NDSU

CANOLA:  Brassica napus L., ‘RaideRR’

Insecticide Seed Treatment Efficacy Against Flea Beetles on Canola Trial C, 2003

Crucifer flea beetle: Phyllotreta curiciferae Goeze
Striped flea beetle: Phyllotreta striolata F.

Trials assessing the different insecticide seed treatments were conducted in research plots located in north central North Dakota near Mohall and Bottineau. Brassica napus cv. RaideRR (Integra Seed Ltd., open pollinated) was seeded on 14 May in Mohall and 22 May in Bottineau. The seeding rate was approximately 14-17 pure live seeds per sq. foot. A RCB experimental design with four replicates was used.  Experimental plots were 3.5 ft. (7 rows) x 22 ft. Two seed treatments, Helix (thiamethoxam) from Syngenta Crop Protection, and Prosper (clothianidin) from Gustafson LLC, were evaluated at their low and high rates that are commercially available. To evaluate flea beetle damage, assessments were taken at 21-22 Days After Planting (DAP) using the following rating scheme:  1 = 0-3 pits per seedling; 2 = 4-9 pits per seedling; 3 = 10-15 pits per seedling; 4= 16-25 pits per seedling; 5 = >25 pits per seedling; and 6 = dead. The dry weight of 10 seedlings per plot was also weighed in grams to indicate the overall vigor of the plant. Prior to drying, all roots were removed from the seedling using a razor.  Roundup (1 pt./acre) + AMS was applied for weed control early in the season. Plots were harvested on 13 Aug in Mohall and Bottineau.  Yield (lbs/acre) and test weight were obtained at the end of the season to facilitate comparisons. Variables were subjected to ANOVA and means compared using Fisher’s PLSD at the 5% significance level.

All insecticide seed treatments had significantly lower damage ratings than the untreated check regardless of the location. Helix xtra, Helix lite, and Prosper 400 also had significantly lower damage ratings than Prosper 200 at Mohall.  At Bottineau, there were no significant differences between the insecticide seed treatments, except Helix xtra had significantly lower damage rating than Prosper 200. The treatments ranked in ascending order for damage ratings include:  Helix xtra, Prosper 400, Helix lite, Prosper 200, and the untreated check. For dry weight, all insecticide seed treatments had a significantly higher dry weight than the untreated check, and there were no significant differences between different insecticide seed treatments. For test weight at Mohall only, all insecticide seed treatments had a significantly higher test weight than the untreated check, and there were no significant differences between different insecticide seed treatments. Insecticide seed treatments had a significantly higher yield than the untreated check by 501 lb/acre at Mohall and 385 lb/acre at Bottineau. There were no significant differences between the insecticide seed treatments, except Helix xtra had a significantly higher yield than Prosper 200 at both Mohall and Bottineau. The yield at Bottineau was negatively affected by severe pod feeding prior to harvest.

Table 1.  Mohall.

Means within a column followed by the same letter are not significantly different (ANOVA, Fisher’s PLSD, P<0.05).
^aDAP = Days After Planting
^bDamage Rating: 1= 0-3 pits per seedling, 2= 4-9 pits per seedlings; 3= 10-15 pits per seedling; 4= 16-25 pits per seedling; 5= >25 pits per seedling; and 6= dead seedling.

Table 2. Bottineau

Means within a column followed by the same letter are not significantly different (ANOVA, Fisher’s PLSD, P<0.05).
^aDAP = Days After Planting
^bDamage Rating: 1= 0-3 pits per seedling, 2= 4-9 pits per seedlings; 3= 10-15 pits per seedling; 4= 16-25 pits per seedling; 5= >25 pits per seedling; and 6= dead seedling.
^cLow yields due to severe pod feeding by flea beetles.

Part II. Materials Tested for Arthropod Management

Insecticide Seed Treatment Efficacy Against Flea Beetles on Canola Trial C, 2003