Special Report, 2009 University of Minnesota, Small Grains Research Initiative Update

2008 Red River Valley On-Farm Disease Management Trials

Varieties responded well to this year’s growing environment, producing excellent yields of high quality grain. A grouped analysis of varieties by FHB-resistance level (susceptible, moderately susceptible, moderately resistant) from the last two years (2007-08) indicates that scheduled growth stage applications of one or more fungicides during low disease years did not significantly increase yield, quality, or net return of varieties in any FHB-resistance level.

During 2008, data were collected from two on-farm locations located near Fisher and St. Hilaire, MN. Both sites represented a collaborative research effort with Ross Seed Co. Small, replicated plots of spring wheat were planted into fields with soybean residue. Fifteen wheat varieties were tested for their responses to six fungicide treatments while an additional 15 varieties/germplasm lines were exposed to two fungicide treatments. Yield and quality responses were determined. Economic analyses for each variety/entry were calculated from representative grain sub-samples that were based on test weight and protein data. For reporting purposes, fictitious grain sales were made based on harvest results to determine the estimated revenue generated from each variety and disease management treatment combination. The sales occurred on 2 October 2008. Deoxynivalenol (DON or vom) levels were either non-detectable (less than 0.05 ppm) or below the 2.0 ppm target threshold so toxin discounts did not apply.

Disease Summary

Tan spot was not a production issue during 2008, and leaf rust established later than normal, causing little if any trouble. However, epidemics of bacterial stripe and black chaff were observed across the Valley. These bacterial diseases were associated with substantial losses at some locations. This comes only three years since our last bacterial stripe epidemic in 2005. Plants showing symptoms of wheat streak mosaic virus, a mite vectored disease, were widespread across the Valley, but incidence was low. Overall prevalence of Fusarium head blight (FHB, scab) was low, but several localized epidemics were reported from the north and central areas of the Valley.

Weather conditions were variable across locations. Scattered thundershowers, rather than large weather systems provided localized precipitation as well as severe wind or tornadoes. The Fisher test site had little precipitation, but plants managed to produce excellent yields in spite of this challenge. The St. Hilaire site had timely and sufficient rains which supported thick, lush plant canopies and incredible yields. This environment promoted powdery mildew development which was moderately severe on Hat Trick, a susceptible variety.

Disease Management Treatments

When averaged over both locations yield responses ranged from Glenn (78.1 bu/A) to Faller (107.8 bu/A), while test weights ranged from 62.7 lb/bu (Samson) to 65.9 lb/bu (Glenn) (Table 2A). Kuntz had the lowest protein (12.7%) while Glenn (14.9%) had the highest. Consequently, Kuntz had the largest protein discount of the varieties tested (-$0.56/bu). Low quality contributed to substantial discounts in several of the experimental germplasm entries tested (Table 2B).

Acknowledgements

This project was funded, in part, by the U.S. Wheat and Barley Scab Initiative, WestBred, and AgriPro. It was supported by Ross Seed Co., Dr. Yanhong Dong, Univ. of Minnesota Mycotoxin Laboratory, BASF, Bayer CropScience, and Syngenta Crop Protection.

This material is based upon work supported by the U.S. Department of Agriculture, under Agreement No. 59-0790-8-070. This is a cooperative project with the U.S. Wheat & Barley Scab Initiative. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.

-- Charla Hollingsworth, Extension plant pathologist, Chris Motteberg, Plant pathology scientist, and Steve Ross, Manager of Ross Seed Co.

Table 2A. Varietal responses to disease management strategies at Fisher and St. Hilaire, MN.

Table 2B. Varietal and experimental germplasm entry responses to two disease management strategies at Fisher and St. Hilaire, MN.

1Fungicide treatment product, rate and timing: None= No fungicide treatment; S= Dividend Extreme, 3 oz/100 lbs as a seed treatment; F= Folicur and Proline 3 fl oz each/A at early flower; L, F= Headline, 3 fl oz/A at the 4-5 leaf stage and tank mix of Folicur and Proline 3 fl oz each/A at early flower; S, F= Dividend Extreme, 3 oz/100 lbs as a seed treatment and tank mix of Folicur and Proline 3 fl oz each/A at early flower; S, L, F= Dividend Extreme, 3 oz/100 lbs as a seed treatment followed by Headline, 3 fl oz/A at the 4-5 leaf stage and tank mix of Folicur and Proline 3 fl oz each/A at early flower. NOTE: Both the Headline treatment and Folicur + Proline (tank-mixed) treatment included 0.125% Induce, a nonionic surfactant.2On 2 Oct. 2008, analysis started with a cash price of $6.66/bu. Protein premiums based up $0.00 per 1/5. Protein discounts based down $0.08 per 1/5. Protein adjustments were averaged across two experiment locations each having four replications.3Fungicide costs based on Dividend Extreme at $133/gal, Headline at $270/gal, Folicur at $53/gal after rebate, Proline at $468/gal and early flower application cost of $5/A. Fungicide costs translate to Dividend Extreme $3.43/A; Headline $6.32/A; Folicur + Proline $12.23/A. No additional cost for application was added for seed treatment as it was treated at time of drill filling and the 4-5 leaf application would be made in combination with herbicide application.