The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
- f LAgricultural Research Center
Research Report RC-1977-11 October 1977
COMMERCE CORNJARfETY TESTITr1a ULTS
FROM S UT-C A 1977
P. Mislevy, R. F. Kalm e, E. S. Horner and P H. Everett-
Corn can be extremely valuable in a livestock feeding program. With
its rapid growth and high yielding ability, corn harvested and stored as
silage, can supplement perennial grasses at times when their production is
low. This crop may follow winter vegetables or be used in a pasture reno-
vation program. High quality corn silage can provide cattle with a substan-
tial carbohydrate input, possibly reducing high grain costs and also providing
growing calves with quality feed.
Well managed corn harvested for silage at the proper stage of maturity
can produce 7-10 tons/acre dry matter in a 3.5 to 4 month period. This
would allow the land to be free for the growth of other crops over the remaining
Corn silage harvested at the hard dent stage is usually high in energy,
carotene, vitamin D, but low in minerals with a protein content of about 8%.
To produce high yields of quality corn forage, adapted hybrids proper seeding
date, high fertility, water control, correct plant populations, and weed and
insect control are necessary.
The purpose of these studies was to evaluate commercial corn hybrids
for silage and/or grain production at Ona and Immokalee.
The experiments were conducted at the Agricultural Research Centers, (ARC)
at Ona and Immokalee. The experimental design at Ona was a randomized complete
block with 4 replications. At Immokalee 5 replications of a split-plot design
was employed. Varieties made up whole plots, while 2 fertility levels made
up sub-plots. At Ona all varieties were also seeded in a non-replicated trial
to monitor the effect of plant performance when no insecticide-nematicide was
used at seeding. Both the replicated and unreplicated studies at Ona were
seeded on Ona fine sand on February 25, 1977. The Immokalee experiment was
seeded on August 2, 1976, but due to seeding failure, reseeded August 13, 1976.
1/ Associate and Assistant Professors, Agricultural Research Center, Ona;
Professor, Agronomy Department, Gainesville and Professor, Agricultural
Research Center, Immokalee, Florida.
Fertilization practices carried out at Ona were 50-92-185 lb/A N-P 05-K20
at seeding followed by 100 lb/A N when corn was 8-10" tall and an additional.
100 lb/A N when corn reached a height of 24-28 inches. Calcium, Magnesium
and pH levels were adequate at the Ona location.
At Immokalee the varieties were grown under 2 fertilization schemes on
the same land that had a spring tomato crop. The first was residual P2O5 and
K 0 remaining from spring grown tomatoes plus 100 Ib/A of N when plants were
18 to 24" tall. The second scheme was 910 lb 0-10-20/A with 50-lb/A of N
after emergence, 100 Ib/A of N when plants were 6-10 tall and 100 lb/A of
N when plants were 18-24" tall.
Plant populations and weed control
Corn at Ona was seeded in.30 inch rows, and at Immokalee in 36 inch rows.
Final plant populations at Ona were 24,000 plants/acre and 22,000 plants/R)
at Immokalee. The herbicide combinations used at Ona were 2 Ib/A AAtrex
(active) and 1.5 Ib/A Duel '" (active) applied pre-emergence in 30 gallons
of water per acre. Immediately following herbicidal application the experi-
mental areas were irrigated. No cultivation practices were employed after
the corn was seeded. The insecticide-nematicide, Furadan 10 G was applied
on the replicated study. The non-replicated study received similar practices
applied to the replicated study, except that Furadan 10 G(R) was omitted.
At Immokalee the herbicide AAtrex (R) at 1.25 lb/A and Lasso at 3 lb/A
(active) was applied pre-emergence. Lannate at 1 quart (formulation) per
100 gallons water was applied on three occasions to control budworms.
Corn was irrigated as needed at the ARC, Ona, with a total application
of 8.95 inches. Hater was not required for the summer study at Immokalee.
Maturity at Harvest
Corn was harvested for silage when the kernels were at the hard dent stage,
with plants containing approximately 44% dry matter. This was coincidental with
black-layer formation in the kernel. The experiments at Ona were also harvested
for grain. Ears contained about 32% moisture at harvest. No lodging was
observed among varieties at Ona or at Immokalee.
Results and Discussion
Significant differences in dry matter yields were observed among the 25
commercial corn varieties grown as forage at the ARC, Ona (Table 1). 'McNair
508' produced the highest dry matter yield, averaging 10.7 T/A. 'Greenwood 45'
was the lowest forage producer averaging 7.1 T/A dry matter.
Dry matter percentage of the entire corn plant, after 118 days of
growth, ranged from a low of 33.7% for 'Dekalb XL 395' to a high of 53.5% for
'Dekalb XL 72B' (Table 1). When selecting a corn hybrid to be grown in south-
central Florida for forage production, one should select a variety that is a
high yielder and contains a high percentage of dry matter at harvest. Gener-
ally limited acreage of a full season hybrid (115-128 days) should be seeded
in south-central Florida. The major corn acreage should be seeded to high
yielding early and mid-season varieties. This would allow corn seeded in
early to mid-February to be at the hard dent stage of maturity in late May to
Six varieties 'McNair 508', 'Funks 04810', 'Dekalb XL 395 A', 'Asgrow RX
114', Pioneer 3369 A' and 'McCurdy 67-14' produced grain yields between 160-
165 bu/A shelled corn @ 15.5% moisture (Table 1). Two of the above varieties
Asgrow RX 114 and Pioneer 3369 A contained ear moisture less than 30%,
averaging 27.8 and 26.4%, respectively after 123 days of plant growth.
In the non replicated study Furadan 10G(R) was purposely deleted to
observe its absence on corn production where corn had been grown 6 consecutive
years on the same site. Differences in forage dry matter production and
grain yields definitely existed among varieties (Table 2) when compared with
the same varieties seeded in combination with Furadan 10G J (Table 1). This
preliminary information may indicate that full season hybrids are less sen-
sitive to nematode problems than early maturing varieties.
Southern corn rust (Puccinia polysora Underw.) was observed on all
commercial corn varieties tested during 1977 (Table 3). The rust appeared on
plants about 1 month later (late May) in 1977 as compared with 1976. Again
as in other years Southern corn rust did not appear to affect corn yield.
Uhen severe rust infestations occur, the corn plant is generally at the milk
stage of maturity. Rust among the varieties ranged from a low of 20 and 21%
for 'PAG 751' and lcNair 508, respectively to a high of 90% for Coker 77.
Several other agronomic characteristics were recorded for each variety
just prior to harvesting the corn as forage (Table 3). They are plant height
at harvest and height to ear-silk; stalk rot at harvest, (10 linear foot section)
and number of ears per stalk (10 linear foot section) when grown at 24,000
plants per acre.
Stalk rot is of considerable importance when growing corn on a commercial
basis. The number of plants containing stalk rot/10 linear feet of row at
harvest (118 days after seeding) varied from 0.0 for 'Dekalb XL 1295' to 5..8
plants for Pioneer 3369A (Table 3). Generally the late maturing varieties.
contained less stalk rot, however this was not always true as evidenced
by PAG 751 a late variety averaging 3.5 plants/10 linear feet.
The eight corn varieties seeded on August 2, 1976 failed to emerge.
Tests proved germination to be 80-90%. Exhumed seeds, which were planted 1-
2 inches deep, were found to be in a state of decay. The corn was seeded
'on-the-flat', not in raised beds. Moisture was too great for proper germin-
ation and emergence. Additionally, soil temperature was high (55C) which may
have affected germination. Corn was replanted on August 13, 1976 at to
inch deep, no appreciable rain followed for 48 hours, and a corn-stand developed.
Corn was harvested on December 3, 1976. Significant differences in
forage yield were found among corn entries. Coker 77 was the highest yielding
entry produced from residual (no P 05 or K20 applied on corn) or applied
fertilizer (Table 4). Yield for this entry was 3.8 and 4.8 T/A, respectively.
Pioneer 3030 produced the lowest yield averaging 2.8 and 2.7 T/A in the
residual and applied fertility plots.
Corn in residual fertility plots produced significantly less dry matter
than those in plots where. fertilizer had been applied to the corn crop.
Comparative yields were 2.7 vs 3.5 T/A, respectively.(Table 4).
Although significant differences among hybrids and levels of fertility
were found, these differences remain purely academic. The fact remains that
the production of corn seeded on the flat, in mid-summer is not practical
in south Florida. Even with high fertility (250-90-180) yield was poor.
Excessive rain not only inhibited seed germination, root development, and
pollination, but also leached N and K from the soil. Plants in this study
had very limited root systems and could easily be pulled from the soil.
Insect damage, particularly from bud worms, was severe. Depredation to
the ears at harvest time was very unacceptable. Ears were small on all
hybrids and imperfectly filled due to poor pollination. In some ears kernels
were germinating on the cob.
Twently five commercial corn hybrids were tested at the ARC, Ona in
1977. Significant differences in forage dry matter and grain yields were
observed among varieties. Growers should carefully study the performance of
corn varieties prior to purchasing seed of a variety to be grown. It is
generally best to select a high silage yielding, early maturing variety
with high grain yielding ability. To obtain consistently high yields,
adequate fertility, proper plant populations, water control, weed and insect
control, and management at harvest time are required.
Eight hybrids were grown at Immokalee ARC in the summer of 1976.
These hybrids were grown with the residual P and K from a spring tomato crop
with 100 Ib N/A applied, and with 250-90-180 N, P205, K,0, respectively.
Significant differences were ouund among varieties and levels of fertility.
Regardless of hybrid or fertility level, results indicate that yields were
too low to be of value from a commercial stand point. These low yields
are the direct result of excessive water and insects. The seeding of corn
on-the-flat is not a recommended practice in south Florida during the
at the ARC-Ona
- -- T/A--
XL 395 A
XL 75 A
rma t ter
Zar ooi s
- -- */
Means within columns
Forage and grain production of non-replicated commercial corn
varieties grown at the ARC, Ona, 1977.'
Forage yield Grain yield
Brand Variety (dry matter) 15.5% moisture
T/A - bu/A- -
Coker 77 12.9 174
Funks G 5945 11.2 195
Dekalb XL 395 11.0 151
PAG 751 10.1 139
Pioneer 3161 10.0 133
McCurdy 67-14 9.1 172
Helena Golden Harvest H 2750 9.0 161
Asgrow RX 114 8.9 152
Funks G 4810 8.9 .127
Dekalb XL 78 8.8 132
McNair S-338 8.7 136
Dekalb XL 394 8.6 126
Greenwood 45 8.6 132
Dekalb 1295 8.6 143
Helena Golden Harvest H 2775 8.6 151
McNair 508 8.3 154
Dekalb XL 395 A 8.3 164
Coker 18 8.3 176
Pioneer 3030 8.0 92
Dekalb XL 75 A 8.0 135
Dekalb XL 80 7.7 156
Greenwood 747 7.6 138
Funks G 4864 7.5 134
Dekalb XL 72 B 7.0 139
Pioneer 3369 A 6.2 164
t The insecticide nematicide Furadan 10G
non-replicated study at seeding.
was not used in this
- -- - -
I _~ _~ __ _
Table 4. Forage yield of commercial corn varieties produced with 2
fertility levels: residual from spring tomatoes + 100 Ibs N/A
and applied (250-90-180) at corn seeding. ARC-Immokalee.
August December 1976.
Brand Variety Residual+ Applied
---Dry matter yield T/A ---
Coker 77 3,8 a 4.8 a
Dekalb XL 80 A 1.9 def 4.0 b
Funks G 4810 2.1 cde 4.0 b
PAG 751 2.8 b 3.6 b
Pioneer 3369 A 1.4 f 2.9 c
McCurdy 67-14 1.5 ef 2.9 c
Helena Golden Harvest 2775 2.5 bcd 2.8 c
Pioneer 3030 2.8 bc 2.7 c
AVERAGE 2.7 3.5
Residual: Grown on fertility from spring tomatoes under
fertilized with 205-40-290 of N-P205-K20.
Means within columns followed by the same letter are not significantly
different. Duncan's LSD. K=100.