Temperature and Water Potential as Parameters for Modeling Weed Emergence in Central-Northern Italy

Weed Science ◽  
2010 ◽  
Vol 58 (3) ◽  
pp. 216-222 ◽  
Author(s):  
Roberta Masin ◽  
Donato Loddo ◽  
Stefano Benvenuti ◽  
Maria Clara Zuin ◽  
Mario Macchia ◽  
...  
Keyword(s):  
Water Potential ◽  
Weed Control ◽  
Seedling Emergence ◽  
Thermal Time ◽  
Base Temperature ◽  
Hydrothermal Time ◽  
Data Set ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Weed Emergence

Predicting weed emergence dynamics can help farmers to plan more effective weed control. The hydrothermal time concept has been used to model emergence as a function of temperature and water potential. Application of this concept is possible if the specific biological thresholds are known. This article provides a data set of base temperature and water potential of eight maize weeds (velvetleaf, redroot pigweed, common lambsquarters, large crabgrass, barnyardgrass, yellow foxtail, green foxtail, and johnsongrass). For five of these species, two ecotypes from two extreme regions of the predominant maize-growing area in Italy (Veneto and Tuscany), were collected and compared to check possible differences that may arise from using the same thresholds for different populations. Seedling emergence of velvetleaf and johnsongrass were modeled using three different approaches: (1) thermal time calculated assuming 5 C as base temperature for both species; (2) thermal time using the specific estimated base temperatures; and (3) hydrothermal time using the specific, estimated base temperatures and water potentials. All the species had base temperatures greater than 10 C, with the exception of velvetleaf (3.9 to 4.4 C) and common lambsquarters (2.0 to 2.6 C). All species showed a calculated base-water potential equal or up to −1.00 MPa. The thresholds of the two ecotypes were similar for all the studied species, with the exception of redroot pigweed, for which the Veneto ecotype showed a water potential lower than −0.41 MPa, whereas it was −0.62 MPa for the Tuscany ecotype. Similar thresholds have been found to be useful in hydrothermal time models covering two climatic regions where maize is grown in Italy. Furthermore, a comparison between the use of specific, estimated, and common thresholds for modeling weed emergence showed that, for a better determination of weed control timing, it is often necessary to estimate the specific thresholds.

Modeling germination and seedling elongation of common lambsquarters (Chenopodium album)

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 149-155 ◽  
Author(s):  
Erivelton S. Roman ◽  
A. Gordon Thomas ◽  
Stephen D. Murphy ◽  
Clarence J. Swanton
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Mechanistic Model ◽  
Chenopodium Album ◽  
Seedling Emergence ◽  
Probit Analysis ◽  
Hydrothermal Time ◽  
Time Model ◽  
Common Lambsquarters ◽  
Radicle Elongation

The ability to predict time of weed seedling emergence relative to the crop is an important component of a mechanistic model describing weed and crop competition. In this paper, we hypothesized that the process of germination could be described by the interaction of temperature and water potential and that the rate of seedling shoot and radicle elongation vary as a function of temperature. To test these hypotheses, incubator studies were conducted using seeds and seedlings of common lambsquarters. Probit analysis was used to account for variation in cardinal temperatures and base water potentials and to develop parameters for a new mathematical model that describes seed germination and shoot and radicle elongation in terms of hydrothermal time and temperature, respectively. This hydrothermal time model describes the phenology of seed germination using a single curve, generated from the relationship of temperature and water potential.

Temperature- and moisture-dependent models of seed germination and shoot elongation in green and redroot pigweed (Amaranthus powellii, A. retroflexus)

Weed Science ◽  
1997 ◽  
Vol 45 (4) ◽  
pp. 488-496 ◽  
Author(s):  
Joseph O. E. Oryokot ◽  
Stephen D. Murphy ◽  
A. Gordon Thomas ◽  
Clarence J. Swanton
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Weed Management ◽  
Germination Rate ◽  
Shoot Elongation ◽  
Thermal Time ◽  
Base Temperature ◽  
Mathematical Function ◽  
Redroot Pigweed ◽  
Mean Temperature

To predict weed emergence and help farmers make weed management decisions, we constructed a mathematical model of seed germination for green and redroot pigweed based on temperature and water potential (moisture) and expressing cumulative germination in terms of thermal time (degree days). Empirical observations indicated green pigweed germinated at a lower base temperature than redroot pigweed but the germination rate of redroot pigweed is much faster as mean temperature increases. Moisture limitation delayed seed germination until 23.8 C (green pigweed) or 27.9 (redroot pigweed); thereafter, germination was independent of water potential as mean temperatures approached germination optima. Our germination model, based on a cumulative normal distribution function, accounted for 80 to 95% of the variation in seed germination and accurately predicted that redroot pigweed would have a faster germination rate than green pigweed. However, the model predicted that redroot pigweed would germinate before green pigweed (in thermal time) and was generally less accurate during the early period of seed germination. The model also predicted that moisture limitation would increase, rather than delay, seed germination. These errors were related to the mathematical function chosen and analyses used, but an explicit interaction term for water potential and temperature is also needed to produce an accurate model. We also tested the effect of mean temperature on shoot elongation (emergence) and described the relationship by a linear model. Base temperatures for shoot elongation were higher than for seed germination. Shoot elongation began at 15.6 and 14.4 C for green and redroot pigweed, respectively; they increased linearly with temperature until the optimum of 27.9 C was reached. Elongation was dependent on completion of the rate-limiting step of radicle emergence and was sensitive to temperature but not moisture; hence, elongation was sensitive to a much smaller temperature range. Beyond mathematical changes, we are testing our model in the field and need to link it to ecophysiological, genetic, and spatially explicit population processes for it to be useful in decision support for weed management.

A Thermal Time Model to Predict Corn Poppy (Papaver rhoeas) Emergence in Cereal Fields

Weed Science ◽  
2009 ◽  
Vol 57 (6) ◽  
pp. 660-664 ◽  
Author(s):  
Jordi Izquierdo ◽  
José L. González-Andújar ◽  
Fernando Bastida ◽  
Juan A. Lezaún ◽  
María J. Sánchez del Arco
Keyword(s):  
Seedling Emergence ◽  
Gompertz Model ◽  
Sowing Date ◽  
Control Measures ◽  
Thermal Time ◽  
Base Temperature ◽  
Time Model ◽  
Data Set ◽  
Winter Cereals ◽  
Cereal Fields

Corn poppy is the most abundant broad-leaved weed in winter cereals of Mediterranean climate areas and causes important yield losses in wheat. Knowledge of the temporal pattern of emergence will contribute to optimize the timing of control measures, thus maximizing efficacy. The objectives of this research were to develop an emergence model on the basis of soil thermal time and validate it in several localities across Spain. To develop the model, monitoring of seedling emergence was performed weekly during the growing season in a cereal field located in northeastern Spain, during 3 yr. Cumulative thermal time from sowing date was used as the independent variable for predicting cumulative emergence. The Gompertz model was fitted to the data set of emergences. A base temperature of 1.0 C was estimated through iteration for maximum fit. The model accounted for 91% of the variation observed. Model validation in several localities and years showed general good performance in predicting corn poppy seedling emergence ( values ranging from 0.64 to 0.99 and root-mean-square error from 4.4 to 24.3). Ninety percent emergence was accurately predicted in most localities. Results showed that the model performs with greater reliability when significant rainfall (10 mm) occurs within 10 d after crop sowing. Complemented with in-field scouting, it may be a useful tool to better timing control measures in areas that are homogeneous enough regarding climate and crop management.

Effect of water on common lambsquarters (Chenopodium album L.) and barnyardgrass [Echinochloa crus-galli (L.) Beauv.] seedling emergence in corn

2002 ◽  
Vol 82 (4) ◽  
pp. 855-859 ◽  
Author(s):  
M. L. Leblanc ◽  
D. C. Cloutier ◽  
C. Hamel
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Chenopodium Album ◽  
Seedling Emergence ◽  
Field Capacity ◽  
Emergence Period ◽  
Common Lambsquarters ◽  
Weed Emergence

A 2-year field study was conducted in corn to determine the influence of rainfall, irrigation and soil water content on common lambsquarters and barnyardgrass emergence. Rainfall or irrigation had no influence on the final weed density and little on the pattern of weed emergence because the soil water content was at or greater than field capacity during the main weed emergence period. Irrigation may hasten the first weed emergence by warming the soil when temperature is limiting for germination. In southwestern Quebec, temperature appears to be the most important factor regulating germination in the spring since soil moisture is normally at field capacity for a long period, in part because of the melting of snow. Key words: Irrigation, weed emergence, soil moisture

Evaluating the EPA's Comparative Product Performance Testing Guidelines for Herbicides in Snap Bean (Phaseolus vulgaris)

1998 ◽  
Vol 12 (2) ◽  
pp. 215-222
Author(s):  
Robin R. Bellinder ◽  
Marija Arsenovic ◽  
Jonathan J. Kirkwyland ◽  
Russell W. Wallace
Keyword(s):  
Weed Control ◽  
Environmental Protection Agency ◽  
Performance Testing ◽  
Good Control ◽  
Field Trials ◽  
Weed Species ◽  
Snap Bean ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Product Comparison

Following suggested guidelines developed by the Environmental Protection Agency (EPA), comparative snap bean herbicide performance field trials were conducted from 1993 to 1995 in New York. Data were obtained on crop injury, weed control, and weed biomass, and crop yield, quality, and losses during harvest. Trifluralin, EPTC, and pendimethalin applied preplant incorporated (PPI) and applications of metolachlor applied preemergence (PRE) provided less than adequate control of redroot pigweed, common lambsquarters, and hairy galinsoga. Cultivation improved weed control with PPI and PRE applications. Metolachlor + fomesafen PRE provided good control of hairy galinsoga, adequate redroot pigweed control, and marginal control of common lambsquarters. Fomesafen applied postemergence (POST), combinations of metolachlor applied PRE with fomesafen or bentazon applied POST, and fomesafen + bentazon applied POST adequately controlled the three weed species without cultivation. Herbicide treatments had little measurable impact on snap bean quality or losses during harvest. Information from product comparison trials may be useful in developing recommendations for growers but may prove less than adequate in providing data necessary for a thorough evaluation of the relative benefits of individual herbicides as intended by EPA guidelines. Difficulties were encountered in following the guidelines, and costs of conducting the product comparison trials for a single crop in one growing region exceeded $90,000 over 3 yr.

Vernal Seedling Emergence Model for Common Lambsquarters (Chenopodium album)

Weed Science ◽  
1993 ◽  
Vol 41 (2) ◽  
pp. 309-316 ◽  
Author(s):  
Stephen J. Harvey ◽  
Frank Forcella
Keyword(s):  
Field Data ◽  
Close Agreement ◽  
Chenopodium Album ◽  
Seedling Emergence ◽  
Coefficient Of Determination ◽  
Chemical Methods ◽  
Common Lambsquarters ◽  
Individual Site ◽  
Seedbed Preparation ◽  
Weed Emergence

Knowledge of timing and extent of weed emergence before and immediately after crop seedbed preparation is needed to decrease need for preplant herbicides and increase efficacy of postemergence weed control in crops with either mechanical or chemical methods. Such knowledge is important for weeds that infest most crops over a wide area. For these reasons a mechanistic seedling emergence model based solely on soil temperature was developed for common lambsquarters. The model was validated using four sets of field data collected in 1988, 1990, and 1991 near Morris, MN. Agreement of predicted and observed emergence values across all site-years was 0.95 and the coefficient of determination (R2) was 0.98 (P < 0.001). Agreement for individual site-years was 0.96, 1.08, 1.08, and 0.98 and associated R2values were 0.99, 0.99, 0.99, and 0.98 (P < 0.001 for each site-year), indicating close agreement between predicted and actual emergence values.

Postemergence Broadleaf Weed Control in Corn (Zea mays) with CGA-152005

1996 ◽  
Vol 10 (4) ◽  
pp. 689-698 ◽  
Author(s):  
Michelle R. Obermeier ◽  
George Kapusta
Keyword(s):  
Zea Mays ◽  
Weed Control ◽  
Field Studies ◽  
Corn Yield ◽  
Sulfonylurea Herbicide ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Growing Conditions

Field studies were conducted in 1993 and 1994 to evaluate broadleaf weed control in corn with the sulfonylurea herbicide CGA-152005, CGA-152005 was applied at 10 to 50 g ai/ha alone and in combination with 2,4-D, dicamba, or atrazine. No corn injury was observed either year. Metolachlor plus CGA-152005 controlled redroot pigweed, velvetleaf, and common cocklebur 95% or more in 1993 and 1994. Common lambsquarters and ivyleaf morningglory control was dependent on CGA-152005 rate, weed size at application, and growing conditions. In 1994, control of velvetleaf and ivyleaf morningglory with CGA-152005 at 10 or 20 g/ha was less when applied as a tank-mix with atrazine and dicamba compared with when it was applied alone, probably due to antagonism caused by the companion herbicide. Generally, corn yield was related to weed control.

Increased weed emergence and seed bank depletion by soil disturbance in a no-tillage system

Weed Science ◽  
1997 ◽  
Vol 45 (2) ◽  
pp. 234-241 ◽  
Author(s):  
Dawit Mulugeta ◽  
David E. Stoltenberg
Keyword(s):  
Seed Bank ◽  
Seedling Emergence ◽  
Soil Disturbance ◽  
No Tillage ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Giant Foxtail ◽  
Tillage System ◽  
Level Of Aggregation ◽  
Viable Seeds

The influence of secondary soil disturbance on the emergence pattern and seed bank depletion of an annual weed community in a long-term, no-tillage corn cropping system was determined in 1992 and 1993. As a component of this research, the seed bank was characterized prior to implementation of soil disturbance treatments. The seed bank was initially composed of common lambsquarters, redroot pigweed, and giant foxtail, with approximately 55, 36, and 8% of the total viable seeds, respectively. The remaining 1% was comprised of five other species in 1992 and eight in 1993. The spatial distribution of viable seeds of each species, except common lambsquarters and redroot pigweed, was described by a negative binomial distribution. Three dispersion indices indicated that seeds of individual and total weed species were aggregated and that the level of aggregation of viable seeds of a species was associated with seed density; at lower seed densities, the level of aggregation was greater. Soil disturbance increased common lambsquarters emergence 6-fold in 1992 relative to nondisturbed soil, but did not influence emergence in 1993. Rainfall was about 50% less in 1993. In contrast, soil disturbance increased giant foxtail and redroot pigweed emergence approximately 6- and 3-fold in 1992 and 1993, respectively. Seedling emergence associated with soil disturbance, relative to nondisturbed soil, increased seed bank depletion of common lambsquarters 16-fold in 1992, and giant foxtail and redroot pigweed and average of 6- and 3-fold in 1992 and 1993, respectively. These results indicated that soil disturbance increased seedling emergence and seed bank depletion of the predominant species in the weed community of a long-term, no-tillage system, but that this response was dependent on rainfall for common lambsquarters.

Low-Rate Applications of Herbicides in Conventional and Reduced Tillage Potatoes (Solanum tuberosum)

1990 ◽  
Vol 4 (3) ◽  
pp. 509-513 ◽  
Author(s):  
Russell W. Wallace ◽  
Robin R. Bellinder
Keyword(s):  
Solanum Tuberosum ◽  
Weed Control ◽  
Production Systems ◽  
Potato Production ◽  
Reduced Tillage ◽  
Tillage Systems ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Significant Yield ◽  
Low Rate

Linuron, metribuzin, oryzalin, and metolachlor were applied at recommended (1X) and two-thirds (0.67X) rates to evaluate control of redroot pigweed and common lambsquarters in conventional and rye-stubble reduced-tillage potato production systems. Regardless of tillage, common lambsquarters control was satisfactory during both seasons at both rates of linuron, metribuzin, and oryzalin. Redroot pigweed control by these three herbicides, although excellent in 1988, was poor in RT plots during 1987. Yields did not differ between tillage systems. Reduced weed control with metolachlor during both seasons, and possible crop injury with linuron in 1987 resulted in significant yield reductions.

Effect of Tillage and Soil-Applied Herbicides with Micro-Rate Herbicide Programs on Weed Control and Sugarbeet Growth

2009 ◽  
Vol 23 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Scott L. Bollman ◽  
Christy L. Sprague
Keyword(s):  
Weed Control ◽  
Field Trials ◽  
Tillage Systems ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Giant Foxtail ◽  
Herbicide Treatments ◽  
Herbicide Programs

Field trials were conducted to determine if tillage and soil-applied herbicides had an effect on weed control and sugarbeet growth with a micro-rate herbicide program. Sugarbeet emergence was earlier in the moldboard plowed system compared with the chisel plowed system at three of four sites. Conditions were dry and sugarbeets emerged 5 d later in the moldboard plowed system compared with the chisel plowed system at the fourth site. Even though the rate of sugarbeet emergence differed between tillage systems at all four sites, final sugarbeet populations did not differ at two of the four sites. Sugarbeet injury from PRE treatments ofS-metolachlor, ethofumesate, and ethofumesate plus pyrazon, followed by four POST micro-rate applications, ranged from 11 to 27% and 1 to 18% in the chisel and moldboard plowed systems, respectively, 6 wk after planting (WAP). Under wet conditions, sugarbeet stand was reduced and injury was greatest from PRE applications ofS-metolachlor. Common lambsquarters, pigweed (redroot pigweed and Powell amaranth), and giant foxtail control in mid-August was consistently higher when a PRE herbicide was applied prior to micro-rate herbicide treatments. Even though there were differences between PRE and no-PRE treatments with respect to sugarbeet injury and weed control, recoverable white sucrose yield did not differ between herbicide treatments. However, recoverable white sucrose yield was greater in the moldboard plowed treatments compared with the chisel plowed treatments at three out of the four sites.

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