Purpose and Objective:
     The crucifer flea beetle, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae), is the most destructive insect pest on canola, and is common in North Dakota where canola is grown. Canola is grown on approximately 1.3 million acres in North Dakota, and this represents 86% of the total canola acres grown in the U.S. (1.5 million acres). The efficacy of an insecticide seed treatment alone was compared to one and two application of a foliar insecticide, and to an insecticide seed treatment plus one application of a foliar insecticide.

Material and Methods:
     Brassica napus cv. RaideRR (openpollinated) was seeded on May 4, 2001 at Minot and May 9, 2001 at Langdon and Carrington. Seeding rate was 8 lbs of live seed per acre at Minot and Carrington, and 5 lbs. at Langdon. Treatments were arranged in a randomized complete block design with six replicates per treatment at Minot, and four replicates per treatment at Langdon and Carrington. Experimental units were 3.5 ft. (7 rows) x 20 ft at Minot and Langdon, and 4.1 ft. (7 rows) x 22 ft. at Carrington. Two commercial seed treatments, Helix (Syngenta) and Gaucho (Gustafson), were evaluated at their low and high rates that are commercially available. The 11 treatments included:
          1) Untreated check
          2) Capture applied once
          3) Capture applied twice
          4) Helix (200 g ai) seed treatment
          5) Helix (200 g ai) seed treatment plus Capture applied once
          6) Gaucho (400 g ai) seed treatment
          7) Gaucho (400 g ai) seed treatment plus Capture applied once
          8) Helix Xtra (400 g ai) seed treatment
          9) Helix Xtra (400 g ai) seed treatment plus Capture applied once
        10) Gaucho Platinum (800 g ai) seed treatment
        11) Gaucho Platinum (800 g ai) seed treatment plus Capture applied once

     The foliar insecticide, Capture (FMC) was applied at the low rate of 1.3 fl. oz/A at 14 days after planting for the "Capture once" treatment. The "Capture twice" treatment included a second application at the same rate at 21 days after plantings. Each seed treatment was sown alone and with one application of Capture (1.3 fl oz/A) applied at 21 days after planting. Spray applications were applied using a CO₂ back pack sprayer. The application rate was 10 GPA using 40 PSI and TJ 8001 nozzles (5 nozzles total).
     Canola plots were swathed on August 2, 2001 and combined on August 9, 2001 at Minot, swathed on August 27, 2001 and combined on September 4, 2001 at Langdon, and swathed on August 6, 2001 and combined on August 16, 2001 at Carrington.

Results and Discussion:
Flea Beetle Population Dynamics & Damage Assessments: (Table 1)
     During 2001, the crucifer flea beetle (FB) activity started late, close to late May, which was later than the year 2000. The average trap catch was 515 beetles per trap week in Langdon, 274 per trap week in Minot, and 192 per trap week in Carrington. There were two major peaks with the major activity in late May, and again in late June.

     At Carrington, the flea beetle pressure was lower than Minot and Langdon. As a result, all of the insecticide treatments, except Gaucho, significantly reduced the damage rating compared to the untreated check regardless application method (foliar, seed treatment, or seed treatment plus foliar) or rate. Minot had the next highest flea beetle pressure - moderate. All of the insecticide treatments had significantly lower damage ratings, except Gaucho and Gaucho Platinum, than the untreated check. The best treatments with a damage rating of <3 included (in descending order): Helix Xtra + Capture, Capture twice, Helix + Capture, Gaucho Platinum + Capture, and Gaucho + Capture. At Langdon, the flea beetle pressures were the highest, and beetles moved into the plots at a younger plant growth stage than Minot. As a result, the seedlings were exposed to flea beetle pressure longer and the damage ratings are generally higher. All insecticide treatments, except Gaucho, Gaucho + Capture, Gaucho Platinum, Gaucho Platinum + Capture, had significantly lower damage ratings than the untreated check.

Harvest - Yield Data: (Table 1)
     For yield (Table 1), Carrington had the smallest differences in yield with 2436 lb/A (untreated check) for the lowest, and 2824 lb/A (Capture twice) for the highest. Minot had significant differences in yield between treatments. The following treatments had significantly higher yields than the untreated check listed in descending order: Helix + Capture, Gaucho Platinum + Capture, Helix Xtra, Helix Xtra + Capture, Helix, Gaucho + Capture, and Capture twice. At Langdon, the top treatments with significantly higher yields included: Helix Xtra + Capture, Helix, Helix + Capture, Helix Xtra, Capture twice, Gaucho + Capture, and Capture once. These data from Carrington, Minot, and Langdon indicate that where flea beetle pressure was heavy, a Capture application over the seed treatments at day 21 after planting or Capture applied twice at day 14 and 21 after planting improved flea beetle control and yield

NDSU Department of Entomology

• NDSU Insect Updates of ND

• Orthoptera of Northern Great Plains

• Flea Beetles of North Dakota

• Moths of North Dakota