Abstract
A 2-yr experiment assessed the potential for using soil degree days (DD) to predict cumulative weed emergence. Emerged weeds, by species, were monitored every 2 wk in undisturbed plots. Soil DD were calculated at each location using a base temperature of 9 C. Weed emergence was fit with logistic regression for common ragweed, common lambsquarters, velvetleaf, giant foxtail, yellow foxtail, large crabgrass, smooth pigweed, and eastern black nightshade. Coefficients of determination for the logistic models fit to the field data ranged between 0.90 and 0.95 for the eight weed species. Common ragweed and common lambsquarters were among the earliest species to emerge, reaching 10% emergence before 150 DD. Velvetleaf, giant foxtail, and yellow foxtail were next, completing 10% emergence by 180 DD. The last weeds to emerge were large crabgrass, smooth pigweed, and eastern black nightshade, which emerged after 280 DD. The developed models were verified by predicting cumulative weed emergence in adjacent plots. The coefficients of determination for the model verification plots ranged from 0.66 to 0.99 and averaged 0.90 across all eight weed species. These results suggest that soil DD are good predictors for weed emergence. Forecasting weed emergence will help growers make better crop and weed management decisions.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 5
Claim · model-written summary
Logistic emergence models fit field data for eight weed species with coefficients of determination from 0.90 to 0.95.
Verbatim
e0“Coefficients of determination for the logistic models fit to the field data ranged between 0.90 and 0.95 for the eight weed species.”
Claim · model-written summary
Common ragweed and common lambsquarters reached the reported emergence threshold before 150 DD.
- Taxon
- Common ragweed and common lambsquarters
Chenopodium album
Ambrosia artemisiifoliae0 - Outcome
- emergencee0
- Value
- before 150 DDe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Common ragweed and common lambsquarters were among the earliest species to emerge, reaching 10% emergence before 150 DD.”
Claim · model-written summary
Velvetleaf, giant foxtail, and yellow foxtail reached the reported emergence threshold by 180 DD.
Not reportedDirection
Verbatim
e0“Velvetleaf, giant foxtail, and yellow foxtail were next, completing 10% emergence by 180 DD.”
Claim · model-written summary
large crabgrass, smooth pigweed, and eastern black nightshade reached the reported emergence threshold after 280 DD.
- Taxon
- large crabgrass, smooth pigweed, and eastern black nightshadee0
- Outcome
- emergede0
- Value
- after 280 DDe0
Not reportedDirection
Verbatim
e0“The last weeds to emerge were large crabgrass, smooth pigweed, and eastern black nightshade, which emerged after 280 DD.”
Claim · model-written summary
Verification plot models had coefficients of determination of 0.66 to 0.99, averaging 0.90.
Verbatim
e0“The coefficients of determination for the model verification plots ranged from 0.66 to 0.99 and averaged 0.90 across all eight weed species.”