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JAN 2 6 1998

University of Florida



COMPARISON OF FOUR NEMATICIDES

TO MANAGE THE JAVANESE ROOT-KNOT NEMATODE

IN FLORIDA FLUE-CURED TOBACCO, 1997*







NFREC Research Report 97: 8


Jimmy R. Rich
University of Florida
Rt. 3, Box 4370
Quincy, FL 32351
850-875-7130


Elmo B. Whitty
University of Florida
304 Newell Hall
Gainesville, FL 32611
352-392-1817


*The authors thank Mr. Phil Crumpacker of Hendrix and Dail for assistance with this test.


Marston Science
L brar,









TOBACCO NEMATICIDE TEST 1997


The trial reported herein was conducted to determine the efficacy of four nematicides

to manage the Javanese root-knot nematode in Florida flue-cured tobacco.



MATERIALS AND METHODS



A field trial was conducted on a 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 it was previously planted to tobacco in

1996. Soil was prepared in early March by moldboard plowing and double-discing. Fumigant

treatments of Telone II, Telone C-35 and Chlor-O-Pic were applied on 12 March 1997 by

chisel injection to 10" deep. The broadcast and in the row applications were made with two

outlets, 6" apart on each chisel shank Inrow fumigant treatments were bedded immediately

after treatment while the broadcast Chlor-O-Pic treatment was cultipacked. The Nemacur 3

and DiTera ES treatments were applied broadcast on 31 March. Applications were made

manually in 56 gallons of water/A using a CO2 sprayer containing Teejet 8006 flat fan nozzles.

Immediately after application, materials were incorporated twice to 3-5" deep with a S-tined

rotavator and all plots were bedded or rebedded. Tobacco cv. Coker 371-Gold was

transplanted on 2 April and placed 18" apart in 48" wide rows. Plots were two rows x 20' long,

and treatments were placed in a randomized complete block design with five replications.

Tobacco was grown according to standard cultural practices and irrigated as required.

Early season observations were made to detect any phytotoxicity, and tobacco was









harvested four times, cured and weighed. Final tobacco harvest was on 28 July and root

galling was rated on 13 August. Four plants in each plot were rated for root galling on a 0-10

scale where 0 = no root galling and 10 = 100% of the root system galled.



RESULTS AND DISCUSSION



Early season phytotoxicity was not observed in any of the chemical treatments. The

Telone H, Telone C-35 and Chlor-O-Pic treatments at 6.0 gallons/A produced tobacco yield

significantly higher than the control. Yield of the other treatments did not differ significantly

from the control. Root-gall index ratings closely followed cured tobacco yield with lowest

galling in the Telone H treatment and the highest in the control plots. Only the Nemacur

treatment did not significantly reduce root-galling compared to the control.

Initial populations of the Javanese root-knot nematode were high in this test and

averaged 56/100 cm3 soil. As a result and toward season's end, many plots exhibited wilting

and premature chlorosis. As evidenced from root galling in this test, nematode populations

were higher than generally encountered in grower fields. Nemacur, for example, has

performed satisfactorily in grower fields and research station trials. In this case, however, the

chemical did not perform well. Similarly, the Chlor-O-Pic (3.0 gallons in the row or the 7.3

gallons broadcast) and DiTera performed marginally.

In the present test and two previous ones, Chlor-O-Pic did not show comparable root

galling reduction to Telone H at the 6 gallons/A standard recommended rate. However,

Chloropicrin at the 6 gallon or higher rates produced yields similar to those of Telone. These

observations indicate less nematicidal effectiveness of chloropicrin, less movement or both









compared to Telone I. High yields in spite of less nematicidal effectiveness indicate that

chloropicrin may reduce secondary microbial activity in soil thus slowing decline (rotting) of

heavily galled roots and helping to maintain tobacco yields.







Table 1. Cured weight and root galling of tobacco treated with four nematicides in a field infested with the Javanese root-knot nematode, 1997.



Application Rate in Yield in Galling
Treatment method1'2 gals./A lbs./A index3


Telone I IIR 6.0 2588 a4 2.30 a

Telone C-35 IIR 6.0 2457 ab 2.50 ab

Chlor-O-Pic IIR 6.0 2452 ab 4.35 bc

Chlor-O-Pic IIR 3.0 2169 abc 4.65 c

Chlor-O-Pic BI 7.3 2145 abc 4.85 c

DiTera ES BCI 24.0 1991 bc 5.45 c

Nemacur 3 BCI 2.2 1913 c 5.95 cd

Control -- -- 1862 c 7.45 d


'injected inrow with a single chisel to 10" deep (IR); broadcast injected (BI) to 10" deep; and broadcast incorporated (BCI) to 3-5" deep.

2Chlor-O-Pic and Telone II applications were made at 6" width increments in the broadcast application and also 6" apart with single in the

row chisel application.

3Root-galling was rated after final harvest on a 0-10 scale with 0 = no galling and 10 = 100% of the root system galled.

4Column means followed by the same letter are not significantly different (P < 0.05) according to Duncan's Multiple Range test.