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.

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.

scholarly journals When do apples stop growing, and why does it matter?

2020 ◽  
Author(s):  
Maria D Christodoulou ◽  
Alastair Culham
Keyword(s):  
Linear Models ◽  
Growing Season ◽  
Apple Fruit ◽  
Maximum Length ◽  
Maximum Diameter ◽  
Growing Degree Days ◽  
Degree Days ◽  
Growing Seasons ◽  
Regular Time ◽  
Log Linear

AbstractBackgroundApples in the commercial food chain are harvested up to two weeks before maturity. We explore apple fruit development through the growing season to establish the point at which the features differentiating those cultivars become evident. This is relevant both for the understanding of the growing process and to ensure that any identification and classification tools can be used both on ripened-on-tree and stored fruit. Current literature presents some contradictory findings on apple development, we explored the size development of 12 apple cultivars in the Brogdale National Fruit Collection, UK over two growing seasons.MethodsFruit were sampled at regular time points throughout the growing season and four morphometrics (maximum length, maximum diameter, weight, and centroid size) were collected. These were regressed against growing degree days in order to appropriately describe the growth pattern observed.ResultsAll four morphometrics were adequately described using log-log linear regressions, with adjusted R2 estimates ranging from 78.3% (maximum length) to 86.7% (weight). For all four morphometrics, a 10% increase in growing degree days was associated with a 1% increase in the morphometric measurement.DiscussionOur findings refine previous work presenting rapid early growth followed by a plateau in later stages of development and are in disagreement with published expo-linear models. We established that apples harvested for commercial storage purposes, two weeks prior to maturity, showed only a modest decrease in size, demonstrating that size morphometric approaches are appropriate for classification of apples, both ripened-on-tree and stored.

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.

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.

scholarly journals Herbicide Application Timings on Weed Control and Jack-O-Lantern Pumpkin Yield

2012 ◽  
Vol 22 (2) ◽  
pp. 201-206 ◽  
Author(s):  
S. Alan Walters ◽  
Bryan G. Young
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Management Practices ◽  
Production Systems ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Growing Season ◽  
Weed Species ◽  
Application Timing ◽  
Over The Top

A study was conducted in a no-tillage (NT) jack-o-lantern pumpkin (Cucurbita pepo) field following winter wheat (Triticum aestivum) harvest to determine the effects of using registered herbicides at various timings on weed control and pumpkin yield. All application timings used in this study were important to maximize weed control over the pumpkin growing season. For an initial stale seedbed burndown treatment, paraquat provided better broadleaf weed control than glyphosate, which lead to greater pumpkin yields. The use of s-metolachlor + halosulfuron-methyl preemergence (PRE) and clethodim postemergence (POST) gave the best results for the second series of herbicide applications which related to higher pumpkin yields compared with none or only a PRE application. The last application timing (midseason POST-directed paraquat application between rows) also improved weed control and provided higher pumpkin yields compared with no treatment. Growers who use a stale seedbed burndown treatment in NT pumpkin production, before seedling emergence or transplanting, will generally use glyphosate although this study indicated that paraquat may prove to be a better choice depending on the weed species that are present at this application timing. Most weed control in NT pumpkin production is achieved by a PRE application of various tank-mixed herbicides for both grass and broadleaf weed control, with a POST grass herbicide, a POST application of halosulfuron-methyl, or both [for control of nutsedge (Cyperus sp.), specific broadleaf weed species, or both] applied 3 to 4 weeks later, and this study indicated that the use of labeled PRE and POST herbicides are essential to optimize weed control and pumpkin yields in NT. Most pumpkin growers do not use a POST-directed application of a nonselective herbicide (such as paraquat) before vines cover the soil surface although it appears that this application may be warranted to control weeds that have emerged later in the growing season to maximize pumpkin yield, especially if POST midseason over-the-top herbicide applications are not used. This study indicated that in addition to applying the limited PRE and POST herbicides available for weed control in pumpkin, the use of other chemical weed management practices (e.g., stale seedbed herbicide treatments or POST-directed nonselective herbicide applications) can provide valuable weed control in NT production systems and should be considered by growers to maximize pumpkin yield.

scholarly journals Effect of Weed Management on the Parasitoid Community in Mediterranean Vineyards

Biology ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Gabriella Möller ◽  
Tamar Keasar ◽  
Idan Shapira ◽  
Daniella Möller ◽  
Marco Ferrante ◽  
...  
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Soil Conservation ◽  
Management Practices ◽  
Ground Cover ◽  
Parasitoid Species ◽  
Parasitoid Community ◽  
Growing Seasons ◽  
Conservation Biocontrol ◽  
Suction Sampling

Enriching agroecosystems with non-crop vegetation is a popular strategy for conservation biocontrol. In vineyards, the effects of specific seeded or planted cover crops on natural enemies are well-studied, whereas conserving spontaneously developing weeds received less attention. We compared parasitoid communities between matched pairs of vineyard plots in northern Israel, differing in weed management practices: “herbicide”, repeated herbicide applications vs. “ground cover”, maintaining resident weeds and trimming them when needed. Using suction sampling, we assessed the parasitoids’ abundance, richness, and composition during three grape-growing seasons. Ground cover plots had greater parasitoid abundances and cumulative species richness than herbicide-treated plots, possibly because of their higher vegetation cover and richness. Dominant parasitoid species varied in their magnitude and direction of response to weed management. Their responses seem to combine tracking of host distributions with attraction to additional vegetation-provided resources. Parasitoid community composition was mildly yet significantly influenced by weed management, while season, year, and habitat (weeds vs. vine) had stronger effects. Vineyard weeds thus support local biocontrol agents and provide additional previously demonstrated benefits (e.g., soil conservation, lower agrochemical exposure) but might also attract some crop pests. When the benefits outweigh this risk, weed conservation seems a promising step towards more sustainable agricultural management.

Applications of the herbicide sethoxydim increase wheat yield in the absence of weeds

1996 ◽  
Vol 36 (5) ◽  
pp. 555
Author(s):  
ID Black ◽  
CB Dyson ◽  
AR Fischle
Keyword(s):  
Leaf Growth ◽  
Wheat Yield ◽  
South Australia ◽  
Growing Season ◽  
Degree Days ◽  
Experimental Site ◽  
Yield Increase ◽  
Growing Seasons ◽  
Positive Linear Correlation ◽  
Area North

In 11 experiments over 6 seasons the herbicide sethoxydim was applied to Machete, Spear and Blade wheat cultivars in the absence or near absence of weeds (10 sites) or where the weeds were controlled by selective herbicides (1 site), in the cropping area north of Adelaide, South Australia. The rates applied included 9-47 g a.i./ha at the 2-3 leaf growth stage and 9-74 g a.i./ha at early tillering. Except for the very long growing season of 1992, there was a highly significant positive linear correlation between the number of degree days in the growing season at each experimental site and relative mean yield increase of these sethoxydim treatments. Yield increases ranged from nil in growing seasons of about 1000 degree days to 32% in a growing season of 1480 degree days, with a median of 8% over the experiments.

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.

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