Literature cited

Group Title: Agronomy research report - University of Florida Agronomy Department ; AY 89-06
Title: Corn yield response to tillage, hybrids, and insecticides
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00056116/00001
 Material Information
Title: Corn yield response to tillage, hybrids, and insecticides
Physical Description: 14 leaves : ill. ; 28 cm.
Language: English
Creator: Espaillat, Josâe Rafael, 1955-
Gallaher, Raymond N
University of Florida -- Agronomy Dept
Publisher: Agronomy Department, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1989?]
Subject: Corn -- Yields -- Florida   ( lcsh )
Tillage -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: J.R. Espaillat and R.N. Gallaher.
Bibliography: Includes bibliographical references (leaves 13-14).
General Note: Caption title.
General Note: Agronomy research report - University of Florida Agronomy Department ; AY 89-06
 Record Information
Bibliographic ID: UF00056116
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 62585560

Table of Contents
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    Literature cited
        Page 14
        Page 15
Full Text

#C Agronomy Research Report AY-89-06 Library

TFEB D8 199(

^-- __ ---
Corn Yield Response to Tillage, Hybrids, and Insecticides

J.R. Espaillat and R.N. Gallaher2

Researchers have reported differential and conflicting

responses of corn (Zea mays L.) to insecticides. This research

was conducted to determine if tillage and corn genotypes could be

the reasons for these responses. Two sets of experiments were

conducted. In one 3-yr study no-tillage (NT) and conventional

tillage (CT) were main plots and four insecticide treatments were

split plots (2.2 kg a.i. Carbofuran ha-1 (CF 2.2), 1.1 kg a.i.

Carbofuran ha-1 (CF 1.1), 2.2 kg a.i. Terbufos ha-1 (TF 2.2), and

a untreated control (C). In the other set six hybrids were main

plots with the same insecticides as split plots. Grain yield and

plant height were measured at harvest. Treatments with CF 2.2

gave higher grain yield in NT, but TF 2.2 gave equal grain

response in CT. When "Asgrow RX777" (developed using TF) was

treated with TF 2.2, it averaged 32 q ha-1 more grain than the C.

Also, "DeKalb XL71" (developed using CF) yield 28 q ha- more

grain with CF 2.2 than with the C. These interactions suggested

that a hybrid will respond better to the insecticide used during

its breeding development.

Graduate student (National Corn Program, The Dominican Republic)

Professor of Agronomy, Agronomy Department, Inst. of Food and

Agr. Sci., University of Florida, Gainesville, Florida, 32611.


Researchers have reported differential and conflicting

responses of corn (Zea mays L.) to insecticides (5).

Environmental factors influence both the magnitude and expression

of genetic resistance. Also, cultural factors such as soil

fertility, soil moisture, pesticides, and plant growth regulators

affect yield and nutritional quality of host plant tissue

appearing to be particularly important in the induction of

resistance (13). Genotypes may react differently in different

environments resulting in populations that were relatively stable

in their original environment, being unstable and fluctuating

greatly in the stress of a new environment (3, 8).

The advantages and disadvantages of no-tillage (NT) on crop

production have been reviewed by Phillips et al (11). No-tillage

induces major modifications in ecological conditions in fields,

especially the conditions affecting soil fauna. These

alterations may enhance, have no affect, or deter the

biopotential of soil arthropods including agricultural pests. It

is generally anticipated that insect infestations will be more

severe in NT systems and that insect control will be more

difficult than in conventional tillage (CT) corn (9). However,

infestations of lesser cornstalk borer (Elasmopalpus lignosellus)

were deterred in NT corn cropping systems (2). Pathogens affect

the absorption of soil applied pesticides. Both root rot

(Giberella zeae S.) and Leaf rust (Puccinia sorghi S.) affected

the translocation of carbofuran from soils into the plant (12).

The method and timing of pesticide application determine the

efficiency of application. Terbufos gave excellent season-long

control of greenbugs (Schizaphis graminum R.) and increased grain

yield when injected into soil. Equivalent rates applied in a

band on the soil surface gave poor control (4). Carbofuran

degradation in some soils is rapid, occasionally failing to

provide adequate control (6, 7). In a tillage-corn genotypes

study 60 commercial hybrids were grown under NT and CT, no

differential response of these hybrids to tillage system was

found (10).

Since high seed yield is likely the overriding objective of

the corn breeder, and since emphasis is directed to higher grain

yields for grain farmers to maintain an existence in farming,

hybrid development is likely carried out under ideal conditions

such as; fertility and pest control. These genotypes (cultivars)

would be developed under relatively specific altered

environments. Furthermore, it is proposed that a hybrid

developed for high seed yield under high fertility and ideal

irrigation may not perform well in other environments of low

fertility and/or non irrigation. The authors hypothesize that if

hybrids are developed using a specific pesticide (insecticide

and/or nematicide) it may not perform the same if grown using

another pesticide (1).

The objective of this research was to determine if tillage

and corn genotype are the reasons why scientist, industry, and

farmers disagree on yield response among pesticides.


This research was conducted in the north-central Florida

region from 1981 to 1983. Two sets of experiments were carried

out on Hernando LFS (Typic Hapludalf) soil. In both cases, a

randomized complete block design was used. The two sets of

experiments were the following: tillage/pesticide, and


Tillage/Pesticide Experiments

In this 3-year study (1981, 1982, 1983) the response of

"Dekalb XL71" corn hybrid to insecticides under two tillage

management conditions was evaluated. No-tillage plus in-row

subsoil versus CT plus in-row subsoil were whole plots with four

replications and three insecticide treatments and a control were

split plots (1.1 Kg a.i. Carbofuran ha-1 (CF 1.1) 2.2 Kg a.i.

Carbofuran ha-1 (CF 2.2), 2.2 Kg a.i. Terbufos ha-1 (TF 2.2) and

a untreated control (C)). Split plots were 10 feet (3.07 m)

wide, and 30 feet (9.20 m) long. There were four rows 30 inches

(0.75 m) apart. Plots were kept under monocrop corn for 6-yr, 3-

yr prior to the implementation of the pesticide treatments, and

during the 3-yr experiment. The corn hybrid DeKalb XL71 at

90,000 seed per hectare was planted from 27 February to 10 March

each year. A Brown Harden in-row subsoil NT planter was used

either where no prior land preparation had occurred or where the

soil had been prepared conventionally with an off-set Harrow and

Rototiller. The pesticide treatments were applied in 6 inch

(0.15 m) bands over the row at planting. Complete fertilizer

including N, P, K, S, Mg, Fe, Cu, B, Zn and Mn was broadcast

prior to planting based on soil test and plant need. Preplant

broadcast fertilization include 200 Kg ammonium nitrate (NO3),

and 225 Kg KMAG ha-1. Also, Ammonium nitrate was sidedressed at

a rate of 168 Kg ha-1 when plants were 10 inches (0.25 m) tall.

Weed control was done 10 days prior to planting with Paraquat

plus X77 surfactant. When corn was about six inches (0.15 m)

tall a post-broadcast application over the top was done with

Atrazine. Atrazine at 2.2 Kg a.i. ha- and 2 L crop oil ha-1 was

used in all experiments.

Collected data consisted of plant height (PH) at the soft

dough stage of grain formation, and corn grain yield (GY) at

harvest time. Statistical analyses were performed using split

plot ANOVA on a TRS-80 model III microcomputer. Means were

tested using Duncan's new multiple range test at the 0.05

probability level.

Genotype/Pesticide Experiments

In this three-location study six commercial hybrids were

evaluated for yield as affected by pesticide treatment. This

genotype/pesticide experiment was conducted during 1982 and 1983,

having different locations. The 1982 experiment was done in

Alachua county, FL and the two 1983 experiments (1983A, 1983B)

were done in Levy county, FL. The three locations had similar

cropping histories, of continuous double cropped NT corn followed

by soybean (Glycine max L.) for 1 yr in the case of the 1982

location, and for the last 4 yr in both 1983 locations.

The hybrids evaluated were the following; Asgrow RX777(A),

DeKalb XL 71(D), Funks G4507A(F), Coker 19(C), Pioneer Brand

3320(P), and Gold Kist 748(G). Hybrids were whole plots with 4

replications. The same insecticides and rates used in the

tillage/pesticide study were split plots. The same plot size and

cultural practices used in the tillage/pesticide experiment were

used in this experiment, such as planting technique, weed

control, and fertilization rate. Data collection, and

statistical analysis were handled in the same manner.


Tillage/Pesticide Experiments

The average of 3 yr of data showed interactions between

tillage and pesticide treatments for both, grain yield (GY), and

plant height (PH) (tables 1, and 2). The highest GY was given

under NT conditions by CF 2.2 which was different from the others

at the 0.05 probability level. It was followed by the other two

pesticide treatments, which did not differ in yield response to

pesticides. All pesticide treatments gave higher GY than the

Control (table 1).

Under CT conditions there was no difference (0.05 prob.

level) among pesticide treatments. However, both pesticides and

rates were better than the Control (table 1). Among the

pesticide treatments, CF 2.2 gave the highest grain yield under

NT conditions. The opposite occurred with CF 1.1, having greater

grain yield under CT conditions. But TF 2.2 did not show any

differences between tillage treatments. For the C, NT grain

yield was higher than CT.

The tallest plants also occurred under NT conditions at the

highest rate of Carbofuran (CF 2.2). The CF 1.1, TF 2.2, and C

did not differ in NT (table 2). Under CT both CF 2.2 and CF 1.1

gave the tallest plants. The TF 2.2 treatment had shorter plants

than the Carbofuran treatments. The C had the shortest plants in

CT. Among the pesticide treatments, tillage treatments were

different only for the highest rate of Carbofuran, and was in

favor of NT (figure 2).

Genotype/Pesticide Experiments

The three-location average showed interactions between

genotype and pesticide treatments under NT conditions for both GY

and PH (tables 3, and 4). Looking at the Grain Yield response to

pesticides within each individual hybrid, note that the highest

GY was obtained with Asgrow RX777 using TF 2.2 (105 g ha-1). All

the other hybrids gave their highest GY with the highest rate of

Carbofuran (CF 2.2). However, Coker 19 responded statistically

equal to Terbufos and the two Carbofuran rates. Also, Pioneer

brand 3320 responded equally to the two Carbofuran rates (table

3). For the same data, the GY response was studied across

hybrids within an individual pesticide treatment (figure 2).

This comparison showed that when CF 2.2 was used the DeKalb XL71

and Gold Kist 748 hybrids gave the highest GY. However when CF

1.1 was used Pioneer brand 3320 and Gold Kist 748 gave the

highest GY. Terbufos seemed to favor Asgrow RX777 grain yield

-- A
over the others. When the hybrids were placed in a untreated

environment the hybrid Pioneer brand 3320 gave the greatest grain


In general the tallest plants occurred by different hybrids

with the highest rate of Carbofuran (CF 2.2). The exception was

DeKalb XL71, which had the tallest plants with TF 2.2 (246 cm).

The Control (C) gave the shortest plants. The PH response among

hybrids within an individual pesticide treatment was evaluated

(table 4). This comparison showed that for both CF rates that

were used Gold Kist 748 gave the tallest plants. The TF 2.2

favored DeKalb XL71 in PH. Again, Gold Kist 748 and DeKalb XL71

gave the tallest plants when placed in a untreated environment.


Tillage treatments were different for the hybrid DeKalb XL71

only when the highest CF rate (2.2 Kg a.i. ha-1) was used, being

in favor of NT. This may have been due to the Growth regulator

effects attributed to CF. The three insecticide treatments gave

equal grain yield in CT. The results showed that it is not

appropriate to use recommendations from research conducted in one

type of tillage and expect the same response in another tillage

environment. Research is needed in both NT and CT in order to

make proper recommendations to growers.

These data indicate that hybrids do not respond equally to

pesticides and this genotype/pesticide relationship is likely the

major reason why scientists disagree from one location to

another. Strong evidence was found to claim that commercial corn

breeders are selecting for a pesticide when it is used during the

development of the hybrid. This appears to be the case of Asgrow

777 which gave the highest yield when TF 2.2 was used. Terbufos

was used throughout its breeding program. All other hybrids were

developed using CF in their breeding program. In order to make

valid recommendations on pesticide use by growers, recommended

pesticides may need to be tested on all recommended hybrids in

order to match up the proper pesticide, rate of pesticide, and

hybrid for maximum response of each hybrid and maximum benefits

from the use of pesticides.

Table 1.

Corn grain yield response to tillage and
pesticides (three year average)

Pesticide Rate No Yes Average

kg a.i. ha-1 --------- q ha----
Carbofuran 2.2 118 a 109 a 114
Carbofuran 1.1 100 b 108 a 104
Terbufos 2.2 102 b 104 a NS 103
Control 0.0 92 c 81 b 87
Average 103 100

a,b,c, = within columns among pesticides.
* = different at .05 P in rows between tillage.
NS = nonsignificant.

Table 2. Corn plant height response to tillage and
pesticides (two year average)

Pesticide Rate No Yes Average

kg ha- ---------- cm -----
Carbofuran 2.2 266 a 252 a 259
Carbofuran 1.1 247 b 253 a NS 250
Terbufos 2.2 247 b 244 b NS 245
Control 0.0 240 b 235 c NS 237
Average 250 246

a,b,c, = within columns among pesticides.
* = different at .05 P in rows between tillage.
NS = nonsignificant.

Table 3.

Corn hybrid grain yield response to pesticides in no-
tillage management (three location average)

Insecticide Treatment
Carbofuran (CF) Terbufos (TF) Control Average
Hybrid 2.2 1.1 2.2 0.0

------------------------ q ha--------------------
A 97 v 92 w 105 u 73 vw 92
b c a d
D 103 u 92 w 90 v 75 vw 90
a b b c
C 92 w 95 vw 93 v 75 vw 89
a a a b
G 104 u 98 uv 84 w 77 v 91
a b c d
F 90 w 83 x 79 w 69 w 80
a b c d
P 98 v 101 u 89 v 91 u 77
a a b b
Average 97 94 90 77

Insecticide rates expressed as Kg a.i. ha-1. A = Asgrow RX777,
D = DeKalb XL71, C = Coker 19, G = Gold Kist G K 748, F = Funks
G4507 P = Pioneer brand 3320. a,b,c = within rows of
pesticides, values not followed by the same letter are
significantly different at the 0.05 level of probability;
u,v,w,x = within columns, values not followed by the same letter
are significantly different at the 0.05 level of probability.

- f

Table 4.

Corn hybrid plant height response to pesticides in no-
tillage management (three location average)

Insecticide Treatment
Carbofuran (CF) Terbufos (TF) Control Average
Hybrid 2.2 1.1 2.2 0.0

----------------------- cm----------------------
A 250 v 234 y 242 w 217 w 235
a c b d
D 242 w 237 x 246 u 236 uv 240
b c a c
C 250 v 230 z 235 x 211 x 231
a c b d
G 255 u 250 u 244 vw 237 u 247
a b c d
F 244 w 242 w 231 y 215 w 233
a a b b
P 253 u 247 v 237 x 234 v 243
a b c d
Average 249 240 239 225

Insecticides rates expressed as Kg a.i. ha-1. A = Asgrow RX777,
D = Dekalb XL71, C = Coker 19, G = Gold kist G K 748, F = Funks
G4507A, P = Pioneer 3320. a,b,c = within rows of pesticides,
values not followed by the same letter are significantly
different at the 0.05 level of probability; u,v,w,x = within
columns, values not followed by the same letter are significantly
different at the 0.05 level of probability.









SCarbofuran 2.2 Kg/ha EM Carbofuran 1.1 Kg/ha
C Terbufoa 2.2 Kg/ha E Control (untreated)



Fig. 1. Corn grain yield response to tillage and pesticides
(three year average).

CF 2.2 CF 1.1 TF 2.2 0.0

Fig. 2. Corn hybrid grain yield response to pesticides in
no-tillage management (three location average).



-- ,

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-- I

9. Musick, G. J. 1975. Insect problems associated with no-

tillage corn production. Proc. N. E. No-tillage Conf. 1:44-


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