Evaluation of High Input vs. Low Input Corn (Zea mays L.) Production Systems

Transcription

1 Evaluation of High Input vs. Low Input Corn (Zea mays L.) Production Systems K. Bradley, B. Hibbard, L. Sweets, & W. Bailey University of Missouri

2 Objectives 1. To determine the effects of various one- and two-pass herbicide programs on grass and broadleaf weed control and corn yield. 2. Determine the effects of nearisogenic corn hybrids containing stacked insect protection traits or no insect protection traits on European corn borer and corn rootworm damage and corn yield. 3. Determine the effects of pyraclostrobin application on end-of-season disease incidence and severity and corn yield.

3 Experiments to Evaluate High-input vs. Lowinput Corn Production: Factors Evaluated 1. Near-isogenic Stacked Corn Hybrids RR RR/ECB (Cry 1a protein) RR/ECB/RW (Cry 1a and Cry 3Bb proteins) 2. Herbicide Programs Full rate PRE only (3 qt Lexar) Full rate PRE fb glyphosate (3 qts Lexar fb 22 ozs Rndup) Full rate PRE fb conv trtmt (3 qts Lexar fb 3 ozs Callisto + 1 pt Aatrex) Half rate PRE fb glyphosate (1.5 qt Lexar fb 22 ozs Rndup) Half rate PRE fb conv trtmt (1.5 qt Lexar fb 3 ozs Callisto + 1 pt Aatrex) 1-pass POST for RR corn (3.6 pts Halex + 1 pt Aatrex) 1-pass POST for conv corn (2 ozs Callisto + ¾ oz Stdfst + 1 qt Aatrex) Untreated 3. Fungicide Application Fungicide at Tasseling 6 oz/a) No Fungicide

4 Materials and Methods: 2 trials conducted each year from (+corn rootworm and -corn rootworm) Near-isogenic corn hybrids no-till planted in early- to mid-may at 28,700 seed/a Individual plots arranged in a split-plot design with 4 replications: main plot= corn type (RR, RR/ECB, or RR/ECB/RW) subplot= herbicide strategy All pesticide applications made with a CO 2 - powered backpack sprayer delivering 15 gpa with XR8002 flat fan nozzles

5 Materials and Methods Predominant weeds across trials: Common Cocklebur Common Ragweed Common Waterhemp Morningglory spp. Prickly Sida Barnyardgrass Fall Panicum Giant Foxtail Large Crabgrass Yellow Foxtail Weed density by species was determined in 2, ½ m 2 quadrats within each plot soon after tasseling

6 Results

7 Influence of Herbicide Programs on Total Weed Density at Tasseling across Six Sites, Herbicide Strategy Weed Density at Tasseling Grass Broadleaf Total Weeds Weeds Weeds # / m pass PRE Only 9 bc 8 b 17 b Full rate PRE fb Glyphosate POST 3 ef 4 cd 7 c Full rate PRE fb Conventional POST 6 cde 1 e 7 c Half-rate PRE fb Glyphosate POST 4 def 3 d 7 c Half-rate PRE fb Conventional POST 7 cd 1 e 8 c 1-pass POST Glyphosate w/residual 2 f 4 cd 6 c 1-pass POST Conventional w/residual 11 b 5 c 16 b Untreated 39 a 16 a 55 a a Means followed by the same letter are not different, P<0.05.

8 Influence of Herbicide Programs on Corn Yield across Five Sites in Missouri, Herbicide Strategy 1-pass PRE Only Full rate PRE fb Glyphosate POST Full rate PRE fb Conventional POST Half-rate PRE fb Glyphosate POST Half-rate PRE fb Conventional POST 1-pass POST Glyphosate w/residual 1-pass POST Conventional w/residual Corn Yield --- Bu/A bc 135 ab 132 abc 137 a 128 c 137 a 118 d Untreated 104 e a Means followed by the same letter are not different, P<0.05.

9 Conclusions: Influence of Herbicide Strategies on Weed Control and Yield 1-pass PRE only and the 1-pass conventional POST w/residual herbicide strategies resulted in higher weed densities at tasseling than any of the remaining strategies evaluated Highest corn yields occurred with: Half-rate PRE fb glyphosate POST Full rate PRE fb glyphosate POST Full rate PRE fb conventional POST 1-pass POST glyphosate w/residual

10 Conclusions Weed Management Strategies Across six site-years, similar weed control and corn yield was achieved with a full rate PRE fb POST conventional herbicide program compared to programs containing glyphosate and the RR trait. However, the use of glyphosate and the RR trait resulted in more strategies that provided optimal weed control and corn yield than conventional herbicide strategies and thus allowed more flexibility in the weed management program.

11 Influence of Insect Resistance Traits in Near-Isogenic Corn Hybrids on Tunneling and Tunnel Length Caused by European Corn Borer Across Four Sites, Near-isogenic Corn Hybrid ECB Damage a Tunnel Tunnels Length -- #/plant mm --- RR 0.20 a 5.50 a RR/ECB b 0.05 b 0.29 b RR/ECB/RW c 0.05 b 0.29 b a Means followed by the same letter are not different, P<0.05. b Contains the Cry1A protein for European corn borer control. c Contains both the Cry1a and Cry 3Bb1 proteins for European corn borer and rootworm control.

12 Influence of Insect Resistance Traits on Root Damage Caused by Corn Rootworm Across Three Sites in Missouri, Rootworm Damage a Near-isogenic Corn Hybrid Avg./plant b RR 0.44 b a 0.56 a RR/ECB 0.55 a ab 0.49 a RR/ECB/RW 0.10 c b 0.06 b a Root damage assessed using a linear 0-3 root damage scale. b Means followed by the same letter are not different, P<0.05.

13 Influence of Insect Resistance Traits on Corn Yield Across Five Sites, Near-isogenic Corn Hybrid Corn Yield a Bu/Acre RR 125 b RR/ECB b 130 a RR/ECB/RW c 127 ab a Means followed by the same letter are not different, P<0.05. b Contains the Cry1A protein for European corn borer control. c Contains both the Cry1a and Cry 3Bb1 proteins for European corn borer and rootworm control.

14 Conclusions: Influence of Insect Protection Traits on Insect Injury & Yield ECB injury was significantly reduced with RR/ECB and RR/ECB/RW hybrids compared to RR alone (data not shown) CRW damage was lowest in the RR/ECB/RW hybrid in 2 out of 3 siteyears Across 3 site-years, CRW injury was not sufficient to cause yield reductions in RR/ECB/RW compared to RR or RR/ECB hybrids Ultimately, will producers have any choice in the future when it comes to stacked insect protection events?

15 Influence of Headline Fungicide Application on Gray Leaf Spot and Common Rust Severity 6 Weeks After Application Across Four Sites, Treatments Gray Leaf Common Spot Rust % a Tasseling 0.41 b 0.07 b No Headline 4.05 a 1.57 a a Means followed by the same letter are not different, P<0.05.

16 Influence of Headline Fungicide Application on Corn Yield Across Five Sites, Treatments Tasseling No Headline Corn Yield a Bu/Acre a 124 b a Means followed by the same letter are not different, P<0.05.

17 Influence of Headline Fungicide Application on Relative Chlorophyll Content of Corn Leaves Across Four Sites in Missouri ( ) Corn Leaf Position Treatments Ear Leaf Ear Leaf Chlorophyll (%) a Tasseling 42.5 a 36.0 a No Headline 43.7 a 36.3 a a Means followed by the same letter are not different, P<0.05.

18 Conclusions: Influence of Fungicide Application on Disease Severity & Yield Application of Headline decreased gray leaf spot & common rust severity, but levels in untreated were <5% Across 5 site-years, all herbicide strategies, and hybrids, Headline increased corn yields by 7 Bu/A. At a selling price of $4/Bu, this yield increase would provide a net return of approximately $8.00/A (year-to-year variation in Headline price and corn market value will determine ultimate return to grower).