Tissue Testing for Nutrient Management of Red Raspberry

Red Raspberry (Rubus idaeus) is a perennial crop.  There are two types of canes in red raspberry plants. Primocanes are first year canes. Some varieties of raspberries produce berries on primocanes and are commonly called fall-bearing or primocane-fruiting raspberries. Other types of raspberries do not bear fruits on the first-year vegetative canes, but they develop flower buds that overwinter and produce berries in the subsequent season. These overwintered buds-bearing canes that will flower and fruit in the subsequent season are referred to as floricanes. After harvest, floricanes are commonly removed and the next cycle of primocanes develops. Sufficient nutrient availability during growth stages of red raspberry is essential for plant vigor, yield, fruit quality, fruit maturity, and sustainable plant health. Nutrient cycling in the soil-plant-air system in perennial plants is complicated and sufficient nutrients should be available before rapid nutrients uptake and requirement growth stages.   

Everbearing raspberries before pruning. Photo by dmp2006

Like any other plants, red raspberry requires seventeen essential nutrients, nine macronutrients (hydrogen (H), carbon (C), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)) and eight micronutrients (iron (Fe), copper (Cu), boron (B), manganese (Mn), molybdenum (Mo), zinc (Zn), chlorine (Cl), and nickel (Ni)). The three most abundant essential nutrients (hydrogen, carbon, and oxygen) are predominately obtained from water and carbon dioxide in the air, while all other essential nutrients are taken up by plant roots from the soil. When the soil is unable to supply sufficient nutrient(s), fertilization is needed for optimum yield and quality of berries. Nutrient application should be based on soil and plant analyses and grower experience in their raspberry production system.

Bowl of Heritage raspberries. Photo by dmp2014.

Plant tissue analysis is an excellent method for growers to monitor nutrient sufficiency levels. Timely plant tissue analysis is helpful for detecting nutrient deficiencies in perennial fruits before visual deficient symptoms show up and minimize loss of yield and quality. Nutrient uptake, accumulation, and relocations in plants are complicated in perennial crops like raspberry, therefore, tissue testing should be based on a consistent sampling in the plant growth stage and time of the day, selection of the appropriate plant part, and the recommended sufficiency levels (please contact UConn’s Soil Nutrient Analysis Laboratory, www.soiltesting.cahnr.uconn.edu for the recommended sufficiency levels) for comparison.

Red raspberry growers are recommended to sample and test leaf tissue from all fields annually.

• When to sample: Tissue samples should be collected when nutrient concentration is stable, thus, collect red raspberry leaf tissue mid-summer.
• What part of a plant to sample: Collect approximately 50 of the 4^th fully expanded leaves located about 12 inches from the tip to make a composited sample for tissue analysis. Collect leaves that are free of disease or other damage. A single composited sample should not represent an area of more than 5 acres. Do not mix leaves from field locations with different soil types or management histories. Separate samples should be taken for different soil types, management histories. For diagnosis purposes, separate samples should be taken in healthy and unhealthy plants.
• How to handle samples: Put a composited sample consisting approximately 50 leaves in a paper bag, clearly labeled the bag, and send it to a local laboratory providing leaf tissue nutrient testing services as soon as possible. Conventional laboratory plant tissue nutrient analysis procedures are shown below.

Schematic flow chart of conventional plant tissue nutrient analysis procedures.

How to guide fertilization with laboratory results?

Compare the laboratory results to the recommended leaf tissue sufficiency levels shown in Table 1. If laboratory results are below the recommended sufficiency levels, fertilizer applications would typically be increased. If laboratory results are within the recommended sufficiency levels, continue with the current fertilization regimes. For recommended sufficiency levels please visit the UConn Soil Nutrient Analysis Laboratory or refer to University of Vermont Extension publication at https://www.uvm.edu/vtvegandberry/factsheets/tissuetest.html. To assist with interpretation of tissue analysis data, record keeping is recommended. In addition to keep records of tissue testing, soil testing results, weather (daily rainfall and temperatures), disease problems, nutrient application rates, form and timing, plant growth (such as cane number and height), yield, leaf color, and fruit quality are also helpful in estimate nutrient requirements in various crop yield potential situations.

Table 1. Recommended leaf tissue nutrient sufficiency levels for red raspberry.

Nutrient	Sufficiency level
N (%)	2.3–3.0
P (%)	0.19–0.45
K (%)	1.3–2.0

Dr. Qianwen Lu, Graduate Research Assistant, University of Connecticut

 

Fall Raspberries

Early autumn is such a great time in New England. We get to visit apple orchards and pumpkin fields, walk through corn mazes and go on hay rides. We snack on popcorn and apple cider, pick apples and pumpkins to cook into pies and butters and just marvel in the wonderful colors of the changing leaves. One of my favorite things about this time of year is the fall raspberry crop. Years ago we discovered that a local orchard had raspberries in the fall and we were so excited. It is something that we continue to look forward to every fall. A few years ago I picked up some raspberry canes from the North Central Conservation District Plant and Seedling sale (more about that at the end of this post) and they have established themselves nicely.

Caroline raspberries in my home garden. Image by Susan Pelton.

In order to have a fall crop of raspberries you will need to have an everbearing variety, Rubus idaeus. Unlike summer-bearing varieties which may have red, black or purple berries, the everbearing raspberries are usually red. The Fall Gold variety with its yellow fruit is actually an albino red raspberry! The cultivar that I have is ‘Caroline’. Since raspberries are self-fruiting it is not necessary to have several cultivars for pollination although each variety brings its own advantages.

With the everbearing varieties you have two options. They can be allowed to bear fruit in the summer and the fall or only in the fall. The crowns and roots of the raspberry are perennial but the individual canes live for two years. The summer-bearing raspberries will not produce on new growth (the primocanes) until the second year (the floricanes). The primocanes of everbearing raspberries will produce fruit in the fall of their first year. They will then bear fruit on those same canes the following summer. I planted canes in the spring three years ago and this was the best production year so far. If only a fall crop is desired all canes should be cut to the base before the new growth appears in the spring. For two crops a year simply thin out primocanes by cutting them back to the last visible node that had fruit or trimming any tips that are browned.

Primocanes and floricanes at Easy Pickin’s Orchard, Enfield, CT. Image by Susan Pelton.

Growing raspberries is relatively easy if you keep a few things in mind. Raspberries prefer to be planted in a narrow row or hedge and trellised. They will be in the same location for up to 15 years so choose a site that is in sun for at least 6-8 hours a day and will not block other plants. I have my canes in full sun but with their backs to a tall fence. This helps to block the wind so that they don’t get desiccated but they still get good air circulation.

A bee pollinating raspberries. Image by Susan Pelton.

If you don’t have raspberry canes as part of your habitat you may want to consider establishing a bed. The Connecticut Conservation Districts hold their Plant and Seedling sales every spring and are a great way to purchase native edible plants. They can be found online at http://conservect.org/. The Connecticut Department of Agriculture has an extensive list of orchards and pick-your-own farms on their website at http://www.ct.gov/doag/cwp/view.asp?a=3260&q=399070.

Image by Susan Pelton.

Susan Pelton

 

Snow on the Daffodils, Raspberries, Summer’s Bounty

        This latest foot of snow has buried my newly emerging bulb foliage. The two inches of daffodil, allium and crocus leaves are about a foot below the cold, white surface. Will my bulbs survive under that much snow? This is a familiar question I hear at the Home and Garden Education Center. I have enough faith and have seen many years of snow on the daffodils and other bulbs to know they will all be ok. The foliage may turn a little yellow but the flower buds are still protected deep inside the bulb itself. If it were much later in the season when the flower buds are exposed above the soil, these cold temperatures and a foot of snow would harm them. Light snow and temperatures just around 30 degrees F usually will not cause damage. Meanwhile, I will wait for spring, dream of the new gardening year and remember my last year’s garden. This is a good time to recall what worked and what didn’t in last year’s garden.

            I am eating reminders of last year garden when I flavor my homemade plain yogurt with raspberry jam made with Heritage raspberries from the back yard. I love this variety’s ever-bearing canes that can be pruned half way for a June crop or down to the ground for a late August crop. I also planted an unknown variety that produces berries on wood grown the previous year. These were darker, larger, less flavorful and seemed to rot on the cane as soon as they became ripe. I am not sure I want to waste the growing space keeping these.

 

             I will again plant plenty of basil for pesto making and freezing. We are just finishing the last of it now. I dried various herbs by hanging upside down bunches in the garage and tried my hand at drying them in the microwave. After one small fire in the microwave, I think I will stick to the slower hanging method! My tomato harvest was light and so was the canning of them. I really miss opening that glass jar filled with summer’s red goodness in January. Much more pickles were made than we actually eat, but the cucumbers produced a bumper crop. The garlic was also plentiful and I should cut back on the area devoted to this bulb. The stored potatoes and winter squash ran out far too soon resorting me to purchase these at a local farm stand that stays open until January.

 

            Even if you don’t grow your own produce, buy from a farmer’s market or local stand to try your hand at storing food for the winter. A good site to check out is the  National Center for Home Food Preservation.  Our own UConn Food and Nutrition folks provide information food storage.

Let the planning begin and hope the snow melts soon.

-Carol