Desmodium Tortuosum Research Articles

Effect of Bait on Capture of Heliothis virescens Males (Lepidoptera: Noctuidae) in Two Different Traps

Identification of pheromone components for the tobacco budworm, Heliothis virescens (F.), (Roelofs et al. 1974, Tumlinson et al. 1975, Klun et al. 1980) in conjunction with the development of the wire cone trap (Hartstack et al. 1979, 1980) have presented opportunities for the development of a pheromone-based trapping system. In insect pest management programs, a durable, inexpensive, easily serviced, and sensitive trap is desirable. The high cost and bulk of the wire cone trap essentially eliminates its use for all but experimental purposes. A commercial version of the wire cone trap, the Scentry Heliothis cone (Scentry, Inc., Buckeye, AZ), is available, but it also is unwieldy and expensive. The possibility of using a different trap, the inexpensive and easy to handle bucket trap, was investigated in this study. An important aspect of H. virescens trapping is the development of a suitable pheromone dispenser. For H. virescens, initial evaluations of a laminated plastic dispenser were made by Hendricks et al. (1977); later evaluations were reported by Hartstack et al. (1980) and Zvirgzdins & Henneberry (1983). Comparisons of laminated plastic and rubber septum dispensers under desert conditions were reported by Flint et al. (1979). They found that the rubber septa were very effective dispensers and lasted for a longer period of time than laminated plastic dispensers. Polyvinyl-chloride (PVC) substrates for dispensing the pheromone of H. virescens have been developed and evaluated by Hendricks (1982, 1983) and Hendricks et al. (1987) and were reported to be more effective than other dispensers tested. Further evaluations of the Ramaswamy, PVC and Flint dispensers were conducted by Lopez et al. (1987). The objective of the present study was to evaluate the effectiveness of cone and bucket traps for capturing H. virescens males when combined with different pheromone dispensing systems. Therefore, the commonly used bait dispensers for H. virescens-the laminated plastic Hercon dispensers (Hercon Laboratories, Inc., South Plainfield, NJ) and the Biolure membrane dispenser (Consep Membranes, Inc., Bend, OR)-were compared with other available dispensers in cone and bucket traps. Scentry cone traps (test 1) and International Pheromones bucket traps (test 2) (Great Lakes IPM, Vestaburg, MI) were positioned 100 m apart and 1 m above ground level in a N-S direction in fallowed fields near Gainesville, FL. The tests were conducted in late September-early October 1989 during a period of relatively low H. virescens moth population. The test area was heavily populated with Desmodium tortuosum (Swartz) de Candolle, an important weed host for H. virescens (Jackson & Mitchell 1984). The traps were baited with different commercial lures (BioLure and Hercon 2or 7-components) or septa (Israeli-Maavit, Tel Aviv, Israel; A. H. Thomas No. 1780J07, Swedesboro, NJ; Wheaton no. 224091, Millville, NJ) prepared locally by Laboratory personnel. Load ratios for the experimental lures (1 mg total/septum) were: tetradecenal, 3%; (Z)-9-tetradecenal, 5%; hexadecanal, 8%; (Z)-7-hexadecenal, 1%; (Z)-9-hexadecenal, 1%; and (Z)-11-hexadecenal, 82%. All synthetic compounds used on the septa formulations were obtained from commercial sources and were analyzed on both capillary and GC

Suitability of Selected Legumes and the Effect of Nymphal and Adult Nutrition in the Southern Green Stink Bug (Hemiptera: Heteroptera: Pentatomidae)

Performance of nymphs and adults of the southern green stink bug, Nezara Viridula (L.), depended on their legume diet and on whether the food of nymphs and adults was the same or different. No nymphs survived to adults on leaves or stems of Glycine max (L.) Merrill (cv. Bedford), or on green pods of Albizia julibrissin Durazzini, Chamaecrista fasciculata (Michaux) Greene, Indigofera hirsuta L., and Sesbania vesicaria (Jacquin) Elliott. When the pod wall of S. vesicaria (which is separated by a large airspace from the seeds) was removed, the immature seeds provided intermediate nymphal mortality, fast development, and high body weight of new adults. Green pods of Sesbania emerus (Aublet) Urban were a superior food, whereas intermediate nymphal performance occurred on green pods of Phaseolus vulgaris L., Desmodium tortuosum (Swartz) DeCandolle, and G. max , and immature seeds of the latter. Scraping the pubescence from G. max pods reduced nymphal mortality by about half. Green pods of Crotalaria lanceolata Meyer and mature seeds of G. max and Arachis hypogaea L. caused poor nymphal performance. Females and males had similar developmental times but 1-d-old females were significantly heavier, weighing 20-40% more depending on food. For each sex across all foods, fresh weight of new adults declined significantly as developmental time increased. Few females laid few eggs with low or 0% hatch when fed pods of C. lanceolata or S. vesicari a, or mature seeds of A. hypogaea or G. max . Egg production was also low on pods of G. max and D. tortuosum , and it was high on pods of S. emerus and P. vulgaris . On most foods, there were no significant differences in longevity between females and males. Adult fresh weight generally increased during the first 2 wk, with females tending to exhibit larger percentage increases than males, although weight loss occurred on pods of C. lanceolata and D. tortuosum and on mature seeds of G. max . Rearing nymphs on P. vulgaris pods and then switching the new adults to the various foods improved longevity and reproductive performance of adult females on those foods that resulted in generally poor performance when fed to nymphs and adults. Thus, foodswitching may be an important component of the nutritional ecology of N. viridula .

Flight activity ofHeliothis virescens (F.) females (Lepidoptera: Noctuidae) with reference to host-plant volatiles

Heliothis virescens (F.) females responded positively via upwind flight in laboratory assays to volatiles emitted from methylńe chloride washes of fresh whole leaves of host plants including cotton, tobacco, and a weed species,Desmodium tortuosum (Swartz) de Candolle. Except forD. tortuosum, the response increased positively with dose; the steepest slope occurred with an extract of cotton squares (flower buds). Almost all of the moths that landed on the extract dispenser also oviposited. Moths simulated by extracts from cotton squares exhibited a full array of behaviors (upwind flight, contact with the dispenser, examination of the cloth substrate with antennae, and oviposition) expected of gravid individuals seeking sites to propagate the species.

Nitrogen Economy, Seed Production Efficiency and Seed Vigour of Panicum maximum by Intercropping of Pasture Legumes

A field experiment was conducted to evaluate the performance of pasture legumes (Desmanthus virgatus, Sesbania aegyptica, Macroptelmm autropurpureum, Desmodium tortuosum, Stylosanthes hamata used as in intercropped element) in terms of nitrogen economy, seed production efficiency and seed vigour potential of Panicum maximum– a grass based management maintained for 1986–88 at Research Farm, Indian Grassland and Fodder Research Institute, Jhansi under rainfed condition. Nitrogen economy under these intercropped pasture legumes was estimated on equating its value against nitrogen treatment i.e. 0, 10, 20, 30 and 40 kg N/ha. Among five intercropped legumes, Stylosanthes hamata and Macroptelium autropurpureum intercropping doubled the seed yield; S. aegyptica and M. autropurpureum brought out 46–55 per cent increase in biomass production over control value of 41.7 kg seed and 223.4 q biomass/ha respectively. These treatment showed 20–40 kg N/ha nitrogen equivalent value. Further more increased seed yield of Panicum maximum under intercropping was attributed to its better ear production, spike length and potential sink strength. Germination potential of harvested Panicum seeds under different treatments did not show variation among themselves. Potential seed production performance of Panicum maximum in the first year as compared to subsequent years might be due to its general transcript of plants and have some interaction with rainfall.

Preferences of matedHeliothis virescens andH. subflexa females for host and nonhost volatiles in a flight tunnel

In flight-tunnel bioassays, mated femaleHeliothis subflexa (Gn.) moths demonstrated in dual-choice tests a significant preference for volatiles from an extract of their only known host,Physalis spp. (groundcherry). However,H. virescens (F.), a polyphagous species, responded positively by anemotaxis to extracts from susceptible tobacco, cotton,Desmodium tortuosum (host plants), and groundcherry, a nonhost.H. virescens females did not fly to volatiles emanating from an extract of a resistant tobacco cultivar.

Ovipositional response of threeHeliothis species (Lepidoptera: Noctuidae) to allelochemicals from cultivated and wild host plants

The role of plant allelochemicals on the oviposition behavior ofHeliothis virescens (F.),H. subflexa (Guenee), andH. zea (Boddie) was investigated in the laboratory using a "choice" bioassay system. Fresh young leaves of tobacco,Desmodium tortuosum (Swartz) de Candolle, groundcherry (Physalis angulata L.), and cotton (Gossypium hirsutum L.) squares (flower buds) were washed in methylene chloride or methanol, concentrated to 1 g equivalent of washed material, and applied to a cloth oviposition substrate. Each of the extracts-including groundcherry, a nonhost-stimulated oviposition byH. virescens. H. subflexa were stimulated to oviposit by groundcherry extract, its normal host, and extract from cotton squares, a nonhost. None of the extracts stimulated oviposition byH. zea, although all except groundcherry were from reported hosts. The sensitivity of the bioassay was confirmed by givingH. virescens andH. subflexa an opportunity to choose between extracts that showed stimulant qualities when tested independently versus only solvent-treated controls. In these tests, tobacco showed the highest level of stimulant activity forH. virescens; groundcherry exhibited the highest level of stimulation forH. subflexa.

Peanut Weed Control Systems Utilizing RE-408851

Abstract RE-40885 (5-(methylamino)-2-phenyl-4-3-(trifluoromethyl phenyl)-3(2H)-furanone), a newly developed herbicide with soil and foliar activity, was evaluated for weed control in peanuts (Arachis hypogea L.). RE-40885 applied to the soil or foliage provided excellent Florida beggarweed (Desmodium tortuosum (Sw.) DC.) and prickly sida (Sida spinosa L.) control at rates of 0.56 to 1.12 kg ai/ha. Sequential applications of RE-40885 were needed to achieve > 90% sicklepod (Cassia obtusifolia L.) control. Texas panicum (Panicum texanum Buckl.) was not adequately controlled by any of the RE-40885 treatments evaluated. Peanuts were not injured by RE-40885 at any of the evaluated rates or application times. The combination of RE-40885 and 2,4-DB applied early postemergence improved sicklepod control 8 weeks after planting when compared to either RE-40885 or 2,4-DB applied alone. The combination of R E-40885 and alachlor applied at peanut emergence improved morningglory (Ipomoea spp.) control 8 weeks after planting and increased peanut yield when compared to either applied alone. All treatments containing RE-40885 resulted in peanut yields that were significantly better than nontreated weedy control plots.

Anthracnose of Florida Beggarweed (Desmodium tortuosum) Caused byColletotrichum truncatum

Greenhouse and growth chamber studies were conducted to determine conditions for infection of the fungal pathogenColletotrichum truncatum(Schw.) Andrus and Moore on Florida beggarweed (Desmodium tortuosum(Sw.) DC. # DEDTO and to determine the host specificity of this fungus. Optimum conditions for disease development were 14 to 16 h incubation in 100% relative humidity (RH) at 24 to 29 C. Control of Florida beggarweed with 105to 107C. truncatumspores/ml was greatest in the cotyledon stage and decreased with plant age. Ten of 18Desmodiumspecies tested were susceptible to the Florida beggarweed isolate ofC. truncatumbut 13 other plant species and varieties were resistant and 61 were immune.

COMPARATIVE CONSUMPTION AND UTILIZATION OF FLORIDA BEGGARWEED AND TWO SOYBEAN GENOTYPES BY PSEUDOPLUSIA INCLUDENS LARVAE (LEPIDOPTERA: NOCTUIDAE)

Larvae of the soybean looper (SBL), Pseudoplusia includens (Walker), were reared on three food types: soybean, Glycine max (L.) Merrill, genotypes ‘Kirby’ (insect susceptible) and GatIR 81-296 (insect resistant), and Florida beggarweed, (Desmodium tortuosum (Swartz) de Candolle. Larval development was longest on GatIR 81-296 (16.7 days) followed by beggarweed (15.5 days) and Kirby (14.1 days). Total consumption and relative consumption rate by ultimate (6th) instar SBL were significantly greatest on Kirby with no difference noted in consumption between GatIR 81-296 and beggarweed. However, approximate digestibility and efficiency of conversion of ingested food by ultimate instars were significantly greatest on beggarweed compared with the two soybean genotypes. Ultimate instar weight gain and growth rate were similar for larvae restricted to Kirby and beggarweed, while larvae restricted to GatIR 81-296 had significantly reduced weight gain and growth rate. Pupal weights of individuals reared on GatIR 81-296 also were significantly reduced compared with those in the Kirby and beggarweed treatments. SBL larvae consumed less beggarweed foliage (mg dry weight) than Kirby soybean, yet compensated to some extent by utilizing beggarweed foliage more efficiently. Beggarweed proved to be a better source of larval nutrition for SBL than the insect-resistant soybean genotype GatIR 81-296.

Absorption, Translocation, and Metabolism of Foliar-Applied Imazaquin in Soybeans (Glycine max), Peanuts (Arachis hypogaea), and Associated Weeds

Absorption of foliar-applied14C-imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} 72 h after treatment was higher than 90% for soybean [Glycine max(L.) Merr. ‘Braxton’], peanut (Arachis hypogaeaL. ‘Florunner’), common cocklebur (Xanthium strumariumL. # XANST), sicklepod (Cassia obtusifoliaL. # CASOB), and Florida beggarweed [Desmodium tortuosum(SW.) # DEDTO]. Both symplasmic and apoplasmic translocation of the herbicide were evident. Imazaquin half-life was 4.4 days in soybean, 5.3 days in peanut, 9.6 days in Florida beggarweed, 12.7 days in sicklepod, and 39.8 days in cocklebur. Tolerance of these species to foliar-applied imazaquin as determined in greenhouse studies with 21-day-old seedlings was as follows: soybean = peanut > Florida beggarweed > sicklepod > cocklebur. Tolerance was directly correlated to imazaquin halflife within the tissue of the respective species.

Weed Control in Peanuts (Arachis hypogaea) with Imazaquin

Field evaluations were made on the effects of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} on Florida beggarweed [Desmodium tortuosum(SW) DC. # DEDTO] and sicklepod (Cassia obtusifoliaL. # CASOB) control in peanuts (Arachis hypogaeaL.). Crop yield was reduced at 392 and 504 g ae/ha and with preemergence applications. Florida beggarweed control was not achieved with this herbicide. Maximum sicklepod control (approximately 80%) was achieved with 392 and 504 g/ha applied postemergence. In a separate study, several herbicide systems utilizing imazaquin were compared to a standard weed control program. All these systems provided weed control and yields that were comparable to the standard weed control system; thus the inclusion of imazaquin offered no advantage over the standard system.

Economic Assessment of Herbicide Systems for Minimum-Tillage Peanuts1

Abstract Field experiments were conducted in 1983 and 1984 on a Dothan loamy sand at Headland, AL to evaluate herbicide systems for minimum tillage peanut (Arachia hypogaea L. Florunner) production. The influence of minimum tillage-herbicide systems on weed control, peanut yield, market grade, and net returns were examined. Two minimum tillage-herbicide systems provided greater yield and higher net returns with equivalent control of Texas panicum (Panicum texanum Buckle.) and Florida beggarweed [Desmodium tortuosum (SW.)DC] as compared to a conventional tillage-herbicide system. One of these systems included oryzalin [4-(dipropylamino)-3, 5-dinitrobenzenesulfonamide] and paraquat (1, 1′-dimethyl-4,4′bipyridinium ion) applied preemergence followed by an early postemergence application of acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide] and dinoseb [2-(1-methylpropyl)-4,6-dinitrophenol] and a postemergence-directed application of cyanazine (2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropanenitrile). The other system included benefin [N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine] and metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2)methoxy-1-methylethyl)acetamide) applied preplant-incorporated within-the-row followed by an early postemergence application of dinoseb and ethalfluralin [N-ethyl-N-)2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine] and a postemergence-directed application of paraquat. Herbicide inputs for these two minimum tillage-herbicide systems were greater than for the conventional tillage-herbicide system.

Observations on Geocoris punctipes (Hemiptera: Lygaeidae) Oviposition Site Preferences

Geocoris punctipes (Say) is a common insect predator in field crops throughout the southeastern United States and has been extensively studied as a potential biological control agent of a number of insect pests. The oviposition behavior of this predator and others of the genus Geocoris is not well known. McGregor and McDonough (1917) reported that G. punctipes eggs could be found deposited in mite colonies on the undersides of cotton leaves. Van den Bosch and Hagen (1966) observed this behavior for Geocoris spp. in California and added that eggs were also frequently found in the terminal growth of cotton plants. Tamaki and Weeks (1972) noted that eggs of G. bullatus (Say) and G. pallens StAl were often found in soil duff and the underside of sugarbeet leaves. They also observed that eggs were more abundant on potatoes and sugarbeets than on brocoli in interplant studies. Wilson and Gutierrez (1980) reported that G. punctipes and G. pallens deposited most of their eggs on the undersides of leaves in preference to other cotton plant parts. As part of a more comprehensive study to examine the influence of plants on the biology and ecology of G. punctipes in Florida soybean (Naranjo and Stimac 1985, 1987) observations were made on oviposition behavior in this predator. This note reports on oviposition site preferences demonstrated by G. punctipes females in laboratory experiments utilizing soybean, Glycine max (L.) Merr. (Bragg variety), and a complex of broadleaf weeds commonly associated with soybean in Florida. One laboratory colony female, 5-10 days of age, was confined in a circular cage containing either two plants of one species or a combination of one soybean and one of ten weed species for a 24 hour period at 27?C. The cage (30cm x 15cm dia.) was constructed of fine mesh (7 divisions/cm) fiberglass screening and two petri dishes. The weeds examined were Amaranthus hybridus L., Ambrosia artemisiifolia L., Bidens alba L., Cassia obtusifolia L., Chenopodium ambrosioides L., Crotalaria spectabilis Roth, Desmodium tortuosum (Sw.) Dc., Heterotheca subaxillaris (Lamb.), Richardia scabra L., and Solidagofistulosa Mill.. Prey (Spodopterafrugiperda (J. E. Smith) eggs) were individually attached to the underside of leaves in the cage. After the test period the predator was removed and the number and location of deposited eggs were recorded, including those on the cage itself. A total of 359 separate cages were examined. Pooling all plant species, females deposited ca. 77.5% of their eggs on cage surfaces in preference to plant surfaces (Table 1). Eggs laid on cage surfaces were found on the screen mesh and in the juncture between the horizontal and vertical surfaces of the cage lids. Eggs were most often found deposited through the screen mesh onto the lid where these two surfaces overlapped. G. punctipes demonstrated specific site preferences when laying eggs on plant surfaces (Table 1). Close to one-half of the eggs laid on plants were desposited on undersides of leaves and a large percentage were laid on main stems. Relatively few eggs were laid on upper leaf surfaces, leaf petioles, or apical growing points.

Weed Control and Response of Peanuts (Arachis Hypogaea) To Chlorimuron1

Abstract Experiments were conducted in 1984 and 1985 on a Dothan loamy sand (Plinthic Paleudults) at Headland, Alabama, to evaluate the effects of the ethyl ester formulation of chlorimuron [2-[[[[4-chloro-6-methoxy-2-pyrimidinyl]amino]carbonyl] amino]sulfonyl]benzoic acid] on Florida beggarweed (Desmodium tortuosum (SW) DC.) and sicklepod (Cassia obtusifolia L.) control, and yield and grade of peanuts (Arachis hypogaea L.) Treatments consisted of a factorial arrangement of five chlorimuron rates (17.5, 35.0, 52.5, 70.0 for 87.5 g ai/ha) and four application times, preplant incorporated (PPI), preemergence (PRE), ground cracking (EPOT) or post-emergence over the top (POT). Crop injury, as indicated by visual ratings at 8 weeks after planting (WAP) and yield, was excessive with 52.5 g/ha and higher applied PRE or EPOT and with 35.0 g/ha and higher applied POT. Florida beggarweed control at 8 WAP was good with all rates; however, full season control was unacceptable. Control of sicklepod remained good through the entire season. In a separate study, several herbicide systems utilizing chlorimuron in combination with other herbicides were compared to a standard weed control system. While most herbicide systems which included chlorimuron provided yields comparable to the untreated check, none offered any advantage in terms of weed control and yield over the standard.

Comparison and contrast of cotton and Desmodium tortuosum as hosts of Heliothis virescens

Desmodium tortuosum (Sw) DC (Papilionaceae) is a preferred wild host of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) which is an important pest of cotton in Tolima, Colombia. From November 1976 until March 1979, cotton and D. tortuosum were compared and contrasted in the field as hosts of the pest. A very high infestation level of H. virescens in cotton in 1977 was preceded by an extremely low infestation level of the insect in D. tortuosum previous to the cotton-growing season. In 1978 and 1979 moderate infestation levels in cotton were preceded by moderately low infestation levels of H. virescens in D. tortuosum previous to the cotton growing season in both years.

Control of Florida Beggarweed (Desmodium tortuosum) in Peanuts (Arachis hypogaea) with Chloramben1

Abstract Experiments were conducted in 1983 and 1984 to evaluate control of Florida beggarweed [Desmodium tortuosum (SW) DC.] in peanuts (Arachis hypogaea L.) with chloramben (3-amino-2,5-dichlorobenzoic acid) applied at 2.2 kg ai/ha at ground cracking; and chloramben (with crop oil concentrate included at 2 L/ha) applied at either 0.6, 1.1, 2.2, or 3.4 kg ai/ha, at either 30, 45, 60, 75, or 90 days after planting (DAP). Maximum control (as indicated by weed weight at harvest) was achieved with the ground-cracking treatment, and with postemergence applications of 2.2 kg/ha, or higher applied at 30 DAP. Later applications resulted in progressively less control. Peanuts were tolerant to all rates evaluated, as indicated by yield and grade, provided the application was either before or after the flowering and pegging period (45 to 60 DAP). Growth chamber studies indicated that a spreader-sticker type adjuvant (i.e. a petroleum or vegetable based oil-surfactant blends) was essential for acceptable postemergence activity. Comparisons of autoradiograms prepared from peanuts and Florida beggarweed plants where 14C-chloramben had been applied to the foliage and thin layer chromatographic analysis of foliar extracts indicated that the relative tolerance of peanuts could be attributed to the combined effects of limited absorption and translocation, as well as the enhanced ability of peanuts to convert the absorbed chloramben to a non phytotoxic N-glucosyl conjugate.

Weed Management in Minimum-Tillage Peanuts (Arachis hypogaea) as Influenced by Cultivar, Row Spacing, and Herbicides

Field experiments were conducted in 1982 and 1983 on a Dothan sandy loam (Plinthic Paleudult) at Headland, AL, to investigate minimum-tillage production of peanuts (Arachis hypogaeaL.). The experiments included two peanut varieties: a) ‘Pronto’ (an earlier maturing Spanish type), and b) ‘Florunner’ (a later maturing runner type). Two row-spacing patterns were used: a) conventional 91-cm rows, and b) a modified twin 18-cm row pattern. A constant seeding rate (140 kg/ha) was used regardless of row spacing. Six herbicide systems were evaluated within each combination of variety and row spacing. The Florunner variety outyielded the Pronto variety across both years and weed management systems. Modified twin 18-cm rows outyielded conventional 91-cm rows across years and peanut varieties. Two of the six weed management systems were successful: 1) paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) + oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) (preemergence), paraquat (ground cracking), naptalam (N-1-naphthylphthalamic acid) + dinoseb (2-sec-butyl-4,6-dinitrophenol) (postemergence); and 2) paraquat + pendimethalin [N-(1-ethylpropyl-3,4-dimethyl-2,6-dinitrobenzenamine] (preemergence), acetochlor [2-chloro-N(ethoxymethyl)-6’-ethyl-o-acetotoluidide] + dinoseb (ground cracking), and cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazine-2-yl]amino]-2-methylpropionitrile} (early postdirected spray). Both systems provided the best overall control of Texas panicum (Panicum texanumBuckl. ♯ PANTE), Florida beggarweed [Desmodium tortuosum(Sw.) DC. ♯ DEDTO], and sicklepod (Cassia obtusifoliaL. ♯ CASOB) and were acceptable for use in minimum-tillage peanut production.

Row Pattern and Weed Management Effects on Peanut Production1

Abstract Field experiments were conducted from 1981 through 1983 on a Dothan sandy loam (Plinthic Paleudults) at Headland, Alabama, to investigate the effects of row patterns and weed management systems on weed control, peanut yield, and net returns to land and management. Treatments consisted of three row patterns, a) conventional 91-cm rows, b) dual twin 18-cm rows, and c) triple twin 18-cm rows, and six weed management systems ranging from none to various combinations of herbicide and mechanical inputs. The experimental area was naturally infested with bristly starbur (Acanthospermum hispidum DC), sicklepod (Cassia obtusifolia L.), Florida beggarweed [Desmodium tortuosum (Sw.) DC.], large crabgrass [Digitaria sanguinalis (L.) Scop.], and Texas panicum (Panicum texanum Buckl.). Results showed that weed control was affected somewhat by row patterns with broadleaf weeds being more responsive to row pattern manipulation than grass weeds. Weed fresh weights were generally lower as row patterns narrowed from conventional 91-cm spacing, however exceptions did occur. Highest yields and net returns were obtained when peanuts were planted in the dual twin 18-cm rows and weed management included benefin applied preplant incorporated, plus alachlor applied preemergence, and two timely cultivations.

Growth and Survival of Tobacco Budworm (Lepidoptera: Noctuidae) Larvae Fed Florida Beggarweed (Fabaceae) and Tobacco (Solanaceae)1

Four age groups (newly hatched, 3-, 5-, and 7-day-old) of tobacco budworm larvae, Heliothis virescens (F.), were each fed three phenological stages of Florida beggarweed, Desmodium tortuosum (Swartz) de Candolle, two stages of tobacco, Nicotiana tabacum L., and pinto bean artificial diet. Larvae were placed onto intact plants inside screen cages or onto artificial diet in cups for both laboratory and field experiments. After 7 days, larvae were either counted and measured (1978) or counted and weighed (1979). Newly hatched larvae grew equally well on all stages of beggarweed and nonflowering tobacco. Older larvae (3-, 5-, or 7-day-old) generally survived better and gained more weight on tobacco than on beggarweed. Larvae fed tobacco only or beggarweed only produced pupae nearly the same size as diet-reared pupae (280 mg). Newly hatched larvae fed artificial diet survived between 1.9 and 7.2-fold better and gained 1.7 to 6.7-fold more weight in 7 days than did those fed tobacco or beggarweed. Older larvae also generally survived better and gained more weight on artificial diet than on the intact plants.

Survey of Heliothis spp. Larvae Found on Florida Beggarweed and Postharvest Tobacco in Florida

Heliothis spp. larvae were collected from pre- and postharvest tobacco and Florida Beggarweed, Desmodium tortuosum. Five distinct adult H. virescens peaks were determined from pheromone-baited cone traps, but only 4 larval Heliothis spp. peaks followed them. The late July larval population was much lower than expected on tobacco and beggarweed, suggesting the existence of another alternate host. Maximum densities on beggarweed were 37 and 18 larvae/sweep sample (10 sweeps) in 1978 and 1979, respectively. The ratio of H. virescens: H. zea increased from 0.2:1.0 in July to over 20.0:1.0 by season's end. Cardiochiles nigriceps parasitized 44.5% of H. virescens larvae from postharvest tobacco, and 9.2% from beggarweed. Archytas marmoratus parasitized 2.9% of the Heliothis larvae collected from postharvest tobacco, but 20.0% of those from beggarweed.