Seedcorn maggot (Diptera: Anthomyiidae) populations on Ohio soybean.
1991; Kansas (Central States) Entomological Society; Volume: 64; Issue: 2 Linguagem: Inglês
ISSN
1937-2353
Autores Tópico(s)Insect behavior and control techniques
ResumoSeedcorn maggot, Delia platura (Meigen) (Diptera: Anthomyiidae) popula tions were sampled from soybean fields located in northwestern, western and southern Ohio during 1987 and 1988. Treatments consisted of two factors, cover crop (the presence or lack of a wheat/rye winter cover) and planting date (two plantings ca. 1 week apart). Cover crops were incorporated into the soil by disking twice, followed by soybean planting immediately or 1-1.5 weeks later. Adult seedcorn maggots were sampled with metal traps placed over the row which collected the positively phototactic flies. All three locations were sampled in 1987; during 1988, only two locations were used because of severe spring drought at the third. Significantly more adult seedcorn maggots were collected in the plots where a cover crop was spring plowed. Numbers of adults collected from soybeans planted on the two dates were significantly different only at one location in 1987. Fly emergence was completed within a short time span at all locations, indicating that eggs were laid during a short period. Results indicate that seedcorn maggot oviposition in soybeans was more influenced by the incorporation of a cover crop than by soybean planting date. Seedcorn maggots, Delia platura (Meigen), are an occasional pest of soybean, often causing severe plant stand reductions resulting in lower yields. Adult flies are attracted to volatiles (albeit unknown) released when organic amendments of living cover crops (e.g., wheat, rye, alfalfa) are incorporated into the soil in the spring and begin to decompose (Hammond, 1984; Hammond, 1990); crop seeds play no apparent role other than providing incidental feeding sites (Funderburk et al., 1983; Hammond, 1990). Observations indicate that the potential for seed corn maggot infestations is low when these cover crops (Hammond, 1990) or the previous crop's residue (e.g., corn or soybean residue) (Hammond and Stinner, 1987) remain on the soil surface. Consequently precautionary measures such as insecticide seed treatments or applications of a granular insecticide need only be taken when a live cover crop is incorporated into the soil, whether intentionally (by the use of a cover crop such as rye, wheat or alfalfa) or unintentionally (from a heavy weed growth in spring). Potential seedcorn maggot infestations also are influenced by planting date. Further, the relative importance of incorporating a cover crop and planting date may vary across a region. Therefore, this study was conducted to examine the influence of incorporated cover crops and planting date on seedcorn maggot oc currence and injury at northern, central, and southern locations across Ohio. Materials and Methods Plots were located at three research branches of the Ohio Agricultural Research and Development Center, The Ohio State University: the Northwestern Branch, Custar, Wood County, located in northwest Ohio; the Western Branch, South Accepted for publication 1 November 1990. This content downloaded from 207.46.13.57 on Sat, 10 Sep 2016 05:00:02 UTC All use subject to http://about.jstor.org/terms VOLUME 64, NUMBER 2 217 Charleston, Clark County, located in west central Ohio; and the Southern Branch, Ripley, Brown County, located in southern Ohio. Similar procedures were used at all three locations except for differences in plot size and local grower practices. Plots were established in October of the year preceding the experiment. Cover crops of either rye (Northwestern Branch) or wheat (Western and Southern Branch) were planted to provide for a winter cover and a green, living crop the following spring. Plot descriptions were: Northwestern Branch?total area was 51 x 51m, divided into a 4 x 4 layout of 16 individual plots each 12.8 x 12.8 m, with 4 replications; Western Branch?total area was 30 x 61 m, divided into a 2 x 6 layout of 12 individual plots each 15.4 x 10.2 m, with 3 replications; Southern Branch?total area was 73 x 73 m, divided into a 4 x 4 layout of 16 individual plots each 18.3 x 18.3 m, with 4 replications. Experimental design was a randomized complete block, four treatments arranged in a two-way factorial. The two factors were cover crop (soil-incorporated cover crop vs. no cover crop) and planting date (two dates ca. one week apart). The design established was as a variant of the strip-block design, with each factor randomly split perpendicular to the other within a block (see Cochran and Cox, 1957). This approach was necessitated by the plot size and nature of the treatments which precluded a conventional randomized complete block design. Cover crops were disked twice and soybean planted on the following dates: Northwestern Branch?1987 diskings on 30 April and plantings on 1 and 7 May (a severe spring drought prevented the experiment from being conducted at this location in 1988); Western Branch?1987 diskings on 6 May and plantings on 7 and 14 May, and 1988 diskings on 3 May and plantings on 4 and 11 May; Southern Branch?1987 diskings on 28 April and plantings on 29 April and 8 May, and 1988 diskings on 29 April and plantings on 29 April and 10 May. Soybean varieties, based on the maturity group and common cultivars grown at each location, were: Northwestern Branch?'Asgrow 3127'; Western Branch?'Beeson'; Southern Branch?'Winchester.' Following soybean planting, plots were sprayed within 24 hr with herbicides at suggested label rates: Northwestern Branch? glyphosate (1.12 kg [AI]/ha), chloramben (2.0 kg [AI]/ha), and metolachlor (2.24 kg [AI]/ha); Western Branch?paraquat (0.56 kg [AI]/ha), imazaquin (1.12 [Al]/ ha) and metolachlor (2.24 kg [AI]/ha); Southern Branch?paraquat (0.56 kg [Al]/ ha), metribuzin (0.43 kg [AI]/ha) and metolachlor (2.24 kg [AI]/ha). Adult seedcorn maggots were sampled with metal traps (1.0 by 0.3 m) placed randomly over the row in each plot (two traps per plot; see Funderburk and Pedigo, 1980 for trap description). Traps were placed in each field approximately 1 wk following the second planting date. These traps capture the emerging, pos itively phototactic adult flies in glass jars coated with Tangletrap? (Tanglefoot Co., Grand Rapids, MI). Traps were sampled weekly until adult flies were no longer captured. Flies were returned to the laboratory and counted. Seedcorn maggots often damage soybean by causing complete seed or plumule destruction. The former injury results in plant stand loss, while the latter results in a plant characteristically known as Y-plants. Although neither injury is a de finitive indication of seedcorn maggot feeding (Higley and Hammond, 1988), both serve as indicators of maggot infestations when combined with population data. Therefore, data on their various plant growth parameters were collected following soybean emergence. The number of plants per 1.8 m row were recorded (which This content downloaded from 207.46.13.57 on Sat, 10 Sep 2016 05:00:02 UTC All use subject to http://about.jstor.org/terms 218 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY Table 1. Mean number of adult seedcorn maggots per trap (X ? [SEM]), percent Y-plants (X ? [SEM]), mean number of total plants per 1.8 m row (X ? [SEM]), and mean yield (X ? [SEM]) per 1.8 m row for the main factors of cropping system and planting date in 1987. X adult seedcorn Treatment maggots/trap % Y-plants Total no. plants/1.8 m Yield per 1.8 m row Cropping system Northwestern branch Rye 5.8* [1.1] 2.3 [0.3] 43.3 [1.2] 341.9 [5.2] No rye 0.1 [0.1] 1.1 [0.2] 47.9 [1.1] 331.3 [6.5]
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