Group Title: Research Report (North Florida Research and Education Center (Quincy, Fla.))
Title: Rates of ditera es for management of the javanese root-knot nematode in flue-cured tobacco
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Permanent Link: http://ufdc.ufl.edu/UF00066141/00001
 Material Information
Title: Rates of ditera es for management of the javanese root-knot nematode in flue-cured tobacco
Series Title: Research Report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 5 leaves : ; 28 cm.
Language: English
Creator: Rich, J. R ( Jimmy Ray ), 1950-
Whitty, E. B
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Research and Education Center
Place of Publication: Quincy Fla
Publication Date: 1997
 Subjects
Subject: Nematocides   ( lcsh )
Tobacco -- Effect of pesticides on   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Jimmy R. Rich, Elmo B. Whitty.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00066141
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71196079

Full Text
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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

treatments.

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.





























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