Friday, September 23, 2011

By Penelope Perkins-Veazie, Plants for Human Health Institute, North Carolina State University and Gina Fernandez, Department of Horticultural Science NC State University

Raspberries are the most perishable of the temperate fruit crops. If you set them on your kitchen counter, you can watch the mold grow within 24 hours. This fruit’s delicate nature is due to its fragile structure, where drupelets are connected together by only a few trichomes (fruit hairs), no cuticle is present, and gray mold (Botrytis cinerea) can set up spores during bloom and produce fuzzy gray fruit as the berries are ripening.

While raspberry fruit mostly produce ethylene from the fruit calyx (the part of the fruit that remains on the plant), there is a small amount of ethylene, the fruit ripening hormone, present in many varieties. This actually can pose an advantage for fruit growers producing raspberries in the warmer parts of the season. Fruit at the pink or even pink-yellow stage will often detach from the calyx with minimal tugging.

We initiated a small test in 2010 to investigate the ability of raspberries to attain full ripeness if harvested unripe. These fruit were harvested in August and September from plants grown in high tunnels at the Upper Mountain Research Station, Laurel Springs, NC. Temperatures within the tunnels were above 85°F for approximately four hours per day. Unripe and ripe raspberries were picked at weekly intervals for the tests, over a three-week period, and one to two clamshells per cultivar and ripeness were used for the study.

Raspberries were picked into halfpint clamshells and transported at 5°C in refrigerated ice chests (Kooltron) to Kannapolis, and held at 39 °F for six days. Subsamples were removed at day 0 to check firmness, color, sugars, and acidity. Subjective ratings were taken after storage by checking each berry for softness, leak, and mold. The overall color of the fruit within the clamshell was determined subjectively as 0 (light red) to 3 (dark purple red). Percent saleable fruit was determined by using the relationship of color to percent (where rating of 0 was 100% saleable to 3 was 0% saleable).

Surprisingly, even fruit picked considerably unripe (yellow-pink) achieved full color, soluble solids content, acidity, and flavor (tasted at random) after six days storage (Table 1). The biggest disadvantage of picking unripe berries was a depression in berry size of 4% to 20%, depending on variety and relative ripeness at harvest. What was clear from ratings was that fruit picked pink was much firmer and less leaky than berries picked at the normal commercial fresh market ripe stage (Table 2). The amount of moldy berries was slight (less than 10%), due to a rigorous fungicide spray program and the protective effect of the tunnels from moisture and wind.

We hoped that berries varieties known to turn dark red after storage, such as Joan J, would be less fully red if picked pink prior to storage. In fact, we found that color could not be slowed enough, with fruit reaching full color as soon as 2 days at 39° F after harvest. Figure 1 illustrates the change in color of ‘Culivar’ in ripe and unripe berries at 0, 5 and 10 days after harvest.

Flavonoids are compounds are compounds that are associated with health benefits, and higher levels in fruit are good. Flavonoids in raspberry include the anthocyanins that give raspberries much of their red color, along with other colorless phenolic compounds. In raspberries picked before full ripeness, flavonoid content was decreased by 5-15% after storage. The slight loss in flavonoids in the less ripe fruit was madeup in the better appearance and firmness of the raspberries.

Harvesting raspberries at the pink stage is possible. We did not observe significant problems with composition and flavor, and early picking improves the number of marketable fruit. However, harvesting less ripe fruit is likely dependent on air temperature (detaching raspberries is difficult in cool weather), and will require more attention and training of pickers during harvest than pulling off fully ripe berries. Although we did not determine optimal temperatures for picking unripe berries in this study, the ability of raspberries to fully color up and soften may depend greatly on having a production environment where temperatures are at 75° F for at least four hours.

Table 1. Comparison of raspberry fruit harvested unripe (pink) or ripe (red)
before and after storage at 4C, averaged for Joan J, Nantahala, Caroline
Variant	Days	Unripe	Ripe	Mean
Total phenolics	0	2858	2866	2862
(mg/kg gallic acid equivalents)	6	3090	3144	3117*
Total anthocyanin	0	508	530	519
(mg/kg cyan-3-glucoside equivalents)	6	510	589	550*
FRAP (Ferric reducing antioxidant potential)	0	28.6	26.8	27.7
(umol/g trolox equivalents)	6	28.5	28.8	28.6
Soluble solids content (%)	0	11.2	10.9	11.1
	6	11.9	11.7	11.8
Titratable acidity (%)	0	1.23	1.26	1.24
	6	1.05*	1.19*	1.12*
Means separated within column and days 0,6 using student's t-test, P<5%.

Table 2. Comparison of raspberries picked unripe (pink) or ripe (red) after storage at 4C for 6 days
	%Leaky berries		%Soft		%Saleable	color
Variety	Unripe	Ripe	Unripe	Ripe	Unripe	Ripe
Autumn Britten	1a	42b	48ab	93a	43b	7b
Caroline	8a	19a	61a	86ab	47b	33ab
Nantahala	2a	37b	38b	75b	67a	47a
Mean	3a	33*	49	82*	52	29*
Means separated within column among cultivars, by letter (P<5%) using REGWQ.

The original version of this article (including photos) appears in Autumn 2011 issue of "The Bramble." To access this article, you must be a member of the North American Raspberry and Blackberry Association. To become a member to: http://www.raspberryblackberry.com/index.cfm and click on Membership in the left purple panel.

Monday, September 12, 2011

Fall Caneberry Field Work 2011

Blackberry and Raspberry (Caneberry/Bramble) Field Work for Fall 2011

Gina Fernandez, Small Fruit Specialist, North Carolina State University

Plant growth and development
• Primocanes continue to grow, but slow down
• Flower buds start to form
• Primocane leaves senesce late fall

Harvest
• Primocane fruit harvest continues until frost

Pruning and trellising
• Spent floricanes should be removed asap
• Optimal time to prune is after the coldest part of the season is over. However pruning can start in late fall if plantings are large (late winter for smaller plantings)
• Start trellis repairs after plants have defoliated

Weed management
• Many summer weed problems can be best managed in the fall and winter using preemergent herbicides. Determine what weeds have been or could be a problem in your area. Check with your states agricultural chemical manual and local extension agent for the best-labeled chemicals to control these weeds.

Insect and disease scouting
• Continue scouting for insects and diseases.
• Remove damaged canes as soon as possible to lessen the impact of the pest.
• Check the Southern Regional Bramble integrated Management Guide for recommendations. http://www.smallfruits.org
• Also check out Hannah Burrack’s blog. She posts timely information on insects of interest. http://ncsmallfruitsipm.blogspot.com/

Planting
• Growers in warmer areas (e.g. extreme southeastern NC) can plant in December. Preparations for winter planting should have already been made. If you have questions about winter planting please contact me at the above email address.
• Prepare list of cultivars for next year’s new plantings. Find lists of nurseries at http://ncsu.edu/enterprises/blackberries-raspberries/?page_id=1496

Fertilizer
• Take soil tests to determine fertility needs for spring plantings.
• Non-nitrogenous fertilizers are best applied in the fall to established plantings.
• If soil is bare, plant an overwintering cover crop (e.g. rye) to build organic matter and slow soil erosion.

Marketing and miscellaneous
• Order containers for next season
• Make contacts for selling fruit next season

Make plans to attend Grower meetings! Blackberries and raspberries are part or all of these programs.
The 2012 North American Raspberry & Blackberry Conference will be January 16-18, 2012 in Sandusky, Ohio, in association w/Ohio Produce Growers and Marketers Association. http://www.raspberryblackberry.com/local.cfm?doc=webdocs/ConferencePreview.htm
Caneberry session at the 2012 GA Fruit and Vegetable conference in Savannah GA. Jan 5-7, 2012

Resources:
Southern Region Integrated Bramble Management Guide and the Southeast Regional Bramble Production Guide: http://www.smallfruits.org/SmallFruitsRegGuide/index.htm

Blackberry and Raspberry Grower Information Portal:http://www.ncsu.edu/enterprises/blackberries-raspberries

My Social Media links:
Twitter: @NCTeamRubus
Facebook : Team Rubus
Blogs: http://teamrubus.blogspot.com/

Friday, September 9, 2011

Flooded berry fields

This article is provided courtesy of Cornell University. Although it was written for flooding situations in the northeast, some information may be useful for parts of NC as well.

DEALING WITH FLOODED BERRY FIELDS

Steve Reiners and Marvin Pritts

Dept. of Horticulture

Cornell University

Record-breaking rains in the East have left many berry growers with unmarketable crops. What had been shaping up to be a decent season for fall raspberries and dayneutral strawberries has quickly turned into a bad situation.

FLOODS AND FOOD SAFETY

There are two types of flooding. The first is more typical and occurs after a heavy downpour when fields become saturated and water pools on the soil surface. This type of flooding can reduce yields and even kill plants but usually will not result in contamination of produce with human pathogens. The second type of flooding is more severe and unfortunately occurred with the recent storm. This occurs due to runoff from stream/river overflows will more likely be contaminated with human pathogens, as well as chemicals. Unless you are absolutely sure that flooding is not from streams and surface water, do not use berries that were covered with flood water.

PLANT SURVIVAL UNDER WATER

How long a crop can live once it is flooded and what may be the effect on yield? Berry crops can tolerate a great deal of flooding when they are dormant, but when actively growing in summer, flooding for any length of time can be detrimental. This time of year is particularly bad because plants are preparing to make flower buds for next year, and stress can compromise this process. If plant roots were under water for more than 48 hours, expect next year’s crop to be compromised as well.

Plants previously flooded may develop an off-green or yellowish color. These plants are suffering from a complex of nutrient deficiencies, nitrogen, phosphorus, potassium and perhaps others, even though the soil contains adequate amounts. But the main deficient element is oxygen. Plant roots need oxygen to take up nutrients and water to utilize the photosynthate from the tops and to grow. With the heavy rains we have had, soils are saturated; that is, nearly all of the pore space is filled with water, leaving little room for air. Ideally, for good root growth 50 percent of the pore space should be filled with air. As soils drain, air is drawn into the soil, but when it rains, the water forces the air out of the pores. As is obvious to all, what is needed now is several rain-free days so the soils can drain and draw in air to stimulate root growth and help disperse toxic compounds that accumulate when plants lack oxygen. Once the plant roots get adequate oxygen they will begin to grow and take up the nutrients present in the soil. Anything that can be done to remove surface water will be helpful.

Many plant diseases will be much worse following flooding rains (e.g. Phytophthora and Botrytis), so closely monitor crops and manage these diseases. Phytophthora spores are spread under flooded conditions, so chemical treatment may be warranted in susceptible crops (e.g. red raspberries and strawberries).

(Thanks to Steve Rieners and Marvin Pritts at Cornell University for sharing this with us.)

Tuesday, September 6, 2011

New Publication

Dr. Ramón Molina-Bravo, was a PhD student that worked with myself and Dr. Bryon Sosinski at NCSU. Dr. Molina-Bravo just published an article that details a study that he conducted as part of his research. In a nutshell, he was able to identify several plants in a population of seedlings that had higher chlorophyll fluorescence, a trait that is associated with heat tolerance. We are using those individuals in our breeding program to see if they will survive the heat in additional locations and we will be using them in crosses in the near future. Congrats Ramon!

Here is a link to that article. doi:10.1016/j.scienta.2011.07.022

Thursday, September 1, 2011

Caneberry Workshop

The Caneberry Workshop was a great success. We had over 60 participants, most were from North Carolina, but some even came from Illinois, Virginia and Kentucky! One of the goals of the workshop was to generate interest in growing caneberries in this part of the state. I think we succeeded in generating interest, I am hopeful that we will see some production in this area in the future.

The workshop featured work being done at the station by Drs. Hannah Burrack, Penny Perkins-Veazie and myself. (NB - this may have been the first workshop lead by all female NCSU faculty in history!) Dr. Burrack focused on her Spotted Wing Drosophila work, Dr. Veazie discussed pre and post harvest handling of fruit and I talked about the replicated trials of blackberries and raspberries in and out of tunnels.

I gave the participants a tour of the replicated breeding trials. The caneberry breeding program has several locations where we test our materials. One of the locations is here at the Upper Mountain Reserach Station in Laurel Springs. This is our highest sight, at about 2500-3000' elevation and is in USDA hardiness zone 6. The average high temperatures in summers are in the low 80's and nights are cool as well....compared to the rest of the state. Raspberries love it here!

At this location we have one of our mirror 'variety' trials. We have a mix of varieties and selections from our breeding program, USDA and other Univ. breeding programs as well as recently named varieties. Each of the varieties was growing both under high tunnels and outside of tunnels. This allows us to compare overall growth, ripening season and fruit quality among lots of other attributes. Primocane fruiting raspberries were in the early part of their season, while floricane fruiting types had finished a couple of weeks ago. Floricane fruiting blackberries were still producing fruit and primocane fruiting types were flowering and had lots of green fruit. We will post the data on the NC Market Ready Portal at the end of the season here: http://ncsu.edu/enterprises/blackberries-raspberries/production/latest-research/
(There is data from other locations at this site that you may want to check out as well).

Dr. Penny Perkins-Veazie discussed pre and post harvest handling of raspberry and blackberry fruit. Participants comments included, "I never knew raspberries came in so many different colors of red". They also learned that most customers don't like dark red berries. She also discussed how picking pink berries will last longer on the shelf. She recently wrote an article about this. I will post a link on a later blog post.

Dr. Hannah Burrack discussed her work with spotted wing drosophila (SWD). This location is what she calls "Ground Zero" for SWD. Participants got to see SWD in all of its stages and learn more about how it impacts fruit production. She has a blog of her own where she regularly updates her findings. http://ncsmallfruitsipm.blogspot.com/p/spotted-wing-drosophila.html

A BIG thanks to all of the folks at the Upper Mountain Research Station that helped get the fields looking tip top and setting up the field and inside venue. I sincerely appreciate all you do for the caneberry programs. Sponsors included the College of Agriculture and Life Sciences, the North Carolina Agricultural Research Service and the North Carolina Cooperative Extension Service at N.C. State University; the N.C. Department of Agriculture and Consumer Services; and the N.C. Tobacco Trust Fund Commission.