| Material Information
||Rates of ditera es for management of the javanese root-knot nematode in flue-cured tobacco
||Research Report (North Florida Research and Education Center (Quincy, Fla.))
||5 leaves : ; 28 cm.
||Rich, J. R ( Jimmy Ray ), 1950-
Whitty, E. B
North Florida Research and Education Center (Quincy, Fla.)
||North Florida Research and Education Center
||Place of Publication:
||Nematocides ( lcsh )
Tobacco -- Effect of pesticides on ( lcsh )
||non-fiction ( marcgt )
||Statement of Responsibility:
||Jimmy R. Rich, Elmo B. Whitty.
| Record Information
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 71196079
RATES OF DITERA ES FOR MANAGEMENT
OF THE JAVANESE ROOT-KNOT NEMATODE
IN FLUE-CURED TOBACCO
NFREC Research Report 97: 5
Jimmy R. Rich
University of Florida
Rt. 3, Box 4730
Quincy, FL. 32351
Elmo B. Whitty
University of Florida
304 Newell Hall
Gainesville, FL. 32611
DiTera Tobacco Nematicide Test- 1996
The trial reported herein was conducted to determine the efficiency of a biorational
nematicide, DiTera ES, from Abbott Laboratories to manage the Javanese root-knot
nematode in flue-cured tobacco.
Materials and Methods
A field trial was conducted on fine sand soil ( 93% sand, 4% clay, 3% silt ) infested with
the Javanese root-knot nematode ( Meloidogyne javanica). The test site was at the University
of Florida Green Acres farm in Alachua County, and tobacco was grown previously in 1995.
Soil was prepared by moldboard plowing and double-discing. The Nemacur 3SC and DiTera
ES treatments were applied preplant and broadcast in 150 gallons of water/A on April 16 and
incorporated 3-5" deep with a S-tined rotavator. Postplant band treatments of DiTera were
applied in 150 gallons of water/A at 30 and 50 days after planting. The 30-day treatments were
applied as a 24" band over the tobacco row. At 50 days, the treatment was applied as a 12"
wide directed band spray to the base of tobacco plants to both sides of the row. Rows were 48"
wide and plots were 2 rows x 20' long. Treatments were placed in a randomized complete
block design with five replications. Tobacco cv. NK 371 was transplanted 18" apart in the row
one day after preplant treatments. Plots were maintained under standard grower conditions
and irrigated as needed.
Tobacco was observed for phytotoxicity and harvested three times over the season,
cured and weighed. At final harvest on July 26, five soil cores ( 1" diam. ) were taken to 12"
deep in each plot and composite. A 100 cm3 soil subsample from individual plots was
processed by a centrifugation-flotation technique and second-stage juveniles counted. Root
galling was rated from four plants in each plot on August 8. Ratings were on a 0 -10 scale
where 0 = 0 root galling and 10 = 100% of the root system galled.
Results and Discussion
No early season phytotoxicity was observed with any treatments. The 30- and 50- day
after transplanting applications of DiTera, however, resulted in phytotoxicity of leaf tissue
directly contacted by the material. Leaves necroses and a general plant stunting resulted in
low yields from these plots. Phytotoxicity on leaves occurred even with 0.25" irrigation applied
within 30 minutes of DiTera applications. With the exception of post-transplant DiTera, all
treatments significantly improved tobacco yield over the control plots. Highest numerical yield
was obtained with the Nemacur standard at 6.0 lbs. a.i. /A. followed by DiTera at 50 lbs. a.i/A
broadcast. Root galling was significantly reduced by all treatments over the control except for
one DiTera (50 lbs. a.i/A) postplant treatment. Higher yielding treatments generally showed
lowest root ratings and similarly, lower nematode numbers were found among these
Initial population densities in this test were very high and averaged 90 second-stage
juveniles per 100 cm3 soil. Normal pretransplant treatment thresholds for the Javanese root-
knot nematode in tobacco can be as low as three to four juveniles. These high populations
resulted in all plots showing various symptoms of nematode damage including premature
wilting and chlorosis in July. High initial nematode populations may have limited effectiveness
of nematicides and rates used in the present test. Nevertheless, yield increases from the best
treatments added over $800/A in gross economic return.
Data from this test indicated slightly greater efficiacy of DiTera as a broadcast and
incorporated treatment compared to a 24" band applications. A possible explanation may
include the nature of lay-by cultivation practices used in this test and by most Florida tobacco
growers. At approximately 7 weeks after transplanting, lay-by cultivation moves soil from
row middles around tobacco stalks to 4-5 high. In the process, untreated soil could have
been moved to the base of tobacco plants in the 24" band DiTera treatments.
In this test, DiTera proved to be nematicidal in nature and approximately the
equivalent in activity to Nemacur application at the 6.0 lbs. a.i/ A. Positive attributes of
DiTera include it's biorational nature and low mammalian toxicity. Possible negatives may
include high use rates (50-100 lbs. Ai/ A) and leaching potential. In particular, leaching of
DiTera may be a problem in the sandy soils of Florida. Targeting use of this product in
heavier soil types or under plastic-mulch systems may be the best approach until further work
is conducted in deep sands.
s a c as
(N ** 9\~ -
- ) '* 0
0o0 0 I
- Nr N -
o V) n =
*^ n r-
l 0 0S
N N "
o N \
N N -
S0 0 0 3
c qe e e
+ A + 5 + +
+ + +
N o o
l m 0 0
z 0 z m
O =I -
Z QQ U e
0N At S 0
00 00Q It I
- l -