Phenology is the study of seasonal
biological development. Growth of plants and animals is
dependent on food, nutrients, water, and light. Assuming that
these are abundant, the factor that determines the speed of
development is temperature. Models of crop and insect
development are thus based on daily temperatures. Developmental
stages are observed to follow the product of temperature and
time: Growing Degree-Days.
Orchard with Flowering Apricot-Trees
(1888, van Gogh
As cumulative Growing Degree-Days increase throughout the
season, milestones in development of each species are passed
when biological treatments and controls may be applied. The
effort and material required to secure future crops are
minimized by applying resources at optimal times.
Mankind's survival has always depended on the study of living
things. Calendars were essential to prepare for harvest and led
to writing and mathematics at the dawn of the Historical
In the 1960s, high-speed digital computing became cheaper, and
building elaborate mathematical models for the growth of plants
and animals became feasible.
How to Approximate Growing Degree-Days
Growing Degree-Days can be measured, but this is tedious to do.
Instead, phenological models are based on approximations. Given
minimum and maximum temperatures each day, an estimate of daily
Growing Degree-Days can be derived.
This announces an extension to
the WeeWX software suite by Tom
Keffer, Matthew Wall, and Gary Roderick, which runs on Linux
operating systems. The software interoperates with several
dozen brands of home and backyard weather stations. This
extension module calculates and charts cumulative Growing
Degree-Days, according to various published models. Also, it
provides a drop-in replacement for the WeeWX Image Generator.
The Phenology Image Generator implements transparent chart
Control of Codling
Codling moth (Cydia pomonella) is a major insect pest of
apples and other fruits and nuts worldwide. It is the
proverbial and the ecological "worm in the apple." The
development models for codling moth are advanced. This document
provides a real-world example, using
the Phenology WeeWX Extension to predict
when to spray control chemicals.
The Phenology WeeWX Extension is
written in Python 3. It was developed
for WeeWX 4.2.0 and has been tested with
Disclaimer: I am a sales associate for a worldwide
discount retailer. I am a systems analyst by training, and I
have worked in the field for a regional grocery distributor, a
worldwide consumer electronics manufacturer, and a "Big 10"
university. Beyond tending a backyard orchard, I have no
credentials whatever in the life sciences.
The information herein is drawn
from sites publicly available on the Internet.