In Field Weather Data: Chilling
Mother nature plays an important role in Agriculture. Chill accumulation is one of those important roles. In stone and pome fruit trees, chilling hours are required for flower and leaf buds to develop. Lack of chill hours during winter will trap the tree from completely leaving its dormancy stage and will result in physiological symptoms. These symptoms include delayed or extended bloom, delayed foliation and reduced fruit set and quality.
Historically, growers track this data to prepare for the upcoming season and compare to past years orchard management practices. Chill Hours and Dynamic (cumulative) Chill Portions are two models growers use to track this data.Â
There are many ways to gather this data, one would be to look up local public weather stations in the area. However, we have found that weather can vary greatly in a small geographic area. Owning your own, personal weather station will give you the most accurate data for your ranch and will track this data for you automatically.
Chilling Models
Chill Hours:
There are several models under the “chill hours” umbrella. All of these models start on November 1st. 1) Hours below 45°F model; 2)Hours between 32°F and 45°F model; and 3) Utah model, this model breaks down in .5 hour increments based on temperature and also accounts for (-) hours when over 60°F. Â
Dynamic Portion Model:
The calculation of “chill portions” through the Dynamic Chill Model has only been available since 2006, this model is still developing as new research comes in. However, this model does a good job of both capturing early chill as well as accommodating for warmer temperatures and how they affect our chilling. This model starts September 1st and uses a range of temperatures around 35-55°F and cancels “portions” when warmer temperatures arise.
Gathering Your Data...
All of the chilling models require hourly temperature data for the calculation… This can be difficult however we have several options to help with this. Check out CIMIS to find a station in your area, you can download hourly data from here. However, you may find the nearest station is quite a ways from your location.
Another option would be your own personal weather station. A few years ago this option may not have seemed economical, however emerging technology and competing companies has made this much more feasible.
At Landmark we offer complete Davis Weather Stations to place in one or all of your ranches. With our Davis Weather Stations and their proprietary Mobilize app, you can easily set up and visualize your chill accumulations plus much more.
Whether you prefer Dynamic (cumulative) Chill Portions or Chilling Hours/Utah Chilling Units, they have it all. Set your start date and target hours to customize your needs.
