Monday, February 13, 2012

Oral Cancer Expert Finds Unexpected Treatment Breakthrough From Raspberries and Old Breast Cancer Therapy

Oral Cancer Expert Finds Unexpected Treatment Breakthrough From Raspberries and Old Breast Cancer Therapy

And....We are starting a large project on black raspberries with the folks at USDA-ARS Corvallis, The Ohio State Univ and Cornell. Look for more exciting black raspberry news in the upcoming years.

Sunday, February 12, 2012

Sweet Repeat Raspberry

Sweet Repeat Raspberry
This is our 'Nantahala', we hope the gardeners out there like it. It really does have an exceptional flavor.

Saturday, February 11, 2012

Chilling part 4

We have made a slight modification to the blackberry chilling model. The model now uses instantaneous temperatures for calculating the inception date for all models. Up until a few days ago, the model used hourly average temperatures to determine when the model starts for a season.  So now, the model now starts about a month earlier, and we have many more hours.  Today at 8 am we have 735 hours. We are still short of what we normally get, but have a few weeks in February to accumulate some more chilling.

With the adjustment in the model, most of the blackberry and raspberry cultivars we grow here have met or are getting close to meeting their chilling requirement for the year.  Many of the selections in my field in Salisbury, NC are breaking bud. We will be monitoring them closely for the next few weeks.

Sunday, February 5, 2012

Chillin' in NC part 3

Based on the blackberry chilling model, as of 2 pm EST today, we have accumulated 343 chilling hours in Raleigh, NC this season.  This is far below where we were last year at this time, at 728 hrs.

The blackberry model accumulates 1 chill unit when temperature is between 0 and 7° C. Chilling inception occurs at the first incidence of -2.2° C (28F). This last part, the inception date,  I believe it the primary problem of the model. This temperature did not occur until December 29, 2011, more than 3 weeks later than the year before (12/06/10).

I am not sure that the blackberry model is valid in assuming the inception date based on a minimum temperature trigger. Other models start on a certain date or in the case of blueberry, once the positive balance is not negated by warm weather (see model definition and link below). Based on the blueberry model, we have accumulated 1055 chilling hours at the same location.

Which one is best? I don't know, I hope we will accumulate more chilling this month. My instincts  say that we should be fine and that the plants have accumulated more than the blackberry model has determined. And... we are taking bud break data and will be watching growth this summer.

The blackberry chilling model posted at 

Blackberry Model accumulates 1 chill unit when temperature is between 0 and 7° C. Chilling inception occurs at the first incidence of -2.2° C.
Warmund, Michele R., and J. Krumme, "A Chilling Model to Estimate Rest Completion of Erect Blackberries," HortScience 40(5):1259-1262. 2005.

I will be following the blueberry model as well, 

Blueberry Model accumulates 1 point for average hourly temperatures below 45° F; 0.5 point for temperatures 45-55° F; -0.25 point from 55-65° F; -1 point for temperatures 65° F and above. The model begins when it has a positive balance that is not negated by warmer weather. Once 800+ chill hours have accumulated, points are no longer negated for temperatures 55° and above. The model ends February 28 at midnight. 

Chillin' in NC part 2

The warm weather continues in NC, articles are appearing in newspapers and we have yet to see a snowflake. And many folks are asking what is happening to the plants and in particular, will they have enough chilling hours this winter to grow normally in the 2012 season.

In the Jan 10th post I discussed chilling hours. Since then, I have been asked by a few folks, what the required number of chilling hours are for different fruit. Here is a table that I use for class. Please note that these are general number of chilling hours and within each type of fruit crop, there are large differences among cultivars.

In general, inadequate chilling would result in low vigor and low productivity.

Grape (vinifera)
Grape (labrusca)
Blueberry (Rabbiteye)
Blueberry (Highbush)
Blackberry (Thorny)
Blackberry (Thornless)

In general, these are the conditions that are used to measure chilling hours:

  • Period of cold temperature during the winter to induce dormancy and promote satisfactory shoot and fruit development
  • Temperatures most effective: 37-55°F
  • Most commonly used for calculation 32 and 45 ° F
  • Freezing temperatures are ineffectual
  • Temperatures above 59 ° F will reverse chilling accumulation
But each crop has its own model, including blackberry. That will be the topic of the next post.