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This is to certify that the

thesis entitled

WHEAT YIELD AND BARLEY YELLOW DWARF VIRUS INFECTION AS
AFFECTED BY PLANTING DATE AND CHEMICAL CONTROL

presented by
Salani Nkhori

has been accepted towards fulfillment
of the requirements for

Master Of Science degree in Crop & Soil Sciences

 

LAMajor ‘professor

Date November 10, 1997

 

0-7 639 MS U is an Wmative Action/Equal Opportunity Institution

 

 

 

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1“ WM“

WHEAT YIELD AND BARLEY YELLOW DWARF VIRUS INFECTION AS
AFFECTED BY PLANTING DATE AND CHEMICAL CONTROL

By
Salani Nkhori

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Crops and Soil Science

1 997

ABSTRACT

WHEAT YIELDS AND BARLEY YELLOW DWARF VIRUS INFECTION AS
AFFECTED BY PLANTING DATE AND CHEMICAL CONTROL.

By

Salani Nkhori

Improving grain production in small grain crops requires adequate
information on how performance is influenced by management practices. A two-
year study examined the main and interaction effects of planting date and
insecticides application on winter wheat performance. In both years the
treatments consisted of factorial combinations of planting date and insecticide
application, assigned to experimental units in a split-plot design. Insecticide
treatments in year 1 (1995/6) were 1) none, 2) lmidacloprid (GAUCHO) as a
seed treatment, and 3) GAUCHO (seed treatment) plus Dimethoate (CYGON)
sprayed in spring, and in year 2 (1996/7) were none and GAUCHO + CYGON.

In both years, the latest planting resulted in the lowest grain yields. The
last plantings produced the lowest test weight in year 1 but highest in year 2.
Kernel weight decreased with delayed planting in a fashion similar to grain yield
declines in year 1, but not in year 2. Maximum grain yield was obtained where
both GAUCHO and CYGON were applied in both years. Barley yellow dwarf
virus infection was heaviest from early-planted wheat. Levels of BYDV were

reduced from some early plantings treated with GAUCHO in year one.

To my parents, wife, sons, and daughter.

iii

ACKNOWLEDGEMENTS

I would like to take this opportunity to thank Dr Richard Ward for his
support, friendship, and serving as my major professor. I would also like to thank
Dr Patrick Hart and Dr Richard Harwood for their support as well as serving on
my guidance committee. I am not forgetting the Wheat Breeding staff who
helped me with my field experiments. I would like to thank Mike Kalishek for
helping me with the extraction of barley yellow dwarf virus from plant samples.
Special thanks are dedicated to my wife Hildah who was patient enough with my

long stay away from home.

iv

TABLE OF CONTENTS

LIST OF TABLES ................................................................................. vii
1.0 INTRODUCTION .............................................................................. 1
1.1 Wheat planting dates .................................................................... 2
1.2 Barley yellow dwarf virus ............................................................... 4
2.0 MATERIALS AND METHODS ............................................................. 8
3.0 RESULTS ...................................................................................... 11
3.1 Crop development ..................................................................... 11
3.2 Planting date and grain yield ........................................................ 13
3.3 Insecticide treatment and grain yield .............................................. 18
3.4 Planting date and Barley yellow dwarf virus ..................................... 20
3.5 Insecticide treatments and Barley yellow dwarf ................................ 22
3.6 Planting date and wheat spindle streak mosaic virus ......................... 24
4.0 DISCUSSION ................................................................................. 25
5.0 LITERATURE CITED ....................................................................... 30

APPENDIX A: PLANT EMERGENCE DATA BEFORE AND AFTER THE
WINTER FROM THE LAST PLANTING DATE IN YEAR 2. .......................... 34

APPENDIX B: GRAIN YIELD, TEST WEIGHT, AND THOUSAND-KERNEL
WEIGHT DATA OBTAINED DURING THE FIRST YEAR (199516) .................. 35

APPENDIX C: GRAIN YIELD, TEST WEIGHT, AND THOUSAND-KERNEL
WEIGHT DATA OBTAINED DURING THE SECOND YEAR (1996/7) ............. 37

APPENDIX D: ELISA VALUES (ABSORBANCE) FROM PLANT SAMPLES
COLLECTED OVER TIME IN THE FIRST YEAR ....................................... 38

APPENDIX E: ELISA VALUES (ABSORBANCE) FROM PLANT SAMPLES
COLLECTED OVER TIME IN THE SECOND YEAR ................................... 4O

APPENDEX F: DAYS OF YEAR OF INTIATION OF STEM ELONGATION AND
ANTHESIS IN YEAR 1 .......................................................................... 41

APPENDIX G: DAYS OF YEAR OF INTIATION OF STEM ELONGATION AND
ANTHESIS IN YEAR 2 ......................................................................... 42

APPENDIX H: THE EFFECT OF PLANTING DATE ON GRAIN YIELD OF
WINTER WHEAT VARIETY ‘HARUS’ IN YEAR 1 AND YEAR 2 .................... 43

APPENDIX I: THE EFFECT OF PLANTING DATE ON TEST WEIGHT OF
HARUS WINTER WHEAT IN YEAR 1 AND YEAR 2 .................................... 44

APPENDIX J: THE EFFECT OF INSECTICIDE TREATMENTS ON GRAIN
YIELD OF HARUS WINTER WHEAT PLANTED IN YEAR 1 AND YEAR 2 ...... 45

APPENDIX K: TEST WEIGHT OF WINTER WHEAT CV HARUS AS
INFLUENCED BY INSECTICIDE TREATMENTS IN YEAR 1 AND YEAR 2 ...... 46

APPENDIX L: THE RELATIONSHIP BETWEEN PLANTING DATE AND
BARLEY YELLOW DWARF VIRUS CONCENTRATION FROM WINTER
WHEAT IN YEAR 1 AND YEAR 2 ........................................................... 47

APPENDIX M: A COMPARISON OF INSECTICIDE TREATMENTS IN

RELATION TO THE CONTROL OF BARLEY YELLOW DWARF VIRUS ON
HARUS WINTER WHEAT IN YEAR 1 ....................................................... 48

vi

LIST OF TABLES

Table 1: Dates of planting Harus winter wheat ............................................ 10

Table 2: Timing of initiation of stem elongation (SE) and 50% anthesis (A) for
'Harus' winter wheat planted at different dates in two years .................. 12

Table 3: Summary of the significance of F tests from separate analyses of
variance for Year 1 and Year 2 of a split plot design of a factorial
combination of planting date and insecticide ..................................... 13

Table 4. Grain yield, test weight, and 1000-kemel weight of winter wheat variety
Harus as affected by planting dates in year 1 (a) and year 2 (b) ............ 15

Table 5: Mean BYDV absorbance, grain yield, test weight and 1000-kemel
weight of ‘Harus’ winter wheat as affected by planting date and insecticide
treatments in 1996 ....................................................................... 16

Table 6: Mean BYDV absorbance, grain yield, test weight and 1000-kemel
weight of ‘Harus’ winter wheat as affected by planting date and insecticide
treatments in 1997 ....................................................................... 17

Table 7. Mean BYDV absorbance of sample plants averaged across sampling
dates for the years 1996 (a) and 1997 (b) field plots ........................... 21

Table 8: Mean BYDV absorbance averaged across planting and sampling dates,
as affected by insecticide treatments ............................................... 24

Table 9: Mean WSSMV absorbance at three sampling times in 1996 (a) and
1997 (b) field plots ....................................................................... 25

vii

1 .0 INTRODUCTION

Wheat (Tn'ticum sp.) is an important worldwide crop; one that is harvested
somewhere every month of the year (Oleson, 1994; Smith, 1995). The crop is
capable of growing over a wide range of agrogeographical regions (Briggle and
Curtis, 1987). Of all wheat species, common wheat (Triticum aestivum L. em.
Thell) is the most widely cultivated. It has ranked as the number one crop for
human consumption, leading all other cereals in production and trade worldwide
(Briggle and Curtis, 1987). World wheat production has been inconsistent,
fluctuating from one year to the other. Over the last seven years (1990—1996),
the largest world harvest (592 million metric tons) occurred in 1990, while the
lowest (528 million metric tons) occurred in1994. During the same period the
area harvested decreased only by 0.4% from 231 to 230 million hectares (FAO,
1997). Despite annual production fluctuations, consumption, primarily as human
food, increased each year (FAO, 1997). Demand increased by over 34 million
metric tons between 1990 to 1994 (FAO, 1997).

Increased crop production can be achieved in two major ways; (i)
expansion of area planted, and (ii) improvement of yield per unit area (Briggle
and Curtis, 1987; Evans, 1993). A combination of improved varieties; agronomic

practices and expansion of the area under cultivation during the 1960’s did

increase wheat production. But the availability of new land for agriculture is now
drastically reduced (CIMMYT, 1995). Improving the yield per unit of area planted
remains the only alternative way to increase wheat yields. This can be achieved
in two ways; (i) improved wheat varieties, and (ii) by using improved agronomic
practices (Briggle and Curtis, 1987).

The crop season for wheat is the period of time and associated
circumstances starting at sowing and ending at harvest. Strategic decisions by
farmers, coupled with circumstances influencing access to land, dictate the
beginning of a crop season. Crop response to the accumulated effect of the
unfolding season determines the end of the crop season. By definition,
therefore, change of planting date alters the nature of the ensuing crop season.
A constant planting date employed for a period of years will also result in a set of
distinct crop seasons. Another major farmer controlled factor influencing crop
season is the choice of variety, which can dramatically influence the timing of
flowering and harvest. This work focused on the relationship of planting date to
performance in winter wheat as measured primarily by yield.

1.1 Wheat Planting Dates

Wheat planting date affects the physiological growth and development of
wheat plants. Under temperature and moisture limiting conditions, it determines
plant stand establishment, which influence grain yield (Dahlke et. al, 1993;
Fowler, 1982). Planting winter wheat at optimum times enables the plants to
develop strong root systems, achieve high winter survival, escape from other

stress factors, and maximize grain yields (Paulsen, 1987).

Optimum planting dates for wheat vary by production area, intended
purpose of the crop (Smith, 1995), and crop season (Coventry et. al, 1993).
There are several underlying principles behind the choice of planting date that
apply in all cases. Grain yield is one of the major criterion for selecting optimum
planting dates for wheat (Paulsen, 1987), although in areas where grazing is
practiced, vegetative biomass become an important criterion. In other areas, for
example, Michigan and Southwestern Ontario, the previous crop planted
influence optimum planting dates. Selection of planting date for wheat is also
governed by the need to avoid temperature and moisture extremities. Both low
and high temperatures have detrimental effects on winter wheat during the
critical early developmental stages. .

Planting wheat too early results in excessive growth in fall, uses up soil
moisture and gives growth leading to increased lodging, susceptibility to winterkill
(Smith, 1995; Fowler, 1983), and high pressure from diseases and insect pests.
On the other hand, planting late tends to limit plant development resulting in
poorly established plants with a lower winter-survival potential (Fowler, 1983).
Such plants do not develop sufficient foliage to trap snow, which helps in the
regulation of ground temperature during the winter. Late plantings of winter
wheat also tend to have their grain filling period shifted into periods of higher
temperatures. High temperatures shorten the duration of grain filling, hence
reducing grain yields (Evans, 1980).

Optimum planting dates in many parts of the world have been arrived at

through research and grower's experience. In Ontario, for example, a 2-wk

optimum planting period for winter wheat has been proposed (Bootsma et al,
1993). The optimum seeding date estimation ranged from as early as 21 August
in the north around Kapuskasing to as late as 15 October for the Windsor area
though varying from one year to the other within the location. In Michigan,
according to Wiese (1979) wheat can be planted 10 days after the hessian fly-
free date (FF D). Hessian fly-free date is the date after which the Hessian fly, a
pest of wheat, is no longer a threat to wheat plants (Wiese, 1979). In lngham
County, for example, the hessian fly-free date is 17 September and planting 10
days later means that planting begins 27 September.

Reports on the relationship between planting date-induced variations in
crop season and performance reveal several patterns. A progressive decline in
yields occurred with each delay in planting in several studies (McLeod et. al.,
1992; Andrews et. al., 1992; Coventry et. al., 1992). In central Alberta, however,
early-planted wheat produced the lowest yields compared to all subsequent
plantings (Jedel and Salmon 1994). Another predominant pattern is where grain
yield is low with early dates, increasing to maximum at mid-planting dates, and
then declining with subsequent delays in planting (Dahlke et. al., 1993; Rourke,
1983; Wiese, 1979).

1-2 5W.

Barley yellow dwarf, an important aphid-transmitted disease, is the most
economically damaging virus disease of cereal crops worldwide (Gary et. al,
1996). Oswald and Houston (1951) were the first to recognize this disease in

California, USA. The disease is caused by barley yellow dwarf Iuteoviruses

(BYDV), which can be subdivided into nine distinct viral groups (Duffus et. al,
1990). Several viral strains have been identified, and the most common
worldwide are PAV (vector non-specific), RMV (transmitted efficiently by
Rhopalosiphum maidis. F itch), RPV (efficiently transmitted by Rhopalosiphum
padi. L.), SGV (transmitted effectively by Schizaphis graminun. Rondani) and
MAV (efficiently transmitted by Sitobium avenae. W.) strains. Nomenclature of
these strains was based on the aphid vector most efficiently transmitting the virus
(Rochow, 1969). More recently, however, classification has been based on
serological properties and deoxyribonucleic acid (DNA) sequence comparisons
(Martin and D’Arcy, 1995).

Transmission of the virus is persistent, i.e. once the virus is acquired by an
aphid, the aphid will transmit the virus for the rest of its life (Burnett, 1990). The
virus is phloem-limited and contains a positive-sense genomic ribonucleic acid
(RNA) (Mathews, 1991; Webster and Granoff, 1994). Symptoms caused by the
virus range from stunted plant growth, leaf tip and margin yellowing, and
reddening depending on variety. Symptoms are more pronounced in barley
(Hordeum vulgare L.) and oats (Avena sativa L.) than wheat (Triticum aestivum
L.) (Carrigan et. al, 1981). Because several factors influence BYDV
epidemiology, development of effective control strategies remains a major
problem for both wheat growers and agronomists.

Diagnosis of barley yellow dwarf virus (BYDV) based on symptoms under
field conditions can be difficult. Symptoms are often not sufficiently developed to

allow visual identification of infected plants. They can easily be confused with

damage due to frost, wet weather, nutrients, and non-infectious agents (Conti et.
al, 1990). Furthermore, the presence of BYDV in most cereals can often be
masked by other cereal diseases (Burnett, 1990). Visual diagnosis should be
confirmed with other diagnostic methods such as serological or hybridization
assays.

Symptoms develop in a period of 7-20 days after inoculation (D’Arcy,
1995), and as a result, wheat growers and experienced agronomists often realize
the presence of BYDV when it is too late to treat the current year‘s crop.
Knowledge on vector population dynamics relative to host crop availability is an
essential factor in developing control strategies. Scouting and monitoring for
aphids could be used to predict BYDV presence. The best control for BYDV will
be to control the vector that transmits the virus.

In most parts of the world where BYDV is a problem, its control is usually
by a single method, using insecticides, relying on biological control, or utilizing
genetic resistance (Plumb and Johnstone, 1995). Little success has yet been
realized in breeding for BYDV resistance in wheat (Gourmet et. al, 1996).
Application of insecticides to kill aphids vectors in cereals is a promising strategy
for decreasing BYDV damage (McKirdy et al, 1996). The application of
insecticides either as sprays or granules to control aphids that transmit BYDV in
Australia resulted in large increases in yields (Plumb and Johnstone, 1995).
Studies conducted at the University of Illinois using lmidacloprid (GAUCHO) as a
seed-treatment insecticide indicated a yield increase of as much as 21%, and

that the percentage of plants infected with BYDV was significantly reduced

(Gourmet et al, 1996). lmidacloprid is a nitroguanidine insecticide (Goun'nent,
1996). Biological control involves the use of natural enemies such as parasites
and predators to control aphids. It has been used successfully in indirectly
controlling BYDV as a result of controlled aphids vectors (Plumb and Johnstone,
1995). While biological control has been found to reduce the incidence of BYDV
in Australasia and South America, introduction, rearing, and maintenance of
predators and parasites populations can be difficult.

In Michigan and similar environments, adult aphid populations dramatically
decline in the period that winter wheat is traditionally planted. Crop season will
vary in season aphid pressure. Studies in the Midwest, US, indicated that winter
wheat planted early and emerging before the first killing frost, was infested with a
complex of viruses, resulting in lower yields (Dahlke et al. 1993). Another
contributing factor to high infestation is the duration of exposure of plants to
aphids. The earlier the planting date, the longer the plants are exposed to
aphids, increasing the threat to BYDV infestation (McGrath et al. 1990). Altering
time of planting the crop is consequently a likely means of escaping early
infection by barley yellow dwarf virus.

Previous studies (Wiese, 1979; Ward, unpublished data) suggest that the
pattern of relationship between planting dates (i.e., initiation of the crop season)
and yield of winter wheat in Michigan is curvilinear. Yields appear to be highest
with crop seasons initiated at a point several days after the fly free date. Yields
from crop seasons initiated 20 to 30 days before or after a year’s maximum are

lower than the maximum. The work reported here sought to further refine our

understanding of the relationship of crop season onset and performance
environments. The major research hypotheses were 1) crop seasons initiated
between early September and late October will vary in performance; 2) the
pattern of relationship between crop season onset and performance is curvilinear
with a single maximum alter the fly-free date; 3) year affects the properties of the
planting date/yield relationship including the date of the maximum, and the rates
of decline in performance on either side of the optimum; and 4) insecticide
control of fall aphid infection can reduce the penalty of planting before the
maximum yield date.
2.0 MATERIAL AND METHODS

Field trials were conducted at Michigan State University’s campus in East
Lansing, Michigan during a two-year period. Trials were conducted on a capac
loam (Aeric Endoaguals, fine-loamy, mixed, mesic) soil. The soft white winter
wheat cultivar ‘Harus’ (T eich, 85) was used in all trials. Fields were prepared by
conventional tillage. Land was tilled immediately before each planting event.
Seed was sown at a rate of 1.8 million seeds per acre in experimental plots
comprised of 7 rows spaced 7 inches apart and 11.0 feet long. A Winterstieger
research plot cone drill was used for planting. Weeds were controlled both
manually and with herbicides during the spring. The previous crop in both years
was soybeans that were chopped and plowed under as green manure. No fall
fertilizer was applied. A single early spring application of N (as Urea 46-0-0) was

applied at a rate of 80 lbs NIA each year.

In both years the treatments consisted of factorial combinations of planting
date and insecticide application. In year 1 (planted in the fall of 1995, harvested
in the summer of 1996), six planting dates (Table 1) and three insecticide
treatments were employed. The insecticide treatments for year 1 were 1) none,
2) lmidacloprid (GAUCHO) as a seed treatment (1 fl ozl100lbs seed), and 3)
GAUCHO as a seed treatment plus spring foliar application of Dimethoate
(CYGON). The spring foliar application began at Feeke’s scale 6 (first
application was on 5/8/96) and was repeated at intervals of 10 - 14 days until
booting (Feeke’s scale 10) at a rate of half a pint per acre.

ln year 2 (planted in the fall of 1996, harvested in the summer of 1997),
four dates (Table 1) and two insecticide treatments were employed. The two
insecticide treatments were 1) none and 2) GAUCHO + CYGON. CYGON was
first applied on 5/13/97 at a rate and interval similar to that in year 1. Several
other seed treatments were included in year 2, but data for those treatment
combinations were excluded from all analyses.

Treatments were assigned to experimental units in a split-plot design
where dates were confounded with main plots. Seed treatments were randomly
assigned to sub-plots within main plots. Outer rows of the main plots were
bordered by untreated Harus.

Dates of initiation of stem elongation and anthesis were assessed each
spring. Data are presented as day of year, i.e., days from the first of January. In
year 2 plant stand count at emergence was taken. Fifteen plots were selected at

random within a replication for each planting date. A total of sixty plots were

10

selected before subjected to stand count. In early spring, a second plant count
was performed on the last planting date using the same procedure. Other

planting dates had developed too many tillers to allow for stand count.

Table 1-Dates of planting Harus winter wheat.

 

Planting year

 

 

Planting event 1995 1996
1 12 Sept 21 Sept
2 18 Sept 30 Sept
3 25 Sept 11 Oct
4 05 Oct 21 Oct
5 09 Oct --
6 17 Oct --

 

Plant samples were acquired for BYDV analysis on four different dates.
The first sample was collected at the onset of the winter and the other three
samples were collected in the spring. Plants were selected at random within
plots. A total of three plants were collected per plot during each sampling event.
All above ground tissue was included in samples. No sampling was done after
booting (Feeke's scale 10) had commenced. Samples were frozen immediately
after their removal from the field. Double antibody sandwich - enzyme-linked
immunosorbent assay (OAS-ELISA) technology was used to quantify BYDV and
wheat spindle streak mosaic virus (WSSMV). This was done at the Plant and
Soil Science Building’s Plant Clinic at Michigan State University. Kits used for

detecting the virus were produced by the Agdia Inc. Company.

II

A 36.6ft2 area from each plot was harvested in August each year with a
small plot research harvester. Grain was dried to a constant moisture content
estimated at 11 percent. Grain yield was determined before a sub-sample of the
grain from each plot was removed for determining test weight (AACC approved
method 55-10, 1995). An electric seed counter was used to obtain thousand
seeds for kernel weight determination. Data were analyzed using Proc. GLM of
SAS (SAS Institute Inc. 1988) and means were separated using Fisher’s
protected least significance difference (LSD) with p-values < 0.05 considered
significant.

3.0 RESULTS

3.1 Crop Development.

The 1995-96 trial (Year 1) was exposed to the harshest winter conditions
in recent history in Michigan (C.R. Olien, pers. Comm.) Rate of growing degree
day (GDD) accumulation was reduced to near zero by October 10, 1995. Scab
(Gibberela zeae), and glume blotch pressures were both severe in that year.
The 1996-97 trial (Year 2) exhibited very little winter kill damage and disease
pressures were light. The average wheat yield for all of Michigan in Year 1 was
38 bulacre, compared to the record setting yield of 62 bulacre Michigan farmers
experienced in Year 2. Plant density data were not collected for Year 1, but it
was clear that the last planting event (10/17/96) suffered from poor emergence
and excessive winterkill. Plant density data for the last planting in Year 2 are

tabulated in Appendix A. Some loss of plants (up to 14%) during the winter was

12

evident. However, winterkill did not appear to be a factor in Year 2 based on

grain yields obtained from the 21 October planting (Table 6).

Table 2-Tlmlng of initiation of stem elongation (SE) and 50% anthesis (A)

for 'Harus' winter wheat planted at different dates in two years.

 

 

Day of Year
Trial Planting Planting SE A
event date

Year1 1 9l12/95 128 162
2 9/18/95 134 163

3 9125/95 134 163

4 10/5l95 137 167

5 10/9/95 140 173

6 10/17/95 149 179

Year 2 1 9/21/96 126 162
2 9/30/96 131 163

3 10/11/96 136 166

4 10/21196 143 169

 

The days of year of initiation of stem elongation (Feeke’s scale 6.0) and
anthesis (Feeke’s scale 10.5) increased as planting date was delayed (Table 2).

The difference in days between the onset of stem elongation and anthesis

13

decreased as planting was delayed in 1997. In 1996, those intervals exhibited
no relationship to planting date. Even though the dates of first stem elongation
and anthesis varied, plants matured within a narrow time span in both years and
all plots in a trial were harvested on a single day (8/1/96 for Year 1, and 7/30l97
for Year 2).

Table 3-Summary of the significance of F tests from separate analyses of
variance for Year 1 and Year 2 of a split plot design of a factorial

combination of planting date and insecticides.

 

 

 

1996 1997

Source Grain Test 1000- Grain Test 1000-

yield weight kernel yield weight kernel

weight weight

Replication * * NS NS * *
Planting date, PD * * * * * *
Insecticides, IN * NS * NS NS NS
PD'IN NS NS NS NS NS NS

 

*, NS = Significant at p < 0.05, and not significant, respectively.

3.2 Planting date and grain yield

Statistical comparisons could not be made across years because planting

dates varied with year. Analysis of variance showed that planting date was a

I4

signflcant factor in determining grain yield (Table 3). Generally, the earliest and
latest plantings decreased yields, while intermediate plantings produced the
highest yields (Table 4). In both years, a quadratic model explained considerably
more variation in the combined yield data (inclusive of all insecticide treatments)
than a simple linear model. The adjusted Rz's for the quadratic models, including
all treatments and replications, were 0.54 and 0.37 for Year 1 and Year 2,
respectively. If mean yield values are used, the R2 values increased to 0.79 and
0.62 for year 1 and 2 respectively (Appendix H). The quadratic equations
predicted that the maximum yields in Year 1 and Year 2 would have been 61.7
bulacre and 83.8 bulacre respectively. These maxima correspond with planting
on 9/23/95 (day of year =266), and 10/5/96 (day of year=278). The maximum
and minimum days of year predicted to provide a yield no more than 5.0 bulacre
below the predicted maximum were 258 (9/15/95) and 273 (9/30/95) for Year 1,
and 269 (9/26/96) and 286 (10/13/96) for Year 2.

Planting date affected test weight somewhat differently in the two years.
In 1996, the response was similar to that observed with grain yields. However,
only the last planting (17 October) resulted in a significant reduction in test weight
in 1996 (Table 4a). In 1997, both early and late plantings increased test weight
significantly compared to intermediate planting dates (Table 4b). Averaged
across insecticide treatments, planting dates that maximized grain yields resulted

in the highest test weight in 1996. In 1997, the opposite was true.

15

Table 4. Grain yield, test weight, and WOO-kernel weight of winter wheat

variety Harus as affected by planting dates in year 1 (a) and year 2 (b)

(a)

 

Trial Planting date Yield Test weight 1000-kemel weight

 

(bulacre) (lbs/bu) (ounce)
Year 1 12 Sept 55.6 ab* 56.5 a 1.18 ab
18 Sept 49.6 b 53.3 a 1.14 ab
25 Sept 62.4 a 57.2 a 1.23 a
05 Oct 49.2 b 56.3 a 1.12 b
09 Oct 49.9 b 56.9 a 1.20 ab
17 Oct 6.2 c 26.9 b 0.64 c

 

(b)

 

 

Trial Planting date Yield Test weight 1000-kernel weight

 

(bulacre) (lbs/bu) (ounce)
Year 2 21 Sept 70.8 bc 59.3 ab 1.45 a
30 Sept 87.7 a 58.9 bc 1.36 b
11 Oct 79.1 ab 58.3 c 1.38 b

21 Oct 67.8 c 59.6 a 1.42 ab

 

* Means followed by a letter in common are not significantly different, p < 0.05,
according to least significant difference.

16

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t. 8.2.. 2...... 28... 8.... as... 8.... .228
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a. «R m. 2.. mac... .8... 2...... .. .226 + 2.2.8
2... as. 0:. 3o... .82.. 28... «S... 2.2.8 28 8
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18

As with test weight, kernel weight responded somewhat differently to
planting dates. In 1996, the trend in kernel weight, averaged across insecticide
treatments, was similar to that observed with grain yields. The response was
significantly different among planting dates (Table 3). Planting dates that
maximized grain yields did maximize kernel weight (Table 4a). In 1997, kernel
weight response to planting dates was different significantly (P<0.05) (Table 3).
The highest 1000 kernel weight was obtained from wheat planted on the first
planting date (Table 4b).

3.3 Insecticide treatments and grain yield

Insecticides in year 1 (Table 3) affected grain yields differently. Planting
dates x insecticide interactions were not significant in the analysis of variance
(Table 3). However, pre-planned comparisons and inspection of the relationship
of grain yield and planting date within insecticide treatments suggested an
interaction did exist. With no insecticide applied, yields increased with planting
date, reaching maximum on 25 September then decreasing with further delay in
planting (Table 5). The GAUCHO and GAUCHO + CYGON treatments showed
less of a decline with the earliest planting. Maximum grain yield with these
treatments was also found with the 25 September planting. Although grain yields
from the 18 September planting were lower than with the 12 September planting
for GAUCHO and GAUCHO + CYGON treatments, the effects of GAUCHO and
CYGON application was prevalent on 12 and 25 September plantings. The

influence of both insecticides then decreased with any further delay in planting

l9

beyond 25 September (Table 5). In 1996, 25 September resulted in the
maximum grain yield. The apparent rate of decline in yield was faster after
optimum planting date (6.6 Bu - control, 15 Bu - GAUCHO, and 16 Bu -
GAUCHO + CYGON) than before. A very steep difference was observed
between the two last planting dates with both insecticide treatments (Table 5).

Grain yields in Year 2 were considerably higher than in Year 1. A
curvilinear grain yield response was observed for both the control and GAUCHO
+ CYGON treatments (Table 6). Maximum grain yields were obtained when
wheat was planted on 30 September for both treatments. Yield differences
between the two insecticide treatments were not significantly different as a main
effect or for any single planting date (Table 3 and Table 6). Minimum decline in
grain yields between planting dates was similar for both insecticide treatments
(17 Bu and 10 Bu) before and after the optimum planting date respectively.
Unlike in 1996, the fastest rate of decline was before the optimum planting date
rather than after.

Kernel weight responded to the effects of insecticide treatments differently
when compared to grain yield in 1996. There were no significant differences
among insecticide treatments for the first five planting dates. Differences .
occurred on the last planting date with the GAUCHO + CYGON treatment
resulting in high 1000-kemel weight (Table 5). At all planting date, except the
last, kernel weight due to GAUCHO treatment was always lower than from other
insecticide treatment. Test weight response to the effect of insecticide

treatments did not vary with planting date except for the last planted wheat. Like

20

1000-kemel weight, the GAUCHO + CYGON treatment resulted in the greatest
test weight. In 1997, both kernel and test weights did not differ significantly
among insecticide treatments within planting dates (Table 6), a similar response
to that observed for grain yield.

3.4 Planting date and BYDV infection

ELISA results indicated that two BYDV strains were present. These were
the RMV isolate, transmitted effectively by a corn leaf aphid (Rhopalosiphum
maidis), and PAV isolate which is vector non-specific. However, the
concentration of the PAV isolate was below levels regarded as adequate for
quantitative analysis in both years and the data was not used in the analysis. All
references to barley yellow dwarf virus (BYDV) will refer to the RMV isolate

unless othenivise indicated.

21

Table 7. Mean BYDV absorbance of sample plants averaged across

sampling dates for the years 1996 (a) and 1997 (b) field plots.

(a)

 

 

 

 

 

 

 

 

 

Izeatment
Planting date Control Gaucho Gaucho-I-Cygon
12 Sept 0.368 (44)? 0.132 (13) 0.232 (25)
18 Sept 0.249 (25) 0.188 (18) 0.188 (19)
25 Sept 0.124 (25) 0.079 (13) 0.212 (19)
05 Oct 0.046 (0) 0.030 (0) 0.043 (0)
09 Oct 0.100 (0) 0.050 (0) 0.076 (6)
17 Oct 0.104 (18) 0.068 (13) 0.086 (0)
LSD 095 =0.195
(b)
_Izeatment

Planting date control Gaucho-I-Cym
21 Sept 0.129 (18) 0.297 (44)
30 Sept 0.364 (56) 0.247 (25)

11 Oct 0.140 (18) 0.115(13)
21 Oct 0.201 (31) 0.188 (19)
LSD 0,05 = NS

T Percentage of positives out of sixteen samples tested for barley yellow
dwarf virus (BYDV) by ELISA serological test

ELISA results for all sampling times and treatment combinations are
presented in Table 5 and 6 for 1996 and 1997 respectively. In year 1, there was
large variation in BYDV levels at different sampling times averaged across
insecticide and planting date treatments. There was a significant difference
among planting dates with respect to BYDV concentration. The concentration of
BYDV (mean absorbance) decreased with planting date, reaching a minimum at
the fourth planting date (Table 7a). For Year 1, wheat planted on 12 September
had the greatest BYDV concentrations (Table 7a). In Year 2, no trend or pattern
was observed with respect to BYDV concentration and planting date (Table 7b),
and Barley yellow dwarf virus concentration was not significantly different among
planting dates. High concentration levels of BYDV were detected from wheat
planted on the 30 September (Table 7b) planting date.

3.5 Insecticide treatments and BYDV infection

High levels of BYDV were detected late in the season from the earliest
planted wheat and early from their late-planted counterpart (Table 5 & 6). In year
1, ELISA values differed significantly among insecticide treatments within a
sampling date. High concentrations of BYDV were obtained from the 27 May
sampling in 1996 (Table 5). Except for the first planting date (12 September),
means ELISA values across sampling dates were not significantly different
among insecticide treatments at any planting date (Table 7a). Across planting
and sampling dates, the GAUCHO treatment significantly reduced BYDV

concentration (Table 8) in year 1. The effect of GAUCHO + CYGON treatment

23

was not different significantly from the control treatments. lnexplicably, the
incidence of BYDV was increased by the application of CYGON in the spring
(Table 5).

In 1997 the GAUCHO treatment was inadvertently omitted. The only
significant difference among insecticide treatments was observed from the 11
June sampling on the first planting date (Table 6). Insecticide treatments were
not significantly different within any planting date (Table 7b). Across planting
dates and sampling times, there was no significant difference among insecticide
treatments either (Table 8).

Out of sixteen samples collected over time and tested for BYDV using
ELISA from each planting date and insecticide treatment, a high percent infection
was observed from the 12 September planted wheat where no insecticide was
applied in 1996 (Table 7a). Wheat planted on 5 and 9 October 1995 showed
zero percent infection. Less infection occurred where GAUCHO was applied
than with other insecticide treatments (Table 7a). In 1997, although the second
planting date resulted in high percent infection, within insecticide treatments,
infection was similar (Table 7b). Percent infection, based on samples that tested
positive for BYDV, was determined on a 0.2 ELISA values positive cutoff point.
Any ELISA values 0.2 and above was considered positive, while those less than
0.1 were negative. Values between 0.2 and 0.1 are ambiguous. This
recommendation was obtained from the Agdia Inc, company from where the kits
used in determining BYDV were obtained (pers. Comm). These results are

similar to those analyzed statistically. GAUCHO +CYGON and the control

24

treatments in both years, resulted in more BYDV positive samples.

Table 8. Mean BYDV absorbance averaged across planting and sampling

dates, as influenced by insecticide treatments.

 

 

—Trial Insecticide Insecticide ilean EW—
event treatment (Absorbance)
Year 1 1 Control 0.162 a*
2 Gaucho 0.091 b
3 Gaucho + Cygon 0.152 ab
Year 2 1 Control 0.208 a
3 Gaucho + Cygon 0.194 a

 

*Means followed by a letter in common are not significantly different, p < 0.05,
according to least significant difference.

3.6 Planting date and Wheat spindle streak mogic virus

In sample 1 in Year 1, levels of wheat spindle streak mosaic virus
(WSSMV) were signficantly higher for the 25 September and 5 October dates
than all other dates. In later samples, virus incidence decreased (Table 9a). The
virus concentration levels did not vary significantly (P = 0.05) among planting
dates. Because of this, differences in grain yield, test weight, and kernel weight
may not be attributed to virus infection.

In 1997, except for the last two planting dates and during the second

25

sampling time, virus concentrations also decreased with sampling time
(Table 9b). Within planting dates high levels of WSSMV was obtained from the
last two planting dates. Therefore, yield reductions recorded from the latest

planted wheat may be associated with these high levels of the virus.

Table 9. Mean WSSMV absorbance detected at three sampling times in
1996 (a) and 1997(b) field plots.

 

 

 

 

 

 

 

 

(a) ELISA values (b) ELISA values
Samplln Date Sampllng its

Planting 18 Gan 27 May’98 4 Jun ‘95 Planting 30 Nov 13 May 11 Jun
d‘ate ‘98 (lite ‘98 ‘97 ‘97
12 Sept 0.023 0.140 0.066 21 Sept 0.113 0.056 0.026
18 Sept 0.331 0.107 0.189 30 Sept 0.136 0.059 0.034
25 Sept 0496* 0.072 0.153 11 Oct 0.093 1.374 0.036
05 Oct 0.704* 0.032 0.146 21 Oct 0733* 2035 0.050

_I

09 Oct 0.048 0.036 0.053
17 Oct 0.059 0.023 0.037

 

*Significantly different at P = 0.05

4.0 DISCUSSION

Wheat crop seasons initiated in the month of September and October
exhibited a range of yields. The relationship between planting date and yield was
curvilinear with a single maximum after the fly free date. The penalty associated
with late planting was substantial in year one. Generally, yields decreased as
planting was delayed beyond September 30 in both years (Table 5). Planting

later than the 'date, which maximized yields both, decreased grain yields and

26

increased days to anthesis. Wrese (1979) suggested that Michigan farmers use
the local hessian fly-free date as their target for planting wheat. In year 1,
planting earlier than this time did not reduce yields dramatically (Table 5). As
observed by other researchers (Knapp and Knapp, 1978; Martin, 1926; Coventry
et. al, 1993), the latest planting dates decreased yields more severely than did
earliest and intermediate planting dates.

A major factor contributing to the reduction in yield from the latest planted
wheat was stand lose resulting from winterkill. Visual observations in both years
and plant stand count conducted in spring 1997 after growth had resumed
indicated that late planting did reduce plant population (data presented in
appendix A). Increased seeding rate might have reduced this effect. In 1996,
there was less snow cover and some frequent freezing and thawing conditions
were observed. Repeated freezing and thawing are reported to increase winter
injury than either condition alone (Gusta and Chen, 1987).

A comparison of planting dates 18, 25 September,\5 and 17 October from
1996 with the four planting dates in 1997 (Table 5), a similar pattern of increase
and then subsequent decline in yield as planting progressed from the first to the
last date was observed. Based on this comparison, the yields of wheat as
affected by planting date followed the trend observed by several researchers
(Rourke, 1983; Dahlke et al. 1993), who found yields to gradually increase,
reaching maximum at mid-plantings, and then declining as planting date was

delayed.

Year had a large effect on the planting date-yield relationship. In year 1,
the observed maximum yield occurred on 25 September, while in year 2 it was
five days later (30 September). The quadratic model based prediction of the
maximum yield planting dates were 9/23/95 and 10l5/96 for years 1 and 2
respectively.

The 17 October planting date caused a significant reduction in test weight
in 1996 while the 21 October did not in 1997. These different responses were
likely due to winterkill. Evans et al, (1971) and Knapp and Knapp (1978)
reported similar findings that planting date affected test weight differently in
different years on winter barley and wheat respectively. Pittman and Andrews,
(1961) however, found that the highest test weight came from the intermediate
planting dates. The result of Pittman and Andrews, (1961) only agrees with
those from year one of this study, where high-test weights coincided with
maximum grain yield.

Although kernel weight is reported to decrease, as planting is delayed
(VVIegand and Cuellar, 1981; Andrews et. al, 1992; Dahlke et. al, 1993), in this
study the decrease was not pronounced. Other studies found kernel weight to
increase with delayed planting (Rocheford et. al, 1988), and concluded that the
increase in kernel weight was a compensatory physiological response to
reduction in other components. This, therefore, suggest that kernel weight

become relatively important in contributing to yield as planting is delayed.

28

Grain yield was increased in treatments where insecticides were applied
both in fall and spring in both years (Table 5). However, those differences were
significant only with the 12 and 25 September plantings in year 1. The effects of
insecticide application on test weight and thousand-kemel weight were not as
pronounced as on grain yield except for 17 October planting in year one (Table
5). The low-test weight from GAUCHO treatment (Table 5) on the first two
planting dates could be attributed to abiotic factors other than biotic ones such as
heat stress during grain filling period.

When GAUCHO was applied alone, BYDV incidence was reduced from
wheat planted on the first planting date in both years. Although GAUCHO
reduced BYDV levels, covariance analysis did not reveal a significant relationship
between mean BYDV at all samplings to grain yield (data not shown). Applying
CYGON in spring did not seem to have an effect on BYDV. This could have
been because infection had occurred in spring already before spraying with
CYGON. Several studies (Gourmet et. al. 1996; Gary et. al, 1996) found that
GAUCHO significantly reduced the incidence of BYDV from treated plots as
compared to untreated plots. These results support the findings of this study
during the first year. The increase in grain yield from plots where CYGON was
applied could be associated with its action on other wheat pests than the vectors
of barley yellow dwarf virus. The effect of GAUCHO on early-planted wheat may
indicate that grain yield can be increased if BYDV is controlled, but further

exploration of this issue needs to be done before concrete recommendations can

29

be made.

It is apparent from this study that both planting date and insecticide
treatments influenced grain yield of winter wheat. Several factors influence the
optimum planting date, which vary from year to year and location to location.
Most experiments conducted on planting date do not encompass all these
possible factors. Furthermore, the nature of crop seasons and consequently the
optimum planting dates are not known until harvest. Resolution of useful
extension messages will require knowledge of the frequency distribution of peak
performance planting dates for a given production zone. Such distributions might
be generated empirically through field experimentation and alternatively crop

modeling may be useful.

30

5.0 REFERENCES.

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Vol. 2: St Paul, MN.

Andrews, C. J., M. K. Pomeroy, W. L. E Seaman, and G. Hoekstra. 1992.
Planting dates and seeding rates for soft white winter wheat in eastern
Ontario. Can. J. Plant Sci. 72: 391 - 402.

Boostma, A., C. J. Andrews, G. J. Hoekstra, W. L. Seaman, and A. E. Smid.
1993. Estimated optimum planting dates for winter wheat in Ontario. Can. J.
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Briggle, L. W and B. C. Curtis, 1987. Wheat worldwide. p. 1-32. In E. G. Heyne
(ed.) Wheat and wheat improvement. Agron. Monogr. 13. ASA and SSSA,
Madison, WI.

Burnett, P. A, 1990. Preface. In P.A. Burnett (ed) World perspectives on barley
yellow dwarf. CIMMYT, Mexico, D. F.

Carrigan, L. L., H. W. Ohm, J. E. Foster, and F. L. Patterson. 1981. Response of
winter wheat to Barley Yellow Dwarf Virus infection. Crop Sci. 21: 377 — 380.

CIMMYT, 1995. CIMMYT world wheat facts and trends supplement 1995.
Ongoing research at CIMMYT: Understanding wheat genetic diversity and
international flows of genetic resources. Mexico, D.F.: CIMMYT. 11-16.

Conti, M., D’Arcy, C. J., Jedlinski, H., and PA Burnett. (1990). The ‘yellow
plaque’ of cereals, barley yellow dwarf virus. P. 1-6. In P.A. Burnett (ed.)
World perspectives on barley yellow dwarf. CIMMYT, Mexico, D.F., Mexico.

Coventry, D. R., T. G. Reeves, H. D. Brooke, and D. K. Cann. 1993. Influence of
genotype, sowing date, and seeding rate on wheat development and yield.
Aust. J. Exp. Agric. 33: 751 — 757.

Dahlke, B. J., E. S. Oplinger, J. M. Gaska, and M. J. Martinka. 1993. Influence of
planting date and seeding rate on winter wheat grain yield and yield
components. J. Prod. Agric. 6: 408 - 414.

D’Arcy, C. J. 1995. Symptomatology and host range of barley yellow dwarf. p. 9-
28. In D’Arcy, C. J., and P. A. Burnett (ed) Barley yellow dwarf. 40 years of

31

progress. APS Press. St Paul. Mn.

Duffus, J. E, B. W. Falk, and G. R. Johnstone. 1990. Luteoviruses-One system,
many variations. p. 86-104. In P.A. Burnett (ed) World perspectives on
barley yellow dwarf. CIMMYT, Mexico, D.F., Mexico.

Evans, L. T., I. F. Wardlaw, and R. A. Fischer. 1980. Wheat. p. 101-150. In L.T.
Evans (ed.) Crop physiology -some case histories. Cambridge University
Press. 101 - 149.

Evans, L. T. 1993. Crop evolution, adaptation and yield. Cambridge University
Press.

Evans, R. G., K. E. Bohnenblust, B. J. Kolp, G. P. Roehrkasse. 1971. Yields and
yield components of winter barley as affected by variety and planting date.
WY. Agric. Exp. Stn. Res. J. 49: 1-10.

FAO, 1997. FAOSTAT Database/PC production, primary crops. Rome, Italy.

Fowler, D. B. 1982. Date of seeding, fall growth, and winter survival of winter
wheat and rye. Agron. J. 74: 1060 - 1063.

Fowler, D. B. 1983. The effect of management practices on winter survival and
yield of winter wheat produced in regions with harsh winter climates. p. 238-
282. In Fowler et al (ed) New frontiers in winter wheat production. Div. Ext.
Comm. Rel., University of Saskatchewan, Saskatoon. SK.

Gary, S. M, G. C. Bergstrom, R. Vaughan, D. M. Smith, and D. W. Kalb, 1996.
Insecticidal control of cereal aphids and its impact on the epidemiology of the
barley yellow dwarf Iuteoviruses. Crop protection. 15: 687 — 697.

Gourmet, 0., K. L. Kolb, C. A. Smyth, and W. L. Pedersen. 1996. Use of
lmidacloprid as a seed-treatrnent insecticide to control Barley Yellow Dwarf
Virus (BYDV) in Oat and Wheat. Plant Disease. 80: 136 - 141.

Gusta, L. V., and T. H. H. Chen. 1987. The physiology of water and temperature
stress. In E. G. Heyne (ed.) Wheat and wheat improvement. p. 115-150.
Agron. Monogr. 13. ASA and SSSA, Madison, WI.

Jedel, P. E., and D. F. Salmon. 1994. Date and rate of seeding of winter cereals
in central Alberta. Can. Plant Sci. 74: 447-453.

Knapp. W. R., and J. S. Knapp. 1978. Response of winter wheat to planting date
and fall fertilization. Agron. J. 70: 1048 — 1053.

32

Martin, J. H. 1926. Factors’ influencing results from rate and date of seeding
experiments with wheat in the Western US. J. Am. Soc. Agron. 18: 193 - 225.

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years of progress. APS Press. St. Paul, Mn.

Mathews, R. E. F, 1991. Plant virology. 3" ed. Academic Press, Inc. San Diego.
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McGrath, P. F. and J. S. Bale, 1990. The effects of sowing date and choice of
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McKirdy, S. J. and R. A. C. Jones, 1996. Use of lmidacloprid and newer
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86 -90.

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and V. F. Rasper (ed) Wheat production, properties and quality. Blackie
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Paulsen, G. M. Wheat stand establishment. p. 384-389. In E. G. Heyne (ed.)
Wheat and wheat improvement. Agron. Monogr. 13. ASA and SSSA,
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Pittman, U. J., and J. E. Andrews. 1961. Effect of date of seeding on winter
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Plumb, R. T, and G. R. Johnstone, 1995. Cultural, chemical, and biological
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Rochford, T. R., D. J. Sammons and P. S. Baenziger. 1988. Planting date in
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33

Rochow, W. F. 1969. Biological properties of four isolates of barley yellow dwarf
virus. Phytopathology 59: 1580 — 1589.

Rourke, D. R. S. 1983. Winter wheat agronomy. p. 359-380. In Fowler et al (ed)
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Smith C W 1995. Crop Production: evolution, history and technology. John Wiley
& Sons,lnc

Teich, A. H. 1985. Harus soft white winter wheat. Can. J. Plant Sci. 66: 161-163.

Webster, R.G, and A. Granoff. 1994. Encyclopedia of virology. Academic Press.
2: 792-798.

Negand, C. L., and J. A. Cuellar. 1981. Duration of grain filling and kernel
weight of wheat as affected by temperature. Crop Sci. 21: 95-101.

Wiese, M. V., R. Loria, K. Dimoff, and N. Klimer. 1979. A derivation of optimal
planting dates for winter wheat in Michigan. Farm Sci. Res. Report. 387: 1-7.

APPENDICES

APPENDIX A

PLANT EMERGENCE DATA BEFORE AND AFTER THE WINTER FROM THE
LAST PLANTING DATE IN YEAR 2.

.955... Sam mxBéN :58 ucflm .i. 0.58 eeEmu .8cm9oEm .ocm mxsé E38 ucflmu =w... ...oEm._.

 

34

 

Nm mm 3 v N 3 F m ”N Fe 3 N NF Ne 2 F
Nm Nm 3 e «N on 3 m N mm 3 N «N X” 3 F
mm 3 9. v mm on 2 n mm mm 2. N mm .3 9. _.
9. 8 NF v 8 3. NF m Fm mm NF N on 8 NF F
NN FN FF 4 «N NF. FF m N 3 FF N .N Ne FF F
mm mm 9 V an we 0.. m on mm 0.. N mm vm 0.. F
9. F... a w 8 3 m m 2 8 m N 8 on m F
B 8 w v N on m m «N on o N 9. NN o F
3.” mm x. v mm mm n n mm mm x. N an me x. F
.N on o v Fm an m m FN S o N N 8 c F
o... R m v 8 «N m m on 3 m N mm 8 n F
Fm Fm v v a... 8 v m N Na v N 8 8 v F
mm 3 n v Nm Nv n m N... Fe m N we on n F
N ow N F. NN Fm N m . on F... N N on B N F
8 Fm F v on 9. F m on 8 F N ov 2. F F
9.....m :3. 9.3m .3. 2.5m :5. «23m :3.

.LeEm .LoEm No... no... .LoEm .LoEm «or. com .oEm .oEm For. gem .oEu .oEm So... com

 

< X_Dzm_mn_<

APPENDIX B

GRAIN YIELD, TEST WEIGHT, AND THOUSAND-KERNEL WEIGHT DATA
OBTAINED DURING THE FIRST YEAR (1995/6).

35

APPENDIX B

 

Replication Planting Insecticide Grain yield Test weight 1000-kernel

 

datet Treatmentl: (Bu/A) (lstBu) weight (grams)

1 1 3 91.1 57.4 34.0
1 1 1 44.5 56.7 31.5
1 1 2 49.0 57.5 35.0
1 3 1 51.0 56.4 34.5
1 3 3 79.8 57.9 36.5
1 3 2 59.3 58.5 36.0
1 6 2 13.1 21.3 15.0
1 6 1 6.0 . 14.0
1 6 3 10.5 21.3 17.5
1 5 2 70.8 57.6 34.5
1 5 3 57.4 57.8 38.0
1 5 1 56.4 57.4 33.5
1 2 2 70.6 56.8 36.5
1 2 3 60.4 57.9 35.5
1 2 1 55.7 56.8 34.5
1 4 2 70.5 56.8 34.5
1 4 1 48.3 56.7 32.5
1 4 3 53.3 57.1 33.0
2 6 3 1.5 . 23.5
2 6 2 0.3 . .

2 6 1 0.3 . 13.0
2 2 1 53.7 55.7 32.0
2 2 3 20.0 54.7 31.0
2 2 2 10.3 23.0 22.5
2 5 3 50.4 56.1 35.0
2 5 2 34.5 55.4 30.0
2 5 1 32.3 55.9 34.5
2 4 1 48.0 54.8 32.0
2 4 3 42.5 56.4 33.0
2 4 2 31.2 55.7 29.0
2 3 3 50.5 55.8 34.0
2 3 1 46.9 56.7 36.5
2 3 2 48.1 54.4 32.5
2 1 2 47.7 55.2 33.5
2 1 1 34.3 56.1 33.5
2 1 3 40.5 55.4 29.5
3 3 3 77.1 56.4 36.5
3 3 2 73.0 58.3 33.5
3 3 1 61.3 57.5 34.0

36

3 4 1 50.2 56.7 30.0
3 4 2 58.2 56.8 31.5
3 4 3 65.8 57.9 36.0
3 6 1 7.9 20.3 15.0
3 6 3 4.3 . 16.5
3 6 2 10.8 19.7 15.0
3 1 3 74.5 58.1 35.0
3 1 2 74.6 57.6 36.0
3 1 1 52.3 57.6 33.5
3 5 3 59.3 57.8 33.5
3 5 1 56.1 57.4 34.0
3 5 2 41.7 57.4 31.0
3 2 3 78.8 58.5 34.0
3 2 1 65.1 57.9 38.5
3 2 2 67.5 57.6 36.0
4 3 3 74.4 58.3 38.5
4 3 1 55.7 57.2 37.0
4 3 2 71.6 58.6 37.0
4 6 2 3.0 . 20.0
4 2 1 1.6 . 23.0
4 6 3 15.3 51.9 27.0
4 1 1 50.7 55.1 30.0
4 1 3 68.9 581 40.6
4 2 1 24.6 49.0 23.0
4 2 2 40.8 54.0 29.0
4 2 3 48.1 57.6 37.5
4 4 3 50.2 57.1 33.5
4 4 2 27.2 53.6 25.0
4 4 1 45.1 56.1 30.5
4 5 1 40.9 55.2 31.0
4 5 2 43.3 57.4 36.0
4 5 3 56.4 57.5 36.5

 

1' Planting dates 1 = 12 September; 2 =18 September, 3 = 25 September", 4 = 5
October; 5 = 9 October; and 6 = 17 October.

:I: Insecticide treatments: 1 = no insecticide (control); 2 = GAUCHO; and 3 = GAUCHO +
CYGON. -

APPENDIX C

GRAIN YIELD, TEST WEIGHT, AND THOUSAND-KERNEL WEIGHT DATA
OBTAINED DURING THE SECOND YEAR (1996/7).

37

APPENDIX C

 

Replication Planting Insecticide Grain yield Test weight 1000-kernel
date Treatment (Bu/A) (IstBu) weight (ounce)

 

1 3 1 67.4 58.1 1.37
1 3 2 67.6 67.9 1.33
1 1 2 55.7 59.1 1.48
2 1 2 68.0 59.2 1.43
2 2 2 93.3 58.5 1.37
1 4 1 65.2 58.3 1.30
2 2 1 85.0 58.1 1.37
2 3 1 88.2 58.5 1.40
1 2 2 91.2 58.8 1.37
2 4 2 72.6 59.2 1.43
2 4 1 75.0 59.7 1.48
2 3 2 91.8 58.8 1.43
2 1 1 63.4 59.2 1.48
1 2 1 . 58.2 1.30
1 4 2 57.6 59.1 1.30
1 1 1 68.2 59.3 1.40
3 1 1 77.1 59.2 1.43
3 4 1 67.3 60.1 1.43
4 1 1 60.2 59.3 1.48
4 3 1 74.9 58.9 1.37
3 3 2 76.6 58.1 1.33
3 2 2 87.6 58.8 1.40
3 2 1 82.4 59.1 1.40
3 3 1 80.4 59.5 1.37
3 1 2 84.7 60.2 1.51
4 2 1 87.6 59.3 1.33
4 1 2 89.3 59.5 1.43
4 3 2 86 58.1 1.37
3 4 2 63.3 60.5 1.51
4 4 1 63.8 59.9 1.48
4 4 2 77.4 60.1 1.43
4 2 2 86L 5&5 1.33

 

T Planting dates 1 = 21 September; 2 =30 September, 3 = 11 October; and 4 = 21
October.
1 Insecticide treatments: 1 = no insecticide (control); 2 = GAUCHO + CYGON

APPENDIX D

ELISA VALUES (ABSORBANCE) FROM PLANT SAMPLES COLLECTED
OVER TIME IN THE FIRST YEAR.

38

APPENDIX D

 

 

 

 

Replication Planting Insecticide Sample 1 Sample 2 Sample 3 Sample 4
date Treatment (18 Jan’96) (13 May’96) (27May’96) (Nun’96)
Absorbance
1 1 3 0.049 0.005 1.605 0.069
1 1 1 0.076 0.155 1.413 0.422
1 1 2 0.111 0.000 0.706 0.109
1 2 2 0.034 0.010 0.003 0.053
1 2 3 0.065 0.043 1.086 0.038
1 2 1 0.142 0.222 0.076 0.068
1 3 1 0.006 0.031 0.220 0.035
1 3 3 0.008 0.021 0.967 0.048
1 3 2 0.038 0.026 0.093 0.063
1 4 2 . 0.032 0.027 0.000 0.089
1 4 1 0.011 0.035 0.017 0.005
1 4 3 0.000 0.054 0.174 0.044
1 5 2 0.000 0.038 0.054 0.063
1 5 3 0.215 0.001 0.022 0.034
1 5 1 0.179 0.057 0.143 0.009
1 6 2 0.255 0.125 0.015 0.051
1 6 1 0.226 0.035 0.098 0.036
1 6 3 0.336 0.026 0.037 0.031
2 1 2 0.017 0.000 0.090 0.166
2 1 1 0.191 0.011 0.132 0.036
2 1 3 0.059 0.010 0.398 0.099
2 2 1 0.016 0.024 0.030 0.127
2 2 3 0.027 0.029 0.031 0.012
2 2 2 0.043 0.078 1.307 0.034
2 3 3 0.073 0.032 0.144 0.026
2 3 1 0.042 0.004 0.345 0.080
2 3 2 0.041 0.012 0.246 0.002
2 4 1 0.082 0.036 0.100 0.034
2 4 3 0.056 0.011 0.070 0.023
2 4 2 0.018 0.009 0.019 0.047
2 5 3 0.066 0.003 0.060 0.027
2 5 _ 2 0.126 0.005 0.061 0.046
2 5 1 0.158 0.014 0.057 0.060
2 6 3 0.011 0.038 0.002 0.014
2 6 2 0.100 0.002 0.024 0.017
2 6 1 0.057 0.008 0.017 0.035

#43-bh-b-b-hhs-h-b-hvh-b-fi-b-h##wawwwwwmwwwwwwwww

030303010101h-h-hwwwNNN-fiA—‘mmmmolmvb-k#wwwNNN-t—t—S

w-lewNA—‘NwN-‘wwN-‘wN-‘NwAN-‘(JOOON-KANwNéw-‘Nw

39

0.046
0.021
0.079
0.038
0.001
0.000
0.081
0.009
0.042
0.072
0.000
0.000
0.102
0.115
0.141
0.739
0.490
0.233
0.010
0.162
0.088
0.040
0.019
0.032
0.026
0.019
0.025
0.035
0.030
0.036
0.194
0.048
0.030
0.059
0.295
0.260

0.470
0.063
0.235
0.030
0.309
0.000
0.046
0.053
0.035
0.045
0.042
0.005
0.016
0.017
0.055
0.038
0.010
0.003
1.097
0.006
0.017
0.131
0.015
0.038
0.022
0.021
0.017
0.032
0.019
0.021
0.026
0.033
0.011
0.015
0.005
0.013

0.561
0.309
0.605
0.785
0.163
0.878
0.497
0.167
0.771
0.117
0.007
0.005
0.290
0.175
0.029
0.022
0.036
0.030
0.880
0.085
0.100
0.466
0.431
0.703
1.213
0.260
0.264
0.041
0.041
0.009
0.057
0.022
0.006
0.033
0.020
0.011

0.086
0.165
0.357
0.035
2.100
0.042
0.142
0.059
0.069
0.023
0.051
0.101
0.041
0.024
0.058
0.006
0.034
0.062
0.190
0.098
0.039
0.068
0.064
0.016
0.049
0.063
0.144
0.043
0.037
0.092
0.049
0.013
0.007
0.061
0.027
0.023

 

T Planting dates: 1 = 12 September; 2 =18 September, 3 = 25 September, 4 = 5

October; 5 = 9 October; and 6 = 17 October.
1: Insecticide treatments: 1 = no insecticide (control); 2 = GAUCHO; and 3 = GAUCHO +

CYGON

APPENDIX E

ELISA VALUES (ABSORBANCE) FROM PLANT SAMPLES COLLECTED

OVER TIME IN THE SECOND YEAR.

40

APPENDIX E

 

 

 

 

#‘b-h-h-hhnk#wwwwwwwwNNNNNNNNA—t-l—t—l—t—l-l

Replication Planting Insecticide Sample 1 95mph 2 iample 3 Sample 4
date Treatment (30 NOV’96) (13 May’97) (31 May’97) (11 Jun’97)
Absorbance
3 1 0.076 0.097 0.086 0.049
1 2 0.253 0.211 0.000 0.081
3 2 0.051 0.212 0.000 0.091
2 2 0.103 0.151 0.054 0.071
4 1 1.221 0.104 0.000 0.004
2 1 0.171 0.145 1.292 0.329
4 2 0.811 0.147 0.063 0.280
1 1 0.214 0.178 0.034 0.077
1 2 0.298 0.216 0.000 0.598
2 2 0.153 0.062 0.000 1.071
2 1 0.261 0.129 0.012 1.236
4 2 0.176 0.108 0.072 0.131
3 1 0.183 0.181 0.009 0.287
4 1 0.159 0.133 0.033 0.056
1 1 0.142 0.025 0.000 0.137
3 2 0.145 0.137 0.000 0.006
1 1 0.273 0.043 0.000 0.535
2 2 0.562 0.639 0.024 0.382
4 1 0.217 0.219 0.112 0.186
2 1 0.426 0.228 0.017 0.747
3 2 0.266 0.094 0.016 0.192
3 1 0.103 0.232 0.090 0.297
1 2 0.376 0.225 0.000 0.000
4 2 0.180 0.165 0.030 0.304
2 2 0.332 0.171 0.000 0.209
1 2 0.223 0.230 0.000 0.321
1 1 0.137 0.130 0.000 0.133
3 2 0.201 0.064 0.001 0.366
3 1 0.128 0.173 0.106 0.141
2 1 0.229 0.137 0.025 0.442
4 2 0.129 0.080 0.018 0.311
4 1 0.231 0.118 0.050 0.369

 

1' Planting dates 1 = 21 September; 2 =30 September; 3 = 11 October; and 4 = 21

October.

1 Insecticide treatments: 1 = no insecticide (control); 2 = GAUCHO + CYGON

APPENDIX F

DAYS OF YEAR OF INITIATION OF STEM ELONGATION AND ANTHESIS IN
YEAR 1.

41

APPENDIX F

 

 

 

190

180 -
170+ J
160 -

150 1

 

140 - + Stem elongation
1 30 1 + Anthesis

Day of initiation
(Day of Year)

 

 

 

120 -
110 -

1 00 I 1 I I
250 260 270 280 290 300

Planting dates (Day of Year)

 

 

 

17 Oct = 290

 

 

Figure 1 - Days of year of initiation of stem elongation and anthesis in
Year 1.

APPENDIX G

DAYS OF YEAR OF INITIATION OF STEM ELONGATION AND ANTHESIS IN
YEAR 2.

42

APPENDIX G

 

 

 

180

170- .————-/'/

150 4

.3

O)

O
1

Day of initiation
(Day of Year)

.3 .3
(.0 «b
O O
l 1

 

1 20 ‘ + stemTelongation
1 10 _ +Anthesis

 

 

 

 

 

100 f I I I I I I
260 265 270 275 280 285 290 295 300

22 Oct =295

 

Planting date (Day of Year)

 

Figure 2 - Days of year of initiation of stem elongation and anthesis in
year 2.

 

APPENDIX H

THE EFFECT OF PLANTING DATE ON GRAIN YIELD OF WINTER WHEAT
VARIETY ‘HARUS’ IN YEAR 1 AND YEAR 2.

43

APPENDIX H

 

 

100
90 ~
80 -
70 -
60 a
50 ~

 

 

+Yield Yr 2
+Yield Yr
—Poly. (Yield Yr 2)
—Poly. (Yield Yr)

404
30~
20%

Average yield (bulacre)

 

 

 

 

1° ‘ LSD = 10.2
0 I I I I
250 260 270 280 290 300

lantin dates Da of Year
ep = 255P 9 I y )17 Oct= 290

 

 

 

12$

 

Figure 3 - Effect of planting date on grain yield of winter wheat variety
'Harus' in year 1 and year 2.

 

APPENDIX I

THE EFFECT OF PLANTING DATE ON TEST WEIGHT OF HARUS WINTER

WHEAT IN YEAR 1 AND YEAR 2.

 

44

APPENDIX I

 

 

 

\I
O

O)
O
l

LSD = 0.63

0|
0
I

.5
O
4

w
0
1

LS = 6.9

Test weight (lbs/bu)

N
O
1

 

.A
O
1

+ Test weight Yr 2
+ Test weight Yr 1

 

 

 

 

 

 

0 I I I I
250 260 270 280 290 300

Planting dates (Day of Year)
12 Sep=255 17 Oct=290

 

 

Figure 4 - The effect of planting date on test weight of Harus winter
wheat in year 1 and year 2.

APPENDIX J

THE EFFECT OF INSECTICIDE TREATMENTS ON GRAIN YIELD OF HARUS
WINTER WHEAT IN YEAR 1 AND YEAR 2.

45

APPENDIX J

 

 

100

 

904
80-
70~
60‘
50*
40~
30-
204
10*
0 r 1 1 1

Yield (bulacre)

 

 

 

+ control Yr 2
+gaucho+cygon Yr 2
+ control Yr 1
+gaucho Yr 1
—1—gaucho+cygon Yr 1

 

 

 

 

 

250 260 270 280 290
Planting dates (Day of Year)

17 Oct = 290

 

Figure 5 - The effect of insecticide treatments on grain yield of

Harus winter wheat in Year 1 and Year 2.

 

APPENDIX K

TEST WEIGHT OF WINTER WHEAT VARIETY HARUS AS INFLUENCED BY
INSECTICIDE TREATMENTS IN YEARS 1 AND 2.

 

46

 

 

 

 

 

 

 

 

 

 

APPENDIX K
70
60 a
_. 3 -
g 50
2 + control Yr 2
_: 40 4 +gaucho+cygon W2
:5, +control Yr 1
g 30 — +gaucho W1
.5 -—I—gaucho+cygon Yr 1
,9 20 ~
10 a
0 f r F r
250 260 270 280 290 300
Planting dates (Day of Year)
12 Sep=255 17 Oct=290

 

Figure 6 - Test weight of winter wheat variety Harus as influenced by
insecticide treatments in years 1 and 2.

 

APPENDIX L

THE RELATIONSHIP BETWEEN PLANTING DATE AND BARLEY YELLOW
DWARF VIRUS CONCENTRATION FROM WINTER WHEAT IN YEAR 1 AND
YEAR 2.

47

APPENDIX L

 

 

 

0.35
0.30 ~
0.25 —
0.20 3

NS
0.15 ~

 

0'10 I +BYDVYr2
+BYDVYI'1

Mean BYDV Absorbance

 

 

 

0.05 - LSD = 0.09

 

 

 

0.00 1 1 1 1
250 260 270 280 290 300

12 Sep = 255 Planting dates (Day of Year) 17 Oct = 29,

 

 

Figure 7 - The relationship between planting date and barley yellow
dwarf virus concentration from winter wheat in year 1 and year 2.

APPENDIX M

A COMPARISON OF INSECTICIDE TREATMENTS IN RELATION TO THE
CONTROL OF BARLEY YELLOW DWARF VIRUS ON HARUS WINTER
WHEAT IN YEAR 1.

48

APPENDIX M

 

 

0.40

 

0.35 -

0.30 -

0.25 .

0.20 -

0.15 q

0.10 «

Mean BYDV Absorbance

0.05 ~

b

LSD = 0.065

 

 

+ control
+ gaucho
+gaucho+cygon

 

 

 

0.00
250

260

270

280

290 300
17-Oct = 290

Planting date (Day of Year)

 

 

Figure 8 - A comparison of insecticide treatments in relation to the
control of barley yellow dwarf virus on Harus winter wheat in Year 1.