PROJECT RESULTS

Management of Fusarium Head Blight and Leaf Spot Diseases of Barley with Foliar Fungicide Applications

Applicant: 

Dr. Gary Platford & Judy Dalebozik
P & D Agro Consulting Inc.
Carman, Manitoba  R0G 0J0  Canada

Table of Contents:

• Background and Objectives
• Procedure and Project Activities
• Results and Discussion
• Conclusions

ARDI Project:

#00-447

Project Status:

Completed March, 2002

Background and Objectives:

This research was initiated through the financial support of the Agri-Food Research and Development Initiative (ARDI), Bayer Inc. and Dow AgroSciences Inc. (formerly Rohm & Haas Canada Inc.). The objectives of this project were to evaluate the efficacy of different fungicides applied as single or as split applications for fusarium head blight and leaf disease under environmental conditions and seeding timings.

In 2001, four trial sites were established with one located at Bayer Farm, one at Manitoba Crop Diversification Centre located at Winkler, one at Manitoba Crop Diversification Centre located at Portage and one located at Agricore Burnside. Adcon weather stations were located at each of the trial sites. Weather data was collected from each site.

Procedure and Project Activities:

Weather Analysis

The levels of fusarium infection were too low to make any meaningful correlations with weather conditions. The conditions that favour FHB development in barley are precipitation of at least 2 mm, 2 to 4 days prior to the heading stage of barley and periods of high relative humidity of at least 90% for at least 10 hours during the heading stage. See barley weather data appendix.

Bayer Farm - Barely Fungicide Efficacy Trial

The barley trial site at Bayer Farm, Portage was a 4 replicate RBCD fungicide efficacy evaluation. The seeding date was May 14 and the variety was Robust. Fertilizer was applied at a recommended rate of 27-27--20 on May 14, 2001, and herbicide applications on June 20, 2001, were Puma Super at 268ml/ac and Buctril M at 400ml/acre. Fertilizer and herbicide applications were consistent for all treatments.

The fungicides used in this study were Folicur, Stratego (used for research purposes only) and an untreated control. Fungicide applications were applied on June 29 Timing A and July 10 Timing B. Leaf disease was absent in both treated and untreated control plots on June 29. Leaf disease assessments were recorded on July 16 and August 8.

Results and Discussion:

Table 1. Results of fungicide efficacy barley trial, Bayer Farm 2001.

Mean averages followed by the same letter are not significantly different at P=0.05.

* A - Flag leaf fully unrolled, ligule just visible up to early boot stage: Flag leaf sheath extending.
  B - 1^st awns visible up to beginning of heading: tip of inflorescence emerged from sheath, 1^st spikelet just visible.

The highest level of leaf disease control was achieved with the treatment of Folicur at flag leaf (Timing A at 145 ml/ha) followed by Folicur at early heading (Timing B at 434 ml/ha). The least effective control was when Folicur was only applied at the flag leaf stage. All treatments reduced leaf disease compared to the untreated control.

The highest yield increases were obtained with the treatments that involved applications of Folicur at flag leaf (Timing A at 145 ml/ha) and Folicur at early heading (Timing B at 434 ml/ha) (Table3). There was only a slight increase when Folicur was applied at the early flowering stage as compared to the flag leaf. Increasing the rate of Folicur applied at early heading by 50 percent resulted in a higher yield. However, this would greatly increase the cost of control. Stratego applied at flag leaf resulted in a higher yield compared to Folicur applied at flag leaf. But the treatments involving Stratego at flag leaf followed by Folicur at early flowering resulted in the same yield when Folicur was applied at the 289 ml rate at early flowering. Stratego at flag leaf was not as good as a half rate of Folicur at flag leaf followed by a one and a half rate of Folicur at early flowering. All treatments showed an increased yield compared to the untreated control.

The purpose of hand harvested untreated control as per protocol was to examine the affect of % fusarium damaged kernels with the 2 different techniques - machine versus hand harvested. All treatments reduced the % FDK when compared to the hand harvested untreated control.

The highest decreases in DON was obtained with the treatments that involved applications of one half rate of Folicur at flag leaf and 1.5 rate of Folicur at early flowering, but the decrease was not appreciably more than that obtained with the normal rate of Folicur applied at early flowering.

Winkler - Barley Fungicide Efficacy Trial

The barley trial site at Manitoba Crop Diversification Centre, Winkler was a 4 replicate RCBD fungicide efficacy evaluation. The seeding date was May 17 and the cultivar was Robust. There was no fertilizer applied at this trial site and herbicide applications on June 22, 2001, were Refine Extra at 8 grams/acre and AgSurf at 0.2%/acre. Fertilizer and herbicide applications were consistent for all treatments.

The fungicides used in this study were Dithane, Folicur, Tilt and an untreated control. Fungicide applications were applied on June19 Timing A, June 26 Timing B, July 7 Timing C, and July 12 Timing D. Leaf disease was absent in both treated and untreated control plots on June 29 and July 7. Leaf disease assessments were recorded on July 18 and August 9.

Table 2. Results of fungicide efficacy barley trial, Winkler 2001.

Mean averages followed by the same letter are not significantly different at P=0.05.

* A - 4 to 6 leaf stage
  B - F-1 or pennuculate leaf
  C - flag leaf out
  D - awns and tip of head slightly emerged

The leaf diseases observed were rust and leaf disease. On July 18, leaf spot disease assessment was conducted to identify and determine incidence and control of disease. The incidence of Net blotch was very low on the flag leaf and the flag-1 leaf with less than one percent infection. On August 9, the second assessment showed a considerable increase of leaf infection. The flag leaf percent infection remaining at approximately six percent and less for all treatments and untreated control. The flag-1 leaf had shown that the two treatments of Dithane and Folicur were better than all other treatments and untreated control. The incidence and severity of rust was absent in all treatments and the untreated control.

The yield analysis indicated that there was a considerable increase with the treatments of Dithane 2.25 kg/ha Timing B; Dithane at 1.1 kg/ha and Dithane at 2.5 kgl/ha Timing A + C; and Dithane 1.1 kg/ha and Folicur at 289 ml/ha Timing A + D over the untreated control. All other treatments were slightly better than the untreated control. Severe lodging in all plots was recorded.

The two treatments of Dithane and Folicur and the Folicur treatment decreased the percentage of fusarium damaged kernels (% FDK) than all other treatments and the untreated control. Reaction to fusarium head blight cannot be accurately assessed solely by differences in percent by weight of fusarium damaged kernels. DON results showed similar results with the Dithane and Folicur treatments and the Folicur treatments with lower levels of DON (ppm).

Portage – Barley Fungicide Efficacy Trial

The barley trial site at Manitoba Crop Diversification Centre, Portage was a 4 replicate RCBD fungicide efficacy evaluation. The seeding date was May 26 and the cultivar was Robust. There were no fertilizer or herbicide applications at this trial site.

The fungicides used in this study were Dithane, Folicur, Tilt and an untreated control. Fungicide applications were applied on June 21 Timing A, June 30 Timing B, July 5 Timing C, and July 9 Timing D. Leaf disease was absent in both treated and untreated control plots on June 30 and July 5. Leaf disease assessment was recorded on August 6.

Table 3. Results of fungicide efficacy barley trial, Portage 2001.