• TABLE OF CONTENTS
HIDE
 Title Page
 Introduction
 Materials and methods
 Results and discussion
 Acknowledgement
 Literature cited






Group Title: Research report - North Florida Experiment Station, University of Florida - NF 91-4
Title: Tropical corn hybrids vs. drought, fall armyworm and late planting
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00073727/00001
 Material Information
Title: Tropical corn hybrids vs. drought, fall armyworm and late planting
Series Title: Research report
Physical Description: 10, 5 p. : ill. ; 28 cm.
Language: English
Creator: Teare, I. D ( Iwan Dale ), 1931-
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Research and Education Center
Place of Publication: Quincy FL
Publication Date: 1991
 Subjects
Subject: Hybrid corn -- Field experiments -- Florida   ( lcsh )
Corn -- Effect of drought on -- Florida   ( lcsh )
Corn -- Diseases and pests -- Florida   ( lcsh )
Corn -- Planting time -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 8).
Statement of Responsibility: I.D. Teare ... et al..
Funding: Research report (North Florida Research and Education Center (Quincy, Fla.)) ;
 Record Information
Bibliographic ID: UF00073727
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 84001367

Table of Contents
    Title Page
        Page 1
    Introduction
        Page 2
    Materials and methods
        Page 3
    Results and discussion
        Page 4
        Page 5
        Page 6
        Page 7
    Acknowledgement
        Page 8
    Literature cited
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
Full Text













Tropical Corn Hybrids

vs.

Drought, Fall Armyworm and Late Planting




I.D. Teare*, D.L. Wright, R.K. Sprenkel,

R.L. Stanley, and D.P. Lilly

.'- 1i Science
Library

A/R 21 199(













I.D. Teare, D.L. Wright, R.K. Sprenkel, R.L. Stanley, D.P. Lilly; North

Florida Res. and Educ. Ctr. Quincy, FL 32351 (Dept. of Agronomy and

Dept of Entomology and Nematology, Institute of Food Sci., Univ. of

Florida, Gainesville, Florida 32611). Florida Agric. Exp. Sta. Res.

Rep. No. NF 91-4. *Corresponding author.







INTRODUCTION

Tropical corn [Zea mays (L.)] can provide a much needed energy

source (grain and silage) for dairy and livestock operations in Florida

(Wright and Prichard, 1988; Wright and Chambliss, 1989) for it is well

suited for its long growing season and tolerance to insects (exception:

fall armyworm (Spodoptera frugiperda (J.E. Smith)], [Teare et al.,1990])

and diseases (Teare et al., 1989). Dry weather normally keeps spring

planted, nonirrigated temperate corn yields around 60 to 80 bu/A in the

Coastal Plain of the southern states and around 30 bu/A when summer

planted (Teare and Wright, 1990a). Low yields and low prices have

dramatically reduced acreages of temperate corn in the southeast.

Farmer acreage of tropical corn increased from 5,000 acres in 1986

to almost 40,000 acres in 1989 in the southern U.S. because growers

wanted a more consistent grain or silage crop that could be grown under

natural rainfall conditions to increase profitability and cash flow, and

provide a rotation crop in lieu of summer legumes (soybean, and peanut,

Teare et al., 1989) to reduce nematode numbers that build up from the

continuous cropping of summer legumes. Since tropical corn is grown,

after harvesting wheat, during the summer months when rainfall is most

bountiful, it should perform more consistently than temperate corn in

the southeast. Initially, there was only one commercially available

tropical hybrid (Pioneer X-304C) and that hybrid is known for its

tolerance to insects and diseases and difficulty in threshing.

Tropical corn yields and quality from these summer plantings of Pioneer

X-304C have been equal or better than the state average for temperate

corn planted at the normal time.







Fall armyworm infestations were heavy in 1989. Avoidance of pest

injury by producing a crop at times when pest populations are in

nondamaging stages or at low population levels is recognized as one of

the more successful integrated pest management practices (Herzog and

Funderburk, 1986). After our experiences in 1989 with fall armyworm

damage on tropical corn, we felt we could recommend a planting date that

would reduce fall armyworm damage on Pioneer X-304C in a wheat-tropical

corn double-crop system by planting before 10 June in North Florida

(Teare et al.,1990).

However, growers wanted improved hybrids that would produce higher

grain yields with increased energy content of silage. The objective of

this study was to provide further information on fall armyworm avoidance

and grain yield results of tropical corn hybrids grown in a no-tillage

system in relation drought and insect stress.

MATERIALS AND METHODS

These studies were conducted on a Norfolk sandy loam (fine, loamy
siliceous, thermic Typic Kandiudult) located on the North Florida
Research and Education Center, Quincy FL. The soil has a compacted
layer located 7 to 14 inches below the surface.
In 1989, the fall armyworm devastated late planted tropical corn
fields, but avoidance of the fall armyworm damage appeared to be
correlated with planting before 10 June in north Florida, thus planting
dates were selected before and after 10 June to provide two levels of
fall armyworm infestation. The only successful 1989 planting date study
was a planting date X N rate study conducted on Pioneer X-304C with
planting dates of 29 May, 15 June, and 14 July. Planting date x N rate
studies were continued with Pioneer X-304C in 1990 comparing the same
five N rates of 0, 50, 100, 150, and 200 lb N/A with three planting
dates (8 June, 14 June, and 12 July [the early 29 May planting in 1990
was delayed by rain to 8 June]).
In 1989, a tropical corn hybrid study (normally planted on 10 June)
was delayed by excess rainfall and late-planted on 29 June (fig. 1)
setting up the situation for heavy fall armyworm infestation (grown
under rainfed conditions). The tropical corn hybrid study in 1990 was
grown under rainfed conditions (summer drought) and limited irrigated
conditions (limited to applications at the early vegetative stage







[Fig.l]). The planting dates were 11 June and 3 July for both water
regimes.
The moderate energy input used in these experiments is the one
described by Teare et al.(1989). A Brown Ro-Till planter was used to
plant the tropical corn into standing wheat stubble at a plant
population of 20,000 plants/A. Twenty lb N/A was applied as starter
fertilizer at planting and 100 lb N/A when the corn was 12 inches tall.
The experiments were not irrigated except as stated. Most of the
tropical corn acreage planted in the southeast from 1988 to 1990 was
based upon these recommendations.
The experiment was a randomized complete block design with four
replications except for the 1990 irrigated and rainfed hybrid trial
which was a split plot with four replications. Interactions are
illustrated according to Teare and Wright (1990b). The rows were 25
feet long with 30 inches between rows. Severe drought was experienced
in 1990. Rainfall data, planting date, 50% tasseling, and harvest date
for 1989 and 1990 are shown for comparison in Fig. 1.
Fall armyworm adults were trapped in 1989, but the traps were
located 200 to 800 yards from the. tropical corn plots. This was
considered too far from the experiment for realistic fall armyworm
counts. Therefore, in 1990, larvae counts were made on ten tropical
corn plants per replication for each of two hybrids and one open
pollenated line of tropical corn.

RESULTS AND DISCUSSION

Environment and phenology

Weather points to two improvements needed in the wheat-tropical corn

double-cropping system. In 1989, high rainfall (twenty inches of rainfall

fell from 21 May to 27 June 1989), delayed tropical corn planting from 10 June

until after 27 June with severe fall armyworm injury and resulting yields of

less than 40 bu/A. Historically, the average tropical corn yield for Pioneer

X-304C was 94 bu/A at NFREC at 120 lb N/A. Tropical corn phenology for 1989

is shown in Fig. 1.

The year of 1990 was dry from early spring to late fall. The rainfall

events and amounts resulting in severe drought are illustrated in Fig. 1. For

this reason a limited irrigated companion study was included with the rainfed

hybrid yield study. Irrigations are illustrated on Fig. 1, but were limited

to applications at the early vegetative stage of tropical corn development.

Tropical corn phenology is shown for 1990 in Fig. 1.







Planting date

In 1989 and 1990, double-cropped Pioneer X-304C was studied at three

planting dates and five nitrogen rates. Yield of no-till tropical corn in

1989 was highest from the May planting and decreased with each successive

planting date (Table 1). Insect pressure from the fall armyworm also

increased as planting dates were delayed (Fig. 2). The 1989 tropical corn

yield data from the planting date by N rate study shows that the yields of

Pioneer X-304C was 113 bu/A on the 28 May planting date, was 68 bu/A on the 15

June planting date, and was 40 bu/A on the 14 July planting date under rainfed

conditions (Table 1). When the fall armyworm larvae counts (Fig. 2) are added

to the previous information, it becomes evident that planting prior to 15 June

results in greater yields and lower fall armyworm larvae counts than later

planting dates. With the availability of Florida 303 wheat, which has the

desirable traits of high yield, resistance to leaf rust and powdery mildew,

and early maturity (14 May, Teare et al., 1990). Common sense dictates that

plantings of tropical corn should not occur after 1 June to avoid fall

armyworms.

Nitrogen rate

Higher rates of nitrogen in 1989 were most beneficial for early planting

dates (Table 1). The trend was insignificant in 1990 because of the drought.

In 1989, a nitrogen rate of 100 lb/A produced highest significant yields for

May planting, 50 lb/A produced highest significant yields from June planting,

and 0 lb/A produced significantly no less yield than any other N rate for the

July planting.

Hybrid yield response

The yield expression of tropical corn hybrids studied in 1989 (severe fall

armyworm damage) and 1990 (severe drought and fall armyworm damage) are shown

5







in Table 2. Under severe fall armyworm stress (1989) the highest yielder was

Pioneer X-304C at 42 bu/A and other hybrid yields went down to 7 bu/A. The

low yields of the rainfed hybrids in 1990 are a confounded expression of

drought (Fig. 1) and fall armyworm damage (Fig. 2). Early planted rainfed

tropical corn yields in 1990 ranged from 18 to 44 bu/A and the late planted

rainfed tropical corn yields in 1990 ranged from 21 to 47 bu/A. Pioneer

X-304C yielded 21 and 40 bu/A, respectively.

Limited early irrigation increased tropical corn yields of many of the new

entries. Five early planted hybrids yielded more than 100 bu/A and the range

went from 36 to 156 bu/A under irrigation. The late planted, irrigated

tropical corn yields ranged from 18 bu to 140 bu/A with two of the hybrids

(Pioneer 3072 and 3098) remained high yielding in both early and late

plantings. Two other tropical corn hybrids also reached 100 bu/A. Sunbelt

1876 (a temperate corn) was grown as a point of reference both years and was

consistently a low yielder at each planting date.

Since most of the useful data on tropical corn hybrid yield comes from

1990, the data should be used guardedly because of the significant interaction

of hybrid X water regime and hybrid x planting date.

Hybrid X water regime

It is better to compare the interaction of corn hybrid yield in relation

to water regime and determine which hybrids did best under rainfed conditions

and which did best under limited irrigation (positive changers) or remained

the same (non-changers) (Fig. 3) for the two planting dates.

Using the asymtote (a line that is the limiting position which the tangent

to a curve approaches) for isolating the positive changers and the

non-changers from the median grouping, we find seven hybrids with a wide range

in yield in relation to water regime and five hybrids with a narrow range in

6







yield in relation to water regime in the early planting study.

In the late planting study, four wide range hybrids in relation to water

regime contained two of the same hybrids as the early planting (Pioneer 3072

and Pioneer 3098) and four of the same narrow range hybrids in the late

planting as in the early planting. Cargill C-501, a narrow range hybrid in

the early planting became a wide range hybrid in the late planting which may

indicate a favorable response of this hybrid to late planting.

Hybrid X planting date

The interaction of hybrid X planting date is illustrated in Fig. 4 for

rainfed and irrigated conditions. Four positive changers were noted in

relation to planting date under rainfed conditions having a wider range of

yield than the others (DeKalb XL 678C, Pioneer X-304C, Pioneer 3214, Pioneer

3078). The irrigated condition gave a wider range response. Three positive

changers that did best when planted on 3 July were Cargill C-501, Pioneer

3072, and Pioneer 6875 with three negative changers that did best when planted

on 7 June (Cargill C-333, Cargill T-327, Cargill T-320). Three other negative

changers that did well when planted on 7 June were Cargill T-321, Pioneer

3098, and Cargill C-611.

Fall army preference

Fall armyworm seems to have definite preferences for certain tropical corn

hybrids. In 1989, Pioneer X-304C showed that it was less susceptible

to fall armyworm than other hybrids tested with resulting higher yields (Table

2). More evidence for fall armyworm preference is shown in Fig. 5 where

Pioneer X-304C had significantly fewer fall armyworm than Flopup (a Florida

open pollenated line) and Sunbelt 1876 (a temperate line) for all dates

counted. In the 1990 limited irrigation hybrid tropical corn trials, fall

armyworm definitely reduced yields of certain hybrids that have higher yield

7









potentials in the absence of fall armyworm. Any hybrid with a grain yield

greater than 75 bu/A was considered somewhat resistant to fall armyworm.

ACKNOWLEDGEMENT

Our thanks to E. Brown, Agricultural Technician IV and B.T. Kidd, Biological

Scientist II; North Fla. Res. and Educ. Ctr. Univ. of Fla., Quincy, FL; for

plot preparation and management, data collection, computer processing, and

data illustration.

LITERATURE CITED

Herzog, D.G., and J.E. Funderburk. 1986. Ecological bases for habitat
management and pest cultural control. p.217-250. In M. Kogan (ed.) Ecological
theory and integrated pest management practice. John Wiley & Sons. New York,
NY.

Teare, I. D. and D. L. Wright. 1990a. Crop yield comparisons and economic
analysis for single and double-crop systems. Univ. of FL, NFREC, Quincy, FL.
Res. Rep. NF 90-6.

Teare, I.D., and D.L. Wright. 1990b. Corn hybrid-starter fertilizer
interaction for yield and lodging. Crop Sci. 30:1298-1303.

Teare, I. D., D. L. Wright, and R. K. Sprenkel. 1990. Early planting reduces
fall armyworm problems in no-till tropical corn. In J.P. Mueller and M.G.
Wagner (ed.) 1990 Southern Conservation Tillage Conference. pp. 38-41. SB
90-1. Raleigh, NC. 16-17 July, 1990. North Carolina State University.
Raleigh, NC 27695.

Teare, I. D., D. L. Wright and D. J. Zimet. 1989. No-till research with
tropical corn in a double-crop system. pp. 43-45. In I. D. Teare, E. Brown,
and C. A. Trimble (ed.). 1989 Southern Conservation Tillage Conf. Proc.
Quincy, FL, 12 July 13 July 1989. Univ of Fla. Quincy, FL.

Wright, D.L., D.P. Lilly, and I.D. Teare. 1990. Planting tropical corn in
minimum tillage systems. pp. 81-83. In J.P. Mueller and M.G. Wagner (ed.)
1990 Southern Conservation Tillage Conference. SB 90-1. Raleigh, NC. 16-17
July, 1990. North Carolina State University. Raleigh, NC 27695.

Wright, D. L., and C. G. Chambliss. 1989. Results of corn hybrid tests in
Florida in 1988, a tropical corn test and results from South Georgia trials.
Univ. of Fla. Agr. Facts No. SS AGR-926.

Wright, D. L., and D. L. Prichard. 1988. Tropical corn production and use.
Univ. of Fla. Agr. Facts No. 228.









potentials in the absence of fall armyworm. Any hybrid with a grain yield

greater than 75 bu/A was considered somewhat resistant to fall armyworm.

ACKNOWLEDGEMENT

Our thanks to E. Brown, Agricultural Technician IV and B.T. Kidd, Biological

Scientist II; North Fla. Res. and Educ. Ctr. Univ. of Fla., Quincy, FL; for

plot preparation and management, data collection, computer processing, and

data illustration.

LITERATURE CITED

Herzog, D.G., and J.E. Funderburk. 1986. Ecological bases for habitat
management and pest cultural control. p.217-250. In M. Kogan (ed.) Ecological
theory and integrated pest management practice. John Wiley & Sons. New York,
NY.

Teare, I. D. and D. L. Wright. 1990a. Crop yield comparisons and economic
analysis for single and double-crop systems. Univ. of FL, NFREC, Quincy, FL.
Res. Rep. NF 90-6.

Teare, I.D., and D.L. Wright. 1990b. Corn hybrid-starter fertilizer
interaction for yield and lodging. Crop Sci. 30:1298-1303.

Teare, I. D., D. L. Wright, and R. K. Sprenkel. 1990. Early planting reduces
fall armyworm problems in no-till tropical corn. In J.P. Mueller and M.G.
Wagner (ed.) 1990 Southern Conservation Tillage Conference. pp. 38-41. SB
90-1. Raleigh, NC. 16-17 July, 1990. North Carolina State University.
Raleigh, NC 27695.

Teare, I. D., D. L. Wright and D. J. Zimet. 1989. No-till research with
tropical corn in a double-crop system. pp. 43-45. In I. D. Teare, E. Brown,
and C. A. Trimble (ed.). 1989 Southern Conservation Tillage Conf. Proc.
Quincy, FL, 12 July 13 July 1989. Univ of Fla. Quincy, FL.

Wright, D.L., D.P. Lilly, and I.D. Teare. 1990. Planting tropical corn in
minimum tillage systems. pp. 81-83. In J.P. Mueller and M.G. Wagner (ed.)
1990 Southern Conservation Tillage Conference. SB 90-1. Raleigh, NC. 16-17
July, 1990. North Carolina State University. Raleigh, NC 27695.

Wright, D. L., and C. G. Chambliss. 1989. Results of corn hybrid tests in
Florida in 1988, a tropical corn test and results from South Georgia trials.
Univ. of Fla. Agr. Facts No. SS AGR-926.

Wright, D. L., and D. L. Prichard. 1988. Tropical corn production and use.
Univ. of Fla. Agr. Facts No. 228.









Table 1. Planting date1 and N rate influence on Pioneer X-304C Yield
(Quincy, 1989 and 1990).



Planting Date
1989 May 28 June 15 July 14



N Rate
lbs/A -- Bu/A-------

0 71 a 39 a 41 a

50 96 b 69 b 44 a

100 113 c 68 b 40 a

150 112 c 81 b 42 a

200 115 c 72 b 43 a


Average 101 66 42


1990 June 8 June 14 July 12

-Bu/A-------------

0 45 a 44 a 47 a

50 49 a 48 a 43 a

100 48 a 48 a 38 a

150 46 a 53 a 43 a

200 51 a 45 a 47 a


Average 48 48 44


1All planted after Florida 303 wheat was harvested in May.









Table 2. Tropical corn hybrid yields for 1989 (severe fall armyworm damage)
and 1990(fall armyworm damage and severe drought).

29 May 1989 7 June 1990 3 July 1990
Rainfed Rainfed Irrigated Rainfed Irrigated
Line Bu/A Bu/A Bu/A Bu/A Bu/A

Flopup 30
Pioneer XCJ 66 36
Pioneer XCH 53 11
Pioneer XCE72 12
Pioneer 3212 16
Pioneer X8965 12
Pioneer 3226 20
Pioneer 3238 7
DeKalb B840 27
DeKalb XL604 14
DeKalb XL678C 14 21 75 34 84
Pioneer X-304X 42 21 73 40 73
Pioneer 6875 9 18 36 24 51
Cargill C-343 26 32 85 36 79
Cargill C-381 18 26 77 36 86
Pioneer 3230 16 24 52 33 49
Pioneer 3210 20 28 76 39 81
Pioneer 3072 38 122 41 140
Pioneer 3214 19 88 34 81
Pioneer 3098 31 130 37 107
Pioneer 3078 25 85 38 94
Sunbelt 1876 (Temperate) 15 25 20 33
Cargill C-333 39 156 35 74
Cargill C-501 27 54 21 101
Cargill C-611 34 102 42 83
Cargill T-327 23 103 25 55
Cargill T-321 44 78 36 52
Cargill T-320 31 92 32 66
Cargill C-805 37 32
Cargill C-701 47 91
Cargill C-803 42 105
Cargill C-955 38 18
Cargill C-606 48 80





1989


J1.,


I,, Ii .1


-50 i6S *"1"JL U"195^1 2 2 220 255 2170 2 3 13

1990


0 0
0 0 !- I-
0~l Q~l -- --

.- -1 O Co < <
I L


I '1 | I I I


DAY OF YEAR
Figure 1. Rainfall, planting date, 50% tasseling,
1989 and 1990 growing season. Three small arrows in
irrigation. Days of year reported in days Julian.


and
1990


harvest date during
indicate the limited


6


(D


-C
-J


Z

cc


JtIJ


15U 103 22u 5Y3 Z1U ^ 240


233 Z/U ~w










No. Larvae/Plant


6

Apr 12
May 16
5 --- Jun 15
Jul 15







3-



2



1-




0
170 178 186 194 200 207 214 221 228 235

Sampling Dates


Figure 2. Fall armyworm larve counts in relation to days after planting on
four planting dates (12 Apr, 16 May, 15 June, and 15 July) in 1990.








Rainfed

Cargill C-333 -
Pioneer 3098 O
Pioneer 3072 O
Cargill T-327 O
Poineer 3214 O
Cargill C-611 -
Pioneer 3078 -
Cargill T-320 -
Dekalb XL678C -
Cargill C-343 -
Pioneer X-304C O
Cargill C-381 -
Pioneer 3210 O
Cargill T-321 -
Cargill C-501
Pioneer 3230
Pioneer 6875
Sunbelt 1876 ---
-60 -40 -20


Pioneer 3072
Cargill C-501
Pioneer 3098
Pioneer 3078
Cargill C-381
Dekalb XL 678L
Pioneer 3214
Cargill C-343
Pioneer 3210
Cargill C-611
Cargill C-333
Pioneer X-304C
Cargill T-320
Cargill T-327
Pioneer 6875
Pioneer 3230
Cargill T-321
Sunbelt 1876


Irrigated


0 20 40 60


UY A
0
0
GA

0 A
0
0
0
0
0 A
p A

0
0 A.

0
0
0 A
0 A
-0 A
S0 A
-60 -40 -20 0 20 40 6(
YIELD DIFFERENCE FROM HYBRID MEAN (Bu/A)


Figure 3. Tropical corn hybrid yield interaction with water regime for early

and late planting dates in 1990.








RAINFED


Dekalb XL 678C
Pioneer X-304C
Pioneer 3214
Pioneer 3078
Cargill C-381
Pioneer 3230
Pioneer 3210
Cargill C-611
Pioneer 6875
Pioneer 3098
Cargill C-343
Sunbelt 1876
Pioneer 3072
Cargill T-327
Cargill T-320
Cargill C-333.
Cargill C-501
Cargill T-321


SA
0 2
4- -2 0 2 4








-40 -20 0 20 40


IRRIGATED


Cargill C-501
Pioneer 3072
Pioneer 6875
Dekalb XL 678C
Cargill C-381
Pioneer 3078
Sunbelt 1876
Pioneer 3210
Pioneer X-304C
Pioneer 3230
Cargill C-343
Pioneer 3214
Cargill C-611
Pioneer 3098
Cargill T-321
Cargill T-320
Cargill T-327
- Cargill C-333


-40 -20 0 20 40
YIELD DIFFERENCE FROM HYBRID MEAN (Bu/A)


Figure 4. Tropical corn hybrid yield interaction with planting date for


rainfed and irrigated water regimes in 1990.


7 June


3 July













































170 178 186 194 200 207

Sampling Dates


214


221 228


Figure 5. Fall armyworm larve counts in relation to two hybrids and one open
pollenated lines of tropical corn in 1990 when planted on 15 June.


X-304C
Flopup
SSunbelt 1876
















I__ _ I




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs