You will notice that we have made a few changes to the Chill Portion data for this season. We have added last year’s historical data to each of the locations as you check the updates to give you an easy comparison from last season to this one. The data logger locations have been broken down into three regions of the county; North, Central, and South. This allows easier access to the data coming out of the region you may be interested in. 2016-2017 will also provide you with a regional historical summary over and above the historical data previously mentioned in each data logger site. Another addition is a regional spreadsheet that will be updated each time we read the loggers that will show the date each individual chill portion has been accumulated for that location. An additional three locations have been added to the Hwy 99 corridor. All sites will be read and updated every couple of weeks until we get closer to January 2017. As we approach and enter January we will then update on a weekly basis if possible. Keep in mind that this is far from an exact science but the website will give you plenty of data to consider and digest. Hopefully this data and information will help you better decide how to manage your cherries in the future.
Devencenzi Ag Pest Management & Research
Chill Portions And The Dynamic Model
Chill portions and the dynamic model have been utilized and implemented for some time now in local cherry orchards. We will not go into a complete dissertation on what they are and how they work; however, many research papers have been written on the subject by University of California. They are all available on the internet and go into detail on the subject. Keeping that in mind let’s discuss where we are at today.
The early rest breaking work done in cherries was based on chilling hours (accumulated hours at or below 45 degrees F), it became evident that they left a lot to be desired for determining the best timing for chemical rest breaking treatment. The Dynamic model, another way to collect and compute chill accumulation that originated in Israel was then considered. It was concluded that after considerable research, that it better predicted when to make a rest breaking application on cherry than the previous chill hour model. The timing parameters – which the model outputs as chill portions- were determined after that and we have been using this information ever since. The Dynamic model still has limitations related to the varieties (it as mainly on Bing) and rootstocks used in the tests. Since 2013 it has been recognized having accurate temperature data for the specific site where rest breaking treatments are being considered is important. Data collected as close as possible to the orchard could help better determine what is happening in there in terms of chilling than data from stations miles away. In Fall of 2013 we set up a network of stations that were closer to our clients’ orchards, than the regional stations used previously. We tried to have most off our orchards within 1.5 miles or closer to a data logging unit. As we could not place a unit in every orchard, this number seemed to be a reasonable place to start. So it was done in 2013-14 and again in 2014-15, with many of the data loggers in the same spots as the year prior. We ran approximately 15 units each year, compiled the data, provided it to our clients and eventually presented the data at the Cherry Research Review in 2014, and at Valent Product Update in 2015.
What we found was interesting. The Chill (CP) accumulation developed in the Winter of2013-2014 portions developed in the winter of 2013-14 showed quite a difference among locations. Chill was very low that winter, and many growers were reluctant to make rest breaking applications, thus most orchards had no rest breaking products applied. Orchards with more CPs ended up breaking bud much better than those areas that did not have the higher CPs, more uniform breaks and bloom, night and day. In 2014-15 we saw similar marginal chill conditions as the year prior, but we timed our rest breaking treatments to better correlate with the levels of chill received at each station. In the majority of the cases this approach helped considerably. Bud break and bloom was much stronger than the previous year where we did nothing and crop set was also much better. Over these last two warm winters we have also observed that. Colt rootstock appears to have the hardest time adapting to low chill conditions, followed by Mazzard, and -out of the three major rootstocks- Mahaleb appeared to respond best to rest breaking treatments made under low chill condition. You may already know this, maybe disagree, but that is what we have observed. I understand there is a lot of work being done with shading, overhead cooling, and bud analysis. I hope some of these trails end with a positive outcome.
The cherry industry has shown considerable interest in the chilling data that we have compiled . As we had ran the program entirely on our own, covering all costs, we were limited in our ability to expand the network to more areas. Realizing this, Devencenzi Ag decided to launch a program that would benefit more cherry growing areas of San Joaquin County. With the support of Valent U.S.A. we will be placing 43 data loggers throughout the county this winter, hopefully within 1.5 miles of most cherry blocks and provide the information to the public through this website. The units will initially be monitored twice a month and more often as we approach the time for rest breaking applications timing. They will run from November 1, 2016 – March 1, 2017. It is because of the support from Valent USA, and Sales Representatives like Robin Malm and Field Development Specialists such as Tino Lopez that this will be made available at no cost to growers. Next time you see these guys thank them for their interest and support!
We will provide up to date CP information to the best of our knowledge, but by no means are we providing advice or recommendations when to make applications to help break dormancy, what to use, or how much to use- unless you are one of our clients. If you are not, we encourage you to discuss rest breaking applications with your PCA. Keep in mind folks, that this is not an exact science by any means. We have tried to place all data loggers within a half mile or less of the point of reference. Some are closer, some a little farther depending on the site availability. If you are raising cherries and we do not have one close by we suggest using the data from the closest data logger available.
Other options would be to place one in your own orchard yourself or use data from other units that may be in the field. The California Cherry Board has been posting updated CP data collected from CIMIS stations over the years, and I assume they are still planning to continue to do so. From what I understand, many of the sheds also collect data and share it with their growers. Even if you collect your own data you will have ours there to compare it to.
Go to Cherry Chill Portions For California Data