Inter-Specific Differences in Weed Susceptibility to Steam Injury

R. G. Leon¹ and D. Ferreira²

Abstract
Thermal weed control methods have been incorporated into weed control programs in organic and conventional production systems. Flaming is commonly used yet steaming has been proposed to increase efficiency of heat transfer to weeds and reduce risk of fire.

The objective of this research was to measure injury to leaves of plant species that differ in leaf morphology and to measure injury to plants at different stages of plant development.

The study was conducted in a glasshouse and plants were exposed to steaming at 400 C during 0.36 s equivalent to a steaming speed of 2 km h^-1. Overall, leaf thickness was the best morphological characteristic to predict injury (r² = 0.51), with greater thickness resulting in less injury.

For broadleaf species only, assessment from visual estimates of injury determined that species with wider leaves were injured more than species with narrower leaves (r² = 0.64). Injury was greatest when plants had fewer than 6 true leaves and when their shoots were less than 10 cm long.

There was a wide range of visual injury across species and the grass species bermudagrass and perennial ryegrass were injured (68 to 81%) more than other species such as common purslane and English daisy (23-34%).

Biomass of all species tested was reduced by approximately 40% indicating that leaf injury was not the sole effect of steaming on plant growth.

These results indicated that considering both visual injury and morphological characteristics is important to properly assess thermal weed control effectiveness.


Source
Weed Technology (2008) 22: 719-723


Author Locations and Affiliations
(1) EARTH University, Crop Protection, San Jose, Costa Rica, E-mail: rleon@earth.ac.cr
(2) California Polytechnic State University, Horticulture and Crop Science, San Luis Obispo, CA, USA


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Posted September 2008