New Chilling Model Website

The NC State Climate Office has updated their chilling model page. Here is the link and I have shown an example for Hendersonville NC for Jan 3, 2022 below.

https://products.climate.ncsu.edu/ag/chill-models/

First you select a model (I prefer the Warmund and Krumme) Model, it takes into account when the temperatures get warm.

The Yazetti and Clark model is also popular.

Select Model(s):

Blueberries (Mainland Model)
Blackberries (Yazetti and Clark Model)
Blackberries (0° to 7°C model with first incidence of  -2.2°C)
Blackberries (Modified Richardson Model)
Blackberries (Warmund and Krumme)
Peaches (Richardson Model)
Apples (Shaltout and Unrath Model)
7.2°C Model (45°F Model)
0° to 7.2°C Model (32° to 45°F Model)

 

Then click on the map to a location that you want, here I chose Hendersonville, NC. 

For Hendersonville Jan 3, 2022, there are 590 chilling hours. On the website, you can see how the chilling has accumulated over time. Late in December there were 621 but the warmer temperatures in the last few days there has been a loss of chilling at this (and probably many other locations).
 

What does this mean? 

Most fruit crops grown in NC require a period of cool weather before they break dormancy and start to grow.  Most blackberries require 400-800 units of chilling. If they do not receive enough chilling you can see irregular bud break (this is common in southern GA, LA, AL, MS and FL). If they have received enough chilling, they will break bud when it is warm. Often times those buds that have started to emerge may get injured by late season cool weather. 

So it is good to monitor what chilling has occurred in an area so you can match those units with the stage of your crop. 

There is also a handy tutorial if you want more informationn

https://products.climate.ncsu.edu/ag/chill-models/#tutorial

Crop Phenology Revisited

It has been a cool spring, but the buds are finally breaking. Now is the time to find that notebook with last years key dates of things happening in the plants growth, also known as phenology.  Some of these events are bud break, bloom, primocane emergence, and harvest.

I posted a longer discussion on phenology last year. Here is a link to that site.


http://teamrubus.blogspot.com/2012/04/crop-phenology-when-things-happen.html

RCA trellis with covers

RCA trellis with rowcover, Piedmont Research Station, Salisbury, NC. Photo: K. Snider. 

Blackberry canes with emerged buds, under rowcovers. Photo: K. Snider. 

At the Piedmont Research Station in Salisbury, NC, we have a set of four RCA trellises oriented  North/South and East/West. The primary objective of this project is to evaluate attributes of fresh blackberry fruit. We are most interested in the level of sun scald based injury to fruit based on canopy orientation.

However, the RCA trellis is used in colder regions of the country as a way to grow varieties that are not cold hardy. In North Carolina, twice in the past decade, we have experienced low temperatures (8 April 2007 and 12 April 2012)  that have resulted in significant crop loss. Developing flower buds and therefore the blackberry crop were killed by late season frost/freeze events. So, we are looking at this trellis system as an option for protection from cold in NC.

Temperatures at the Piedmont Research Station in Salisbury, NC, for the have been cold, 20F on 21 March. We had emerged buds so we protected blackberry plants under rowcovers. Although the buds would likely have survived, we wanted to protect them, just in case. We have data loggers recording temperatures under the covers and will download them next time we get to the field and update this post to include those temperatures.

Budbreak 2013

Black raspberry bud 14 March 2013. 

Navaho bud 14 March 2013. 

Prime-Ark 45 bud 14 March 2013

Von bud 14 March 2013

Budbreak on this first day of spring appears to be holding off due to the cooler temperatures we have been experiencing in NC. These pictures were taken at the Sandhills Research Station last week by my student, CM Bradish. Only Prime-Ark 45 is showing any signs of green leaves.

I was looking at the Team Rubus blog post from last year and see that in March (10th), at the CEFS pruning demonstration, blackberry buds were a bit tighter, but not much. http://teamrubus.blogspot.com/2012/03/pruning-workshop-at-center-for.html

No budbreak at this time is a good thing. We have accumulated plenty of chilling and once it gets warm, these buds will grow quickly. We don't need a repeat of 12 April 2012 when flower buds were killed by low temperatures. http://teamrubus.blogspot.com/2012/04/freeze-2012-field-visits.html

If you have time to take some pictures and send them to me (labeled with variety and date photo taken), it would be great to have a snapshot in time from various locations, to see how the crop is developing.

Gina_Fernandez@ncsu.edu

Chillin' in NC?

Today it was 56 F in Raleigh, NC. I am loving the warm temperatures, but I am getting worried about lack of chilling. As of 4 pm today, we have accumulated 119 chilling hours, last year on the same date, we had 399 hours. We usually get about 1000 or more hours in the area.

High chilling/low chilling. Most of the blackberries and raspberries we grow in NC need to accumulate a high number of chilling hours in order to break bud and grow 'normally' next summer. Contrary to what you may initially think, we don't want low chilling plants. We want high chilling plants that can stay dormant when we get January thaws. However, this year it does not look like we are making progress to that high chilling number. We will be keeping track of it over the next few weeks. 

If you live in the SEUS, you can find probably find out the chilling hours in your area.  The NC State Climate office has a great tool you can use if you want to calculate the chilling hours in your area. Here is a link. http://www.nc-climate.ncsu.edu/cronos/blackberry/