University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article


CARING FOR RASPBERRIES

Dr. Leonard Perry, Extension Professor
University of Vermont
 
If you have a raspberry patch, either planted this year or existing, there are a few key cultural practices to follow for best yields for many years.  These relate mainly to pruning, pests, and diseases.
           
If you just planted raspberries this year, you should be aware that it really isn't until the third year that you'll get fruit.  In the meantime, visit local farmers' markets, or U-pick farms.  When picking, either at a farm or your own patch, berries picked on sunny days have the highest vitamin content.  Handle them carefully so not to bruise the tender berries.  Use small picking containers as too many berries piled up will crush the ones below.  Move the fresh berries out of sun, washing and refrigerating as soon as possible.  Washing is done easily by placing berries (not too many at a time) in a colander, and dunking in cold water.
           
Berries hold chilled for a couple days.  To store longer, remove any bad or mushy berries, spreading the good ones in a single layer on a cookie sheet.  Place in the freezer for a day, then place loosely in bags or containers specially made for freezing.  They can store up to a year frozen.  Freezing, then placing in containers, keeps them from freezing into one large mass, so you can remove only what you want and have individual berries. Raspberries, fresh or frozen, have many uses such as homemade pies, jams, jellies, juice, and even wine.
           
You should be aware also that there are two main classes of raspberries, those that bear once and those that bear twice (again in the fall, often called "everbearing" although they really aren't).  Examples of red, once-bearing are Latham, Newburgh, Taylor, and Viking.  Fall or twice-bearing red raspberries include Durham, Fall Red, and Heritage.  Amber is a yellow or gold once-bearing variety, Fall Gold is obviously fall-bearing.
           
The reason you need to know the differences in bearing, in addition to planning your harvest, relates to pruning--one of the keys to good berry production.  All berries can be pruned the same the first 2 years.  Plants should be spaced about 2 feet apart, which can be done when planting or plants moved if the first year, or pruned if an existing patch. 
           
In the second year, prune plants to about 2 inches high in spring.  This encourages strong "canes" (raspberry stems).  Prune plants back to about 4 feet tall in fall to make a stiff plant that wont topple with wind and snow. 
           
In the third year, prune out sucker plants that come up in the wrong places, keeping rows about two feet wide.  Brambles such as raspberries often sucker prolifically, so as the patch grows more pruning will be needed.  Canes of red and yellow raspberries should be about 6 inches apart, those of black or purple raspberries 8 to 10 inches apart. 
           
Keep in mind, too, that although raspberries are woody perennials the canes are biennial, bearing fruit on canes produced the previous year.  Once canes fruit they wont again, so should be pruned off at ground level after fruiting in late summer.  Otherwise, the patch will become a mass of dead canes and die out over time.  Diseases overwinter in old canes too.  At this time also cut out any weak canes (they often wont bear fruit), and any sickly ones. 
           
Fall-bearing varieties will bear two crops, in fall on first year canes, then again the following summer on these canes. But, if you prune all canes of these varieties back to the ground each spring, you'll get only one crop (fall) but berries will be larger and more bountiful. 
           
Since canes are thorny, consider investing in long-handle clippers.  If using normal garden pruners, consider rose gloves which have long gauntlets to protect arms and are thick enough that thorns don't penetrate.
           
Weeds are a problem, as they compete with plants for nutrients.  With shallow roots, brambles are hard to hoe and not disturb roots.  Best is to prepare the soil well, removing weeds prior to planting.  Then mulch heavily with bark mulch or straw that wont pack down.  New berry canes easily push through several inches of such mulch. Between rows you can either mow a grass strip, or if cultivated, use a weed fabric or thick layers of newspapers, covered with mulching material. 
           
Fortunately there are just a few diseases to watch for, but unfortunately there are few controls for most except to remove infected canes and burn or destroy them.  Proper cane spacing through pruning, weed control, avoiding too much nitrogen, not planting near wild brambles or tomatoes and peppers (or where they were last year), all help avoid diseases.
           
Watch for new leaves curling down (leaf curl virus), marbled green and yellow leaves (mosaic virus), gray blotches on bark (anthracnose which you can spray for), sudden wilt of canes in midsummer (verticillium wilt), and fleshy growth on roots (crown gall). You can find an easy-to-use photo diagnostic tool for berry diseases online (www.hort.cornell.edu/diagnostic/).      
           
There are few insects of raspberries, the cane borer being the most common.  You'll see the tops of new canes wilt, caused by larvae that eventually eat down the cane and kill it.  They are easy to control by cutting the tips off and destroying them as soon as they wilt.  Look for two complete circles near cane tips, the entrance point of the larvae, and cut off below these. 
            

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