Elliott: Effect of neonicotinoid seed treatments on flea beetle damage and performance of Argentine canola (Brassica napus) in 2003-2006
Date: June 2007
Term: 4 years
Status: Completed
Researcher(s): Bob Elliott, Larry Mann and Owen Olfert, Agriculture and Agri-Food Canada, Saskatoon
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: MCGA, Canola Council of Canada, Syngenta
Project Summary
The objectives of this study were to determine the effect of neonicotinoid seed treatments on flea beetle damage and the performance of Argentine canola seeded in early and late May. Seed treatments reduced flea beetle damage and improved the performance of open-pollinated and hybrid Argentine canola in all tests. Treatments that provided the longest flea beetle protection usually provided the best seedling establishment, highest plant weight and highest yield. Differences among seed treatments were greater when flea beetle infestations were high than when infestations were low.
The crucifer flea beetle, Phyllotreta cruciferae, is a major pest of Argentine canola (Brassica napus) in western Canada. After overwintering, adult beetles migrate into canola fields and feed on emerging seedlings. Feeding injury to the cotyledons, true leaves and stems results in seedling mortality, reduced seedling growth, delayed maturity, reduced grade and lower seed yield. Cultural practices and biological agents provide limited regulation of flea beetle populations, so canola producers depend on seed treatments and foliar-applied insecticides. An insecticidal spray is recommended when flea beetles damage more than 25% of the cotyledon or leaf surface.
The objectives of this study were to determine the effect of neonicotinoid seed treatments on flea beetle damage and the performance of Argentine canola. Field experiments were conducted in 2003-2006 on certified seed lots of an op and hybrid canola. Seeds were treated with Foundation Lite® (fungicides only), Assail 50 SF® (400 g acetamiprid/100 kg seed), Gaucho CS FL® (400 g imidacloprid/100 kg seed), Prosper® (200 g and 400 g clothianidin/100 kg seed), Helix® (200 g thiamethoxam/100 kg seed) and Helix XTra® (400 g thiamethoxam/100 kg seed). Untreated and treated seeds were seeded in early May (May 10-13) when soil temperatures averaged 5-10°C and in late May (May 25-28) when soil temperatures averaged 15-20°C. Experiments focused on the effect of the treatments on stand establishment, shoot growth, biomass accumulation and seed yield. Shoot biomass was calculated from the number of seedlings/m-row and shoot weight.
Yearly comparisons
Flea beetle damage and the performance of canola in early and late May plantings varied depending on the year, variety and seed treatment. Flea beetle damage was higher in 2003 and 2004 than in 2005 and 2006. Shoot dry weights and shoot biomass after 14, 21 and 28 days were 1.4-1.8 times higher in hybrid canola than op canola. Seed yields were, on average, 11-17% higher in hybrid canola than op canola. Interactions indicated that treatment effects were similar in the two canola types from year to year.
Flea beetle damage
Seed treatments had a significant effect on flea beetle damage to op and hybrid canola 14, 18 and 21 days after seeding. In all tests, damage was highest in seedlings grown from untreated seed and seed treated with Foundation Lite®.
In early-seeded plots, flea beetle damage to untreated seedlings after 21 days was higher in 2003 (77-90% damage) than in 2004 (10-12% damage), 2005 (9-13% damage) and 2006 (18-19% damage). Seed treatments containing a neonicotinoid insecticide reduced damage to 26-79% in 2003 and damage to 10% or less in 2004, 2005 and 2006. Over 4 years, Helix XTra® followed by Assail®, Prosper® (400 g rate) and Helix® provided the best protection in op canola, reducing damage to 11-15%. Helix XTra® followed by Helix®, Assail® and Prosper® (400 g rate) provided the best protection in hybrid canola, reducing damage to 11-19%.
In late-seeded plots, flea beetle damage to untreated seedlings after 21 days was higher in 2003 (38-39% damage) and 2004 (43-49% damage) than in 2005 (10-11% damage) or 2006 (13-14% damage). Prosper® (400 g rate), Helix® and Helix XTra® provided the best protection in most tests. Over 4 years, the treatments reduced damage to 4-9% in op canola and 5-10% in hybrid canola.
Stand establishment
Stand establishment in early- and late-seeded plots varied depending on the year and seed treatment. Untreated seed and seed treated with Foundation Lite® had the poorest establishment in each test.
In early-seeded plots, establishment over 4 years averaged 61-64% with untreated seed, 60-61% with Foundation Lite®, 72-73% with Assail®, 75-82% with Gaucho® and 81-83% with Prosper® (200 or 400 g rate), Helix® or Helix XTra®.
In late-seeded plots, establishment over 4 years averaged 79-80% with untreated seed, 80% with Foundation Lite® , 84-85% with Assail® and 87-89% with Gaucho®, Prosper® (200 or 400 g rate), Helix® or Helix XTra®.
Shoot growth
In early-seeded plots, untreated seed and seeds treated with Foundation Lite® had the lowest shoot dry weights after 14, 21 and 28 days. Seeds treated with Prosper® (400 g rate), Helix® or Helix XTra® had the highest shoot weights after 14, 21 and 28 days. Compared to untreated seed, treatments improved shoot weights by 1.4-1.8 times after 28 days. Improvements in shoot growth were generally greater in op canola than in hybrid canola.
In late-seeded plots, untreated seed and seeds treated with Foundation Lite® or Assail® had the lowest shoot dry weight after 14, 21 and 28 days. Seeds treated with Prosper® 200 or 400 g rate), Helix® or Helix XTra® had the highest shoot weights after 28 days. Compared to untreated seed, the treatments improved shoot weight by 1.4-1.5 times in op canola and by 1.1-1.3 times in hybrid canola.
Biomass accumulation
In early-seeded plots, untreated seed and seed treated with Foundation Lite® had the lowest shoot biomass after 14, 21 and 28 days. Seeds treated with Prosper® (400 g rate), Helix® or Helix XTra® had the highest biomass. Compared to untreated seed, the treatments improved shoot biomass by 1.6-1.9 times after 28 days.
In late-seeded plots, seeds treated with Prosper® (400 g rate), Helix® or Helix XTra® had the highest biomass after 14, 21 and 28 days. Compared to untreated seed, the treatments improved shoot biomass by 1.4-1.8 times after 28 days.
Seed yield
Untreated seed had the lowest yield in plots seeded in early May. Compared to untreated seed, yields in op canola over 4 years increased by 6-12% with Gaucho® or Assail®, by 19-22% with a 200 or 400 g rate of Prosper® and by 25-27% with Helix® or Helix XTra®. Compared to untreated seed, yields in hybrid canola over 4 years increased by 12% with Gaucho®, by 17-19% with Assail® or Prosper® (200 or 400 g rate) and by 24-27% with Helix® or Helix XTra®. The treatments improved economic returns in op canola by $14.00-66.50/acre and returns in hybrid canola by $30.86-66.50/acre.
Untreated seed had the lowest yield in plots seeded in late May. Compared to untreated seed, yields in op canola over 4 years increased by 12% with Assail®, by 18-22% with a 200 or 400 g rate of Prosper® and by 22-24% with Gaucho®, Helix® or Helix XTra®. Compared to untreated seed, yields in hybrid canola over 4 years increased by 6-9% with Gaucho®, Assail® or Prosper® and by 12-13% with Helix® or Helix XTra®. The treatments improved economic returns in op canola by $28.70-53.90/acre and returns in hybrid canola by $16.10-37.80/acre.
Flea beetle emergence
Seed treatments had little or no effect on emergence of the next generation of flea beetles in August-October. Emergence varied greatly depending on the year and planting date. Emergence was higher in 2004 than in 2005 and 2006. In each year of testing, emergence was higher from canola seeded in late May than from canola seeded in early May. Seeding in early May rather than in late May reduced emergence of the fall generation of flea beetles by 29% in 2004, by 91% in 2005 and by 70% in 2006.
For information on related studies, go to:
Elliott.CARP2004-14.1. Effect of neonicotinoid seed treatments on flea beetle damage and performance of Polish canola (Brassica rapa) in 2003-2005
Elliott.CARP2004-14.3. Effect of seeding date and seeding rate on flea beetle damage and agronomic performance of open-pollinated and hybrid Argentine canola under different tillage practices in 2001-2006
Elliott.CARP2004-14.4. Effect of seeding rate on flea beetle damage and agronomic performance of sized seeds of open-pollinated and hybrid Argentine canola in 2004-2006
Elliott.CARP2004-14.5. Effect of seed quality on the performance of hybrid Argentine canola in early- and late-seeded plots with conventional and minimum tillage
Elliott.CARP2004-14.6. Effect of production practices and seed quality on the performance of open-pollinated Argentine canola in conventional, minimum and zero tillage