EVALUATION OF CHLORFENPYR FOR DBM CONTROL ON HEAD CABBAGE, 1996:

R. F. L. Mau and L. R. Gusukuma-Minuto
University of Hawaii
Dept. of Entomology
3050 Maile Way, Rm. 310
Honolulu, HI 96822
Phone: (808) 956-7063
 
R. S. Shimabuku
Cooperative Extension Service
310 Kaahumanu Ave., Bldg. 214
Kahului, HI 96732
 
D. R. Colbert
American Cyanamid
2133 Jackson Street
Lodi, CA 95240

 

HEAD CABBAGE: Brassica oleracea L. ‘Tastie’

Diamondback moth (DBM); Plutella xylostella (L.)

The insecticides were evaluated at the Kula Research Station, Maui Agricultural Park, from April to May. The field was set up in a randomized block design with eight treatments and four replications (blocks). Treatments were applied using a CO2 backpack sprayer set at 60 psi with an output of 100 GPA. One hollow cone nozzle (TX-26) was used per row. The first treatment was applied one week after transplanting into the field on 9 Apr. Subsequently, six applications were made weekly until the week before harvest on the following dates: 16, 23, 30 Apr, 7, 14, 21 May. The treated check treatment consisted of Bacillus thuringiensis aizawai (BTA) or Proclaim applied using the University of Hawaii DBM resistance management protocol. BTA products are used prior to the cupping stage of growth. Proclaim 0.15 EC @ 6.0 oz./A is applied if DBM densities exceed 1.0 larva per plant. Proclaim is used after cupping if DBM densities exceed 0.5 larva/plant and 1-2 applications are made during the two weeks prior to harvest if DBM is present. Larval thresholds were determined by making larval counts on 10 plants/treatment replication. Mattch @ 2.0 qt./A was the BTA product used and it was applied on 16 and 23 Apr. Proclaim was applied on 30 Apr, 7 and 14 May.

A pre-treatment census for larvae was made the day before the first field spray application. Subsequent evaluations were conducted on a bi-weekly schedule for a total of five surveys. Ten plants were randomly selected from each treatment plot and carefully examined for larvae. For the pretreatment survey, 22 Apr and 20 May surveys, plants were assessed for larvae in the field. Plants were removed for the 6 May survey and at harvest. Marketability assessments were made at harvest.

Alert was effective against field DBM populations that has been shown to be resistant to nearly all registered insecticides. Both formulations of Alert provided good to excellent control of DBM at all rates based on larval census and marketable yield results. Performance even exceeded that of the treated check. Although treatment with Alert produced good marketable yields at the 0.05 lb. ai rate, treatment rates of 0.075 lb. ai/A or greater should be used when moderate to high DBM densities occur.

 

                                                        _________________Mean number of DBM/10 plants_______________  
                                                       

Pre-treatment
_____(8 Apr)_____

     

6 DAT 2
____(22 Apr)_____

     

6 DAT 4
_____(6 May)______

Treatment     Rate/Acre     Larvae   Pupae       Larvae   Pupae       Larvae   Pupae
Alert 2 SC     0.05 lb. (AI)     0.00+0.00a   0       0.58+0.13ab   0       1.03+0.32ab   0.18+0.07a
Alert 2 SC     0.075 lb. (AI)     0.00+0.00a   0       0.35+0.11bc   0       0.33+0.11bc   0.03+0.03a
Alert 2 SC     0.12 lb. (AI)     0.00+0.00a   0       0.08+0.04c   0       0.20+0.07c   0.08+0.04a
Alert 50 WDG     0.05 lb. (AI)     0.00+0.00a   0       0.65+0.15ab   0       0.43+0.11bc   0.15+0.06a
Alert 50 WDG     0.075 lb. (AI)     0.03+0.03a   0       0.18+0.07bc   0       0.23+0.08c   0.13+0.06a
Alert 50 WDG     0.12 lb. (AI)     0.03+0.03a   0       0.00+0.00c   0       0.05+0.03c   0.10+0.05a
Treated Check     ---     0.03+0.03a   0       0.35+0.12bc   0       0.20+0.08c   0.05+0.03a
Untreated check     ---     0.00+0.00a   0       0.95+0.20a   0       1.38+0.30a   0.20+0.03a

Means in each column followed by a different letter are significantly different (Tukey's studentized range test P<0.001 SAS for Windows, version 6.11). Data was transformed by square root (X+0.5) prior to analysis. Untransformed means are presented.

 

 

 

                                                        ______________________Mean number of DBM/10 plants____________________
                                                       

6 DAT 6
______(20 May)_____

       

Harvest
______(28 May)______

         

Seasonal
_______mean no.______

Treatment     Rate/Acre     Larvae   Pupae       Larvae   Pupae       Larvae   Pupae
Alert 2 SC     0.05 lb. (AI)     0.03+0.03a   0.00+0.00a       0.08+0.08b   0.08+0.08ab       0.34+0.08b   0.05+0.02ab
Alert 2 SC     0.075 lb. (AI)     0.08+0.04a   0.00+0.00a       0.03+0.03b   0.08+0.06ab       0.16+0.03bcd   0.02+0.01b
Alert 2 SC     0.12 lb. (AI)     0.00+0.00a   0.00+0.00a       0.10+0.08b   0.00+0.00b       0.08+0.02d   0.02+0.01b
Alert 50 WDG     0.05 lb. (AI)     0.00+0.00a   0.00+0.00a       0.43+0.40ab   0.28+0.14ab       0.30+0.09bc   0.09+0.03ab
Alert 50 WDG     0.075 lb. (AI)     0.00+0.00a   0.03+0.03a       0.10+0.06b   0.05+0.05b       0.11+0.02cd   0.04+0.02ab
Alert 50 WDG     0.12 lb. (AI)     0.00+0.00a   0.00+0.00a       0.05+0.03b   0.00+0.00b       0.03+0.01d   0.02+0.01b
Treated Check     ---     0.00+0.00a   0.00+0.00a       0.25+0.12ab   0.00+0.00b       0.17+0.04bcd   0.01+0.01b
Untreated check     ---     0.03+0.03a   0.03+0.03a       0.48+0.10a   0.33+0.10a       0.57+0.08a   0.11+0.03a

Means in each column followed by a different letter are significantly different (Tukey's studentized range test P<0.001 SAS for Windows, version 6.11). Data was transformed by square root (X+0.5) prior to analysis. Untransformed means are presented.

 

 

Treatment     Rate/Acre       % Marketable heads
Alert 2 SC     0.05 lb. (AI)       95.0+8.77b
Alert 2 SC     0.075 lb. (AI)       100.0+0.00a
Alert 2 SC     0.12 lb. (AI)       97.5+4.39b
Alert 50 WDG     0.05 lb. (AI)       87.5+4.39d
Alert 50 WDG     0.075 lb. (AI)       100.0+0.00a
Alert 50 WDG     0.12 lb. (AI)       100.0+0.00a
Treated Check     ---       92.5+8.00c
Untreated check     ---       0.0+0.00e

Means in each column followed by a different letter are significantly different (Tukey's studentized range test P<0.0001 SAS for Windows, version 6.08). Percent marketable datum was transformed by arcsin prior to analysis. Untransformed means are presented.

 

 

 

Trade Composition\Common name     Formulation         name     Source
Alert     LV         chlorfenpyr     American
Cyanamid
                       
Alert     WDG         chlorfenpyr     American
Cyanamid
                       
Mattch     ME         B. thuringiensis     Mycogen
                       
Proclaim     WDG         emamectin benzoate     Merck