NC State Extension Publications

General

Irrigation is recommended for caneberry production. Water is the most critical factor for optimal fruit growth and primocane development. Water is essential for minimizing plant loss and establishing healthy roots and shoots during the first few months. A newly set plant has shallow roots and therefore needs frequent irrigation. Any restriction of growth in the first year negatively impacts both the current season’s and the following year’s crops. A shortage of water during primocane development in any year will limit fruit size and the number and diameter of primocanes.

Nearly all of the moisture used by blackberries and raspberries comes from the top 6 inches of the soil, which is the primary rooting zone. If moisture is applied by overhead irrigation, blackberry and raspberry plants generally need at least 1 inch of water during each seven-day interval of the growing season. Higher irrigation amounts are required with sandy soils and in southern Georgia.

Trickle Irrigation

Trickle irrigation, either from a tape or tube, is recommended for caneberry production in the southern region. Set up trickle irrigation systems before plants are set in the ground. When using plastic mulch during establishment, it is common to place two lines of drip tape on either side of the row. Replace drip tape with tubing one or two years after plant establishment. Place drip tubes on wires about 12 to 18 inches above the soil surface.

Trickle irrigation reduces fruit rot because water is applied to the soil under the plants instead of overhead. It is important for the water to be clean and the system to be maintained properly so that the trickle system does not become clogged. Test both well water and surface water from ponds or streams for chemical and biological impurities, and provide recommended treatment and filtration for optimal function of a drip irrigation system. Contact your local Extension center for more information on how to collect a sample and where to take it for an evaluation.

Mulching

Mulches can help conserve moisture. Large volumes of material and many hours of labor are required to apply mulch to a field, and some mulch must be replaced each year. Mulches may also introduce weed seeds, encourage rodent infestation and crown gall, and be a fire hazard. However, weed-free mulches of small-grain straw or other suitable materials conserve moisture, minimize erosion, aid in weed control, and add organic matter to the soil. Do not use hay because it may contain the chemical picloram (Grazon) or aminopyralid (Milestone). Give mulches serious consideration when growing blackberries on lighter soils with low organic matter. Black plastic is a good mulching option in locations where orange velvet algae is a serious problem. Black plastic mulch has been observed to reduce algae problems by reducing soil splashing and providing a drier microclimate around the base of the bush. For more information on orange velvet algae (orange felt) see University of Georgia Extension’s Orange Felt (Orange Cane Blotch) of Blackberry factsheet.

Authors:

Extension Specialist (Small Fruits)
Horticultural Science
Professor
University of Arkansas
Professor
University of Tennessee

Publication date: Nov. 2, 2015
Last updated: Sept. 27, 2017
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