Using models as Orchard Decision Aids
- PDF file covering the idea of using forecast models for apple pest and crop
Introduction - PDF file on how Orchard Radar works and some
1) Use your common sense in applying this information.
Orchard Radar provides educated guesses to be used as supplementary tools for IPM decision making.
decision making tools are the experience and knowledge between your ears,
input from direct orchard observations. Final judgment and
responsibility lies with the grower. The University of Maine
is not liable for over-reliance or misuse of pest forecast
2) Be cautious in
extrapolating from one location to another. Temperature,
and especially rain, estimates for the nearest Radar site may not
accurately reflect conditions at your location.
3) Each table or
chart shows the time when forecast values begin. This time should be 2AM
or 2PM of today's date. If an older date is showing, try selecting
"Refresh" from the Internet Explorer View menu (hitting the F5 function key does
the same thing) This forces the browser to retrieve the file from the web
instead of using a older version of the file stored on your computer from a
previous browsing session.
Not all pages are updated every day. Only those Radar web pages
that will be affected by new weather information are updated each day. For example,
the Flyspeck respray interval tables for August will not change until August dates come
into the 10 day forecast range. So those tables do not begin updating until late
July. For the same reason, once a table or chart has all of the data it will ever
need, it stops being updated.
Orchard Radar is updated three times a day, 7 days a week,
starting at approximately
4:20am, 5:30am, and 3:50pm. The update times for
each site are shown below the "32 Day Rain Chart".
Charts and tables are designed for a minimum screen resolution of
1024 x 768.
Be nice to your eyes, read
your Orchard Radar display.
To better understand how the estimates are made, read the
background information pages. Each model
output in table format has a link to the background page for
Why call it
Radar' is a catchy name for a simple concept: using desktop computers and the
internet to acquire updated weather observation and forecast data, feed it into apple
pest management and horticulture models, and then use the internet to distribute the
output to growers.
use the term "Radar" because it implies an appropriate way to view these
products as tools that help you gauge the relative nearness (in time) or size
(severity) of something. Orchard Radar gives you early warning about
apple pest risks similar to the way true radar indicates the
nearness and size of an approaching object. These products are only like radar in
this conceptual sense. There is no direct use of radar technology in translating
the weather data into orchard estimates.
familiar with relationships between weather variables such as temperature and
rainfall and events in the field. Some of these relationships are simple,
like knowing that warm weather leads to earlier bloom or maturity date. Others are
more detailed, such as the interactions of temperature, rain, and leaf wetness on
apple scab infection potential.
relationships have been formally quantified and published in scientific
literature. Others are used as informal "rules of
thumb", such as "Imidan coverage on foliage loses effect if there is two inches
of accumulated rain during the 10 days after application, or if that does not
happen, after 1.5 inches accumulated rain up to a maximum of 14 days." The
models that make up Orchard Radar consist of both formal and informal
relationships have been known for years, but the difficulty in collecting
and processing weather data on individual grower computers has prevented full use of the
available information by orchard decision makers. The emergence of the
internet into mainstream use has provided a path by which a single computer can handle the
large volume of weather data for multiple sites, process that data, and then quickly,
inexpensively, and automatically broadcast the estimates to growers.
As with any decision-making aid, common sense is required to use Orchard Radar
tool prudently and effectively. There is no guarantee
for the validity of each model for each location
These are experimental
tools still undergoing development.
Grower feedback is important
and appreciated. Are there better ways to
present the information? Which Orchard Radar products are useful, which are
Some people associate the term "model" with either God-like accuracy or
useless numerical futility. The truth is between those two extremes. Orchard Radar,
like much of agricultural decision making, is educated guessing.
intention in providing Orchard Radar is NOT to have a machine attempting to make
management decisions. The intention is to improve the quality of the
information base upon which YOU make decisions. In no way is Orchard Radar
intended to reduce reliance on your existing means of arriving at decisions. As with
any other source of information, you should look at the Radar estimates as one more piece
of the puzzle.
My hope is
that with experience in referring to the Radar products and how they relate to the real
world in your orchard, you will find that they are a useful addition to your Management
toolbox. Like any tool (including pesticides), the Orchard Radar products are only
useful to the degree that they are used properly.
data are tailored for specific orchard locations by interpolating between values received
from surrounding National Weather Service reporting sites. Be cautious in extrapolating from another site to yours. Some rains are
caused by the movement of large fronts that deliver consistent amounts of
rain across large areas. Other rains, such as summer
thunderstorms, can be a very localized event, causing a nearby site to have estimates that
do not match conditions at your location.
In addition to interpreting weather observations, the Orchard Radar also uses
forecast data. Weather forecasting is less than perfect, but it is much
better than using simple climatic averages. Rain forecasting is
significantly better than climatology out to about 5 days. Temperature forecasting is
significantly better than climatology out to about 7 days.
Radar uses forecast information out to 10 days, but the last 3 days
are essentially just a trend back to the climatic average, not daily specific forecasts.
Beyond 10 days it uses climatology to provide useful guidance for
‘about when’ things are likely to happen.
the date of a predicted event approaches, climatic and forecast
values used in the estimate are replaced by observed values.
Thus, the nearer the event, the better the estimate.