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Studies of Pest and
Beneficial Insects in
Arizona Stub and Planted Cotton

°U . S . Department of Agriculture
Agricultural Research Service

Agricultural Research Results* A RR-W-3 2/October 198 3

A copy of this publication is available upon request from the
Western Cotton Research Laboratory, 4135 East Broadway Road,
Phoenix, Ariz. 85040.

International Standard Serial Number (ISSN) 0193-3817

Agricultural Research Service, Agricultural Research Results, Western Series,
No. 32, October 1983

Published by Agricultural Research Service (Western Region), U.S. Department of
Agriculture, Oakland, Calif. 94612

ABSTRACT

In each of 3 study years (1978, 1979, 1980), stub cotton,

Gossypium spp., fruiting in commercial fields began approximately 4 to
6 weeks earlier than fruiting in planted cotton. The numbers of male
pink bollworm, Pectinophora gossypiella (Saunders), moths caught early
in the growing season in gossyplure-baited Delta traps were signifi-
cantly higher in stub cotton than in planted cotton. Pink bollworm
larval infestations in squares and bolls and Heliothis spp. oviposition
occurred 4 to 6 weeks earlier in stub cotton than in planted cotton.

Under controlled experimental conditions, approximately 2.6 times
more moths from overwintered pink bollworm larvae emerged in stub
cotton than in planted cotton. About 62 percent of the moths emerging
in stub cotton, compared with 10 percent of the moths emerging in
planted cotton, had host material (squares) available for reproduction
as a result of the earlier growth of the stub cotton. Boll infesta-
tions in the stub cotton were first found during the week ending June
21, and economic infestation levels of 15 percent or more were reached
by the week ending July 26. In contrast, economic level boll infesta-
tions occurred in adjacent planted cotton during the week ending
August 16 and in distant (265 m) planted cotton during the week ending
August 30.

Infestations of boll weevil, Anthonomus grandis Boheman, were
found in squares and/or bolls, or adults were caught in grandlure-
baited traps in stub cottonfields on three ranches in western Maricopa
County in 1978, the first year of the stub cotton study. The wet, cold
winter of 1978 to 1979 limited stub cotton production during 1979, and
no boll weevils were found during the 1979 growing season. When
approximately 24,000 ha of stub cotton were grown in 1980 and 1981,
boll weevils were found in squares, bolls, and/or caught in traps in
stub cottonfields on 6 ranches in the Cosmos area and 1 ranch near Gila
Bend during 1980, and on 1 ranch in Rainbow Valley, 2 ranches near
Buckeye, 1 ranch in Harquahala Valley, 12 ranches in the Cosmos area, 3
ranches near Gila Bend, 3 ranches in the Hyder area, and 3 ranches near
Aztec in 1981 in stub and planted cotton.

Lygus spp.; whitemarked fleahopper, Spanagonicus albofasciatus
(Reuter); cotton fleahopper, Pseudatomoscel is seriatus (Reuter); and
cotton leafperf orator , Bucculatrix thurberiella Busck, populations
during the 3 years of the study were not of economic significance in
either stub or planted cotton. Beneficial predaceous insects were high
in both stub and planted cotton production systems early in the season
and declined thereafter.

iii

Insecticide applications were applied earlier to stub cotton than
planted cotton but averaged only about one additional application to
stub cotton vs. planted cotton and controlled pink bollworm and
Heliothis spp. effectively in both cotton cultural systems.

KEYWORDS: Stub cotton, planted cotton, pink bollworm, boll

weevil, traps, infestations, Heliothis , overwintering,
gossyplure, grandlure, bolls, squares, beneficial
predaceous insects, insecticide applications, commer-
cial grower fields, emergence, flowering cycle, field
cages, diapausing larvae, Arizona, southern California,
populations, oviposition, plant terminal damage, plant
bugs, cotton leaf per f orator , cultural control prac-
tices, cotton production systems.

This paper contains the results of research only. Mention of
pesticides does not constitute a recommendation for use, nor
does it imply that the pesticides are registered under the
Federal Insecticide, Fungicide, and Rodenticide Act as
amended. The use of trade names in this publication does not
constitute a guarantee, warranty, or endorsement of the pro-
ducts by the U.S. Department of Agriculture.

CONTENTS

Page

Introduction 1

Procedures 2

General • 2

Pink bollworm and boll weevil 2

Heliothis spp 4

Other insects...... 5

Insecticides 5

Results 5

Pink bollworm 5

Boll weevil 10

Heliothis spp 11

Other insects — plant bugs and cotton leafperf orator 11

Insecticide applications 11

Discussion 11

Acknowledgment 14

Literature cited 14

Figures :

1. — Experimental stub and planted cottonfield locations in

Arizona in 1978, 1979, and 1980 3

2. — Mean number of male pink bollworm moths caught per

trap/night in stub and planted cottonfields in Arizona.. 17

3. — Mean number of male pink bollworm moths caught per trap/

night, May through July, in stub, adjacent and distant
planted cotton, and in the Arizona desert 17

4. — Mean number of male pink bollworm moths caught per trap/

night, August through October, in stub, adjacent and
distant planted cotton in Arizona 18

5. — Mean percentages of pink bollworm infested cotton

squares in stub and planted cotton in Arizona 18

6. — Mean numbers of cotton flowers in stub and planted

cotton in Arizona 19

7. — Mean percentages of pink bollworm infested cotton bolls

in stub and planted cotton in Arizona 19

8. — Mean numbers of cotton flowers per cage per day over

stub and planted cotton in Arizona 20

9. — Mean numbers of pink bollworm infested cotton flowers

per cage per day. Cages placed over stub cotton

April 1 and June 5 20

10. — Mean numbers of pink bollworm infested cotton flowers
per cage per day. Cages placed over planted cotton on
June 4 21

Page

F igures :

11. — Mean percentages of pink bollworm larvae in diapause in

September, October, and November 1980 in Arizona 21

12. — Cottonfield locations showing spread and distribution

of boll weevils found in squares, bolls, and/or traps
in 1978, 1979, 1980, and 1981 in Arizona 22

13. — Mean number of Heliothis spp. eggs per 100 terminals in

stub and planted cotton in Arizona 23

14. — Mean number of Heliothis spp. larvae per 100 terminals

in stub and planted cotton in Arizona 23

15. — Mean percentages of Heliothis spp. damaged terminals

in stub and planted cotton in Arizona 24

16. — Mean numbers of plant bugs per 100 sweeps in stub and

planted cotton in Arizona 24

17. — Mean numbers of cotton leafperf orators per 100 sweeps

in stub and planted cotton in Arizona 25

18. — Mean numbers of beneficial predators per 100 sweeps in

stub and planted cotton in Arizona 25

Tables :

1. — Weekly stub and planted cotton sampling periods in 1979,

1980, and 1981 in Arizona 6

2. — Mean number of pink bollworms per 25 cotton bolls from

plants in field cages placed over stub and planted
cotton, Arizona State University Experimental Farm,

Tempe , 1980 8

3. — Percentages of pink bollworm infested cotton squares in

stub, adjacent planted, and distant planted cotton,

Arizona State University Experimental Farm, Tempe, 1980. 8

4. — Mean percentages of pink bollworm infested bolls in

stub, adjacent, and distant planted cotton, Arizona

State University Experimental Farm, Tempe, 1980 9

5. — Mean number of insecticide applications per month in

experimental stub and planted cottonfields in Arizona in
1978, 1979, and 1980 12

STUDIES OF PEST AND BENEFICIAL INSECTS IN ARIZONA
STUB AND PLANTED COTTON

By D. Bergman, T. J. Henneberry, L. A. Bariola,

and J. M. Gillespie1

INTRODUCTION

The cotton, Gossypium spp., plant is perennial in growth habits; however,
in most of the United States it is grown as an annual plant because (1) it fails
to survive killing frosts and (2) it has more pest problems when grown as a
perennial (Wene 1965 ; Fye 1968; Fye and Parencia 1972; van Schaik et al . 1962) . 2
Evanson (1970) reviewed the reports of stub or ratoon cotton grown in many parts
of the world. He concluded that in some circumstances, perennial cotton was
advantageous and had been reported successfully grown in Peru, British Guiana,
Brazil, Western United States, South Africa, Israel, and northwestern Australia.
Yields were equal to or higher than those from annual planted cotton when one
managed to avoid insect pests, diseases, and weeds, but he reported lint quality
data were conflicting. Ratoon cotton was characterized as flowering earlier and
requiring less fertilizer but having more serious weed problems than the annual
crop. Disease and insect pest problems varied considerably. For example, in
Egypt, early regrowth of ratoon cotton supported populations of spiny bollworm,
Earias insulana (Bdv.), and annual cotton in close proximity to ratoon cotton
suffered higher losses from bollworms than in the absence of ratoon cotton
(Bishara 1930). In South Africa, Rainey and Smith (1950) reported similar
experiences with the red bollworm, Diparopsis castanea (Hmps.), and the
cotton stainer, Dysdercus fasciatus (Sign.).

Stub cotton has been grown in Arizona except when prohibited under State
and Federal quarantines because of the threat of spreading pink bollworm,
Pectinophora gossypiella (Saunders), and boll weevil, Anthonomus grandis
Boheman, infestations. Wene (1965) concluded that stub cotton was related to
increased problems with pink bollworm, and Fye (1968) reported that damage from
the boll weevil in Arizona was greater in stub cotton than in planted cotton.

xBe rgman is a research technician, Department of Entomology, University of
Arizona, Tucson; Henneberry and Bariola are entomologists, Western Cotton
Research Laboratory, Western Region, Agricultural Research Service (ARS) , U.S.
Department of Agriculture (USDA) , Phoenix, Ariz.; and Gillespie is Manager,
Pheromone Programs, Hereon Division, Health-Chem Corp., Phoenix.

2The year in italic, when it follows the author's name, refers to Litera-
ture Cited, p. 14.

van Schaik et al . (1962) reported that the incidence of cotton leaf crumple
disease, transmitted by the sweetpotato whitefly, Bemisia tabaci (Gennadius), in
Arizona and southern California increased with the practice of stubbing cotton.
Extensive grower interest in stub cotton culture because of potential yield
increases, the availability of new chemicals for pest control, and increased
energy and other production costs prompted the initiation in 1978 of a coopera-
tive research study involving the University of Arizona, USDA-ARS, Arizona
Commission of Agriculture and Horticulture, and participating cotton growers to
evaluate pest, disease, agronomic, and economic aspects of stub cotton growing
with currently available production technology (Beatty 1977). Some of the
results of the agronomic, weed, and disease studies have been reported elsewhere
(Taylor and Hathorn 1979a, 1979b, 1979c, 1981) as well as progress reports of
the entomological work (Gillespie et al . 1979; Bergman et al . 1980, 1981). The
present paper is a complete analysis of the entomological research results from
1978 to 1981.

PROCEDURES

General

In 1978, commercial stub and adjacent planted cottonfields of at least 32
ha were selected as experimental sites at each of 10 locations. Stub, adjacent
planted, and distant planted cotton (0.8 to 1.6 km from stub fields) were
selected at each of two and five locations in 1979 and 1980, respectively. In
1981, 5 stub and 10 planted fields (about 32 ha each) were selected for boll
weevil studies. Numerous other fields were also inspected to detect and study
the spread of infestations of the insect. In 1979, each of the three treatments
was replicated twice at each of the two locations. Experimental stub and
planted fields at all locations in 1979 and 1980 were about 17 to 28 ha each.
Cottonfields in each year of the study were in Maricopa and Pinal Counties in
Arizona (fig. 1).

Sampling in commercial fields for pink bollworm, Heliothis spp., cotton
leafperforator , Bucculatrix thurberiella Busck, boll weevil, plant bugs, Lygus
spp., cotton fleahopper, Pseudatomoscelis seriatus (Reuter), whitemarked flea-
hopper, Spanagonicus albofasciatus (Reuter), and selected insect predators
(( Orius spp., Geocoris spp., assassin bugs (Reduviidae) , Nabis spp., green
lacewings ( Chrysopa spp.), and lady beetles (Coccinellidae) ) was initiated the
last week in April to May 7 in each year, except in the 1981 boll weevil
studies, and continued through the last week in September.

Pink Bollworm and Boll Weevil

Five gossyplure-baited Delta traps (Sandia Die and Cartridge Co., Albuquer-
que, N. Mex.) were installed in each stub and planted cottonfield to study pink
bollworm male moth activity in each type of cotton culture (Foster et al. 1977).
Traps were installed the first week in May and operated through the last week of
September in each year. Pheromone baits, containing 1 mg gossyplure on rubber
septa (Flint et al . 1976), were replaced monthly. Traps were replaced when

Figure 1. — Experimental stub and planted cottonfield loca-
tions in Arizona in 1978, 1979, and 1980.

catches exceeded 50 moths. In addition, in 1979 and 1980, to measure male moth
activity outside cottonfields and in cotton fields prior to cotton fruiting, two
sets of five pink bollworm pheromone traps were placed in the desert at least
0.4 km from the nearest cotton at each location April 24 to 26, and operated
until June 30. Boll weevil traps (Legget and Cross 1971), baited with 3 mg of
grandlure, were installed in each field. Traps were checked weekly and baits
changed every 2 weeks. Additionally, boll weevil traps were installed in other
cottonfields when infestations were detected to record movement and spread of
infestat ions .

Fifty to 100 mature squares were collected weekly in each field until the
end of August and examined for pink bollworm and boll weevil feeding punctures,
eggs and larvae, and darkened pollen sacs, indicating plant bug feeding. In
1979, numbers of flowers were counted on all plants in 1.1 m of row at each of
five locations in each field and in 1980 on all plants in 30 m of row at two
locations in each field to compare boll set curves of stub and planted cotton
in relation to the availability of bolls as oviposition sites for pink bollworm

moths. One hundred firm green bolls (about 14 to 21 days old) were collected in
each stub field beginning in mid-June and in planted fields beginning in
mid-July and continuing through September. Bolls from each sample were examined
for exit holes and cut open to determine the presence of pink bollworm larvae
and boll weevil larvae, pupae, and adults.

Pink bollworm overwintering and seasonal development in stub and planted
cotton were also studied at Arizona State University Experimental Farm, Tempe ,
in 1980. The cotton stalks in 16 rows of a 5.6-ha cottonfield from seed planted
in 1979 were cut (stubbed) to about 7.5 cm in height in March 1980. The
remaining stalks were cut and shredded, and the field was plowed, disked, and
cultivated. On April 14, 1980, 290 rows of cottonseed were planted adjacent to
the stubbed cotton. The stub and planted cotton plots were irrigated as needed
from April 7 until October 3, 1980.

The numbers of pink bollworm moths emerging from overwintered larvae in
stub and planted cotton were determined by placing 24 screened pyramid ( 1 m2 )
emergence cages (Shiller 1946), over the soil in the stub and planted cotton
plots from March 26 to April 23, 1980. Emerged pink bollworm adults in the
cages were counted and sexed daily from March 27 to June 30.

Infestations developing from pink bollworm moths emerging in stub cotton
and infestations augmented by moths moving into the stub cotton from outside
sources were compared by placing four screened field cages (7.3 X 2.7 X 1.8 m)
over stub cotton on April 1 and four screened field cages over stub cotton
approximately 8 weeks later on June 5. Four screened and four unscreened field
cages were placed over planted cotton on June 4.

The total numbers of flowers and pink bollworm infested flowers were
counted daily, except on weekends, in all field cages from June 5 to October 20.
Twenty-five firm green bolls (about 14 to 21 days old) were collected from the
cotton plants in each field cage weekly and held for 21 days in ventilated
plastic boxes, as described by Fye (1976). During the third week after collec-
tion, pink bollworms were counted and all bolls were opened and inspected for
larvae.

The effect of pink bollworm populations developing in the stub cotton and
infestations in the adjacent planted cotton, as well as planted cotton 265 m
distant, was determined by collecting mature cotton squares and firm green bolls
(100 each) from each of the areas twice weekly. The squares and 50 of the bolls
were opened and examined for pink bollworm larvae. The remaining 50 bolls,
were held in ventilated plastic boxes as previously described. Beginning in
August, larvae collected from the plastic boxes were used to determine the
percentages of larval diapause, as described by Bariola and Henneberry (1980).

Heliothis spp.

Beginning the first week of May each year, 100 plant terminals in each of
the commercial stub cottonfields were examined for the presence of Heliothis
spp. eggs, larvae, and terminal damage. Similar sampling in all planted fields

began about the third week in May of each year. Damage was recorded if the
terminal bud and/or pinhead or older squares showed evidence of Heliothis spp
larval feeding.

Other Insects

The numbers of adult and immature forms of pest and selected beneficial
insects ( Orius , Geocoris, Nabis , Chrysopa, Reduviidae, Coccinellidae, Collops ,
and spiders) were recorded weekly in standard samples of 100 sweeps of cotton
rows beginning late April to early May in each stub field and during June in
the planted fields. Sampling in each year was continued until mid-September.

Insecticides

Information concerning insecticides applied, rates, and dates of applica-
tion on commercial grower fields was obtained from insecticide applicators
and/or grower-employed pest control advisors.

Data tabulation for the 1978, 1979, and 1980 studies in commercial fields
was facilitated by adjusting calendar dates to numbered weeks of the stub and
planted cotton-growing season for each year, as shown in table 1. Data were
tabulated as the means for each species for each sampling period for the 3 yeard
of the study. All data were subjected to analyses of variance arrd Duncan's
multiple range mean separation at the 19:1 probability level.

RESULTS-

Pink Bo 11 worm

For the first 8 weeks of gossyplure trapping, significantly more male pink
hollworm moths were caught in grower stub cottonfields than in planted fields
(fig. 2, average of 3 years' trapping data).3 After July 1, the numbers of
male moths caught in traps in stub and planted cotton were not significantly
different.

The 1979 and 1980 data show that in early season (May through July), male
moth trap captures in desert areas averaged about one male pink bollworm moth
per trap/night (m/t/n) through the first 3 weeks in May and declined thereafter
(fig. 3). No male moths were caught in the desert after mid-June. Through May
and June, traps in the stub fields caught an average 1.5 m/t/n, ranging from 0.8i
to 3.3. During the same period, captures in traps were less in the adjacent
planted fields and averaged 0.6 m/t/n, ranging from 0.3 to 0.8, while captures

3Figures 2 to 18 follow the text, beginning on p. 17.

Table 1. — Weekly stub and planted cotton sampling periods in 1979, 1980

and 1981 in Arizona

Month

Week of
sampl ing

Actual sampling dates

1978

1979

1980

May

4/30-5/6

4/29-5/5

4/27-5/3

5/7 -5/13

5/6 -5/12

5/4 -5/10

5/14-5/20

5/13-5/19

5/11-5/17

5/21-5/27

5/20-5/26

5/18-5/24

5/28-6/3

5/27-6/2

5/25-5/31

June

6/4 -6/10

6/3 -6/9

6/1 -6/7

6/11-6/17

6/10-6/16

6/8 -6/14

6/18-6/24

6/17-6/23

6/15-6/21

6/25-7/1

6/24-6/30

6/22-6/28

July

7/2 -7/8

7/1 -7/7

6/29-7/5

7/9 -7/15

7/8 -7/14

7/6 -7/12

7/16-7/22

7/15-7/21

7/13-7/19

7/23-7/29

7/22-7/28

7/20-7/26

August

7/30-8/5

7/29-8/4

7/27-8/2

8/6 -8/12

8/5 -8/11

8/3 -8/9

8/13-8/19

8/12-8/18

8/10-8/16

8/20-8/26

8/19-8/25

8/17-8/23

8/27-9/2

8/26-9/1

8/24-8/30

September

9/3 -9/9

9/2 -9/8

8/31- 9/6

9/10-9/16

9/9 -9/15

9/7 -9/13

9/17-9/23

9/16-9/22

9/14-9/20

9/24-9/30

9/23-9/29

9/21-9/27

in traps in the distant planted fields averaged 0.9 and peaked the first week in
June at 1.7. Early in July, average male moth captures in the adjacent planted
field increased abruptly and were greater than the average male moth captures in
the distant planted fields. The monthly average for moths captured was greater
in the stub fields than in either adjacent or distant planted fields in August,
but greater in the adjacent planted fields than in either stub or distant
planted fields in September (fig. 4). Male moth captures increased and were
similar in all fields during October.

Square infestations in commercial fields (average of 3 years' data) were
initiated in stub cotton by May 11 to 20 (fig. 5). An average of 1.1 percent
(range 0 to 12 percent) of the squares sampled from stub fields in early May to
early July were infested with pink bollworm larvae. No square infestations were
found in planted cotton until the last week in June. Square infestations in
stub and planted cotton were not different in mid-July through mid-August, but
increased dramatically in stub cotton in late August and early September.

Flowering (boll set) in stub cotton began approximately 4 weeks earlier
than in planted cotton (fig. 6). Peak flowering in stub cotton occurred the
first week in July, decreasing thereafter to mid-August. In contrast, flowering
in planted cotton began in late June, peaked in late July, and decreased to late
August. From June 3 to 20, 1 to 3 percent of the sampled bolls in stub cotton
were infested with pink bollworm larvae (fig. 7). Susceptible bolls were not
available to pink bollworm in planted cotton until June 29 to July 8. During
July and August, percentages of infested bolls were numerically higher in stub
cotton than in planted cotton except for 1 week in late July, but the dif-
ferences were not statistically different (fig. 7). Infestations in both stub
and planted cotton bolls decreased to less than 1 percent in September as a
result of insecticide applications.

The results of the 1980 pink bollworm overwintering studies in stub and
planted cotton grown under controlled experimental conditions showed that from
April 1 through June 23, 52 pink bollworm moths (21,700/ha) emerged in cages
placed over stub cotton, and 20 moths (8,300/ha) emerged in cages over planted
cotton with peak emergence occurring May 6 to May 26. However, approximately 62
percent (32) of the moths emerging in the stub cotton (first square May 15) and
only 10 percent (2) of the moths emerging in the planted cotton (first square
June 4) had host material (squares) available for pink bollworm reproduction
(fig. 8, squares occurred about 3 weeks before flowers). Thus, about 90 percent
of the moths emerged suicidally in the planted cotton compared with only 38
percent in the stub cotton (Bariola 1978).

Flowers per field cage were greater in the stub cotton than in the planted
cotton until mid-July (fig. 8). The first flowering cycle in the stub cotton
peaked on June 20 with flowering decreasing thereafter until August 21 when the
second flowering cycle began. The second flowering cycle in the stub cotton
peaked on September 15 and declined thereafter. In contrast, the first
flowering cycle did not begin until June 24 in the planted cotton, peaked July
28, and declined thereafter. The second flowering cycle in the planted cotton
began increasing September 8 and peaked October 2.

The number of pink bollworm infested flowers per field cage from June 23 to
July 3 was significantly greater in stub cotton caged June 5 than in stub cotton
caged April 1 (fig. 9). The numbers of pink bollworm infested flowers per open
field cage over planted cotton from July 17 to 28 were significantly greater
than infested flowers in the screened field cages over planted cotton (fig. 10).
Initial boll infestations (July 2) were significantly greater from stub cotton
caged June 5 than boll infestations in stub cotton caged April 1 (table 2).

From August 6 through September 17, pink bollworm larvae per 25 bolls from open
cages over planted cotton were significantly greater than in bolls from cotton
in the screened field cages.

In open field plots, stub cotton squares sampled during the week ending
June 7 were infested (5.0 percent) with pink bollworm larvae (table 3). Planted
cotton square infestations were not found until the week ending July 5. Square
infestations in the stub cotton were higher than in either adjacent or distant
planted cotton during 11 of 16 weeks throughout the sampling period. Square
infestations were higher in the adjacent planted cotton than in the distant
planted cotton throughout August and September.

Table 2. — Mean 1 number of pink bollworms per 25 cotton bolls from plants in
field cages placed over stub and planted cotton , Arizona State University
Experimental Farm, Tempe , 1980

Planted cotton caged

Sampling Stub cotton caged June 4 June 4

date April 1 June 5 (screened) (open)

July

2 b

8 a

4 a

11 ab

21 a

0 c

3 be

7 b

30 a

0 b

8 b

1 b

24 a

1 b

9 b

August

5 c

37 a

0 c

17 b

50 b

103 a

3 c

42 b

54 a

88 a

8 b

64 a

67 b

106 ab

14 c

123 a

September

38 be

57 b

20 c

111 a

55 b

91 a

24 b

87 a

58 b

59 b

25 c

91 a

55 a

76 a

57 a

66 a

*Means

of 4 replications.

Means in the

same row

not followed

by a

common

letter are

significantly different according

to Duncan

1 s mu 1 1 ip le

range

test ,

P=0 .05 .

Table 3. — Percentages of pink bollworm infested cotton squares in stub, adjacent
planted , 1 and distant planted 2 cotton, Arizona State University Experimental
Farm, Tempe, 1980

Week ending

Percent

square infestations

Stub cotton

Planted

Adjacent

cotton

Distant

June

July

August

September

* Planted

cotton

adjacent to the stub cotton.

2 Planted

cotton

265 m distant from the

stub cotton.

Stub cotton boll infestations were first found the week ending June 21
(table 4). Economic infestation levels of 15 percent or more were found in the
stub cotton by the week ending July 26 and in the adjacent planted cotton during
the week ending August 16, but not in the distant planted cotton until the week
ending August 30.

The first diapausing larva was found on August 29. The percentages of
larvae in diapause were not different in stub and planted cotton, and the data
are combined in figure 11. The percentage of larvae in diapause remained low
through mid-September, then increased rapidly and reached 82 percent by October
7. This diapause response is similar to that reported by Bariola and Henneberry
{1980) for Arizona and southern California.

Table 4.. — Mean * percentages of pink bollworm infested bolls in stub, adjacent , 2
and distant 2 planted cotton, Arizona State University Experimental Farm,

Tempe , 1980

Percentages infested

Planted cotton

Week ending

Stub cotton Adjacent Distant

June

July

August

September

October

November

*50 bolls per twice weekly sample.

2Planted cotton adjacent to stub cotton.

3 Planted cotton 265 m from the stub cotton.

Boll Weevil

The first boll weevil infestation was found on August 31, 1978, in a
commercial stub cottonfield on a ranch (Gl, fig. 12a) near Gila Bend. Approxi-
mately 11 percent of 811 squares examined were damaged by feeding and/or ovi-
posit ion punctures. Square and boll infestations ranged from 2 to 22 percent
from September to November 1978. Infestations occurred in another stub
cottonfield on this ranch in 1978, but none were found in planted cottonfields
in the area. Boll weevil traps caught about 27 adults per trap from September
to December 1978. These insects and one boll weevil adult caught during October
1978 in a trap operated beside a stub cottonfield on a ranch (Rl, fig. 12 A) in
Rainbow Valley were identified1* as Anthonomus grandis Boheman, Mexican boll
weevil form.

Boll weevils were found on an adjacent ranch at the same location (G2 , fig.
12 a) in early February 1979. Developmental cells (107) were found in 33 percent
of the dry bolls collected from cotton stalks that remained in the stub cotton-
field from the 1978 season. The cotton stalks on both ranches remaining from
the 1978 season were shredded and the fields plowed during March 1979. Boll
weevil traps (5 to 14) caught about 28 adults per trap on ranch Gl and about 16
adults per trap on ranch G2 from January through April 1979. Traps were
operated through June 1979, but no additional boll weevils were caught. No boll
weevil infestations were found in 1979 planted or stub cottonfields sampled
during the growing season since only about 600 ha of stub cotton were grown in
Arizona in 1979 (no stub cotton was grown in 1979 on or near the ranches with
1978 boll weevil infestations) because high mortality of 1978 stalks occurred
during the wet, cold 1978-79 winter months. However, evidence of boll weevil
infestations in 1979 cottonfields was found in another area in early February
1980 when developmental cells, averaging about 3750 per ha, were found in dry
bolls remaining in 1979 stub cottonfields on two ranches (fig. 12B, C2, C 3 ) at
the Cosmos location.

Boll weevil infestations occurred on these two and four additional ranches
(fig. 12B, Cl, C4, C5, and CIO). During the 1980 growing season, when about
24,000 ha of stub cotton were grown, boll weevil square infestations were about
2, 12, and 32 percent on May 6, June 10, and June 30, respectively, and peak
boll infestations occurred June 16 to 23 in stub cottonfields on ranch C2 in the
Cosmos area during 1980. Infestations ranging from about 1 to 3 percent were
found in bolls collected from November to December 1980 in adjacent stub cotton-
fields on ranches Cl, C3, C4, and C5. Infestations were not found in planted
cottonfields in the area. Two adults were caught in traps operated on ranch CIO
during September. Adult boll weevils were found feeding in blooms, and larval
infestations occurred in both squares and bolls during September 1980 in a stub
cottonfield on the same ranch (fig. 12B, Gl) near Gila Bend where infestations
occurred in 1978. A mild winter also preceded the 1981 cotton growing season,

4 Horace Burke, Texas A&M University, College Station, Tex.

and about 24,000 ha of stub cotton were grown commercially. Adult boll weevils
were trapped and/or infestations were found in squares or bolls on 25 ranches
(fig. 12C), extending westward to Aztec and northwest to Harquahala Valley.

Heliothis Spp.

Oviposition, larval development, and damaged terminals caused by these
insects were observed in commercial stub cottonfields the first week in May
(figs. 13, 14, and 15), whereas, infestations were not found in planted fields
until mid- to late June. Weekly averages for eggs per 100 terminals in both
stub and planted cultures increased similarly through July and August, but
significantly higher populations occurred in planted fields in September.
Higher numbers of larvae were found in planted cotton in July. Plant terminal
damage followed trends similar to egg and larval populations.

Other Insects--Pl ant Bugs and Cotton Leafperforator

Lygus spp., white marked fleahopper populations, and cotton leafperforator
numbers were low and of little consequence in either stub or planted cotton -
during the study (figs. 16 and 17).

Beneficial Insects

High numbers of beneficial insects ( Orius spp., Geocoris spp., Coccinelli-
dae, Chrysopa spp., Reduviidae, Nabis spp., Collops spp., and spiders) were
found early in the season in both planted and stub cultures (fig. 18). Popula-
tions were high through early July and declined thereafter. These results may
have occurred because of insecticide applications and/or lack of prey since
insect populations were generally low.

Insecticide Applications

The average number of foliar insecticide applications in stub and planted
cotton commercial experimental plots (1978-80) was 11.1 and 10.3, respectively
(table 5). Earliest applications to stub cotton occurred in February and to
planted cottonfields in June. Insecticides effectively controlled pink bollworm
and Heliothis spp. in both stub and planted cottonfields as indicated by the
relatively low infestation levels in both stub and planted cotton grown under
commercial conditions.

DISCUSSION

Early stub cotton regrowth resulted in fruiting forms available by mid-
April to early May, depending on temperature, as oviposition sites and as a

Table 5. — Mean 1 number of insecticide applications per month in experimental
stub and planted cottonfields in Arizona in 1978, 1979, and 1980

Cotton cultural type

Month

Stub

Planted

January

Feburary

March

April

May

June

1.1

July

2.7

2.0

August

4.4

4.7

September

2.2

2.6

October

Total

11.0

10.3

^Means of 19 fields each of stub and planted cotton for years 1978, 1979,
and 1980.

source of larval food for initiation of pink bollworm infestations. Pink boll-
worm infestations were not initiated in planted cotton until mid-May to early
June (Slosser and Watson 1972).

Under commercial growing conditions, insecticide applications were
initiated an average of 5 weeks earlier in stub cotton than in planted cotton
because of earlier insect infestations, but were applied to planted fields 2
weeks longer. Insecticide applications for pink bollworm and Heliothis species
control probably account for the low populations of cotton leaf perforator , Lygus
spp., whitemarked fleahopper, and cotton fleahopper. Insect infestations in
stub or planted cotton were low in commercial study fields as a result of
insecticide treatments and did not contribute to reduced yield (Taylor and
Hathorn 1979a, 1979b).

In controlled experimental plots where no insecticides were applied during
the growing season, more pink bollworm moths emerged the following spring from
stub cotton than from planted cotton. These results agree with those of Watson
et al. (1974), which demonstrated that cotton stalk destruction and plowdown
significantly reduced overwintering pink bollworm populations. The earlier
availability of host material (squares) resulted in potential reproduction for
over 60 percent of the emerged moths in the stub cotton as compared with 10
percent of the emerged moths in the planted cotton where host material was not
available until later in the season. Moths emerging in the surrounding area
were attracted to the earlier fruiting stub cotton since higher infestations

were found in stub cotton that had been exposed longest during the spring moth
emergence period compared with stub cotton which had been protected by caging to
exclude moths from outside sources. The development of an earlier pink bollworm
generation in stub cotton squares also resulted in economic infestation levels
in the stub cotton bolls occurring earlier in the season.

Pink bollworm moths of the first generation developed on stub cotton moved
to the planted cotton when flowering decreased in the stub cotton. This was
demonstrated by the significantly greater number of infested flowers which
occurred in the open field cages over planted cotton compared with the number of
infested flowers in the screened planted cottonfield cages.

Economic level boll infestations in the planted cottonfield plots adjacent
to the stub cottonfield plots occurred 2 weeks earlier than in the planted
cotton 265 m distant from the stub cotton.

Measurable infestations of the boll weevil had not been recorded in Arizona
cotton since 1966 when stub cotton growing was banned and mandatory plowdowns
and planting dates were enforced to maintain a host-free period. Boll weevils
were found in stub cottonfields on three ranches during 1978 (the first year of
the stub cotton research program) and the spring of 1979, but none were found
during the 1979 growing season when stub cotton acreage was limited to about 600
ha. Boll weevils were found on seven ranches during 1980 and 25 ranches during
1981 in stub and planted cottonfields when about 24,000 ha of stub cotton were
grown each year.

Stub cotton fruiting in April and May and early development of the plant
canopy in stub fields probably provide suitable habitats for the development of
early generations of weevils. In 1980 and 1981, increasing numbers of boll
weevils were caught in grandlure-baited traps, indicating higher population
levels. Fye et al. (2969) suggested that the threat of major boll weevil
infestations was minimal until late season due to the high temperatures during a
normal Arizona midsummer. They reported that temperatures above the range 30°
to 35°C prolonged the development of the boll weevils. Also, frequent and pro-
longed exposure to soil temperatures greater than 38°C induced high levels of
larval mortality in infested cotton squares that fall to the soil during May and
June (Fye and Bonham 1970). Early foliage shading in stub cotton cultural
systems reduced soil temperatures below the canopy and thus increased the
development time and reduced larval mortality of boll weevils in infested cotton
squares .

The results of the present study support the conclusions of Fye et al .
(1970) and Fye and Parencia (2972) that the early destruction of cotton stalks
and subsequent burial of all debris are essential cultural control practices to
prevent the development of high boll weevil populations in Arizona, as well as
other late-season insect populations, such as the pink bollworm and bollworm
complex.

Taylor and Hathorn (1981) reported that the costs of producing stub and
planted cotton were similar, but higher yields were obtained from stub cotton
culture. Flint et al. (1980) also reported that in an unreplicated field trial
in Arizona, economical stub cotton production occurred without increased
insecticide costs. The short-term advantage of higher yields must be carefully

considered in relation to the disadvantage of developing an additional genera-
tion of pink bollworm and the possible establishment of the boll weevil as a
permanent pest in Arizona cotton production systems.

ACKNOWLEDGMENT

The authors are grateful to Brian Beard and Jay Schied for their assistance
in collecting and tabulating data and to the cotton growers and pest control
advisors for their support and cooperation during these studies.

LITERATURE CITED

Bariola, L. A.

1978. Suicidal emergence and reproduction by overwintered pink bollworm
moths. Environmental Entomology 7:189-192.

and T. J. Henneberry.

1980. Induction of diapause in field populations of the pink bollworm in the
Western United States. Environmental Entomology 9:376-380.

Beatty, T.

1977. We need stub cotton research. Arizona Farmer-Ranchman 56:38.

Bergman, D., L. A. Bariola, and T. J. Henneberry.

1981. 1980 Boll weevil infestations in Arizona cultivated cotton. Proceed-
ings of the Beltwide Cotton Production Research Conference, p. 70-75.

T. J. Henneberry, L. A. Bariola, and T. Watson.

1980. Cotton insect populations in Arizona stub cotton systems. Proceedings
of the Beltwide Cotton Production Research Conference, p. 271-276.

Bishara, I.

1930. Ratoon cotton in relation to insect pests. Technical and Science Ser-
vice (Plant Protection Section), Bulletin No. 96. Ministry of Agriculture,
Egypt. 68 p.

Evanson, J. P.

1970. Ratooning of cotton: A review. Cotton Growing Review 47:1-7.

Flint, H. M. , S. S. Salter, and S. Walters.

1980. Development of cotton and associated beneficial and pest insect popula-
tions in a ratoon field at Phoenix, Ariz. U.S. Department of Agriculture,
Science and Education Administration, Agricultural Reviews and Manuals,
ARM-W-15, 14 p.

R. L. Smith, and L. A. Bariola.

1976. Pink bollworm: Trap tests with gossyplure. Journal of Economic
Entomology 69:535-538.

Foster, R. N., R. T. Staten, and E. Miller.

1977. Evaluation of traps for pink bollworm. Journal of Economic Entomology
70:289-291.

Fye, R. E.

1968. Populations of boll weevil in selected fields in Arizona in 1965 and
1966. Journal of Economic Entomology 61:377-380.

1976. Improved method of holding cotton bolls for detecting pink bollworms.
U.S. Department of Agriculture, Agricultural Research Service, ARS W-37, 3 p.

and C. D. Bonham.

1970. Summer soil surface temperatures and their effect on boll weevil sur-
vival in fallen squares. Journal of Economic Entomology 63:1599-1602.

J. E. Leggett, and C. D. Bonham.

1970. Winter survival of the boll weevil complex in Arizona. Journal of
Economic Entomology 63:1071-1074.

and C. R. Parencia, Jr.

1972. The boll weevil complex in Arizona. U.S. Department of Agriculture,
Production Research Report No. 139, 24 p.

R. Patana, and W. C. McAda.

1969. Developmental periods for boll weevils reared at several constant and
fluctuating temperatures. Journal of Economic Entomology 62:1402-1405.

Gillespie, J. M., T. F. Watson, T. J. Henneberry, and L. A. Bariola.

1979. A comparison of 1978 insect populations on stub and planted cotton in
central Arizona. Proceedings of the Beltwide Cotton Production Research
Conference, p. 99-103.

Leggett, J. E., and W. H. Cross.

1971. A new trap for capturing boll weevils. U.S. Department of Agriculture,
Cooperative Economics Insect Report 21:773-774.

Rainey, R. C., and B. Smith.

1950. Cotton and its pests in South Africa. Ratooning as a threat to the
revival of cotton growing in the Union. Union of South Africa Science
Bulletin No. 308, 17 p.

Shiller, I.

1946. A hibernation cage for pink bollworm. U.S. Department of Agriculture,
Bureau of Entomology and Plant Quarantine, ET226, 6 p.

Slosser, J. E., and T. F. Watson.

1972. Population growth of the pink bollworm. Arizona Agricultural Experi-
ment Station Bulletin No. 195, 32 p.

Taylor, B. B., and S. Hathorn, Jr.

1979a. A close, new look at stub cotton 12 years after the State ban. Pro-
gressive Agriculture, Arizona 17:12-13.

Taylor, B. B.

1979b. Pros and cons of stub cotton. Proceedings of the Beltwide Cotton
Production Mechanization Conference, p. 25-26.

and S. Hathorn, Jr.

1979c. Stub cotton in Arizona. Proceedings of Western Cotton Production Con-
ference, p. 31-32.

and S. Hathorn, Jr.

1981. Stub cotton in Arizona. A three-year program summary. In Cotton,
College of Agriculture report. Arizona Agricultural Experiment Station,
Series P-53, p. 21-23.

van Schaik, P. H., D. C. Erwin, and M. J. Garber.

1962. Effects of time of symptom expression of the leaf crumple virus on
yield and quality of fiber of cotton. Crop Science 2:275-277.

Watson, T. F., K. K. Barnes, J. E. Slosser, and D. G. Fullerton*

1974. Influences of plowdown dates and cultural practices on spring moth
emergence of the pink bollworm. Journal of Economic Entomology 67:207-210.

Wene, G. P.

1965. Cotton. In Cotton, a College of Agriculture report. Arizona Agricul-
tural Experiment Station, Series P-1, p. 63-64.

WEEK OF THE GROWING SEASON

MAY ! JUNE I JULY I AUG ! SEPT I

Figure 2. — Mean number of male pink bollworm moths caught per
trap/night in stub and planted cottonfields in Arizona.

(Means of 3 years — 1978, 1979, 1980 — for each data point.
Means for each sampling date with different letters are
significantly different, according to Duncan's multiple range
test , P = 0.05.)

Figure 3. — Mean number of male pink bollworm moths caught per trap/night, May
through July, in stub, adjacent and distant planted cotton, and in the Arizona
desert. (Means of 2 years — 1979, 1980 — for each data point. Means for each
sampling date with different letters are significantly different, according to
Duncan's multiple range test, P = 0.05.)

Late Season

Figure 4. — Mean number of male pink bollworm moths caught per trap/night, August
through October, in stub, adjacent and distant planted cotton in Arizona.
(Means of 2 years — 1979, 1980 — for each data point. Means for each sampling
date with different letters are significantly different, according to Duncan's
multiple range test, P = 0.05.)

Figure 5. — Mean percentages of pink bollworm infested cotton squares
in stub and planted cotton in Arizona. (Means of 3 years — 1978,
1979, 1980.)

STUB COTTON
PLANTED COTTON

WEEK OF THE GROWING SEASON

I MAY I JUNE i JULY ! AUG I SEPT I

Figure 6. — Mean numbers of cotton flowers in stub and
planted cotton in Arizona. (Means of 3 years — 1978,
1979, and 1980.)

WEEK OF THE GROWING SEASON

I MAY I JUNE I JULY I AUG I SEPT I

Figure 7. — Mean percentages of pink bollworm infested cotton
bolls in stub and planted cotton in Arizona. (Means of 3
years — 1978, 1979, and 1980.)

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A “ Ranches with boll weevils in squares, bolls and/or traps.
/V - Ranches with boll weevils in traps only.

A (1978-79) Hvalleyala phoenix

B (1980) *valleAyHALA phoenix

Figure 12. — Cottonfield locations showing spread and dis-
tribution of boll weevils found in squares, bolls, and/
or traps in 1978, 1979, 1980, and 1981 in Arizona.

Figure 13. — Mean number of Heliothis spp. eggs per 100 terminals in
stub and planted cotton in Arizona. (Means of 3 years — 1978,
1979, and 1980.)

Figure 14. — Mean number of Heliothis spp. larvae per 100 term-
inals in stub and planted cotton in Arizona. (Means of 3
years — 1978, 1979, and 1980.)

25i

Figure 15. — Mean percentages of Heliothis spp. damaged terminals
in stub and planted cotton in Arizona. (Means of 3 years —
1978, 1979, and 1980.)

Figure 16. — Mean numbers of plant bugs per 100 sweeps in stub
and planted cotton in Arizona. (Means of 3 years — 1978, 1979 ,
and 1980.)

Figure 17. — Mean numbers of cotton leafperf orators per 100 sweeps
in stub and planted cotton in Arizona. (Means of 3 years — 1978,
1979, and 1980.)

Figure 18. — Mean numbers of beneficial predators per 100 sweeps in
stub and planted cotton in Arizona. (Means of 3 years — 1978, 1979,
and 1980). Includes Orius, Geocoris , Nabis , Chrysopa , Reduviidae,
Coccinellidae , Collops , and spiders.)

U. S. DEPARTMENT OF AGRICULTURE

AGRICULTURAL RESEARCH SERVICE
WESTERN REGION
1333 BROADWAY, SUITE 400
OAKLAND, CALIFORNIA 04012

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300

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U. S. DEPARTMENT OF
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