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Weed control & Crop Tolerance to Broadcast Flaming as Impacted by Time of Day

Weed control & Crop Tolerance to Broadcast Flaming as Impacted by Time of Day. Stevan Knezevic et al. University of Nebraska. “ Our Flame Weeding Team ”. Agronomy Department & Haskell Agricultural Lab: Dr. Stevan Knezevic & Dr. Jon Scott (Weed Technologist)

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Weed control & Crop Tolerance to Broadcast Flaming as Impacted by Time of Day

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  1. Weed control & Crop Tolerance to Broadcast Flaming as Impacted by Time of Day Stevan Knezevic et al. University of Nebraska

  2. “Our Flame Weeding Team” • Agronomy Department & Haskell Agricultural Lab: • Dr. Stevan Knezevic & Dr. Jon Scott (Weed Technologist) • Santiago Ulloa (PhD student) & Dr. Avishek Datta (Post Doc) • Heverton Teixiere, Andray Domingous, Claudio Costa, Jaymo Nato, Sidnei (Brazil) • Pierre Marteau (France), Robert Leskovsek (Slovenia), • Dr. Goran Malidza, Igor Elezovic, Strahinja Stepanovic (Serbia) • Department of Mechanical Engineering: • Dr. George Gogos and Chris Bruening (PhD student), Brian Nelson, (MS) Jared Miller and Dustin Simpson • - Organic producers: Liz Sarno, Mike Ostry, Larry Stanislav, Randy Fendrich, Gerald Humlicek, Paul and Dan Huenefeld , Mark Ramaeker

  3. Introduction • Variability in flaming efficacy has been observed following early or late day flaming applications. • The variation in leaf relative water content (RWC) at various times of day is thought to contribute to this differential response. • Leaf RWC is a ratio of the amount of water in the leaf tissue at sampling compare to when fully turgid.

  4. Objectives • To describe DOSE RESPONSE CURVES for time of day as influenced by propane rates on 4 species • (green foxtail, velvetleaf, soybean and maize). • To select PROPANE dose from the curve to: • - Minimize crop injury • - Maximize weed control

  5. Greenhouse Study: • 4 flaming times: 6AM, 10AM, 2PM and 6PM • 4 propane rates: 0, 30, 60 and 90 kg/ha • 4 species: green foxtail, velvetleaf, soybean and maize • Air Temp, Rel-Hum. light and RWC were recorded at treatment application • RWC was measured @ procedure modified from Barrs and Weatherley (1962) • It is a function of the relative water content (RWC) • - RWC is the ratio of the water volume in a leaf to the maximum water volume of the leaf at full turgor. • - Typically, RWC is high in the AM and lower in PM hours

  6. RWC during day time All plant species presented the lowest RWC around 6 to 9 hours after sunrise

  7. Results: Green foxtail flamed with 90kg/ha (~ 18GPA) Control 6am 10am 2pm 6pm

  8. Velvetleaf flamed with 90kg/ha (~18GPA) Control 6am 10am 2pm 6pm

  9. Plant injury at different rates as influenced by time of day

  10. Conclusions • Flame weeding is more effective if conducted in the afternoon, but crop injury will be higher, regardless of the propane rate. • Practical implications • Flaming could be done around the noon time in order to obtain the maximum weed control with the minimum crop damage. • May not be always possible with large fields

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