Page 10—Corn Talk, Lancaster Farming, Saturday, February 10, 1996
ROpTWORMS
Del Voight
Lebanon County
Agronomy Agent
Many producers found the
presence of white worms
which invaded com fields and
destroyed roots to the point that
the com goosenecked or was
easily blown over with wind.
This little worm, which
becomes a small beetle, infests
com fields almost exclusively
where com was grown the fol
lowing year.
The adult beetle lays eggs
around the com base in mid
summer. These eggs hatch in
the spring around the time fire
flies are noticeable and begin
feeding on the roots of com.
For this reason, an insecti
cide is recommended in a com
on-com situation. For a com
plete explanation of rootwoims
and their identification, call the
extension office and ask for
Extension Circular 333.
The following information is
from Steve Spangler and Den
nis Calvin’s research sum
mary. They tested 13 insecti
cide treatments for control of
com rootworm at the Rockspr-
ing farm in 1995. The results
are shown in'Table 1,
For your review, they use
the common “Iowa” root rating
system to determine damage to
roots: a rating of 1 is an un
damaged root system, a rating
of 6 is the most severely
damaged (all three nodes are
:hewed completely back), and
ratings of 2 to 5 arc intermedi
ate. Entomologists generally
relieve that economic damage
regins to occur when the root
-ating exceeds 3 to 3.5.
From the root ratings shown
n Table 1, three general group
ings appeared to occur. The
best treatments (lowest root
ratings; 2.6 to 3.2) occurred
with Counter 15G™ T-band,
Fortress 2.5 G™ T-band and in
furrow, all Force™ treatments,
Furadan 4F™ broadcast + culti
vation, and Lorsban 15G™ T
band. Less effective were the
Dyfonate ll™ T-band and Fur
adan 4F™ broadcast treatments
(root ratings of 3.9 to 4.4). All
these treatments were signific
antly better than the untreated
plots (root rating of 5.4). This
was our first side-by-side com
parison of Furadan 4F™ with
the granular materials.
Despite the drought in July
and August, there was ample
moisture during May and June,
which would favor effective
ness of Furadan 4F M . It also
appears that it is important to
cultivate after application of
Furadan 4F™, because the root
rating with cultivation (2.6)
was significantly lower than
without cultivation (3.7). Steve
and Dennis also collected yield
date, but because of the
extreme drought and heavy
eom rootworm pressure during
July and August, they were so
low (11 to 40 bushels/acre) and
rad little correlation to insecti-
Table 1. Assessment of 13 nsecticide formulations for r ootworm control in Centre
Co., PA, during 1995.
Treatment = orm- Application Root Yield
ulation Rate 1 method 2 Rating 3.4 (Bu/A)4
Force , 3G 0.12 T-Band 3.2cde 13.4 a
Force 3G 0.12 In-furrow 2.Bde 14.7 a
Force 1.5 G 0.12 T-Band 2.Bde 19.2 a
Force 1.5 G 0.12 In-furrow 3.ocde 31.9 a
Dyfonate II 15G 1.20 T-Band 4.4 b 14.6 a
Lorsban 15G 1.20 T-Band 3.ocde 18.7 a
Counter 15G 1.20 T-Band 2.7 e 23.9 a
Regent 1.5 G 0.12 T-Band 3.2cde 16.0 a
Regent 1.5 G 0.12 In-furrow 3.9bc 23.1 a
Fortress 2.5 G 0.15 T-Band 2.6 e 18.3 a
Fortress 2.5 G 0.15 In-furrow 3.lcde 13.0 a
Furadan 4F 1.20 BRD/CLT 2.6 e 36.2 a
Furadan 4F 1.20 BRD 3.7bcd 14.1 a
Untreated - 5Aa IOJa
Rates are expressed as oz./1000 ft of row
T-band and In-furrow granular applications were made at planting
(May 16). BRD/CLT = Furadan broadcast on Jun 16, followed
immediately with cultivation; BRD = broadcast with Furadan 4F only
Ratings done with the lowa method (I=no damage, to 6=three nodes or
more missing).
Means followed by the same letter in the same column are not
statistically different
-ide treatment.
There will be two new root
worm insecticides registered
'or the 1996 growing season;
\ztec and Fortress. Axtec is
from Bayer, and is a combina
ion of an organophosphate
'2.0% tebuprimiphos) and a
jyrcthroid (0.1 percent cyflu
iirin). Fortress, from DuPont,
.s an organophosphate (cho
lorethoxyfos), and will be
available in either a 2.SG or SG
formulation. Both these com
pounds will be applied at much
lower rates (2.5 oz active
Save 6% to 24%
on these genuine
KINZE Planter Partsf
as as ait
Mk! DtutiiUn frig frig
Burn SMCmt $765 $5.95
00999 think $14995 $135.16
BA2OIS Ofmrßlu/Atumhli $1995 nut
8A3914 Ofunr luriig $695 $5.95
am Stlfl Whul $4195 $37.95
03131 brtmFMCa $750 $5.95
853153 tU. Dim Font tfrinf $595 $5.35
8A3964 Clullf Whul tfrilf $695 $5.95
SA39U HD Bun fomS frill $695 $7.95
8A3199 tlfhuifuOCtfAliflir $1025 $9.55
8A3119 Sun Whnl Am $995 $5.95
5A3595 Clullf Whul $2695 tx.7o
SAS999 offw9nah,9nahhhlir $695 $5.95
Save from now ’
HTUVT mmiDCr 133 Rolhawilla Station Road _
Bessr®!? u&tiaim bm
SSSflr °« MBB
ingredient/acre for Aztec and
2.6 for Fortress), compared to
Dther granulars (typically 21
3z. active ingredient/acre).
Trials in Pennsylvania and
lowa indicate that these new
compounds compare favorably
with others presently
registered.
When selecting an insecti
cide, refer to your Agronomy
Guide to be sure you control
other pests such as seed com
maggot and garden symphalan.
If you are unsure of what pro
duct to use, please do not hesi
tate to call me. If I am out of
the office, simply leave a mes
sage and I will be in touch with
you.
as as stif
hinhir Butrilllu friu frig
aim Clullf Whnl Am $2195 $17.95
695219 finlhl Am Onillj $045 $9.35
881945 tut tilt $595 $451
881941 tm till Brim Sfnckll $495 $3.95
601045 CmhhlirHmlif $795 $5.59
881973 UnhUlSutßlUl $250 $1.99
SBIOIS Clullf Whul Tin $4 50 $3.95
SBI9U Bun Wail Tin $1695 $15.90
BBm FliftrCirriuw/fmh $2295 $19.95
6110933 flint Whul Aumllt $2295 $39.95
81K312 But Bill Brin Ullt Kll $695 $5.95
613213 Bmul Chun. Brin Wu Alt $695 $5.95
il March 9, 1996!