Microtopography, Microenvironments, and Weed Populations in Ridge-Tilled Soybean

2006 ◽  
Vol 20 (3) ◽  
pp. 593-604
Author(s):  
Thomas W. Jurik
Keyword(s):  
Seedling Emergence ◽  
Growing Season ◽  
Growing Degree Days ◽  
Degree Days ◽  
Weed Species ◽  
Redroot Pigweed ◽  
Giant Foxtail ◽  
Green Foxtail ◽  
Weed Emergence

The effects of microtopographic position on soil microenvironment and weed populations in ridge-tilled soybean were evaluated on three farms in Iowa in 1989 and 1990. In both years, over all weed species (primarily giant foxtail, green foxtail, yellow foxtail, redroot pigweed, and Pennsylvania smartweed), seedling emergence was highest in late May and early June, with few seedlings emerging after mid-June. Weed populations were highest in May and early June, after which rotary hoeing and cultivation reduced weed numbers in all plots. Microtopographic position (row, shoulder, and furrow) had a large effect on soil microenvironment and weed populations. Furrows were the wettest position through most of the growing season. Rows were the warmest position early in the season and the coolest position late in the season. Cumulative weed emergence early in the season was closely related to growing degree days, which accumulated faster in the row position than the furrow position. Following rotary hoeing and cultivation, the row position had significantly more total weeds than the shoulder and furrow positions on all farms in August of both years.

Influence of establishment timing on growth and fecundity of two itchgrass (Rottboellia cochinchinensis) biotypes grown in Louisiana

Weed Science ◽  
2020 ◽  
Vol 68 (4) ◽  
pp. 418-425
Author(s):  
Douglas J. Spaunhorst
Keyword(s):  
Yield Loss ◽  
Seedling Emergence ◽  
Common Garden ◽  
Growing Season ◽  
Growing Degree Days ◽  
Initial Growth ◽  
Common Garden Experiment ◽  
Degree Days ◽  
Humid Climate ◽  
Rottboellia Cochinchinensis

AbstractItchgrass [Rottboellia cochinchinensis (Lour.) W.D. Clayton] is among the most troublesome weeds in subtropical climates where sugarcane (Saccharum spp. interspecific hybrids) is cultivated. Two R. cochinchinensis biotypes commonly infest sugarcane in Louisiana. The Louisiana-1 biotype is daylength neutral, but Louisiana-2 flowered when daylength decreased to 13 h. Coupled with biotype diversity, seedling emergence has been reported to occur earlier in the growing season, as sugarcane emerged from winter dormancy. Both R. cochinchinensis biotypes were established in a common garden experiment in Louisiana during periods of sugarcane development and field preparation to simulate discontinuous emergence. Plant height and raceme production were recorded weekly for each biotype and establishment timing; aboveground biomass was harvested in autumn. Louisiana’s subtropical humid climate stimulated rapid plant growth that typically began in May and persisted through September. Without sugarcane competition, maximum R. cochinchinensis heights for Louisiana-1 and Louisiana-2 were 206 and 179 cm and growing degree days to 20-cm height in 2017 ranged from 546 to 832 and 865 to 1,160, respectively. Slower initial growth reported with Louisiana-2 would allow more time for growers to treat escaped plants with POST herbicides. Total raceme production, by autumn, was zero for Louisiana-2 established in June or later, but Louisiana-1 established in June produced up to 202 racemes. The present study demonstrated the importance of managing the Louisiana-2 biotype in March and April to limit seed production, but fields infested with Louisiana-1 were at greater risk for potential crop yield loss, because plants produced high quantities of seed when established over a wide period of time.

Feeding Preferences of Weed Seed Predators and Effect on Weed Emergence

Weed Science ◽  
2007 ◽  
Vol 55 (6) ◽  
pp. 606-612 ◽  
Author(s):  
Sharon S. White ◽  
Karen A. Renner ◽  
Fabian D. Menalled ◽  
Douglas A. Landis
Keyword(s):  
Common Ground ◽  
Field Experiments ◽  
Field Cricket ◽  
Feeding Preferences ◽  
Weed Species ◽  
Seed Predators ◽  
Redroot Pigweed ◽  
Greenhouse Study ◽  
Giant Foxtail ◽  
Weed Emergence

We determined feeding preferences of invertebrate seed predators and the effect of seed predation on weed emergence. Feeding choice studies were completed with three species of common ground beetles: (Amara aeneaDeGeer,Anisodactylus sanctaecrucisF., andHarpalus pensylvanicusDeGeer) (Coleoptera: Carabidae) and the northern field cricket (Gryllus pennsylvanicusDeGeer) (Orthoptera: Gryllidae).Anisodactylus sanctaecrucis,H. pensylvanicus, and the female and maleG. pennsylvanicusconsumed more redroot pigweed seeds compared with giant foxtail seeds;A. aeneaseed consumption did not differ between these two weed species. All invertebrates consumed fewer velvetleaf seeds compared with redroot pigweed and giant foxtail seeds; however, when seed biomass was compared,A. aeneaconsumed similar biomass of velvetleaf, giant foxtail, and redroot pigweed, whereasA. sanctaecrucisandH. pensylvanicusconsumed greater biomass of velvetleaf compared with giant foxtail seed. Seed burial depths of 0.5 or 1.0 cm reduced redroot pigweed and giant foxtail seed consumption byA. aeneaandA. sanctaecrucisbut not by the larger carabid beetle,H. pensylvanicus. In a greenhouse study,A. sanctaecrucisdecreased total weed emergence by 15%, andG. pennsylvanicusfemales and males decreased weed emergence by 16 and 5%, respectively. Emergence of redroot pigweed, but not velvetleaf or giant foxtail, decreased whenA. sanctaecrucisand the maleG. pennsylvanicuswere present, whereas the emergence of all three weed species decreased in the presence of the femaleG. pennsylvanicus. In field experiments, vertebrate access to velvetleaf seeds reduced emergence from 4 to 9% across field sites; invertebrate access reduced emergence 4 to 6%. Vertebrate access to giant foxtail seeds reduced emergence 3 to 7%, and invertebrate access reduced emergence 4 to 13%. These results suggest that predation of weed seeds by both vertebrates and invertebrates may reduce weed emergence and influence the weed community.

Tillage and seed depth effects on velvetleaf (Abutilon theophrasti) emergence

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 76-82 ◽  
Author(s):  
Theodore M. Webster ◽  
John Cardina ◽  
Heather M. Norquay
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
Seedling Emergence ◽  
Growing Season ◽  
Growing Degree Days ◽  
No Tillage ◽  
Degree Days ◽  
Growing Seasons ◽  
Continuous Corn ◽  
Emergence Patterns

Understanding patterns of weed seedling emergence within a growing season and over years is important to develop models to predict optimum timing of weed management practices. A study was conducted in a field with no previous velvetleaf infestations to describe emergence patterns following seed burial at three depths in two tillage systems. Freshly harvested velvetleaf seeds were planted 0, 2, and 6 cm deep in moldboard plowed (MP) and no-tillage (NT) corn stubble in October 1990. Velvetleaf seedling emergence was monitored over the following 4 yr in continuous corn. Emergence was higher in NT than in MP plots throughout 4 yr of observation. The first growing season following seeding, emerged seedlings represented 9.3 to 15.8% of the seeds sown in NT, compared with 0.1 to 0.8% of seeds sown in MP. After four growing seasons, emerged seedlings were 12.5 to 25% of seeds sown in NT but only 6 to 7.4 % of seeds sown in MP. Emergence was consistently higher from the 0-cm depth than from the 6-cm depth in NT, but seeding depth did not influence emergence in MP due to mixing of the soil during tillage. Velvetleaf emergence was related to growing degree days (base 7.5 C), with greater consistency in NT than in MP. Averaged over years and planting depths, 50% velvetleaf emergence occurred within 8 and 13 d of the predicted date in NT and MP systems, respectively.

Characterization and Modeling of Itchgrass (Rottboellia cochinchinensis) Biphasic Seedling Emergence Patterns in the Tropics

Weed Science ◽  
2015 ◽  
Vol 63 (3) ◽  
pp. 623-630 ◽  
Author(s):  
Ramon G. Leon ◽  
Jordi Izquierdo ◽  
José Luis González-Andújar∗
Keyword(s):  
Field Experiments ◽  
Seedling Emergence ◽  
Thermal Time ◽  
Second Phase ◽  
Growing Degree Days ◽  
Degree Days ◽  
Weed Species ◽  
Time Model ◽  
Emergence Patterns ◽  
Emergence Phase

Itchgrass is an aggressive weed species in tropical agroecosystems. Because of phytosanitary restrictions to exports, pineapple producers must use a zero tolerance level for this species. An understanding of itchgrass seedling emergence would help producers to better time POST control. The objective of the present study was to characterize itchgrass seedling emergence patterns and develop a predictive model. Multiple field experiments were conducted in four agricultural fields in Costa Rica between 2010 and 2011 for a total of 9 site-years. Itchgrass consistently showed a biphasic emergence pattern, with a first emergence phase that was faster and more consistent across site-years than the second one. Weibull + logistic models based on chronological time (R2adj= 0.92) and thermal time withTbase= 20 C (R2adj= 0.92) provided the best fit for the combined emergence data for two experimental locations in 2010. Both models predicted itchgrass seedling emergence adequately for most site-years, but the thermal-time model was more accurate (R2adj= 0.64 to 0.86) than the chronological model (R2adj= 0.31 to 0.74), especially when temperatures were high. Both models showed high accuracy in the first emergence phase but tended to underestimate emergence rate during the second phase. The models predicted 50% emergence at 14 d or 80 growing degree days and the stabilization of the first emergence phase at approximately 25 d or 200 growing degree days. Thus, these models can be used to properly time itchgrass POST control. More research is needed to understand the regulatory mechanisms responsible for the variability of the second emergence phase.

Emergence Pattern of Five Weeds in the Central Great Plains

1996 ◽  
Vol 10 (4) ◽  
pp. 744-749 ◽  
Author(s):  
R. L. Anderson ◽  
D. C. Nielsen
Keyword(s):  
Great Plains ◽  
Seedling Emergence ◽  
Growing Season ◽  
Crop Canopy ◽  
Emergence Pattern ◽  
Proso Millet ◽  
Annual Crops ◽  
No Till ◽  
Green Foxtail ◽  
Wheat Stubble

Seedling emergence was characterized for five weeds that infest summer annual crops in the central Great Plains as affected by crop canopy or tillage. The study was established in winter wheat stubble between 1987 and 1990, with seedling emergence recorded weekly between April 1 and November 1. Kochia emerged primarily from early April to late June, whereas green foxtail, wild-proso millet, and redroot pigweed began emerging in late May and continued until August. Volunteer wheat emerged throughout the growing season. Tillage did not affect the emergence pattern of any species, but the numbers of kochia, volunteer wheat, and green foxtail seedlings were increased in no-till. Conversely, wild-proso millet emergence was greater with tillage. Only volunteer wheat's emergence was affected by crop canopy, as fall emergence of volunteer wheat was more than three times greater in corn than in proso millet.

CHLOROGENIC ACID CONTENT OF SUNFLOWER SEED FLOUR AS AFFECTED BY SEEDING AND HARVEST DATE

1976 ◽  
Vol 56 (4) ◽  
pp. 901-905 ◽  
Author(s):  
D. G. DORRELL
Keyword(s):  
Chlorogenic Acid ◽  
Acid Content ◽  
Vegetative Growth ◽  
Sunflower Seed ◽  
Growing Season ◽  
Growing Degree Days ◽  
Degree Days ◽  
Normal Field ◽  
Seed Flour ◽  
Seeding Date

The effect of seeding date on the chlorogenic acid content of sunflower seed flour was determined by seeding the cultivars Krasnodarets and Peredovik at seven dates, starting on 14 May, over 3 yr. Sequential plantings were made at increments of approximately 70 growing degree days (base = 5.6 C). Plants were harvested at normal field maturity. The time and rate of deposition of chlorogenic acid was determined by harvesting plants at 7-day intervals from 21 to 49 days after flowering. The seeds were dehulled and defatted before determining the chlorogenic acid content of the flour. Chlorogenic acid content declined steadily from an average of 4.22% for the first seeding to 3.30% for the last seeding. About one-half of the total chlorogenic acid was present 21 days after flowering. Deposition continued rapidly for the next 14 days then the level began to stabilize. Delay in seeding tended to shorten the period of vegetative growth and shift the deposition of chlorogenic acid to a cooler portion of the growing season. It is suggested that a combination of these factors caused the reduction in chlorogenic acid content of sunflower flour.

Timing and rate of bud formation in Pinus resinosa

1971 ◽  
Vol 49 (10) ◽  
pp. 1821-1832 ◽  
Author(s):  
Edward Sucoff
Keyword(s):  
Quantitative Data ◽  
Shoot Growth ◽  
Pinus Resinosa ◽  
Growing Season ◽  
Axillary Buds ◽  
Growing Degree Days ◽  
Degree Days ◽  
Bud Formation ◽  
Late Season ◽  
Apical Dome

During the 1969 and 1970 growing season buds were collected almost weekly from matched trees in northeastern Minnesota. Cataphyll primordia for the year n + 1 shoot began forming at the time that internodes in the year n shoot started elongating (late April) and continued forming until early September. Primordia for axillary buds started forming about 2 months later and stopped forming at the same time as cataphylls. The size and deposition activity of the apical dome simultaneously increased during the early growing season and decreased during the late season. The maximum rates in July were over nine cataphylls per day.Rate of cataphyll deposition paralleled elongation of the needles on subtending shoots. Forty to fifty percent of the cataphylls had been formed when shoot growth was 95% complete. Although the bulk of the depositions occurred earlier in 1970, when growing degree days were used as the clock, the 2 years were similar.The results provide quantitative data to complement the histologic emphasis of previous studies.

Spatial Analysis of Climate-Viticulture Indices for the Eastern United States

2016 ◽  
Vol 7 (4) ◽  
pp. 23-37 ◽  
Author(s):  
Rosalyn Francine MacCracken ◽  
Paul R. Houser
Keyword(s):  
United States ◽  
Spatial Analysis ◽  
Growing Season ◽  
Climate Indices ◽  
Growing Degree Days ◽  
Eastern United States ◽  
Degree Days ◽  
The Us ◽  
Resolution Dataset ◽  
Effective Degree

This study characterizes the climate structure in the Eastern United States for suitability of winegrape growth. For this study, the Eastern US is defined as the 44 contiguous Eastern most states. This excludes the premium wine growing states of California, Washington, Oregon and Idaho. For this characterization, a comparative study is performed on the four commonly used climate-viticulture indices (i.e., Average Growing Season Temperature, Growing Degree Days, Heliothermal Index and Biologically Effective Degree Days), and a new climate-viticulture index, the Modified-GSTavg (Mod-GSTavg). This is accomplished using the 1971 – 2000 PRISM 800-meter resolution dataset of climate temperature normal for the study area of 44 states and 62 American Viticultural Areas across the Eastern United States. The results revealed that all the climate indices have similar spatial patterns throughout the US with varying magnitudes and degrees of suitability.

Interference between pigweed (Amaranthusspp.), barnyardgrass(Echinochloa crus-galli), and soybean (Glycine max)

Weed Science ◽  
1998 ◽  
Vol 46 (5) ◽  
pp. 533-539 ◽  
Author(s):  
Paul Cowan ◽  
Susan E. Weaver ◽  
Clarence J. Swanton
Keyword(s):  
Competitive Ability ◽  
Field Experiments ◽  
Yield Loss ◽  
Seedling Emergence ◽  
Growth Time ◽  
Weed Species ◽  
Soybean Yield ◽  
Competitive Index ◽  
Loss Maximum ◽  
Weed Emergence

Field experiments were conducted to determine the influence of time of emergence and density of single and multispecies populations of pigweed and barnyardgrass on soybean yield and competitive abilities of pigweed and barnyardgrass. Pigweed and barnyardgrass were established at selected densities within 12.5 cm on either side of the soybean row. Pigweed and barnyardgrass seeds were sown concurrently with soybean and at the cotyledon stage of soybean growth. Time and density of pigweed and barnyardgrass seedling emergence relative to soybean influenced the magnitude of soybean yield loss. Maximum soybean yield loss ranged from 32 to 99%, depending upon time of emergence relative to soybean. Pigweed was more competitive than barnyardgrass across all locations, years, and time of weed emergence. When pigweed was assigned a competitive index of 1 on a scale from 0 to 1, the competitive ability of barnyardgrass ranged from 0.075 to 0.40 of pigweed, depending upon location and time of emergence. This is the first multiple weed species study to include time of weed emergence relative to the crop. Competitive index values for multiple weed species must be calculated from field experiments in which weeds are grown with the crop under differing environmental conditions.

Response of Weed Seeds to Ethylene and Related Hydrocarbons

Weed Science ◽  
1979 ◽  
Vol 27 (1) ◽  
pp. 7-10 ◽  
Author(s):  
R. B. Taylorson
Keyword(s):  
Chenopodium Album ◽  
Active Form ◽  
Amaranthus Retroflexus ◽  
Weed Species ◽  
Hydrocarbon Gases ◽  
Common Lambsquarters ◽  
Setaria Faberi ◽  
Redroot Pigweed ◽  
Giant Foxtail ◽  
Common Purslane

AbstractGermination of seeds of 10 grass and 33 broadleaved weed species was examined for response to ethylene. Germination was promoted in nine species, inhibited in two, and not affected in the remainder. Of the species promoted, common purslane (Portulaca oleraceaL.), common lambsquarters (Chenopodium albumL.), and several Amaranths, including redroot pigweed (Amaranthus retroflexusL.), were affected most. Transformation of phytochrome to the active form (Pfr) gave interactions that ranged from none to syntergistic with the applied ethylene. In subsequent tests seeds of purslane, redroot pigweed, and giant foxtail (Setaria faberiHerrm.), a species not responsive to ethylene, were examined for germination response to 14 low molecular weight hydrocarbon gases other than ethylene. Some stimulation by the olefins propylene and propadiene was found for purslane and pigweed. Propionaldehyde and butyraldehyde were slightly stimulatory to purslane only.

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