March 2020 - 21

Fertigation on peppers fights heat, blossom rot
By Dean Peterson
VGN Correspondent
Georgia's hot weather gets peppers
to market sooner in the spring and
opens a fall market after Northern
growers have their first frost. But that
hot weather - plus coarse-textured
soils - makes blossom end rot a real
problem with losses of up to 30% in
some seasons.
These concerns make a fine-tuned
fertility program a must.
" Georgia is a very different part
of the country, " said Timothy
Coolong, University of Georgia
(UGA) Extension specialist and
associate professor in the Horticulture
Department. Coolong was a speaker at
the recent Great Lakes Fruit, Vegetable
& Farm Market EXPO in Grand
Rapids, Michigan.
Proper prebedding with fertilizer
is vital. " Growers apply lots of lime
preplant to keep the pH up when
using beds for two and possibly three
years, " Coolong said. " By that second
and third year we can get pretty low in
fertility - especially in potash. "
All commercial pepper production is
on plastic mulch, but alone that will not
control Georgia's heavy weed pressure -
especially yellow nutsedge - and nearly
all pepper
production
is fumigated.
" Fumigation
drives our
TIMOTHY
COOLONG
system, "
Coolong
said. A
combination
of Telone II,
chloropicrin
and Vapam-
called the
Georgia three-way - is the standard
program.
The plastic on the raised bed must
be put down tight and smooth to
contain the fumigants. " We don't want
any divots in our plastic, " Coolong
said. " We want a really nice, tight bed
to hold that fumigant. Growers put
new plastic down in the spring, reuse it
in the fall on squash and reuse it again
the next spring. "
Drip irrigation is standard - and
frequent - which minimizes root
stress on the coarse-textured soils and
minimizes blossom end rot. Irrigating
two to five times a week is typical.
" Some growers irrigate twice a day
because they're so concerned about
leaching, " Coolong said.
Fertigation is the standard practice
and lots of low analysis liquid fertilizer
is used - generally a 7-0-7 or 4-0-8.
Most is custom mixed locally which
minimizes transportation cost. " We
very much recommend a nitrate-based
fertilizer because of blossom end rot, "
Coolong said. Ammonium forms of
nitrogen can compete with calcium for
uptake in the plant.
UGA's standard fertilizer
recommendation is 175 pounds to 200
VGN | MARCH 2020 | 19
pounds of actual nitrogen per acre and
up to 200 to 225 pounds per acre on
the most coarse-textured soils.
These recommendations are for beds
with six-foot centers or 7,260 linear
foot of row per acre. Beds with fivefoot
centers should use 20% more.
" Peppers are fertigated on such a large
scale it's best done on a linear foot of
row, " Coolong said. An industry standard
for the calculations is UGA's Georgia's
Bulletin 931, " Conversion Tables,
Formulas and Suggested Guidelines for
Horticultural Use, " available at: www.hort.
caes.uga.edu/extension/publications-andfact-sheets.html.
" Fertigation
has dramatically
reduced the amount of preplant
fertilizer we're using, " Coolong said.
Fertigation is typically a single row
drip. This raises questions on how
many nutrients are getting to the
shoulders of the raised beds which
are often eight to 10 inches from the
central drip.
UGA researchers studied the issue
and found two drip lines a few inches
apart provide a more uniform nutrient
distribution into the shoulders of the
raised beds. " Some growers don't like
it because of the cost, " Coolong said.
There's also the issue of putting a second
set of holes in plastic that's being reused.
UGA researchers also recently
looked at applying a small amount of
calcium nitrate (9% nitrogen) with the
other fertigated nutrients to manage
blossom end rot.
In the first year of the study, the
incidence of blossom end rot was
significantly lower and marketable
yield significantly higher with the
extra calcium. In the second year
of the study, there was no real
difference. " That supplemental
calcium might not be necessary
in all seasons but it's pretty cheap
insurance, " Coolong said. VGN
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March 2020

Table of Contents for the Digital Edition of March 2020
