Tuesday, September 9, 2014

Evaluation of raspberries for tunnel and field production in North Carolina

Evaluation of raspberries for tunnel and field production in North Carolina

Penelope Perkins-Veazie and Gina Fernandez

Raspberries are a highly popular fruit with consumers, and also a high value crop for producers.  One of the major limitations to production in North Carolina is heat.  Raspberry plants often respond to heat stress by reducing fruit size.  Also, the warm temperatures encountered during harvest can lead to a very short postharvest loss, as berries are softer and easier to bruise when harvested warm.  In this multi-year study, raspberry cultivars and NC breeding selections were evaluated in high tunnel and field production systems.

Harvest and Handling:  Pick firm fruit and place in shallow vented containers. Red raspberries can be harvested when pink and come off the plant with minimal tugging. The most often used container is a plastic ½ pint with vents in top, bottom, and sides to aid air flow. Containers for raspberries should be shallow, as only a few layers of berries should be in the box to prevent fruit collapse and leaking.  The best time to pick raspberries is early in the morning, while fruit are still cool.  Picking wet raspberries after rainfall or heavy dew is not recommended as the shelf life quickly drops.
Raspberries can be cooled at temperatures slightly below freezing (31 F) as the high sugar content acts as an anti-freeze.  It is better to cool fruit soon after harvest and hold raspberries below 40°F as long as possible.  If cooling is delayed, storage life is lost in proportion to the delay (a one hour delay can mean a one day loss in shelf life). 

Best cultivars and selections for postharvest life when grown in North Carolina. These suggestions are based on several years trials at research stations in NC. Check http://rubus.ces.ncsu.edu for yield data of these selections and cultivars. Note that some yield data is still being collected in fall 2014.
10-14 day shelf life if held at 35°F within 2 hours from harvest
Joan J

7-10 day shelf life            
For local use only (less than 5 days)

Thursday, July 24, 2014

Summer tissue sampling for fertility recommendations

Here is a re-post from last year, its almost time for you to take your leaf tissue samples

Now is the time to do some tissue sampling in blackberry. Plant tissue samples will help you determine needs and adjustments. IN NC, samples should be taken after fruit harvested from the plants. Leaves from the 3-5th node of the primocane plant should be sampled and sent to NCDA and they will make recommendations for the following season. Keep your records so you can see if there are trends in your fields. Below are the recommended levels of macro and micronutrients.

More about how to determine most recently matured leaf (MRML) is at http://www.ncagr.gov/agronomi/pdffiles/sampta.pdf

 Nutritional Status change for primocane MRML about 10 days - 2 weeks after harvest








Monday, July 21, 2014

Blackberry flowers to fruit: most fruit ripe or picked! (as of July 17)

For each cultivar, we tagged 5 flowers in the same field. As the season progressed, we had wind damage, picker damage and other sorts of damage. So in most cases, we ended up with less than 5 ripe fruit.  

As of July 17, most of the fruit we labeled in the field has been harvested. Only 2 Von samples were still in the field. 

Based on our guesstimates* of harvest dates, the number of days from flower to fruit are:

Natchez 51
Osage 44
Ouachita 51
Navaho 51
Von 58

* these are based on only 3-4 flowers, so what you may see in your field may vary. 

Thanks to Abby Whitaker and Daniel Shires for their help with data collection and taking pictures on all these dates. 

Wednesday, July 9, 2014

Blackberry flowers to fruit project: More ripe fruit July 3

Pictures from last week, July 3, show that Osage was picked, Natchez and Ouachita were ripe, Navaho is red and Von is still green. We have five fruit of each cultivar labeled, so there is some variation in ripeness. Once all fruit is black, we will average he number of days that it took five fruit to get from flowers to fruit in 2014. 

Sunday, June 29, 2014

Flowers to fruit June 27 seeing red and black!

Natchez won the race, it is the first cultivar to produce a ripe fruit. Two of the five flagged berries are ripe. One was picked before the picture was taken and this one was fully ripe. It took 38 days for this berry to go from a fully open flower to a ripe fruit. We will calculate the number of days for the rest of the fruit as they ripen and post that list at the end of the season.

The flower below was actually at a stage we call petal fall, the flower has been pollinated (you can tell because the anthers are all brown, indicating that the pollen has been released).  It was probably in full bloom a day or so before the picture was taken.

Ouachita, Osage, Navaho are all at the red stage. Von was the only cultivar that still had only  green fruit.

In this little trial, we are determining how long it takes a group of five berries to progress from a flower to a ripe fruit. Fruit in the field are at a range of stages. We have been picking Natchez, Osage and Ouachita in our research plots for over a week.

Photo credits and big thanks to Abby Whitaker and Daniel Shires. Photos taken at Killdeer Farm, Kings Mountain, NC.

Friday, June 20, 2014

Flowers to fruit images from 5 dates

Here is an update on the flower to fruit project. Thanks to Abby Whitaker and Daniel Shires for their work. Navaho, Osage and Natchez are showing a little color change. All of the other  cultivars are still green.

Note, in the field, Natchez, Ouachita, and Osage are already starting to to be picked in some locations. The images below are showing  how long it takes a marked flower to turn into a ripe fruit, and we started taking these images all on the same day.