" SERIALS RECORD

  
  
   
    
    
 
   
   
    
    
    
 

amage Assess
f Wireworms in

.‘ arY

opulations of the true wireworm, Aeolus mel-
(Say), were determined with baited traps of
_ m seed. Trap catches were highest 1 or 2
gs after trap establishment. The number of
s orms found in traps was twice the number
nt in one linear row foot. A population level
 Wireworm per linear foot of row usually
ged approximately 10 percent of the planted
 which caused a reduction in plant stand but
.._- grain yield.

everal insecticide seed treatments reduced
Lorm numbers and damaged seed, and some
red in increased plant stands but not yields.
yne appeared to affect seed germination.
ofuran and Dasanit® (O, O-diethyl O-P-
ihylsulfinyl-phenyl) phosphorothioate] ap-
to hold promise as replacement seed treat-
_ for the standard chlorinated hydrocarbon
-:icides.

- uction

   
    
  
    
  
 
   

t e economic importance of false Wireworms
lbrionidae) and true Wireworms (Elateridae)
'ts of sorghum planting seed is not well
. The seriousness of these seed pests has
l asked because of the extreme effectiveness
tain chlorinated hydrocarbon insecticides,
as dieldrin, which have been routinely
d to seed before planting usually by com-
,1 seed companies. Daniels (1955, 1957, 1961,
and 1971) reported that Wireworms were

1- te Professor, The Texas Agricultural Experiment Station
y ment of Entomology).

  
   
 

B-1l67

and Control
rain Sorghum

6

George L. Teetes*

sporadic pests of sorghum in the Texas High
Plains. He also concluded that control was possi-
ble using several organochlorine insecticides
applied as seed or soil treatments or by rotation.

Daniels and Chedester (1975) reported that soil
treatments of thiofanox, Dasanit®, and carbofuran
were more effective in controlling Wireworms in
grain sorghum than disulfoton, aldicarb, phorate,
or a one-to-one combination of disulfoton-Das-
anit®.

The current trend toward banning certain
chlorinated hydrocarbon insecticides for use in
soil pest control has created the need to find re-
placement insecticides in the phosphate or carba-
mate groups. Seed treatments versus in-furrow or
band applications would reduce the amount of tox-
icant and would not require extra farming opera-
tions. There is also a need for a method of assess-
ing the severity of wireworms in the absence of
treated seed and a monitoring tool for determining
the need for the implicaion of control measures.
Therefore, the research reported here was con-
ducted.

Methods and Materials
Baited traps

A modification of a baiting system used in the
corn belt to monitor soil pests of corn was used to
determine Wireworm populations in soil to be
planted to grain sorghum. The traps consisted of
holes that were approximately 5 inches in diame-
ter and 8 inches deep. Three ounces of untreated
sorghum seed were placed in each trap and cov-
ered with moist soil. Wire mounted flags were
used to mark trap locations in the field.

Traps were positioned in the center of 100-foot
long plots, four rows wide and were arranged in a

September 1976

randomized complete block design with four repli-
cations. The test was conducted in a l-acre field at
the Texas Agricultural Experiment Station at Lub-
bock. The field had been planted to grain sorghum
for the preceding 3 years.

Twenty-four traps were established March ll,
1975. At weekly intervals for 3 weeks, eight (2/rep)
of the traps were inspected and wireworms
counted.

On May 9, 1975, the field was planted to a
commercial hetero-yellow endosperm hybrid. To
assess the level of damage to seed and the sub-
sequent effect on stand of untreated seed, 50 feet of
each 100-foot plot was planted to dieldrin treated
sorghum seed. In addition, the number of
wireworms per linear row foot in the seed drill was
determined in the area planted to untreated seed
for subsequent comparison with the number of
wireworms caught in baited traps.

Insecticide Seed Treatments

Several insecticides representing the three
major insecticide classes were applied to sorghum
planting seed to determine both their efficacy in
controlling wireworms and their effect on germina-
tion.

Insecticides, formulation, and rate per 100
pounds of seed are shown in Table 3. Equivalent
amounts of technical ingredient insecticide were
applied to 2-pound lots of sorghum seed. Seeds
were treated March 24, 1975 in a small tumble-turn
slurry machine. Water and Captan® fungicide
were mixed with each insecticide formulation be-
fore application to seed. After treatment, seeds
were stored in paper bags and allowed to dry.

Germination tests were initiated April 12, 1975
using the standard cotton seed germination tech-
nique. One hundred seeds of each treatment were
placed on wetted paper towels and held at 68° F (16
hours) and 86° F (8 hours) during each 24-hour cy-
cle. There were six replications for each seed
treatment. Percent seed germination was recorded
at 7 and 10 days after placement in the incubation
chamber.

Equal amounts of seed treated with each in-
secticide were planted in two separate tests to de-
termine effectiveness for wireworm control.

TABLE 1. COMPARISON OF NUMBERS OF WIREWORMS CAUGHT IN BAITED TRAPS AND WIREWORMS PER LINEAR
AND SUBSEQUENT PLANT POPULATIONS AND YIELD, LUBBOCK,1975 1

  
  
    
  
   
   
 
  
    
   
  
  
   
   
 
 
  
  
   
   
  
  
   
   
  
 

Treatments were arranged in a randomil
plete block design with three replicatio
were four rows, 50 feet long. l?

Five days following planting on May
wireworm damaged seed and wireworm l“
were determined in one linear row foot;
plot. After plant emergence, plant stan

were made at weekly interyals for 4 wee 

At harvest, seed yields were obtain
heads cut from 13.1 row feet of each 
heads were threshed and the seeds w?‘
weighed, and yields (lb/acre) were calcul

Results and Discussion

Baited Traps

Comparison of the number of true w' ,1
Aeolus mellillus (Say), caught in baited tr
wireworms per linear row foot and sub
plant populations and yield are shown in -
The number of wireworms found in baited’,
or 2 weeks after establishment was abo
(2.1 and 2.3, respectively). However, wi
numbers in baited traps after 3 weeks Q
than one-half the number caught 1 or 2 w,
viously. The decrease in number of wirew.
traps after 3 weeks may have been becau
extensive rotting and moulding of sprou
unsprouted seed. "

In several of the baited traps some s - i,
in dry soil, and germination did not takl
Few wireworms were found in these are’
wireworms were found in areas of the tra f
germination had begun or in the moist s0
cent to the seeds. Based on these data, i‘
appear that baited traps should be inspe i‘
ing the first 2 weeks after establishment. 

A comparison of wireworm numbers c l’
baited traps with the population of wirewol
linear row foot showed that the baited trapsj
about twice the number of wireworms as W
sent in one linear foot of row, and that this
tion level was capable of destroying about?
cent of the seed present. This l0 percent w‘
seed was less than the 17 percent reduc;
plant population resulting from planting un
seed. Plant stand counts (mean of four sam
revealed a per acre population of 47,103

WIREWORMS/BAITED

PLANT POP. Yl .3

    

TRAP q

AFTER INDICATED /ACRE LBS:

WEEK WIREWORMS/LINEAR PERCENT DAMAGED AND 1%) AN’

TREATMENT 1 2 3 FT SEED DECREASEl DEC

Dieldrin 47,103 a 3666 *
Untreated 2.1 2.3 1.0 1.0

 

10 39,087 (17) b 3266 '

lMeans followed by the same letter are not significantly different at the 5% level (Duncan's multiple range test).

2

 

lots planted to dieldrin treated seed and 39,087 for
e check. However, the 17 percent reduction in
tand resulted in only an ll percent reduction in
ield and did not constitute a significant differ-

nce. The percent reduction in yield compares

v losely with the percent damaged seed.
The data are not sufficient to establish a dis-

inct correlation between wireworm infestation

evels and stand or yield reductions of sorghum.
5 e baited traps, however, provide a means of de-
yermining pest populations before planting.

‘ secticide Seed Treatments

g The effect on germination of various insec-
'cide seed treatments is shown in Table 2. Percent

IABLE 2. EFFECT OF INSECTICIDE SEED TREATMENT ON
ERMINATION OF SORGHUM PLANTING SEED

PERCENT
GERMINATION
AT INDICATED

oz. Al DAY AFTER

 RATE/100# TREATMENT
EATMENT FORMULATION SEEDS 7 10
11115511151 3#EC 1.5 92.5 93.7
lordane 40% WP 1.5 88.5 90.0
i lordane 8#EC 1.5 92.0 92.6
'rbofuran 75% WP 2.0 90.2 90.5
Tbofuran 75% WP 4.0 87.0 90.3

. m: 6#EC 2.0 86.0 88.3
'. zinon-Lindane 11+16.6% WP 1.5 + 2.3 83.7 84.3
zinon 4#Ec 2.0 91.7 92.2
ldrin 50% WP 1.0 91.3 93.0

_ eck 90.0 92.5

Irmination of sorghum planting seed following

tment with heptachlor, chlordane (8#EC), car-
furan (2 oz AI/ 100 lbs seed), diazion, or dieldrin
as as high or higher than the percent germina-
y of the untreated seed (90.0 and 92.5 percent at
and 10 days, respectively). Chlordane, carbofu-
 (4.0 oz AI/100 lbs seed), and Dasanit® only

slightly reduced seed germination. The greatest
reduction in seed germination resulted from the
application of diazinon-lindane (83.7 and 84.3 pre-
cent at 7 and l0 days, respectively). The effect of
germination was apparently a result of the lindane
because diazinon did not affect germination when
used alone.

Most insecticides applied to the seed before
planting resulted in a reduction in wireworm num-
bers (Table 3). However, the effect of the
wireworms was not reflected in damaged seed
since few damaged seed were found. The small
percentage of damaged seed, except in the check,
may have been a direct result of the reduction in
wireworm numbers, sampling, or as Daniels (1961)
concluded that the insecticides demonstrated re-
pellant action.

Plant stand counts among treatments did not
differ greatly and were significantly reduced only
in plots planted to diazinon-lindane treated or un-
treated seed. The stand reduction in the check was
apparently because of the wireworm damage;
whereas, stand reduction in the diazinon-lindane
plots was apparently because of reduction in ger-
mination (Table 2). Yields did not differ signifi-
cantly among treatments.

In an identically arranged test in another
field, results similar to those described above were
obtained (Table 4). Both wireworm numbers per
linear foot and percent damaged seed were less in
plots planted to insecticide treated seed than in
plots of untreated seed. Plant populations in plots
planted to heptachlor and carbofuran treated seed
were higher than those planted to untreated seed.
Yields from treated plots were not significantly
higher than the untreated plots, and only the
chlordane (40 percent D) treatment resulted in
lower yield.

Based on these preliminary efficacy data, it
would appear that some phosphate or carbamate

' BLE 3. EFFECT OF INSECTICIDE SEED TREATMENTS APPLIED FOR CONTROL OF WIREWORMS IN GRAIN SORGHUM, LUB-

c1<, 1975, TEST 1

PLANT POP.

OZ. AI WIREWORMS/ PERCENT /ACRE YIELD/ACRE

_. RATE/100 LBS LINEAR DAMAGED AND I%) AND I%)
ECTICIDE FORMULATION SEED FT_1 SEED INCREASEZ INCREASE2
 . hlor 3#EC 1.5 0.5 o 48533 (21) bc 3700 (14) a
rdane 40%D 1.5 0.3 3 44633 I15) cd 3333 I4) a
rdane 8#EC 1.5 0.9 7 44200 I14) c 3600 I11) a
' furan 75% WP 2.0 0.5 0 50267 I24) b 3633 I12) a
yfuran 75% WP 4.0 1.0 O 48967 I22) bc 4366 I27) a
nit 6#EC.. 2.0 0.3 O 51133 I25) ab 3300 I5) a
inon+Lindane 11 + 16.6% WP 1.5+2.3 1.3 0 37267 I0) e 3200 I0) a
inon 4#EC 2.0 0.4 O 47233 I19) bcd 2800 I0) a
drIn 50% WP 1.0 1.0 0 55033 I31) a 3900 I18) a
‘ 1.4 16 38133 I—) e 3200 I—) a

 1<

 eworms/baited trap 2.1.

ns followed by the same letter are not significantly different at the 5% level (Duncan's multiple range test).

TABLE 4. EFFECT OF INSECTICIDE SEED TREATMENTS APPLIED FOR CONTROL OF WIREWORMS IN GRAIN SORGHUM}

BOCK, 1975, TEST 2

  

I

a
v

PLANT POP. .
oz. Al WIREWORMS/ PERCENT /ACRE YIELD/f
RATE/100 LBS LINEAR DAMAGED AND (%) AND (~
INSECTICIDE FORMULATION SEED FT1 SEED INCREASE2 INCRE
Heptachlor 3#EC 1.5 0.5 0 54600 (24) ab 4666 (11
Chlordane 40% D 1.5 0.3 0 45500 (9) bc 3566 l0)‘
Chlordane 8#EC 1.5 0.0 0 52433 (21) 55¢ 4066 (otj
Carbofuran 75% WP 2.0 0.3 3 55467 (25) ab 4400 (6)
Carbofuran 75% WP 4.0 0.0 0 61100 (32) a 5100 (1_
Dasanit 6#EC 2.0 0.3 0 49833 (17) bc 4533 (9)
Diazinon+Lindane 11 + 16.6 WP 1.5 +2.3 0.3 0 45067 (8) bc 4466 (7
Diazinon 4#EC 2.0 0.3 3 50267 (17) bc 4100 P.
Dieldrin 50% WP 1.0 0.3 2 48100 (14) bc 4663 (11
Check 0.7 7 41600 (-) c

 
  
  
   
   
 

 

4133 l-i;

1Wireworms/baited trap 1.3.

zMeans followed by the same letter are not significantly different at the 5% level (Duncan's multiple range test).

insecticides applied as seed treatments may pro-
vide effective replacements for the standard
chlorinated hydrocarbon insecticides previously
used as seed protectants against wireworms.
Presently, diazinon and diazinon + lindane are
registered for use on sorghum planting seed as a
planter-box treatment. Carbofuran or Dasanit® are
not registered as a sorghum seed protectant
against wireworms.

In addition, there is some concern about the
phytotoxic effects of carbofuran and Dasanit®
applied directly to seed, even though no effect on
germination was shown in the tests reported here.
The phytotoxic effects may appear if the seed must
be stored for a considerable length of time after
treatment and before planting.

In past years dieldrin has performed effec-
tively as a seed protectant both for soil pests and
for stored grain pests. This quality or dual role
may be lost with the use of phosphorate and car-
bamate insecticide seed treatments.

Acknowledgments

The author appreciates the financial support
of the Texas Grain Sorghum Producers Board and
the assistance of Mr. Curtis Schaefer, Alvin Wade,
and Brad Pate. The cooperation and assistance of
Dr. Earl Minton are also gratefully acknowledged.

KEYWORDS: grain sorghum seed / wireworm, Aeolus
me1Ii1Ius (Say) / insecticides / Texas.

The Texas Agricultural Experiment Station, J. E. Miller, Director, College Station, Texas

2M — 9-76

  
  
  
 
   
   
     
     
  
 
 
   

Literature Cited

Daniels, Norris E. 1955. False wireworm control in sorgy‘
Tex. Agr. Exp. Stn. PR-l793. p.Z. Av
Daniels, Norris E. 1957. False Wireworm control in wheat.)
Agr. Exp. Stn. PH-l978. p.Z. '
Daniels, Norris E. 1961. Protecting young grain sorghum?
soil insects. Tex. Agr. Exp. Stn. PR-2l72. p.13. 
Daniels, Norris E. 1966. Soil insect control and insecticidal
due detection. I. Econ. Entomol. 59:410-413. _A
Daniels, Norris E. 1971. Detection of insecticidal residuf .
control of soil insects. I. Econ. Entomol. 64:175-177. 
Daniels, Norris E. and Louis D. Chedester. 1975. Wireworin
trol in grain sorghum. Tex. Agr. Exp. Stn. PR-3306. p.

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report does not contain recommendations for the use of i‘
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