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Group Title: Research report - North Florida Research and Education Center ; 90-7
Title: Late planting increases fall armyworm damage and reduces yields in tropical corn
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00066080/00001
 Material Information
Title: Late planting increases fall armyworm damage and reduces yields in tropical corn
Series Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 10 p. : ill. ; 28 cm.
Language: English
Creator: Teare, I. D ( Iwan Dale ), 1931-
Wright, D. L ( David L )
Sprenkel, Richard K
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Flordai Research and Education Center
Place of Publication: Quincy Fla
Publication Date: 1990
 Subjects
Subject: Corn -- Florida   ( lcsh )
Fall armyworm   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 6-7).
Statement of Responsibility: I.D. Teare, D.L. Wright, and R.K. Sprenkel.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00066080
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71152090

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Full Text





90o-








Late Planting Increases Fall Armyworm Damage
and
Reduces Yields in Tropical Corn


Central Science
Library

MAY 29 1990

University of Florida


I.D. TEARE, D.L. WRIGHT, and R.K. SPRENKEL










I.D. Teare, D.L. Wright, and R.K. Sprenkel, 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). Research Report NF-90-7.










INTRODUCTION

Farmers in the Southeast became interested in tropical corn [Zea

mays (L.)] in 1984 and planted about 5,000 A predominately Pioneer Brand

X-304C hybrid [coded X-304C]. By 1988, plantings had increased to about

10,000 A with good yields and in 1989 approximately 40,000 A were sown

to tropical corn. A moderate energy input system for tropical corn was

described by Teare, et al.(1989) based on four years research growing

X-304C when planted after winter wheat [Triticum aestivum (L.)]

(harvested around 24 May each year).

Overman and Gallaher (1989) conducted a date of planting study in

1988, where X-304C was grown in a high energy input system (no-till

planting at 34,400 plants/A, 270 lb N/A and irrigation) with three

planting dates (Mar, May, Aug). These authors reported yields of 150,

114, 78 bu/A for the three respective planting times and attributed

yield reduction to differences in temperature and daylength. Increased

pest problems were only mentioned. Bustillo and Gallaher (1989) state

"insect control needs further research [ on tropical corn ], to

determine the most effective and economical control program".

Experience in South America (J.E. Funderburk, 1988, personal

communication) indicated that IPM practices must be adhered to for

control of lesser cornstalk borer [Elasmopalpus lignosellus (Zeller)]

and fall armyworm [Spodoptera frugiperda (J.E. Smith)]. Few insect or

disease problems were experienced during 1985 to 1988, but the 1989

season was different.

Fall armyworm is a polyphagous, highly mobile insect that normally

arrives in North Florida by late-May. The population probably

2









originates each spring from continuous breeding populations in southern

latitudes (Barfield, et al.,1980). The erratic occurrence of fall

armyworm "outbreak years" and irregular distribution of heavy

infestations indicate that fall armyworm is a "boom or bust" pest. The

last "boom" year in the southeastern US was in 1977. Fall armyworm

larve developing on corn usually has six larval instars requiring a

period of 21 days. However, the life cycle is temperature dependent and

can range from 66 to 18 days at temperatures of 64 to 950F (Barfield et

al.,1978) .

Fall armyworm eggs laid on leaves in the whorl, generally escape

most natural predators, but egg masses laid after the tassel has emerged

are subject to greater predation (Martin et al.,1979). Natural enemies

have been observed to move sequentially through crops coupled by pest

flows and reduce population densities of fall armyworm in a very short

period (Martin et al.,1979).

Many practices are employed to plant, maintain, and harvest any

crop. Pest injury avoided by producing a crop at times when pest

populations are in nondamaging stages or at low population levels is

recognized (Herzog and Funderburk, 1986).

Our experiences in 1989 with tropical corn indicates a cultural

practice that improves the wheat-tropical corn doublecrop system

proposed by Teare et al. (1989) in relation to planting and fall

armyworm. The objective of this note is to document our observations

during 1989 on the effect of early and late planting on the

susceptibility of X-304C to fall armyworm and to suggest a planting

window after wheat harvest (24 May) where tropical corn seems to escape

the fall armyworm in a production environment.

3









MATERIALS AND METHODS

The fall armyworm observations reported in 1989 are from an on-going

tropical corn research program at the North Florida Research and

Education Center (NFREC) and surrounding tropical corn fields in Gadsden

county. The soils are a Norfolk sandy loam soil [fine-loamy, siliceous,

thermic, Typic Kandiudult]. All plantings were grown under the moderate

energy input system: no-till planting at a plant population of 18,000

plants/A 120 lb N/A [20 Ib/A as starter fertilizer at planting and 100

Ib/A when the corn was 12 inchs tall (approximately 31 days after

planting)], and no irrigation. The major difference from previous years

was rainfall, date of planting, and incidence of fall armyworm. Rainfall

data was collected at the NFREC weather station located approximately

200 to 800 yd from the tropical corn experiments. The early planted

experiment at the NFREC was planted 26 May 1989 to X-304C (four

replications in a randomized block design). The 1989 early planted

farmer field was planted to X-304C4 June eight miles west of Quincy.

The excessive rainfall from 21 May to 27 June delayed other tropical

corn plantings and flooded poorly drained areas. About half of the

early planted farmer field was not harvested because of excessive

soil-water causing oxygen stress in tropical corn. Only the yield of

the well-drained area is given. The 1989 late planted (29 June) study

was a tropical corn hybrid yield trial (four replications in a

randomized block design) containing X-304C and 15 other tropical corn

hybrids (Table 1). Grain yields were corrected to 15.5 % moisture

content.








RESULTS AND DISCUSSION

Excessive rainfall, delayed planting, and fall armyworm injury were

the major differences that we observed between the years of 1989 and

1985 through 1988. Rainfall from 21 May to 27 June 1989 was 20 inchs.

Rainfall during the tropical corn growing season of 1989 can be compared

with the rainfall for 1988 (Fig. 1). Only two fields of X-304C were

planted early in North Florida that we knew of, the rest, including the

tropical corn hybrid yield trial, were delayed until after 27 June.

The yield of the early planted tropical corn in 1989 was 61 bu/A at

NFREC and 65 bu/A in the farmers field compared to 94 bu/A yield average

for 1986, 1987, and 1988 at NFREC. Fall armyworm damage in the 1989

early planted X-304C was only noticeable on leaves about the same as

observed in 1985 to 1988. The 1989 late planted, fall armyworm infested

X-304C (planted 29 June) yielded 42 bu/A. Therefore, we have suggested

a window between 24 May and 10 June where fall armyworm damage is at a

low risk.

Under severe infestations as observed in 1989 late planted tropical

corn, the fall armyworm will skeletonize leaves in early instars or

produce ragged holes in later instars and eat the tassels and silks. We

have not observed much fall armyworm damage on the ears or stems of the

ears of X-304C, but grain fails to develop from lack of pollination.

Percent tasseling and silking curves for early planted X-304C in

relation to day of year for 1988 show little observable fall armyworm

damage, but percent tasseling and silking curves for late planted X-304C

in 1989 show extensive fall armyworm damage. The 1989 change in

tasseling pattern was observed on 240 day of year (28 Aug) when fall

armyworm consumption of tassels made it appear that tasseling had

5









ceased, followed by a slight increase and then a negative slope at 250

day of year (7 Sept). The consumption of silks in 1989 reduced the

silking slope at 244 day of year and it became negative after 250 day of

year. This indicates that fall armyworm populations were at their

highest levels during tasseling and silking. A very susceptable stage

of growth for any corn in relation to grain yield.

A late planted hybrid tropical corn yield trial with 16 hybrid

entries was conducted for the first time in 1989 and the effects of fall

armyworm infestation are shown in relation to mean yield and standard

error of the treatment mean in Table 1.

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 data illustration and for plot preparation and

management.

REFERENCES

Barfield, C.S., E.R. Mitchell, and S.L. Poe. 1978. A temperature

dependent model for fall armyworm development. Ann. Entomol. Soc.

Am. 71: 70-74.

Barfield,C.S., J.L. Stimac, and M.A. Keller. 1980. State-of-the-art for

predicting damaging infestations of fall armyworm. Fla. Entomol.

63:364-375.

Bustillo, J.J., and R.N. Gallaher. 1989. Dry matter Partitioning in

No-tillage Tropical Corn in Florida. p.40-42. In I.D. Teare, E.

Brown, and C.A. Trimble (ed.) 1989 Southern Conservation Tillage

Conference. SB 89-1. Tallahassee, FL. 12-13 July, 1989. Univ. of

Fla., North Fla. Res. and Educ. Ctr., Quincy, FL 32351.

6









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.

Overman, D.L., and R.N. Gallaher. 1989. Growth and Partitioning of Dry

Matter Between Temperate and Tropical Corn. p.38-40. In I.D. Teare,

E. Brown, and C.A. Trimble (ed.) 1989 Southern Conservation Tillage

Conference. SB 89-1. Tallahassee, FL. 12-13 July, 1989. Univ. Of

Fla., North Fla. Res. and Educ. Ctr., Quincy, FL 32351.

Martin, P.B., P.A. Goodman, and F.A. Marshall. 1979. Integrated

management of insects of pastures and forages in the Coastal Plain

of Georgia. Dept. of Entomol. and Fisheries Series 78: D.1-D.329.

Teare, I.D., D.L. Wright, and D.J. Zimet. 1989. Four years experience

with tropical corn in a doublecrop system. Univ. of Fla., North

Fla. Res. and Educ. Ctr., Quincy, FL. Res. Rep. NF-89-4.










Table 1. Hybrid tropical corn yields (bu/A) and standard error of the hybrid
in relation to brand and ranked by hybrid within brands during 1989 when the
hybrid tropical corn yield trial was late planted (June 29) and with severe
fall armyworm infestation in a moderate energy-input system.


Replications


Brand


Pioneer






















DeKalb







Cargill


Hybrid


X304C

XCJ66

326

3210

3230

3212

XCE72

X8965

XCH53

6875

3238



B840

XL678C

XL604



C-343

C-381


77.9

70.5

14.4

23.1

36.6

33.8

21.7

27.0

19.5

19.9

21.3



23.9

36.5

27.6



41.1

31.3


31.6

24.9

18.7

8.4

24.5

6.7

20.6

11.8

2.7

3.0

4.6



34.6

25.4

6.1



17.2

14.2


28.0

36.4

25.8

24.0

2.5

3.0

0.9

0.6

22.7

9.9

3.6



29.1

20.2

16.8



16.2

20.9


30.5

13.1

22.0

23.3

1.3

19.7

3.2

7.1

0.4

1.6

0.1



22.0

25.0

7.6



30.7

4.0


42.0

36.2

20.2

19.7

16.2

15.8

11.6

11.6

11.3

8.6

7.4



27.4

26.7

14.5



26.3

17.6


S. E.


12.0

12.4

2.4

3.8

8.6

7.0

5.5

5.6

5.7

4.2

4.7



2.8

3.5

5.0



5.9

5.7


Grain yields corrected to 15 % moisture content.













1 1988


,I, I 1


,1t


140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310
-j
...J
S 7
LL 1989
Z
< 6
0: 0

z-

1-4
Z Z) >




r, I I


2 -


1



140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310

DAY OF YEAR

Figure 1. Rainfall, planting date, 50% tasseling, and harvest date
during 1989 and 1988 tropical corn growing seasons. Days of year
reported in days Julian.


5 -


. ,1


I Ij














I00

80

60
0 0 . . .. . ... ... ... ... ... ... ... ....

s o.8 ... 11- 1 .................... ................... ........ .......-- -- -- ...................

6 0 ................................................. .............. ....................... .....- .-- - ..................

4 0 ...................................... ... ... ..... .............. .................... ......-- -


lI I f I II I 'l
223 229 236


247


253


223 229 235 241 247 253


DAY OF YEAR


Figure 2. Comparison of tasseling and silking for 1989 in relation to 1988.
Negative slope after 250 days Julian (7 Sept) indicated time of severe fall
armyworm damage in 1989.


n -''L


I t I I #I I I I I 1 I I !


1988


1989




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