Early-planted Corn Research Articles

Efficacy of select insecticide seed treatments and in-furrow applications for managing the brown stink bug, Euschistus servus (Say) (Hemiptera: Pentatomidae), in seedling maize

The brown stink bug, Euschitus servus, is an important early season pest of field corn. It feeds directly on the growth point of developing plants leading to delays in growth, stunting, and a reduction in yield when injury is severe. Injury from stink bug feeding is often observed days to weeks after it occurred at which point management provides no benefit. This study, conducted in Suffolk, VA in 2018 and 2019, examined prophylactic insecticide options, including seed treatments and in-furrow applications, for their efficacy against brown stink bug. Seed treatments are applied by manufacturers to many commercially available corn seed at different rates for below ground pests. In 2018 and 2019, brown stink bugs were artificially infested in seedling corn plots treated with clothianidin applied to the seed, bifenthrin applied in-furrow, or terbufos applied in-furrow. In 2019, an early and late planting date were used. The impact of stink bug feeding in the presence of each of these treatments, as well as the impact of the treatments on stink bug feeding behavior and mortality, were assessed. We found that clothianidin seed treatments have the potential to mitigate early season feeding from brown stink bugs and prevent yield reduction. We also observed reduced feeding activity and plant injury in early planted corn, suggesting later planted corn is more susceptible to stink bug injury. These results suggest that no additional management may needed for brown stink bugs in seedling corn when planting seed treated with insecticides.

Decline in Sublethal Effects of Bt Corn on Corn Earworm (Lepidoptera: Noctuidae) Linked to Increasing Levels of Resistance.

As part of an ongoing longitudinal study in North and South Carolina, this study reports the recovery of Helicoverpa zea (Boddie) pupae in field trials with genetically engineered corn, Zea mays L., hybrids that produce insecticidal toxins from Bacillus thuringiensis (Bt) in 2017-2019. In total, 10,400 corn ears were collected, which led to 3,927 H. zea pupae (2,215 in South Carolina and 1,712 in North Carolina). Late-planted corn led to a 3.39-fold increase in recovery of pupae compared to early-planted corn. Bt corn expressing Cry1F + Cry1Ab and Cry1A.105 + Cry2Ab2 had 1.67-fold and 2.51-fold fewer pupae than non-Bt near-isolines, respectively. Only six pupae were recovered from the hybrid expressing Cry1F + Cry1Ab + Vip3Aa20. Averaged across trials, Bt corn expressing either Cry1A.105 + Cry2Ab2 or Cry1F + Cry1Ab significantly reduced pupal weight compared to non-Bt near-isolines in North and South Carolina. Combining our data with a previous study at the same locations (Bilbo et al. 2018), reduction in pupal weight between Bt and non-Bt near-isolines significantly declined from 2014 to 2019 for Cry1Ab + Cry1F in North and South Carolina. This decline in levels of a sublethal effect of Bt corn expressing Cry1Ab + Cry1F on H. zea at both locations is likely correlated with resistance development.

Impact of Lepidoptera (Crambidae, Noctuidae, and Pyralidae) Pests on Corn Containing Pyramided Bt Traits and a Blended Refuge in the Southern United States.

Blended refuge for transgenic plants expressing Bacillus thuringiensis (Bt) toxins has been approved in the northern United States as a resistance management strategy alternative to a structured refuge. A three-year study (2012-2014) was conducted with 54 trials across nine states in the southern United States to evaluate plant injury from lepidopteran pests of corn and yield in a corn hybrid expressing Cry1F × Cry1Ab × Vip3Aa20 (Pioneer Brand Optimum Leptra) planted as a pure stand and in refuge blends of 5, 10, and 20% in both early and late plantings. Injury by corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), and fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), was generally proportional to the percentage of non-Bt corn within each refuge blend. Across locations, ear injury in plots with 100% Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) corn ranged from no injury to a maximum of 0.42 cm(2) per ear in Mississippi in 2013. Leaf injury ratings in 100% non-Bt plots in early and late planted trials in 2014 were 86- and 70-fold greater than in 100% Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) plots. Plants in plots with blended refuges had significantly greater leaf injury in 2012 (5, 10, and 20% refuge blends), in the early-planted corn in 2013 (10 and 20% only), and in both early- and late-planted corn in 2014 (20% only) as compared with leaf injury in a pure stand of Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) seen during these years. Corn ears in plots with blended refuges also had significantly greater area of kernels injured in 2012 (5, 10, and 20%), in early- and late-planted corn in 2013 (5, 10, and 20%), and in early (10 and 20% only)- and late-planted corn (5, 10, and 20%) in 2014 as compared with ear injury in a pure stand of Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) seen during these years. Infestations of southwestern corn borer, Diatraea grandiosella Dyar (Lepidoptera: Crambidae), were also significantly reduced by Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra). Despite these differences in injury, yield averaged across locations varied among refuge blends only in the late-planted trials in 2013, with greater yields in the 0% refuge blend than in the 20% blend; however, when examining yield separately by location, only two of nine locations had higher yields in the 100% Bt plots than in any of the blended refuge plots. As a complement to studying the contribution of blended refuge to delaying resistance, quantifying injury and yield in a range of refuge blends is a necessary step to provide management information on the range of lepidopteran pests that occur in the southern United States.

Forage Radish Cover Crop Suppresses Winter Annual Weeds in Fall and Before Corn Planting

Forage radish (Raphanus sativus L. var. longipinnatus) is a new winter cover crop in the Mid‐Atlantic region. The objective of this project was to characterize the repeatability, amount, and duration of weed suppression during and after a fall‐planted forage radish cover crop and to quantify the subsequent effect on no‐till seeded corn (Zea mays L.). Forage radish cover crops were grown in 10 site‐years in the coastal plain of Maryland and followed by a corn crop in seven site‐years. Forage radish was compared to rye (Secale cereale L.) and no cover crop treatments. Early and typical corn planting dates along with contrasting herbicide management strategies were compared over four site‐years. Forage radish produced 3.9 to 6.6 Mg ha−1 of shoot dry matter and 1.3 to 3.2 Mg ha−1 of fleshy root dry matter when planted before 1 September. Forage radish did not reduce population or grain yield in subsequent corn crops. Forage radish provided complete suppression of winter annual weeds in fall and early spring but the suppression did not persist into the subsequent cropping season. When forage radish cover crops were used in place of preplant burndown herbicide treatments to control weeds in early planted corn, some weeds were present at the time of corn emergence but corn yields were not reduced as long as emerged weeds were controlled with a postemergence herbicide. Strategies to use the weed suppression of forage radish cover crops should focus on fall weed suppression and the early spring preplant window of weed control.

Composition and Abundance of Stink Bugs (Heteroptera: Pentatomidae) in Corn

The species composition and abundance of stink bugs (Heteroptera: Pentatomidae) in corn, Zea mays L., was determined in this on-farm study in Georgia. Seven species of phytophagous stink bugs were found on corn with the predominant species being Nezara viridula (L.) and Euschistus servus (Say). All developmental stages of these two pests were found, indicating they were developing on the corn crop. The remaining five species, Oebalus pugnax pugnax (F.), Euschistus quadrator (Rolston), Euschistus tristigmus (Say), Euschistus ictericus (L.), and Acrosternum hilare (Say), were found in relatively low numbers. Adult N. viridula were parasitized by the tachinid parasitoid Trichopoda pennipes (F.). There was a pronounced edge effect in distribution of stink bugs in corn. Population dynamics of N. viridula and E. servus were different on early and late-planted corn. Oviposition by females of both stink bug species occurred in mid-to-late-May and again mid-to-late-June in corn, regardless of planting date. In early planted fields, if stink bug females oviposited on corn in mid-July, the resulting nymphs did not survive to the adult stage in corn because ears were close to physiological maturity and leaves were senescing. Density of stink bug adults in early planted corn was relatively low throughout the growing season. In late-planted corn, females of both stink bug species consistently laid eggs in mid-to-late-July on corn with developing ears. This habitat favored continued nymph development, and the resulting adult population reached high levels. These results indicate that corn management practices play a key role in the ecology of stink bugs in corn agroecosystems and provide information for designing management strategies to suppress stink bugs in farmscapes with corn.

Corn Response to Nitrogen Fertilizer as Affected by Planting Date and Hybrid

Producers of the eastern Corn Belt are often forced to either delay corn (Zea mays, L.) planting or replant due to unfavorable early season growing conditions. In these situations producers may decrease N rates due to decreased yield potential or switch to short season hybrids to reduce the risk of frost injury prior to maturity. Hybrids with differing yield potential may have different N requirements, but definitive research to determine the impact of hybrid selection on N response is lacking. Field experiments were conducted in Ohio during 2006 and 2007 to evaluate if corn grain yield and stalk lodging attributed to N fertilizer is affected by hybrid or planting date. This experiment evaluated two planting dates (late April/early May and early/mid-June), with subplots comparing N fertilizer rates (0, 60, 120, and 180 lb N/acre), and sub-subplots containing corn hybrids of differing maturities (104, 108, 109, and two 113 days relative maturity). In 2006, planting date did not affect the economically optimum N fertilizer rate (EONR), although late planted corn did produce lower grain yields. In 2007, late-planted corn was less responsive to N with the optimum N rate being 38 lb N/acre less than early-planted corn. Differences in N response between hybrids were noted, but optimum N rates were not markedly different.

Spectral Detection of Emergence in Corn and Cotton

Multispectral reflectance of emerging cotton (Gossypium hirsutum) and corn (Zeamays) seedlings was measured during the 2000 and 2001 growing seasons. Reflectance in blue, green, red, and near infrared (NIR) wave lengths was used to detect seedling emergence, to monitor leaf area growth, and to measure the effect of bare soil reflectance on scene (bare soil and seedlings) reflectance. Cotton and corn seedlings were detected 1 day after initial emergence (1 DAE) in 2000 by the red band. The red band detected seedlings in 2001 at 9 and 8 DAE in early and late planted corn, respectively, and on 0 DAE for cotton. The normalized difference vegetative index (NDVI) detected seedlings at 1 DAE or 2 DAE in both years. Seedling ground cover in 2000 on the initial detection date in the target areas averaged 1.3% and 0.9%, respectively, for cotton and corn; comparable values in 2001 for cotton, early planted corn, and late planted corn, were 1.4%, 0.4%, and 0.8%, respectively. The red wave band was the most sensitive single band for detecting the presence of seedlings, but NDVI was the most sensitive spectral indicator, which was apparently due to the red band since the NIR band did not always detect seedlings. Seedling leaf area was linearly correlated with NDVI values beginning at 1 or 2 DAE. Bare soil was the major component of the scene during stand establishment and dominated single band reflectance and NDVI values. A dry soil surface that was smoothed and sealed by rain usually caused single band reflectance to increase. The high variability in spectral characteristics of bare soil restricted the interpretation of the spectral data to concluding whether or not seedlings were emerging, but without estimating numbers and seedling size.

Effect of Planting Date, Residual Herbicide, and Postemergence Application Timing on Weed Control and Grain Yield in Glyphosate-Tolerant Corn (Zea mays)1

Studies were conducted in 1998 and 1999 in Ohio to determine the effect of postemergence (POST) application timing of glyphosate on weed control and grain yield in glyphosate-tolerant corn, and how this was influenced by corn planting date and the use of soil-applied herbicides. Glyphosate was applied based on giant foxtail height. Two applications of glyphosate provided better weed control than a single application, especially when applied to weeds 10 cm or less in early-planted corn. Yield was reduced occasionally with a single application on 5- or 10-cm weeds, because of weed re-infestation. Failure to control weeds before they reached a height of 15 to 30 cm also resulted in occasional yield loss. Application of atrazine or acetochlor plus atrazine prior to glyphosate did not consistently increase weed control or yield. Results suggested that glyphosate should be applied before weeds reach 15 cm in height to avoid corn grain yield loss.Nomenclature: Glyphosate; giant foxtail, Setaria faberi Herrm. #3 SETFA; corn, Zea mays L.Additional index words: Herbicide-resistant crops, weed interference.Abbreviations: CEC, cation exchange capacity; POST, postemergence; PRE, preemergence; RS, respray; WAP, week after planting.

In-row Spacing and Cultivar Affects Ear Yield and Quality of Early-planted Sweet Corn

Early-planted fresh market sweet corn (Zea mays) is prone to nonuniform ear length and quality due to uneven germination in cool soils. Growers compensate by reducing in-row spacing at seeding, to increase final plant stand. This risk management strategy was suspected to be reducing quality of early-planted sweet corn, based upon buyer feedback. Four experiments were conducted in upstate New York, to examine the effects of in-row spacing and cultivar on early-planted sweet corn ear yield, length and uniformity. Cultivars examined included `Temptation' (4 years), `Sweet Symphony' (3 years) and `Seneca Spring' (2 years). In-row spacings tested ranged from 6 to 9 inches (15.2 to 22.9 cm), using a 30-inch (76.2-cm) between-row spacing. In-row spacing and cultivar influenced marketable yield, husked ear weight and length of early-planted corn, but the extent varied by year. Despite improvements in individual ear weight and length at wider in-row spacing, marketable yield was usually higher at more narrow spacings. Increases in ear weight at wider spacings were usually associated with increases in weight of the outer, green husk. Average ear length of a cultivar varied between 0.2 and 0.6 inches (0.5 to 1.5 cm) in response to spacing. If ears longer than 7 inches (17.8 cm) were desired, 40% to 60% of ears satisfied this criteria if harvested from plants grown at 8-inch (20.3-cm) in-row spacing or a plant population of 26,000 plants/acre (64,200 plants/ha). Ear weight and length of `Seneca Spring' was not as affected by the in-row spacing treatments compared to the other two cultivars, perhaps due to the small size of this cultivar. Selection of smaller sized sweet corn cultivars for planting at high plant populations (6-inch in-row spacing) may reduce the variation in ear weight under challenging early season conditions. For cultivars with similar growth characteristics and maturities of `Temptation' and `Sweet Symphony,' a minimum in-row spacing of 8 to 9 inches or a plant population of 23,200 to 26,000 plants/acre (57,300 to 64,200 plants/ha) was recommended to minimize variation in ear yield and quality from first bareground plantings in the northeastern United States.

Reduced Input Corn Weed Control: The Effects of Planting Date, Early Season Weed Control, and Row-Crop Cultivar Selection

Concerns of pesticide detection in ground and surface water and the desire to lower external or off-farm inputs have renewed interest in mechanical weeding to reduce herbicide use and weed control costs. Field research was conducted to evaluate weed control using S-tine, minimum-till, rolling, and C-shank rowcrop cultivators in corn (Zea mays L.) planted 25 April, 5 May, and 15 May. Rotary hoeings or a 10-in. band of atrazine plus metolachlor PRE herbicide were used for early season in-row weed control. The field had a silt loam soil and high annual weed pressure and the previous crop was corn. Weed control was excellent with banded herbicide at all planting dates. Weed control with the rotary hoe was less than that of the banded herbicide but improved as planting was delayed. Banded herbicide resulted in better weed control, higher corn yield, and less corn population reduction than rotary hoeing. Weed control, corn population reduction, and corn yield were similar for all row-crop cultivators. Early planted corn treated with banded herbicide and cultivated twice gave the highest economic return. Research Question Corn producers seek weed control methods that reduce herbicide use to minimize potential surface and groundwater contamination. Mechanical weed control is not new, but has received little attention following the advent of highly selective and effective herbicides. The objective of this study was to compare two early season weed control strategies (banded herbicide and rotary hoeing), followed by two cultivations with four row-crop cultivator models, over a range of corn planting dates in a reduced tillage system. Literature Summary Mechanical weeding was a standard practice in corn production until recently. Even when weeds are controlled with herbicides, cultivation often improves corn yield. Planting date and soil tillage affect cropweed interactions. Delayed planting allows corn to germinate after the peak germination period of some weed species and also enhances corn's competitiveness because seeds are planted in a warmer soil. Rotary hoeing and band-applied herbicides try to control early emerging in-row weeds, which is the row-crop cultivator's main weakness. Iowa data show that banded herbicides, complemented with cultivation, reduce chemical inputs by two-thirds without decreasing corn yields. Relatively little research on row-crop cultivation has been done in recent years. Study Description The study was conducted in 1990 and 1991 at the University of Wisconsin Arlington Research Station on a Plano silt loam soil. Corn was planted in 30-in. rows and cultivated twice. The study was set up as a complete factorial with three factors. Factor 1. Early season in-row weed control Banded herbicide (applied preemerge in 10-in. bands) Rotary hoeing (twice) Factor 2. Planting date 25 April 5 May 15 May Factor 3. Row-crop cultivator design S-tine Minimum-till Rolling C-shank Applied Questions How do banded herbicide and rotary hoeing compare as methods to lower corn weed control inputs and does date of planting affect these strategies? Two years of field research show that preemergence herbicide applied in a 10-in. band and complemented with two timely cultivations controls more than 90% of the in-row weeds in corn planted from late April to mid May (Table 1). If rotary hoeing without herbicides is the only early season weed control method, corn planting should be delayed until at least late April to avoid earlier emerging weeds. Rotary hoe weed control may be improved by delaying planting from early to mid May, however, maximum yields are attained if corn is planted before 15 May in Wisconsin. Are row-crop cultivators equal in effectiveness or is one design better suited than another to a particular weed control system? When properly adjusted, all row-crop cultivators tested controlled weeds similarly in a chisel plowed silt loam soil when corn was cultivated at 5- and 20-in. heights. What are important considerations if shifting to a lower input weed control system? Corn population may be reduced 2 to 3% for each mechanical weeding operation. Producers using systems based on two rotary hoeings and two cultivations should increase corn seeding rates 8 to 10% above those based on a single cultivation. A 10-in. herbicide band is adequate to achieve efficient weed control with cultivation. Costs of rotary hoeing plus two cultivations are comparable with those of a banded herbicide and two cultivations. Both reduced input systems have lower costs than a broadcast application of the recommended rates of most corn herbicides. Table 1. Average visual weed control and corn yield for two methods of early weed control and three planting dates.† In-row weed control‡ Corn yield Early weed control Bandedherbicide Rotaryhoeing Bandedherbicide Rotaryhoeing ------- % -------- ------ bu/acre ------ Planting date 25 April 95 69 189 176 5 May 98 87 186 177 15 May 98 89 162 157 † Data averaged over 2 yr and four between-row cultivators. ‡ Visual evaluation taken 90 d after planting.

Whole-plant corn, forage sorghum, and grain sorghum silages for growing cattle (1993)

Agronomic and cattle performance traits were measured for eight silages produced in 1991. The silages were: irrigated Pioneer 3377 corn; dryland (early-planted) DeKalb 535 corn; irrigated and dryland DeKalb DK 42Y grain sorghum; and dryland forage sorghums Cargill 200F, Pioneer 947, Northrup King (NK) 300, and Funk's 102F. The irrigated corn and NK 300 and Funk's 102F forage sorghums had the highest whole-plant dry matter (DM) yields per acre; early-planted corn had the lowest yield. The dryland grain sorghum had the highest grain yield and the early-planted corn, the lowest. Average daily gains (ADG) were excellent for steers fed each of the eight silage rations and reflected the relatively high grain contents of the silages and the high DM intakes (2.37 to 2.81% of body wt). As expected, the irrigated corn silage produced the fastest and most efficient gain; the late-maturing, Funk's 102F forage sorghum produced the slowest and least efficient gain.

Annual Phytomass Production of a Rye‐Corn Double‐Cropping System in Ontario

AbstractA rye (Secale cereale L.)‐corn (Zea mays L.) double‐cropping system has the potential to maximize annual phytomass production in Ontario. Field experiments were conducted at Elora and Woodstock, ON, from 1981 to 1984 to evaluate the impact of rye harvest and corn planting date combinations during the spring as well as tillage methods on annual above‐ground phytomass production. Winter rye was planted in late September or early October after corn harvest and either chemically killed in early May or harvested as silage before corn planting. The rye/tillage treatments consisted of no‐rye/rototill, rye/rototill, and rye/no‐till. Corn phenology was monitored during the growing season and corn above‐ground dry matter was harvested in late September. Rye phytomass was 2.7 and 4.5 Mg ha−1 at the middle of May in Elora and Woodstock, respectively, and 5.4 Mg ha−1 at the end of May in Elora. Rate of leaf appearance and plant height during early development was reduced, silking date was delayed, and plant moisture at corn harvest was higher for corn following rye in comparison to single‐crop corn. The impact was largest in the no‐till treatments. The combination of rye harvest date/corn planting date and tillage treatment that resulted in the highest phytomass production in the rye‐corn double‐cropping sequence was 6 to 10% higher than that of early planted corn. The reduction in corn dry matter accumulation due to the preceding rye crop and the delay in date of corn planting negated to a large extent the contribution of rye phytomass to the total phytomass production of the rye‐corn double‐cropping sequence.

Generalization and Testing of a Soil Moisture Budget for Different Drainage Conditions

Abstract An empirical site-specific water balance model was generalized to account for cropland drainage effects on soil moisture and evapotranspiration (ET). In predicting soil moisture for well-drained (WD) soils, usually total water use is equated to infiltrated precipitation, stored soil moisture, and ET. In much of the eastern U.S. Corn Belt, however, row crop production is on soils which are poorly drained (PD) and underlain with perched water tables. These provide an additional source of soil water, capillary flow (C) into the crop root zone. Consequently, ET from PD soils is usually greater than that from WD soils. At West Lafayette, Indiana, from 1970 through 1974, for a PD soil the shallow water table furnished about a fourth of the total water used by late-planted corn (Zea mays L.) and a fifth of the water used by early-planted corn. A soil moisture budget model accounting for shallow water table influences, developed experimentally for a tile-drained Typic Argiaquoll soil, was generalized for...

EFFECTS OF A NATURAL BIVOLTINE STRAIN OF THE EUROPEAN CORN BORER, OSTRINIA NUBILALIS (LEPIDOPTERA: PYRALIDAE), ON GRAIN CORN YIELDS IN SOUTHWESTERN ONTARIO, 1973–77

AbstractA 5-year study of a bivoltine strain of the European corn borer, Ostrinia nubilalis (Hübner), showed that first-generation moths deposited more eggs on early-planted corn, whereas second-generation moths oviposited more frequently on late-planted corn. The second generation was much larger than the first generation and caused the greater reduction in yield, regardless of whether the yields were based on physiological losses or a combination of physiological losses and dropped ears. It was shown that delay of harvest beyond the time that moisture content of the corn was sufficiently low for machine harvesting could result in severe yield losses from broken stalks and dropped ears during autumn storms.

Lower Stalk Development and Staging of Corn1

AbstractHail insurance adjustors determine corn (Zea mays L.) leaf stages after leaf number one has deteriorated and prior to tassel emergence by examining the longitudinal section of the lower stalk. They assume the sheath of leaf five is attached to the node immediately above the first elongated internode and determine leaf stage by” counting the leaves above leaf five. Since the leaf area destroyed vs. grain yield loss chart is based on plants with 18 leaves, adjustors modify the leaf stage on earlymaturing hybrids which develop fewer than 18 leaves.To test these techniques of plant staging, we conducted field experiments during 1973–75 to determine the effect of hybrid maturity, planting date, plant density, and geographical location on lower stalk morphology and leaf development of hybrids adapted to the northern corn belt. Experiments were conducted at Lamberton, Minn. on a Webster clay loam (Typic Haplaquoll), St. Paul, Minn. on a Waukegan silt loam (Typic Hapludoll), and Staples, Minn. on a Sverdrup sandy loam (Udic Haplaboroll). Leaf number five (counting the leaf with the rounded tip as number one) was spot sprayed with red paint. Subsequently the 10th leaf was similarly identified before leaf number five sloughed from the plant. At tasseling, plants were dug and stalks split to identify and record the leaf number attached to the node immediately above the first elongated internode. The number of leaves developed, number of leaves on the plant at tasseling, and length of the first four elongated internodes were recorded.In 2 of the 3 years, early planted corn had 0.5 to 0.8 more unelongated internodes compared with late planted corn. The number of unelongated internodes was negatively correlated (r = −0.99) with both heat units (base 10 C) and summation of maximum soil temperature (5 cm depth) for the 2nd week after planting. Hybrid maturity, density, and geographical location had no effect on the number of unelongated internodes.Number of developed leaves and number of leaves at tasseling increased as relative maturity increased in 2 of the 3 years. Averaged over entries, the lower 6.4 leaves sloughed as the stem enlarged and aerial adventitious roots developed. Number of developed leaves was greater for early planted compared with late planted corn but was not affected by test location or plant density.Lengths of the four lowest elongated internodes were greatest for early hybrids and decreased as maturity approached full season. The first elongated internode was longer on early planted than on late planted corn in 1974.Our data indicate early planted corn could be “understaged” by approximately one leaf by using the current procedure of splitting the lower stalk and assuming leaf five is attached to the node immediately above the first elongated internode. Understaging would result in underpayment of a hail loss claim. The early maturing hybrids develop fewer than 18 leaves. Therefore, the leaf stage should be modified (as is currently done) when adjusting loss claims on hybrids which develop fewer than 18 leaves. Without stage modification, loss claims would be underpaid.

Corn Forage Production in No‐Till and Conventional Tillage Double‐Cropping Systems1

AbstractDouble‐cropping systems involving feed grains are becoming increasingly important for the long growing season in the Southeast and to meet consumer demands for food. Therefore, corn (Zea mays L.) forage production and quality were evaluated in double‐cropping systems following wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). These systems were evaluated at two locations in Georgia Upper Coastal Plain (soil is member of the clayey, kaolinitic, thermic family of Typic Hapludults) regions. Variables in this study were no‐till (NT) vs. conventional tillage (CT), irrigated vs. non‐irrigated, and early vs. late planting date. Forage yields from corn NT planted in small grain stubble (harvested for silage) in April were about equal to those from CT‐planted corn. Corn forage yields when NT was planted in small grain stubble in mid‐June were reduced compared with that planted in April in the Coastal Plain Region of Georgia, while forage yields in the Piedmont Region were nearly equal for corn planted early and late. The lower yields of late planted corn were related to a lower percentage of ears in the forage than early planted corn. Forage yield increases due to irrigation varied from zero to over 100%, depending on season and location. A high forage yield potential for double cropped NT corn planted early (mid‐April) throughout the Southeastern USA is evidenced. With present varieties and known management, forage yields of late planted (June corn) will usually be lower than those for early corn in the Coastal Plain region.

Population Fluctuations of the European Corn Borer, Ostrinia nubilalis , 1 at Waseca, Minnesota, 1948–70 2

Seasonal changes of populations of the European corn borer, Ostrinia nubilalis (Hubner) were observed in one early-planted corn field in Waseca, Minnesota, from 1948 to 1970. The results of the 1st 10 years, 1948 to 1957, were published in 1959. This paper presents the results from 1958 to 1970, and discusses the population changes for the entire 23-year period. During this period some agricultural practices, natural enemies, and the varied climatic factors have been responsible for the haphazard variations of corn borer populations from year to year. Superimposed on these changes, there was a long term cooling trend from 1960 to 1969. The temperature in 1970 showed an upturn that was responsible for the highest corn borer population since 1949–52 peaks. It is concluded that corn borer populations in the area were kept at relatively low levels by environmental factors, but can return to an economically significant level when temperature becomes favorable.

Forage Soybeans for Grazing, Hay and Silage

Livestock producers need a high-protein summer forage. Forage soybeans fit well in a production system following small grains or early planted corn. This document is SS-AGR-180, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised January 2003.
 SS-AGR-180/AG184: Forage Soybeans for Grazing, Hay, and Silage (ufl.edu)

Influence of Height and Stage of Development of Dent Corn on Oviposition by European Corn Borer Moths

Studies conducted at Lafayette, Indiana, indicated that the relationships between these factors and the number of eggs laid are curvilinear and best expressed by a second-degree parabola where Yc = A+BX+CX2 . In the effect of stage of development the coefficients of the X and X2 terms were negative and positive, respectively, whereas in the effect of height the sign of the X2 term was negative. On early-planted corn 15 percent of the eggs deposited by second-generation moths were laid on the ears. In all, about three times as many eggs were deposited on late-planted corn, but only 1 percent of these were laid on the ears and the number laid on the leaves increased correspondingly. A theoretical curve of oviposition based on the data from these studies showed that for 10 days before and after midsilking, height at midoviposition and stage of development (as measured by the date of midsilking) both are effective and are highly correlated with each other.