The Blueberry News – July 2019

FloridaBlueberryGrowers.org The Blueberry News | 9

bark has only moderate nutrient holding

capacity. This can result in leaching of fertilizer

below the root zone during times of heavy

rainfall or irrigation, and may require higher

applications of N fertilizer.

More frequent applications of smaller

amounts of fertilizer, as opposed to larger

single applications, is recommended in order

to minimize leaching loss. In addition, new

pine bark (either in new beds or added to

supplement existing beds) can immobilize the

ammonium form of N, leaving an insufficient

amount available for uptake by the plants.

Growers should consider applying N to new

bark beds at least three months prior to planting,

and increasing the amount of N applications in

the months following the addition of new pine

bark to an existing bed, to compensate for the

N immobilized by fresh pine bark. A reference

for fertilizing blueberry plants in pine bark can

be found by scanning the QR code to the right.

Leaf nutrient analysis should be performed

at least once per year to determine plant

nutritional status. This is typically done just

prior to post-harvest hedging, but can also

be performed during the first post-hedging

flush (after leaves are fully expanded), or

at other times during the year if symptoms

of possible nutrient deficiency or toxicity

appear. The primary use of this analysis is to

assist in designing a fertilizer program, by

determining both the current status and the

sufficiency over time of essential nutrients in

blueberry plantings, considering variables such

as weather conditions, management practices,

and yield.

Leaf samples should be mature leaves from

the current season’s growth, and should be

taken separately for each cultivar. Each sample

area should have a uniform soil type, the same

fertilization and irrigation program, and not

exceed 10 acres.

There is considerable variation in the

recommended frequency and volume of fertilizer

applications depending on fertilizer type, plant

age, climate, soil/media type, and management

practices (including irrigation and weed control).

Decisions on fertilizer application should be made

based on soil and leaf nutrient analysis, levels of

plant growth and development, environmental

conditions, and grower experience using fertilizer

on their site.

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CREDITS

by JEFFREY G. WILLIAMSON, Horticultural Sciences Department, and DOUG PHILLIPS,

Blueberry Extension Coordinator, both with the

University of Florida/IFAS.

Figure 1. Excavated southern highbush blueberry plant grown in a pine bark bed. The shallow, fibrous

root system was primarily limited to the depth of the pine bark, with very few roots penetrating

the underlying soil.

photo by J. Williamson

by J. WILLIAMSON and D. PHILLIPS