The Effect of Conventional Versus Zero Tillage with Different Agronomic Practices On Insect Pests of Canola
Date: March 1997
Term: 2 years
Status: Completed
Researchers: Dr. Lloyd Dosdall, Alberta Research Council; Mr. Michael Dolinski, Alberta Agriculture
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: Alberta Canola Producers Commission, Alberta Agriculture Research Institute, Farming for the Future, Alberta Research Council
Project Summary
In central Alberta, infestations of root maggots (Delia spp.) and flea beetles (Phyllotreta spp.) cause substantial economic losses in canola. The objective of this study, conducted in 1995 and 1996, was to evaluate the impact of conventional versus zero tillage systems, used in conjunction with three different row spacings and three seeding rates on infestations of root maggots and flea beetles in canola. The results show that in spite of an increase in root maggot infestations with zero tillage compared with conventional tillage, the yield of canola grown in zero tillage substantially exceeded yield for plants grown with conventional tillage. Several recommendations for canola producers resulted from this research for root maggots and flea beetles.
In central Alberta, infestations of root maggots (Delia spp.) and flea beetles (Phyllotreta spp.) cause substantial economic losses in canola. In recent years, canola producers have been encouraged to adopt minimum or zero tillage systems. However, little research has been conducted on the impact of conventional versus zero tillage systems on populations of insect pests.
The objective of this study, conducted in 1995 and 1996, was to evaluate the impact of conventional versus zero tillage systems, used in conjunction with three different row spacings and three seeding rates, on infestations of root maggots and flea beetles in canola. Polish (Brassica rapa cv. Horizon) and Argentine (B. napus cv. Delta) canola were grown under conventional and zero tillage regimes at two sites in central Alberta, near Vegreville and northwest of Westlock. The study included three different row spacings (10, 20 and 30 cm) and three seeding rates (5.0, 8.7 and 10.0 kg/ha). Infestations of root maggots and flea beetles were assessed at various intervals in the season.
The study showed that root damage from feeding by larval root maggots was greater under zero tillage than under conventional tillage. Plants grown at higher densities (10.0 kg/ha) had less root damage than plants grown at low (5.0 kg/ha) densities. Canola plants grown at wider row spacings (30 cm) had less root damage than plants grown at narrower spacing (10 and 20 cm). Plants of B. rapa were significantly more susceptible to infestations by both root maggots and flea beetles than were plants of B. napus. Although row spacing and seeding rate had no significant effect on flea beetle damage, flea beetles caused significantly greater damage on plots subjected to conventional tillage compared with zero tillage.
In spite of the increase in root maggot infestations with zero tillage than with conventional tillage, the yield of canola grown in zero tillage substantially exceeded yield for plants grown with conventional tillage. The increased soil moisture levels that are characteristic of zero-till systems can help canola compensate for increased maggot feeding pressure.
From this research, several recommendations can be made to canola growers:
Argentine canola (B. napus) is less susceptible to root maggot and flea beetle infestation than is Polish canola (B. rapa). Canola growers in regions of Alberta that are infested annually with high population densities of root maggots and flea beetles should seed B. napus rather than B. rapa, if producers can seed B. napus early enough in the growing season.
Even though canola grown in zero tillage was subjected to increased attack by root maggots than canola grown in conventional tillage, improved yield still occurred with zero-till systems over conventional systems. Zero tillage is therefore an appropriate agronomic practice in areas infested with high populations of root maggots.
Increasing row spacing to 30 cm resulted in comparatively less root maggot damage than narrower row spacings of 10 or 20 cm. Increasing row spacing is an appropriate cultural control practice for root maggots in canola.
Increasing seeding rate to 10 kg/ha rather than 5 kg/ha resulted in decreased root maggot infestations and is therefore an appropriate cultural control practice for root maggots in canola.
Scientific Publications
Dosdall, L.M., L.Z. Florence, P.M. Conway, and N.T. Cowle. 1998. Tillage regime, row spacing, and seeding rate influence infestations of root maggots (Delia spp.) (Diptera: Anthomyiidae) in canola. Canadian Journal of Plant Science 78: 671- 681.
Dosdall, L.M., L.Z. Florence, P.M. Conway, and N.T. Cowle. 1998. Tillage regime, row spacing, and seeding rate influence infestations of root maggots (Delia spp.) (Diptera: Anthomyiidae) in canola. Canadian Journal of Plant Science 78: 671- 681.
Dosdall, L.M. 1999. Integrated management of root maggots (Diptera) in canola. Proceedings of the 10th International GCIRC Rapeseed Congress, Canberra, Australia, 26-29 September, 5 pp.
Dosdall, L.M., M.G. Dolinski, N.T. Cowle, and P.M. Conway. 1999. The effect of tillage regime, row spacing, and seeding rate on feeding damage by flea beetles, Phyllotreta spp. (Coleoptera: Chrysomelidae) in canola in central Alberta, Canada. Crop Protection 18: 217-224.