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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #299768
Title: Quantifying the effects of uniconazole on growth and yield of pyrethrum in Australia

Author
item PETHYBRIDGE, SARAH - Botanical Resources Australia Pty Ltd
item Gent, David - Dave
item HINGSTON, L - University Of Tasmania
item FROST, P - Botanical Resources Australia Pty Ltd

Submitted to: New Zealand Journal of Crop and Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2013
Publication Date: 1/2/2014
Citation: Pethybridge, S.J., Gent, D.H., Hingston, L., Frost, P. 2014. Quantifying the effects of uniconazole on growth and yield of pyrethrum in Australia. New Zealand Journal of Crop and Horticultural Science. 42(1):50-59.

Interpretive Summary: This study describes the potential for use of a plant growth regulator, uniconazole (Sumagic®) for incorporation into pyrethrum production. The effect of factors influencing reliability of response, including field age, product rate and timing, and use with a surfactant were assessed. Application was able to manipulate canopy architecture and height and increase field productivity by decreasing losses from lodging and directly increasing the number of harvestable flowers. This information has formed the basis for a cost-benefit analysis for the adoption of uniconazole into pyrethrum production in Australia. Moreover, the results demonstrate the potential for plant growth regulators to be used beneficially to manipulate the pyrethrum cropping system for enhanced productivity.

Technical Abstract: The efficacy of the plant growth regulator uniconazole (Sumagic®) was evaluated in replicated and field-scale demonstrations trials in each of three years (2009 to 2011) for manipulating pyrethrum canopy architecture and enhancing yield, in commercial fields across northern Tasmania, Australia. Trials examined the efficacy of, and factors influencing, reliability and magnitude of responses, including product rate, application timing, the benefits of adding a non-ionic organosilicone surfactant (Activator®), and combining application with urea. Trials were conducted in fields approaching first and subsequent harvests to test for field age being a significant variable in the cost-effectiveness of application. Results suggested that a rate of 50 g L-1 uniconazole (1 L ha-1 Sumagic®) was the most cost-effective, and that the addition of Activator® was unnecessary. Timing of application was not critical for efficacy and yield enhancements were observed when uniconazole was applied when stem ranged in length from 16 to 36 cm, coinciding with a 30-day period in spring. Physiological responses from uniconazole were significant reductions in the height of stems (approximately 6 cm at flowering), increases in green leaf area, and the number of flowers produced per unit area; physiological responses were independent of field age. The benefits from application of uniconazole to pyrethrum productivity may be a direct function of reduced losses through lodging and/or increases in flower number in plants. Lodging can result in substantial losses of flowers through an increase in the incidence of flower blights and a reduction in numbers recovered by mechanical harvesters. This information has formed the basis for a cost-benefit analysis for the adoption of uniconazole into pyrethrum production in Australia. Moreover, the results demonstrate the potential for plant growth regulators to be used beneficially to manipulate the pyrethrum cropping system for enhanced productivity.