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Research and IPM

Phenology Model Database

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Johnsongrass

Scientific name: Sorghum halpense

Phenology models predict timing of events in an organism's development. For many organisms which cannot internally regulate their own temperature, development is dependent on temperatures to which they are exposed in the environment.

Information in this database comes from published articles. It may be used in conjunction with field monitoring and a degree-day calculator.

Note: Before using a model that was not field tested in your location, you should test the model for one or more seasons under your conditions to verify that it will work for you.

Model 1 of 1

Satorre, E.H., C.M. Ghersa, and A.M. Pataro. 1985. Prediction of Sorghum halepense (L.) Pers. rhizome sprout emergence in relation to air temperature. Weed Research 25:103-109.

Location of study: Rojas, Argentina (field studies)

Developmental threshold
Lower:59°F(15°C)

Method of calculation: Max-Min Method: Degree-days = [(Tmax - Tmin)/2] - To, where Tmax is the daily max air temperature, Tmin is the daily min air temperature, To is the lower threshold. Set Degree-days to 0 when To > (Tmax - Tmin)/2.

Degree-day accumulations required for each stage of development

Biofix: June 1 (Southern Hemisphere)

 DD (°F)DD (°C)
25% Rhizome sprout emergence from the soil surface342190
50% Rhizome sprout emergence from the soil surface630350
75% Rhizome sprout emergence from the soil surface1044580

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