn1. The information generated in this study on the distribution of E. turcicum races in Ontario corn will help growers to select appropriate hybrids with required resistance genes and will assist seed companies in deploying resistance genes in corn hybrids across the province or within a particular region.

Comparative population structure and trichothecene mycotoxin profiling of Fusarium graminearum from corn and wheat in Ontario, central Canada

Fusarium graminearum causes fusarium head blight (FHB) of wheat and gibberella ear rot (GER) of corn in Canada and also contaminates grains with trichothecene mycotoxins. Very little is known about trichothecene diversity and population structure of the fungus from corn in Ontario, central Canada. Trichothecene genotypes of F. graminearum isolated from corn (n = 452) and wheat (n = 110) from 2010 to 2012 were identified. All the isolates were deoxynivalenol (DON) type. About 96% of corn isolates and 98% of wheat isolates were 15‐acetyl deoxynivalenol (15ADON) type. The fungal population structures from corn (n = 313) and wheat (n = 73) were compared using 10 variable number tandem repeat (VNTR) markers. The fungal populations and subpopulations categorized based on host, cultivar groups, years and geography showed high gene (H = 0.818–0.928) and genotypic (GD = 0.999–1.00) diversity. Gene flow was also high between corn and wheat population pairs (Nm = 8.212), and subpopulation pairs within corn (Nm = 7.13–23.614) or wheat (Nm = 19.483) populations. Phylogenetic analysis revealed that isolates from both hosts were F. graminearum clade 7. These findings provide baseline data on 3‐acetyl deoxynivalenol (3ADON) and 15ADON profiles of F. graminearum isolates from corn in Canada and are useful in evaluating mycotoxin contamination risks in corn and wheat grains. Understanding the fungal genetic structure will assist evaluation and development of resistant cultivars/germplasm for FHB on wheat and GER on corn.

Agronomic Management Strategies to Reduce the Yield Loss Associated with Spring Harvested Corn in Ontario

Some growers in northern corn (Zea mays L.) producing regions forgo the typical autumn harvest for various reasons, but not without the risk of significant yield loss. Therefore, strategies are needed for managing the risks to yield when harvesting corn in spring. Field experiments, with various management strategies, were initiated in Ontario, Canada near Belmont and Ridgetown in 2009 and near Belmont, Ridgetown, and Lucan in 2010. Management strategies investigated the use of hybrids with a range in maturity, the use of standard and reduced plant populations, and the use of a foliar fungicide applied around tasseling. The parameters examined were stay-green in autumn, lodging in spring, and grain yield, moisture, and test weight of corn harvested in autumn and spring. Standard corn production practices consist of using a full-season hybrid planted at 80,000 plants&middotha-1 with no late-season fungicide application; however, if over-wintered at Belmont, corn managed using these practices resulted in a 23.1% yield loss (12.1 vs 9.3 Mg&middotha-1) averaged across years when the crop was harvested in the spring. An overwintering management strategy for corn was identified, which consisted of planting at a reduced plant population (60,000 plants&middotha-1) and spraying the crop with QUILT&reg (azoxystrobin + propiconazole at 200 g a.i. ha-1) at the VT to R1 growth stage. Averaged across all hybrids, this strategy minimized yield losses through improvements on corn standability with only a 3.5% yield loss at Ridgetown and a 13.2% yield loss at Belmont. Furthermore, grain test weights for corn with the overwintering strategy were similar to or greater than corn overwintered with the standard production practice. However, weather conditions have the potential to overwhelm any management strategy. In spite of the favorable data indicating reduced risks with a spring harvest, lodging was still higher than expected and yield losses would likely be unacceptable for most growers to make a spring corn harvest a widely accepted practice, unless autumn grain moistures are extremely high, drying charges are high, and if stalk strength going into the winter was exceptional.

Fusarium species and mycotoxins associated with oat in southwestern Ontario, Canada

Fusarium graminearum Schwabe [teleomorph: Gibberella zeae Schwein. Petch] is the predominant Fusarium species pathogenic to wheat, barley and corn in Ontario and produces the mycotoxin deoxynivalenol (DON) in grain. The first objective of this study was to determine the Fusarium spp. and mycotoxin concentrations (DON, HT-2, and T-2) from commercial oat (Avena sativa L.) fields grown in the same area as wheat, corn and barley in Ontario. The second objective was to measure DON level across cultivars grown in the Ontario Performance Trial (OPT) after spray-inoculation with F. graminearum. Fusarium sporotrichioides, F. graminearum and F. poae were the predominant species identified in oat. The highest level of DON in commercial oat fields were 0.3, 0.1, 0.2 and 1.2 ppm in 2005, 2006, 2007 and 2008, respectively. The highest concentrations of HT-2, and T-2 in 2006 were 0.5 and 0.2 ppm, respectively, whereas the levels in 2007 were both under 0.2 ppm. The relatively low level of DON in commercial oat fields confirmed that oat is in general less affected with F. graminearum than other cereals. However, this study supports the importance of monitoring Fusarium spp. and concentrations of mycotoxins in oat in Ontario, especially during growing conditions, as experienced in 2008, which favored Fusarium infection and DON accumulation. Differences in percent of Fusarium spp. infected kernels and DON level (ppm) were identified amongst the cultivars in the OPT in naturally infected oat samples and after inoculation, respectively. Key words: Oat, Fusarium spp., mycotoxins

Weed Control and Yield Response to Foramsulfuron in Corn

Foramsulfuron has recently been registered for weed control in corn in Ontario, but there is very little information on the rate of foramsulfuron required to obtain at least 90% weed control. Our objective was to determine the foramsulfuron rates giving at least 90% weed control while maintaining crop yield loss due to weed interference and injury at less than 5%. Ten field trials were conducted at five Ontario locations (Exeter, Harrow, Ridgetown, Woodslee, and Woodstock) in 2001 and 2002 to evaluate the effectiveness of foramsulfuron at rates ranging from 8.75 to 140 g ai/ha. To obtain a reduction in biomass of 90% (I90) at 78 d after treatment (DAT), foramsulfuron must be applied to common lambsquarters at 68 g/ha and to common ragweed at 86 g/ha, respectively. For green foxtail a foramsulfuron rate of 25 g/ha was required to achieve 90% control. The application of foramsulfuron caused injury to corn at 7 DAT at Ridgetown and Woodstock only, but did not exceed a rating of 10%; by 14 and 28 DAT no corn ...

Sweet Corn Hybrid Sensitivity to Clopyralid

Limited information exists on sweet corn tolerance to postemergence (POST) applications of clopyralid under Ontario growing conditions. Eight sweet corn hybrids were evaluated for tolerance to clopyralid in three field experiments conducted in 2001 and 2002 in Ontario. Clopyralid was applied POST at 200 and 400 g ai/ha, the proposed and twice the proposed registered rate for use in sweet corn in Ontario. Sweet corn response to clopyralid did not vary among the hybrids tested. In 2001, visual injury among hybrids 7 d after treatment (DAT) with clopyralid at 400 g/ha was less than 3%. Subsequent visual injury evaluations at 14 and 28 DAT showed no differences among sweet corn hybrids at either rate of clopyralid evaluated. The application of clopyralid at 200 and 400 g/ ha had no detrimental effect on plant height or marketable yield of any of the eight sweet corn hybrids. On the basis of visual injury, height, and marketable yield response ‘Calico Belle’, ‘CNS 710’, ‘DelMonte 2038’, ‘GG 222’, ‘GG 246’, ‘GH 2684’, ‘Reveille’, and ‘Rival’ are all tolerant to the POST application of clopyralid.

Sweet Corn Cultivar Sensitivity to Bentazon

Five sweet corn cultivars were evaluated for tolerance to bentazon in five field experiments conducted during 2 yr in Ontario. Bentazon was applied postemergence (POST) at 1.08 and 2.16 kg ai/ha, the highest registered rate and twice the highest registered rate, respectively, used in sweet corn in Ontario. When bentazon was applied POST at 1.08 and 2.16 kg/ha to sweet corn cultivar ‘DelMonte 2038’, injury included plant stunting and leaf damage ranging from 6 to 69% and 15 to 90%, respectively. Plant height was reduced to 48 and 100% of the untreated check when treated with bentazon at 1.08 and 2.16 kg/ha, respectively. The visual injury and height reductions were reflected in the marketable yields, which were reduced to 94% when treated with bentazon. Significant reductions in height and marketable yield were not observed in the other four cultivars tested. No correlation was observed between bentazon sensitivity and endosperm genotype. Based on visual injury ratings, sweet corn height, and marketable yield, it was concluded that ‘Calico Belle’, ‘GH 2684’, ‘Reveille’, and ‘Rival’ are tolerant to POST application of bentazon.

Annual Meeting, Ottawa, Ontario, 2004

Annual Meeting, Ottawa, Ontario, 2004

Soil tests for predicting the N requirement of corn

Several soil N tests were compared with the one currently used for predicting the N requirement for corn in Ontario. The current test involves a measurement of nitrate (NO3−, 0–30 cm) before N fertilizer sidedressing. The study was done to determine the efficacy of other tests for N fertilizer prediction. The tests chosen varied in the quantity of N “extracted” and included hot KCl-extractable NH4+, anaerobically released NH4+, extractable NH4+ following autoclaving in CaCl2 solution and total N of soil sampled to a depth of 30 cm. The 3-yr study was conducted on a sloped (simple) field site, which provided a wide range in soil organic matter (SOM) contents. A corn crop was grown each year following a barley crop with or without red clover cover crop residues incorporated in the spring and with or without N fertilization. Corn grain yields were obtained at the end of the growing season. Grain yields were lowest at the shoulder and backslope locations and highest at the footslope and toeslope locations. Corn plant shoot biomass and N content and soil mineral (NH4+and NO3−) N (0–30 cm) were measured biweekly to provide an estimate or index of available N. Plant and soil samples were taken at the summit, shoulder, backslope, footslope and toeslope locations providing a wide range of SOM levels, which, in turn, provided a range in available N for comparing the various soil N tests. The increase in estimated available N during the growing season was most rapid in the 120–180 day of year (DOY) period and substantially slower in the 230–260 DOY period. An available N index (AVN) was obtained by averaging the N measured with three plant and soil samples taken in the late August to early September period. Thus, the AVN was determined during a period when the increase in available N was relatively slow. Regressions of corn grain yield (not fertilized with N) on AVN produced R2 values ranging from 0.61 to 0.93. Values of R2 for AVN vs. the soil tests ranged from 0.34 to 0.88 where red clover crop residues were not involved. The AVN values were less correlated with the soil N test values where red clover cover crop residues were incorporated with R2 values ranging from 0.11 to 0.92. It was concluded that the hot KCl test would be a suitable alternative to the currently used soil NO3− test because of relatively simple soil sample preparations and storage, and analytical procedures. Key words: Soil N tests, corn, available N index, soil organic matter, landscape location

First Report of Gray Leaf Spot Caused by Cercospora zeae-maydis on Corn in Ontario, Canada.

During an annual corn disease survey in mid-September 2001, sporadic symptoms typical of gray leaf spot (causal agent Cercospora zeae-maydis Tehon & E.Y. Daniels) (4), consisting of long, narrow, rectangular, 0.3 to 0.5 × 2 to 5 cm, tan or gray-to-tan spots, were found in nine fields in southern Ontario. Leaf samples with symptoms were placed in petri dishes containing moistened filter paper to maintain high humidity and stored at room temperature for 48 h. Clustered conidiophores arose from stomata on both leaf surfaces. Slightly curved, hyaline conidia, 4 to 8 × 25 to 88 µm long with 3 to 5 septa appeared on the tops of conidiophores, similar to those described by Kingsland (3). When single-spore isolates were cultured on carrot leaf decoction agar (2) at room temperature, aerial mycelia were rare, but slightly larger conidia were produced in 3 weeks. When single-spore isolates were cultured on V8 agar (1) at room temperature, aerial mycelia were abundant, and conidiophores and conidia were produced on the tops of mycelia in 1 to 2 weeks, but conidia were slightly smaller. Greenhouse-grown plants of two commercial corn hybrids (Pioneer 32Y52 and Zimmerman NX7208) were inoculated at the 8- to 10-leaf stage by injecting a suspension of 5 × 103 conidia per ml (washed from a V8 agar culture with sterile water) into the whorl and by spraying the suspension on the leaves. High moisture was maintained in the greenhouse by a misting system. After 14 to 21 days, typical symptoms of gray leaf spot and typical conidiophores and conidia were observed. Gray leaf was reisolated from inoculated plants, fulfilling Koch's postulates. We have suspected that gray leaf spot has been present in Ontario for a few years based on unconfirmed reports from the seed corn industry, but to our knowledge, this is the first confirmed report of this pathogen in Canada. Voucher specimens of field material, dried cultures, and greenhouse-inoculated leaves have been deposited in the National Mycological Herbarium (DAOM 229597 to 229600) in Ottawa, ON, Canada; and the isolate has been deposited with the Canadian Collection of Fungal Cultures (CCFC).

An Outbreak of Stewart's Bacterial Wilt of Corn in Ontario, Canada

An Outbreak of Stewart's Bacterial Wilt of Corn in Ontario, Canada

Feeding Ecology of the Red-Winged Blackbird in Field Corn in Ontario

Feeding Ecology of the Red-Winged Blackbird in Field Corn in Ontario

Head Smut, a New Disease of Corn in Ontario

(1980). Head Smut, a New Disease of Corn in Ontario. Canadian Journal of Plant Pathology: Vol. 2, No. 3, pp. 176-178.

Blackbird damage to ripening field corn in Ontario

Blackbird damage to ripening field corn is widespread throughout Ontario. On a grain corn basis, the total losses to blackbirds in Ontario were in the order of 39 200 tonnes, which is equivalent to a 0.7% reduction in yield. Percentage reductions in yield for each county and losses in fields with damage in previous years also were determined. The reductions in yield on a provincial and county basis do not reflect the high levels of damage by blackbirds that were sustained in some areas.

Effect of Adverse Growing Conditions on Corn Maturity and Feeding Value for Poultry

Adverse growing conditions for corn in Ontario during 1974, resulted in loss of crop yield. Field reports also suggest that the feeding value of this reduced yield may be affected. Corn samples from this crop were assayed for metabolizable energy (M.E.), net protein utilization (N.P.U.) and proximate analysis. Average M.E. value at 3219 kcal./kg. (85% dry matter) was some 3% less than expected standards. These samples ranged in crude protein from 7.6 to 10.9%, although protein quality in terms of N.P.U. was not affected.Differences in corn maturity at harvest are related to composition data; in particular sugar and starch levels. Samples of low M.E. value were considered ‘immature’ and contained lower proportions of starch and higher proportions of sugar than corresponding mature samples. M.E. values are correlated with crude protein, starch, sugar, pigment score and bushel weight. A correlation matrix involving M.E. and composition data is presented.Multiple linear regression equations show the expected changes in corn M.E. values with unit changes in various composition parameters.

Isolation of the antifungal substance, 6-methoxybenzoxazolinone, from field corn (Zeamays L.) in Canada.

THE presence of an antifungal substance which is inhibitory to the growth of Fusarium moniliforme (Sheld.) and Gibberella zeae (Schw.) Petch., two pathogenic fungi associated with root and stalk rot of corn in Ontario, has been reported1. The present communication reports the isolation and identification of the antifungal substance.

STUDIES OF FUNGI IMPERFECTI: I. PHIALOPHORA

Some notes are given concerning the structure and occurrence of phialides and phialospores and their relationship with spermatia. The genus Phialophora is not sharply delimited and with many transitional species gradually merges with several genera of the Fungi Imperfecti. A new species Phialophora radicicola Cain, is described from the roots of corn in Ontario.

STUDIES ON ROOT ROT OF CORN IN ONTARIO

Root rot of corn in Ontario is caused primarily by parasitic soil micro-organisms, the most important of which are species of Pythium, Helminthosporium, and Fusarium in that order. The disease causes a decrease in the stand by pre-emergence killing and a dwarfing of the plants by the parasitic invasion and destruction of their roots by the organisms. The pathogens have different optimum soil temperatures but the lower ranges favour those that cause the most severe damage. The roots of other field crops can be parasitized by the organisms found associated with corn root rot, but their effect on the development of the crop varies greatly. It has been proved under greenhouse conditions that the severity of the disease is greatly reduced if the corn is preceded by cover crops of soybeans and materially increased when preceded by timothy. Other crops tested have an intermediate effect.