Phenology — Phenology Models

4.4 Phenology Models

The repertoire of models is given in $SKIN_ROOT/Phenology/phenology.conf. It has one stanza: [Phenologies]. Each species of crop and pest has its own stanza within [Phenologies], for example:

[Phenologies]      
    [[Cydia pomonella]]
        name_common = "Codling Moth"

Within the species stanza are stanzas for each model that pertains to the species. These models are drawn principally from U. C. Agriculture and Natural Resources and Coop, for example:

        [[[Model C0038]]]

#         Bethell, R. S.  1978.  Pear pest management.  U.C. Div. Agr. Sci.
#         Publ. #4086. pp. 22-41.

#         Location of study:  California

          ref = "http://ipm.ucanr.edu/PHENOLOGY/ma-codling_moth.html"

          threshold = 11.1, degree_C
          cutoff = 27.8, degree_C
          method = dd_conventional
#         start_date = When twilight temperatures are > 60°F (15.6°C)
          start_date = Jan, 1

          [[[[Stages]]]]
#           Host  Pear
            "Eggs" = 88.9, degree_C_day
#           "Larvae" = 263.9, degree_C_day
#           "Pupae" = 222.2, degree_C_day
#           "Generation time (egg to adult)" = 575.0, degree_C_day
#           "Pre-egglaying adults" = 27.8, degree_C_day
#           "Generation time (egg to egg)" = 602.8, degree_C_day
#           "Start of adult emergence" = 402.8, degree_C_day
#           "First hatch of their eggs" = 430.6, degree_C_day

Note that this model was tested on the West Coast for codling moth on pear trees. It may have limited applicability in the Midwest on apples. When choosing an insect-development model, be sure to check the host crop and the region of the country where the research was done. Find one that was validated near you.

The Phenology extension assigns a unique number to each model. This one is C0038.

4.4.1 start_date

C0038 requires a start_date. A start_date of New Year's Day is given, but this is not appropriate. If you decide to use this model, you are expected to edit phenology.conf to change the start_date each season to record the advance of "twilight temperatures."

Once a start_date is recorded and 90 Growing Degree-Days Celsius (GDDC) have accumulated thereafter, codling moth eggs will likely be present. If you choose this model, the cumulative_growing_degree_days.html report displays this. This model predicts several stages of codling moth development, but only the "Eggs" stage will show in the report because the others are commented out. You may, of course, edit phenology.conf to show whichever stages you wish.

4.4.2 Southern Hemisphere Adjustment

The [Phenologies] stanza has one scalar, which is normally commented out:

[Phenologies]
#    southern_hemisphere_start_month_offset = 6

All the models were developed and tested in the Northern Hemisphere. Consequently their start dates typically are in midwinter. These start dates are not appropriate for the Southern Hemisphere because they occur in midsummer there. If you plan to run the Phenology extension in the Southern Hemisphere, please change the start dates of the models you are using or at least uncomment the scalar.

4.4.3 Biofixes

Some models rely on a "biofix" rather than a "start_date." M001 is such a model. Instead of a date, biofix specifies a Growing Degree-Day base. Then stages of development are assumed to be offsets relative to this base, rather than relative to zero on some arbitrary start date. If you choose one of these models, you will need to modify phenology.conf each season to provide the Growing Degree-Days at which you observe the biofix, whatever it is; otherwise, the cumulative_growing_degree_days.html report will not show any development stages.

4.5 Skin Mods

The Phenology extension is released with the M001, C0004, and C0023 models pre-selected as examples. Here is the Extras stanza of $SKIN_ROOT/Phenology/skin.conf:

[Extras]
    phenologies = phenology.conf
    models = M001, C0004, C0023

You will wish to modify Phenology/skin.conf to specify only the models of interest to you.

4.5.1 generation_date

The Extras stanza of Phenology/skin.conf can contain a "generation_date" scalar:

[Extras]
#    generation_date = 2018, 6, 30, 0, 0

This is not meant to be used day-to-day and should normally remain commented out, but it may be helpful occasionally when you want to take a backward peek at what the models would have shown in previous seasons.

4.5.2 Charts

The Growing Degree-Day charts produced by the Phenology extension are four-week charts and are specified in the [[four-week_images]] stanza of $SKIN_ROOT/Phenology/skin.conf:

[ImageGenerator]
    [[four-week_images]]
        [[[Codling Moth]]]
            [[[[M001_accum]]]]
        [[[Apple Maggot]]]
            [[[[C0004_accum]]]]
        [[[Cabbage Maggot]]]
            [[[[C0023_accum]]]]

The model numbers to be charted must match exactly those listed in the "models" scalar of the [Extras] stanza. When you change them there, please change them here, as well.

The file name of each chart is the stanza name. Thus, the chart for the M001 model is named $HTML_ROOT/phenology/Codling Moth.png. Be aware that both $HTML_ROOT/phenology/index.html and $HTML_ROOT/phenology/cumulative_growing_degree_days.html show these charts and expect them to be named according to the common name of the species modeled. Please use the common names as the chart names. That is, the common name of the species modeled, the stanza name, and the chart file name have to be identical.

4.6 Restart WeeWX

After you make changes to the models to be charted, you need to restart XTypes Services so that the Report Generator can use the models.

sudo /etc/init.d/weewx stop
sudo /etc/init.d/weewx start

— or —

sudo systemctl stop weewx
sudo systemctl start weewx