Frost

Click here to access Frost Tolerance Reports

How Does the Frost Service Work?

We are all well aware that this spring has been early and cold, with the CCCGA Frost Service issuing numerous times already. The purpose of this communication is to explain some of the nuances for how the Frost Committee and the resulting Frost Service operates, as there has been some recent questions raised by growers and we thought it was a good time to refresh everyone on how things work and get some of the questions answered. There is a lot of science and hard work that goes into the Frost Service and valuable resources that can help make predicting a frost event on your own bog a little less stressful.

What Is The CCCGA Frost Committee?

The Frost Committee is a collaboration of CCCGA staff, growers and researchers that are tasked with providing the frost warning service to CCCGA members. The committee meets several times a year to evaluate the program. Committee members also participate in checking for bud or berry tolerance weekly during the growing season. The committee is chaired by Glenn Reid and its members include Gavin Bartlett, Scott Conner, Carolyn DeMoranville, Keith Mann, Mary McCaffrey, Rob Rubini and Erika Saalau-Rojas. Other researchers from the Cranberry Station assist as well, such as Peter Jeranyama and Giverson Mupambi. CCCGA staff provide much of the support for the committee, plus their own experiences and this includes Anne Cote, Patti Silvia and Brian Wick.

What is the CCCGA Frost Service?

The Frost Service puts the work of the Frost Committee to use each day and night during the spring and fall or when the weather indicates otherwise. Anne Cote supervises the frost warning service, with the assistance of Patti Silvia. They are the dedicated voices that you hear on frost nights with over 30 plus years of experience. They calculate for frost at noon time and then again in the evening, every day. They utilize the formulas and processes that were developed by the Cranberry Station’s first director, Dr. Franklin, back in the 1930s. The Frost Service, along with the chair of the Frost Committee compares information each night before deciding to issue a warning. If a frost is determined to be occurring that night, the calls/texts are made as appropriate. You all should be getting those and the Frost Advisory that is mailed to members each year has more details on the frost issuances.

Why Don’t You Issue Frost Warnings For The Newer Hybrid Varieties?

We do! There is not as much research on the newer hybrids but a good rule of thumb that we suggest is that early season varieties act more like Ben Lears and later season are like Stevens. There are so many different varieties now, this is just a general observation. A lot depends on what the dominant parent crosses are, check with your breeder or vine source. You also should adjust your tolerance based on your own location and experience with hybrid vines.

Where Are The Photos You Used To Include On The Text Message?

The UMass Cranberry Station has an extensive collection of photographs of buds at different stages of development. They have also created a new Spring and Fall Frost Guide that is full of excellent pictures and information. All of these are available on the Cranberry Station’s web site at www.umass.edu/cranberry. There are printed frost guides available at the Cranberry Station and CCCGA office for free but with the COVID-19 situation, those offices are closed. If any grower wants a guide now, you can print one off of the UMass web site.

How Is Tolerance Determined?

Each week, members of the CCCGA Frost Committee visit Rosebrook Bog in Wareham and look at beds of Ben Lear, Early Black, Howes and Stevens. They then compare these buds to the Frost Guide and their own experience to determine tolerance for each variety. After the visual determination is made, researchers also bring buds back to the Cranberry Station, are sliced under a microscope and their internal structure observed, including looking for any frost damage. This helps to reinforce what is being visually observed. The science shows that in some springs, particularly when it has been warm than a prolonged period of cold, that the buds start to develop and then appear to stop. However, inside, the buds are advancing and can be more susceptible to damage than what the naked eye may expect. Tolerance is very much part science, observation and experience.

I Thought You Were Using Degree Day Models To Determine Tolerance?

In trying to bring as much science into the process as possible, the Frost Committee is evaluating the use of a few different degree day models. These can be used to help determine when frost protection should be starting in the spring based on temperature. However, as we are learning, they are more accurate in some years than others. We will continue to use and evaluate these models and learn from them. It would be great to be able to rely completely on a degree day model but they are not yet reliable enough to use as stand-alone tool. You still cannot beat personal experience and visual clues.

Why Do You Only Use Rosebrook Bog For Establishing Tolerance?

Dr. Franklin established the frost formula and tolerance process that is still largely used today by using the vines at State Bog at the Cranberry Station. When Route 25 was built, State Bog became warmer than it historically had and then in 2010, the bog was renovated, further changing how it had run. The decision was made that Rosebrook Bog was similarly located to State Bog but was more representative of how State Bob used to progress in the spring and fall. Rosebrook also has all of the major varieties at one location, keeping an important level of consistency.

Why Do The Tolerances Seem To Be Higher Than What I’m Seeing On My Bog?

Tolerance checks are performed once per week, more if needed. Depending on the weather, the buds may progress at varying speeds. The tolerance is also only checked at one location, as noted above. Growers in different locations and with very specific climatic conditions are going to have different tolerances. The Committee always errs on the side of caution, often having higher tolerances because conditions may change quickly in a week’s time and they don’t want growers to be caught unprotected. It’s better to be conservative and over protect than to be cavalier and miss protection. The tolerance established by the Frost Committee is intended to be a guide. Growers should always compare what the committee sees with their own bog and then adjust as necessary. Further, growers may wish to look at their own vines and then compare what you see with how that compares to the Frost Guide and/or the pictures on the Station’s web site.

Does The Frost Committee Use Vines Along The Edge To Determine Tolerance?

No, the committee uses interior vines from a similar spot on the bed each time, for consistency. They do not seek out a rogue advanced bud or berry but they do make note of what could be representative of as little as 5-10% of the bed. The reason is that a grower does not want to lose 10% of their crop potential by not protecting for the advanced buds or berries. Again, this is a conservative approach and individual growers may have more comfort not protecting based on their own conditions and experience.

Why Do You Issue on Nights When You Know There’s Not Going To Be A Frost?

There are several different categories of frost potential, all of which are explained in the CCCGA Frost Advisory. Besides running the formulas, the weather is also considered carefully. You know the New England weather, it’s never reliable. If there is an opportunity for clouds to clear or pockets of the growing region to be conducive for frost conditions, we are going to issue in order to make growers aware. This doesn’t mean that you should frost protect. We always explain why we are issuing on these marginal nights and it’s just what it’s intended to be, a warning of a possible frost. This enables growers to be aware without necessarily having to protect. As you have probably gathered by now, the work of the frost employees is to be conservative with frost warnings and better to be safe than sorry.

Why Do You Use So Many Abbreviations On The Text Messages?

CCCGA is charged for each character of text, as well as the length of the phone calls when we issue for frost. We try to save money where possible yet still get the relevant information out to growers as quickly as possible. The abbreviated text messages save your Association money over the course of the season. This is also why we ask growers to choose either text or phone messaging and to have only those that need these messages to be included on the list each year. It all adds up.

In closing, we hope that you have found this information useful and may have answered some of your most common frost related questions. We can’t emphasize this enough, the Frost Warning Service is a guide for what growers may be experiencing on their bogs. Ultimately, the individual grower needs to determine what is the best course of action on their bog. Location, variety, management practices and experience are all factors that growers should be utilizing when making frost management decisions. The CCCGA Frost Service is there to help guide growers along that decision path.

With a cross-section of growers, researchers and experienced staff, the Frost Committee is a good team working on your behalf. If you have further questions or concerns, please let us know. Talk to a member of the committee or contact CCCGA and if we can’t answer your question, we can put you in touch with the right person who can.

You can also download this chart by clicking here.

The Spring Frost Tolerances Photo Fact Sheet is available for pick up at the Cranberry Station and the Cape Cod Cranberry Growers' Association.

You may also download it by clicking here.

The Fall Frost Tolerance Photo Fact Sheet can be accessed by clicking here.