Sweet Corn Ears Research Articles

Prolific maize hybrids for baby corn

Prolific maize hybrids with small ears suitable for marketing as baby corn have been developed at the Newe Ya’ar Experiment Station. All female flowers on a single stalk reach the silking stage within 1-2 days after the silking of the first female flower. The new hybrids were tested in field trials with other sweet corn and field corn cultivars currently used for baby corn production. The prolific maize hybrids had more harvested baby corn eats per plant in a single non-selective picking. Several non-selective harvesting dates were tested between silking and four days later. Total net yield of dehusked baby corn ears (cobs) was greater in all hybrids tested when picked 3-4 days after silking. Total net yield of baby corn ears of the commercial sweet corn and field corn cultivars was higher than that of the prolific hybrids, but yield of marketable baby corn ears was significantly greater in the prolific maize hybrids. Several factors affecting harvest date were considered. The question of baby corn yield, quality, and marketable baby corn ears recovered from gross yield is discussed.

Evaluation of Food Baits for Pre-Plant Sampling of Wireworms (Coleoptera: Elateridae) in Potato Fields in Southern Florida

Experiments were conducted during two consecutive growing seasons to evaluate food baits for pre-plant sampling of wireworms that attack potato in southern Florida. Wireworm species studied were: Melanotus communis (Gyllenhal), southern potato wireworm, Conoderus falli Lane, C. amplicollis (Gyllenhal), and C. rudis (Brown). Baits evaluated were hybrid sweet corn seed, hybrid sorghum-sudangrass seed, a 1:1 mixture of corn and sorghum-sudangrass seed, a whole sweet corn ear, potato seed pieces, a 1:1 mixture of oatmeal and corn flake, rolled oats, and carrots. In the first year, numbers of wireworm larvae did not differ between food bait and soil samples for most food baits tested. Melanotus communis larvae were most numerous in the oatmeal-corn flake and sorghum-sudangrass seed baits. Conoderus spp. larvae were most numerous in the sorghum-sudangrass seed and corn ear baits. In the second year, M. communis larvae were more numerous in food baits than in soil samples, and more numerous in the oatmeal-corn flake and rolled oat baits than in other food baits. Numbers of Conoderus spp. larvae did not differ between food bait and soil samples nor among food baits. In addition to attracting more wireworms, oatmeal-corn flake and rolled oat baits had some of the shorter processing times. The use of one of these two baits is currently recommended for pre-plant sampling of wireworms in potato fields in southern Florida.

Seasonal Flight Activity of Several Lepidopterous Pests of Vegetables in Southern Florida

Several species of lepidopterous pests attack vegetables grown from late August until early June in the Everglades Agricultural Area near Belle Glade, Fla. Cabbage loopers (CL) Trichoplusia ni (Hubner), and beet armyworms (BAW), Spodoptera exigua (Hubner), feed on a number of vegetables, including celery, various types of lettuce, and cole crops. Fall armyworms (FAW), S. frugiperda (J. E. Smith), attack a wide variety of vegetables, but are most serious on sweet corn. Corn earworms (CEW), Heliothis zea (Boddie), were previously reported to be the primary insect attacking ears of sweet corn in southern Florida (Janes 1973), but more recently FAW has been the more serious pest (Foster 1985). Seasonal flight of CL, BAW, and FAW adults was measured with pheromone traps from June 1985 until May 1988. Three trapping sites were established on the 325 ha Everglades Research and Education Center (EREC) farm and a fourth site was established on a local farm approximately 16 km away. There was one pheromone trap at each site for each of these three insect species. Plastic stored pest pheromone traps (I. P. Systems, Merseyside, U. K.) were baited with a 4-component FAW pheromone supplied by the Southern Grain Insects Laboratory in Tifton, Ga. or Cl or BAW pheromones produced by Zoecon Corp. A single Hartstack 75-50 cm cone trap (Hartstack et al. 1979) baited with Hercon CEW pheromone was established Jan. 1986 at EREC. The insects in each trap were identified and counted at least weekly. Pheromone sources were changed every two weeks during warm months (April-October) and every three weeks during cool months (November-March). CL adults were caught in the pheromone traps throughout the year and the catches reached a peak in May or June in each of the three years (Fig. 1). Chalfant et al. (1974) also found CL adults to be active throughout the year at several locations in southern Florida, including Belle Glade. However, their CL catches had two peaks, late winter through spring and late summer through early fall, with lower catches in the summer. BAW adult catches were also higher during the warm months of May and June, but were much lower in July and August when vegetables were not being grown. In 1985, BAW adult catches were very low during October, November, and December, averaging 6 moths per trap per week (Fig. 1). However, in 1986 and 1987, the adult catches were much higher during this period, averaging 133 and 114 moths per trap per week, respectively. The reasons for this difference are unknown but, BAW must be considered a threat to vegetables both in the fall and spring. Tingle & Mitchell (1977) reported reduced BAW catches in July and August and November-February in traps at Hastings, Fla. Adult FAW catches were fairly high throughout the year (Fig. 1). The highest FAW catches were observed from March through June and from October through December, which agrees with Waddill et al. (1982), who found peak FAW moth catches in spring and fall at Homestead, Fla. Substantial numbers of CEW moths were captured only from July through October (Fig. 2). No moths were caught from November through March. Interestingly, CEW adult catches coincide with the period during which sweet corn ears are not present. The asynchrony of CEW adults and the crop helps explain

Strategies for Protecting Sweet Corn Ears from Damage by Fall Armyworms (Lepidoptera: Noctuidae) in Southern Florida

A study was conducted near Belle Glade, Florida during 1986 and 1987 to evaluate strategies for protecting sweet corn ears from damage by fall armyworms (FAW), Spodoptera frugiperda (J. E. Smith). It was found that maintaining the crop relatively free of FAW before the plants began to silk reduced the number of insecticide sprays needed during the silking period to protect the ears. The grower practice of concentrating sprays toward the beginning of the silking period instead of spacing the sprays evenly throughout the silking period provided little if any benefit. There was great variation between seasons in the number of insecticide sprays necessary to achieve the desired level of 98% undamaged ears, ranging from no sprays in the spring of 1986 to more than 10 sprays during the 21 day silking period in the spring of 1987.

Resistance to Kernel Infection by Fusarium moniliforme in Inbred Lines of Sweet Corn and the Effect of Infection on Emergence

Kernels from silk-inoculated and noninoculated sweet corn ears were evaluated for incidence of symptomatic infection of kernels by Fusarium monoliforme (i.e., the percentage of kernels showing signs or symptoms of F. moniliforme), incidence of asymptomatic infection of kernels, and emergence. A total of 138 inbreds were evaluated in at least 1 yr, and 17 were evaluated in each of 3 yr (...)

Control of European Corn Borer on Early Sweet Corn, 1987

Abstract This study was performed on the University of New Hampshire Kingman Farm, Madbury, N.H., and used 'Honeymoon' sweet corn that was planted 7 May. Each plot consisted of a single 30-ft row of corn, and each treatment was replicated 4 times and arranged in a randomized block design. The spray treatments were applied using an R&D CO2-pressurized (40 psi) single-nozzle hand-held sprayer that delivered 14.4 gal/acre. The granular treatment was applied by hand. All applications were directed into the whorls when the corn plants were in the late whorl-pretassel stage and showed signs of European corn borer leaf feeding injury. Two spray spplications were made 5 days apart; the granular treatment received a single application. Evaluation for the percentage of injured tassels was made on 24 Jul. The percentage of injured stalks and ears was determined at harvest time (6 Aug) by examining all the plants in each treatment.

Control of European Corn Borer on Early Sweet Corn, 1986

Abstract This study was performed on the Hugh Tuttle Farm, Dover, NH and utilized ‘Senaca Star’ sweet corn that was planted 30 Apr. Each plot consisted of a single 30 ft row of corn and each treatment was replicated 4 times and arranged in a randomized complete block design. Treatments were applied using a B&G C02 pressurized (35 psi) single nozzle hand-held sprayer that delivered 14.4 gal/acre. The granular treatments were applied by hand. All applications were directed into the whorls when the corn plants showed signs of European corn borer leaf feeding injury and before tassels began to emerge from the whorls. Two spray applications were made 5-days apart while the granular treatments were applied once. Evaluations for % injured stalks and ears were made at harvest time (28 Jul) by examining all the plants in each treatment.

Insect Distribution and Insecticide-induced Mortality in Corn and Potatoes as Affected by Plot Size and Location

This study was designed to determine if results of insecticide tests were affected by size and location of field plots used. Population density of insects in plots treated with carbaryl varied with plot size. Feeding damage by the potato leafhopper, Empoasca fabae (Harris), to potato foliage dropped rapidly as the treated plot size increased from 4 to 99 m2 and then continued to decline gradually to 1,000-m2 plots. Thus, a plot of ca. 100 m2 may be the minimum size to accurately determine insecticidal effect on the potato leafhopper. Corn earworm, Heliothis zea (Boddie), egg numbers changed the most sharply as plot size increased from 3 to 31 m2. Larval numbers dropped most sharply when plot size was increased from 3 to 14 m2. A minimum plot size of ca. 30 m2 appears to be necessary for corn earworm infesting sweet corn for tests done under similar conditions. Taylor’s index of aggregation and Lloyd’s mean crowding index and patchiness index were calculated for potato leafhopper injury in potatoes, caterpillar feeding damage in sweet corn ears, and numbers in sweet corn plots of Orius insidiosus (Say), Coleomegilla maculata (De Geer), corn earworm eggs and larvae, and European cornborer larvae, Ostrinia nubilalis (Hubner), in treated and untreated areas of plots.

Control of European Corn Borer on Early Sweet Corn, 1985

Abstract This study was performed on the Hughe Tuttle Farm, Dover, NH and utilized ‘Seneca Star’ sweet corn that was planted on 11 Apr. Each plot consisted of a single 30-foot row of corn and each treatment was replicated 4 times and arranged in a randomized block design. The spray treatments were applied using a B&G CO2 pressurized (40 psi) single nozzle hand-held sprayer that delivered 14.4 gal/acre. The granular treatments were applied by hand. All applications were directed into th( whorls when the corn plants showed signs of ECB leaf feeding injury and before tassels began to emerge from the whorls. Two spray applications were made 5 days apart while the granular treatments were applied once. Evaluations for the percentage of injured tassels was made on 15 Jul and percentage of injured stalks and ears were made at harvest time by examining all the plants in each treatment.

Control of European Corn Borer on Early Sweet Corn, 1984

Abstract This study was performed on the Robert Wiggin Farm, Stratham N.H. and utilized sweet corn that was planted on 25 May ’84. Each plot consisted of a single 30-ft row of corn and each treatment was replicated 4 times and arranged in a randomized block design. The spray treatments were applied using a B & G CO2 pressurized (40psi) single nozzle hand-held sprayer that delivered 14.4 gal/acre. The granular treatments were applied by hand. All applications were directed into the whorls when 58.6% of the corn plants showed signs of European corn borer leaf feeding injury and before tassels began to emerge from the whorls. Two spray applications were made 5 days apart and the granular treatment was applied once. Evaluations for the % of injured stalks and ears were made at harvest time on 20 Jul ’84 by examining all plants in each treatment.

The Effects of Corn Leaf Rust on Maturity and Quality of Fresh Market Ears of Sweet Corn

Abstract The influence of common leaf rust (Puccinia sorghi Schw.) on 2 sweet corn (Zea mays L.) hybrids was compared in rusted and nonrusted plots for several maturity and ear quality characters. Differences were found for time of silking, ear length, ear diameter, and percentage of moisture between rusted and nonrusted plots. The percentage of Brix ranged from 4% to 25%, with the rusted plots always having reduced mean values. Correlations (P = 0.01) were found between ear diameter and percentage of moisture, percentage of Brix and percentage of moisture, and between ear length and ear diameter.

Sweet Corn Response to Application of Three Sewage Sludges

AbstractAnaerobically digested sewage sludges from Portland, Salem, and Rock Creek, Oreg., and (NH4)2SO4 were applied to Willamette silt loam soil for 3 consecutive years to determine their effects on yield and elemental composition of sweet corn (Zea mays L.) leaves and kernels. In the first and second year, sweet corn ear yields increased nearly proportionally to the sludge NH4‐N content at the low rate of sludge application, but were not further increased at the high rate of sludge application. In the first 2 years ear yields of plants grown on sludge‐amended soils were less than yields obtained with the optimal rate of (NH4)2SO4. However, in the third year yields on sludge‐amended soils equaled or exceeded those with optimal (NH4)2SO4. Banding concentrated superphosphate at planting tended to increase yields, particularly of fully mature ears. Response to banded P was more pronounced with (NH4)2SO4 than with sewage sludge as the N source.Leaf‐tissue Zn and Cd content increased with sludge or commerical N application, with the highest Zn and Cd content occurring in plants grown on soils amended with the sludge that contained the highest concentration of trace metals. Kernel metal content varied less with N rate or source than did leaf metal content. Liming had little effect on yield or the metal content of kernels. Metal content of kernels did not increase with second and third sludge applications.

European Corn Borer Control in Early Sweet Corn: Role of Pre-Silk Applications and Leaf Feeding Resistance1

A high proportion of 1st-generation larvae of Ostrinia nubilalis (Hubner) in the ears of an early planting of a sweet corn variety resulted from initial whorl infestation, with subsequent stalk boring and eventual migration into the shank portion of the ear. Hence, for the fresh market, insecticide applications to silks alone did not provide acceptable control. Multiple pre-silk applications were unnecessary if methomyl (0.5 kg/ha) or encapsulated methyl parathion (0.6 kg/ha) were used; a single late-whorl application of either followed by 3 silk sprays was sufficient. However, with carbaryl (1.7 kg/ha), even a full schedule of 2 whorl and 3 silk applications provided inadequate control. Addition of a carbofuran planting-time systemic treatment (2.2 kg/ha) to 3 silk spray schedules did not improve control. Use of B49×B68, a leaf feeding resistant dent genotype, coupled with 3 silk sprays of any tested material provided a degree of control comparable to a full schedule on susceptible sweet corn with the best insecticides.

Corn Earworm and Fall Armyworm: Comparative Larval Populations and Insecticidal Control on Sweet Corn in Florida12

Ten insecticides, singly or in combination, were evaluated on the ears of sweet corn during 1973–75 for effectiveness in controlling the corn earworm, Heliothis zea (Boddie), and the fall armyworm, Spodoptera frugiperda (J. E. Smith). The fall armyworm was the more abundant species. Compared to highly effective methomyl as a standard, the following compounds gave good worm control when used alone: chlorpyriphos, leptophos, tetrachlorvinphos, and Bay NTN 9306 (O-(4-(methylthio)-phenyl)S-propylphosphorodithioate). TH 6040 (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea) at 0.2 lb AI/acre, or FMC 33297 (3-phenoxybenzyl (±) cis-trans-3-(2, 2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate) at 0.15 lb were inadequate. Toxaphene was not very effective when used singly but gave good control when combined with methomyl or methyl parathion; chlordimedant form was of little value when used with toxaphene. A combination spray containing only 0.125 Ib AI/acre of each methomyl and chlordimeform appears very promising for controlling both insect species as it was highly effective in the spring and fall.

A Preliminary Evaluation of a Centrifuge Technique for Measuring Maturity in Sweet Corn1

Abstract Sample ears of sweet corn (Zea mays L.) were run through a modified hand cutter in such a way as to leave me pericarp on the cob and remove the endosperm and embryo. A 50g sample was combined with 50 ml of 80% ethanol and blended at ‘chop’ speed for 4 minutes with a blender. The blend was then centrifuged at 3000 rpm for 10 minutes. The centrifuged product was distinctly layered. The ratio of the volume of the 2 semisolid layers changed significantly with maturity and is suggested as a criterion of the same. The ratio appears to be less affected by moisture stress in plants at time of sampling than criteria used in other tests.

Corn Earworm and Fall Armyworm Occurrence and Control on Sweet Corn Ears in South Florida12

Studies of populations in field over five-year period, 1967–72, showed Heliothis zea (Boddie) to be the principal insect pest on the ears of sweet corn in south Florida. Spodoptera frugiperda (J. E. Smith) also was regularly present, and in certain seasons it was the dominant species. Evaluations of chemical and biological insecticides for control of these insects were made fall spring 1917-72 as a continuation of work previously reported. Among several insecticides tested, Dipel® (Bacillus thuringiensis Berliner) + corn oil, leptophos, methomyl, monocrotophos, and acephate gave 95 percent or higher injury-free sweet corn ears when applied at 2- to 3-day intervals against predominantly S. frugiperda. Malathion also was effective but at high application rate.

Corn Earworm Control on Sweet Corn Ears in Central and South Florida, 1969-7012

Chemical and biological insecticides were evaluated for control of Heliothis zea (Boddie) on sweet corn during 2 years in central and south Florida. CIBA C-9491 ( O -(2, 5-dichloro-4-iodophenyl) O,O -dimethyl phosphorothioate), diazinon, Dursban® ( O,O -diethyl O -(3,5,6-trichloro-2-pyridyl) phosphorothioate), Fundal® (N’-(4-chloro- o -tolyl)- N,N -dimethylformamidine hydrochloride, Gardona® (2-chloro-1-(2,4,5-trichlorophenyl)vinyl dimethyl phosphate), methomyl, Monitor® ( O,S -dimethyl phosphoroamidothioate), parathion + methyl parathion, parathion + toxaphene, Phosvel® ( O -(4-bromo-2,5-dichlorophenyl) O -methyl phenylphosphonothioate), and Union Carbide UC-34096 (4-[[(dimethylamino)methylene]amino]- m -tolyl methylcarbamate hydrochloride) gave 95% or higher control when applied approximately daily, whereas certain other chemicals and the HD-1 Brownsville strain of Bacillus thyuringiensis Berliner were inadequate. Insecticides applied at less frequent intervals did not give adequate control.

Timing of Insecticide Applications for European Corn Borer Control in Sweet Corn12

In 1964, observations of Ostrinia nubilalis (Hubner) egg laying on corn indicated that larvae from the eggs laid after 70% tassel-height ratio had been reached were those most responsible for infestation of the cars of sweet corn. It was postulated that chemical control to prevent ear infestation would have to be applied sometime after this stage of development. Plot experiments conducted in 1967, 1968, and 1970, in which chemical sprays were applied at various times, indicated this hypothesis to be true. Generally, those sprays applied during the silking period were as effective, or more effective, than any others in reducing injury to sweet corn ears.

Reduction in Insect Damage to Cucumbers, Tomatoes, and Sweet Corn Through Use of Electric Light Traps1

The degree to which insect damage to vegetables could be reduced through use of electric light traps was investigated in Central Indiana from 1958 through 1967 in both small-plot and large plantings. In small-plot studies, larval damage from the European corn borer, Ostrinia nubilalis (Hübner), to sweet corn ears and stalks was consistently reduced by use of blacklight (BL) traps. Corn earworm, Heliothis zea (Boddie), larval damage was reduced by light traps when populations were low, but with medium to heavy populations damage was not noticeably reduced. The use of light traps in both small and large plantings consistently reduced tobacco hornworm, Manduca sexta (Johnnson), and tomato hornworm, M. quinquemaculata (Haworth), larval infestation of tomato plants, while damage to tomato fruit was reduced to a much lesser degree. In small-plot trials with cucumbers including both BL traps and dieldrin insecticide applications, both treatments permitted significant increases in yields through reducing damage caused by striped cucumber beetles, Acalymma vittatum (F.), and spotted cucumber beetles, Diabrotica undecimpunctata howardi Barber. In commercial cucumber plantings, however, no significant differences in yields occurred between dieldrin-sprayed and unsprayed cucumber plants, nor were there significant yield differences attributable to light-trap treatments. This disparity is attributable to differences in varieties and husbandry practices.

An Unusual Occurrence of Loopers Feeding on Sweet Corn Ears in Florida12

An Unusual Occurrence of Loopers Feeding on Sweet Corn Ears in Florida12