The Blueberry News – July 2019

8 | The Blueberry News FloridaBlueberryGrowers.org

IRRIGATION

SHB have a shallow root system with no

root hairs, which restricts water uptake capacity

and increases susceptibility to drought stress.

Water use by blueberry plants peaks during

late summer (August and September) when

plant canopies are large, temperatures are high,

and day lengths are long. Proper irrigation

management is especially important during

this time when canopy regrowth is occurring

and plant water demands are high.

SHB in Florida are typically planted either

in pine bark beds prepared on top of the soil,

or in soil beds amended with pine bark. Pine

bark adds organic matter to the blueberry root

zone, and helps keep pH in the range of 4.

• 5.5, which is necessary for good blueberry
  growth and nutrient availability. However,

pine bark does not retain water very well, and

the majority of SHB roots tend to stay within

the pine bark layer (Figure 1), or in the top 7

to 10 inches of soil (Table 1). Over-irrigation,

especially in this system, can lead to inefficient

water use and leaching of nutrients below the

root zone.

During periods of high water demand,

daily plant water requirements may exceed the

amount of water that is retained by the pine

bark, or pine bark amended soil, in the plant

rootzone. Therefore, during these periods of

high water demand, light irrigations applied

multiple times per day will increase water use

efficiency and reduce potential leaching of

fertilizers and pesticides, compared to irrigating

less frequently for longer time periods. The

frequency of irrigation will depend on weather

conditions, cultivar, soil type, and the use of

pine bark as a substrate or amendment.

FERTILIZATION

For young blueberry plants, the focus for

fertilization is on maximizing plant growth and

ensuring survival. For mature plants, the goal is

to maintain a good balance between vegetative

and reproductive growth, to promote optimal

yield. These goals are accomplished by applying

essential nutrients in advance of plant needs.

One of the most important nutrients for

plant growth is nitrogen (N). Recent research

indicated that the highest uptake of N in young

SHB blueberry plants takes place from late

summer through the middle of fall during

rapid canopy growth; this is likely also true

for mature blueberry plants. Therefore, it is

important to have sufficient N (as well as other

nutrients) available during the summer and

early fall months to support this growth.

As is the case with irrigation, the effects of

pine bark growing media must be considered

when developing a fertilizer program. In

addition to low water holding capacity, pine

field management

Irrigation and Fertilization

Practices for the Summer Months

SOUTHERN HIGHBUSH BLUEBERRIES (SHB)

experience a significant amount of canopy growth

during the summer months following post-harvest

pruning. Most of the fruiting wood for next year’s

crop is produced during the summer months. Careful

irrigation and fertilization management is needed

to ensure that the plants have sufficient water and

nutrients to support this growth.

Proper

Planning