Cereals: Wheat: Tan Spot (Pyrenophora tritici-repentis)

Excerpt from Chapter 4, Field Crop Protection Guide, Order this publication

Table of Contents

1. Integrated Pest Management Options
• pyraclostrobin – Headline EC
• azoxystrobin + propiconazole - Quilt
• propiconazole – Tilt 250 E
• propiconazole – Bumper 418 EC
• prothioconazole - Proline
• tebuconazole – Folicur 432 F
• trifloxystrobin + propiconazole – Stratego 250 EC
• mancozeb – Dithane DG, Rainshield NT
2. Related links...

Integrated Pest Management Options

Reduced tillage and cool, cloudy, humid weather promote this disease. This disease survives in crop residues. Avoid planting wheat in conservation tillage fields in which wheat was grown during the preceding 2 years.

See Appendix F , Cereal Growth Stages, on page 91.

pyraclostrobin – Headline EC

Comments (Days to harvest, label precautions, etc.)
Ground and aerial application. Apply only up to flag leaf fully emerged stage (Zadok's 39). Do not apply at boot stage (Zadok's 47) and beyond. Maximum 2 applications/season.

azoxystrobin + propiconazole - Quilt

Comments (Days to harvest, label precautions, etc.)
Ground and aerial application. Apply once between stem elongation (Zadok’s 29–37) and half-head emergence (Zadok’s 49–55). Maximum 1 application/season. 45 days to harvest for grain and straw. Do not harvest for forage. Use higher application rate of 1 L/ha when expecting high disease pressure from stripe rust and wheat leaf rust.

Comments (Days to harvest, label precautions, etc.)
Ground and aerial application. Early application at GS 12–23. Use low rate for early-season disease suppression. Use higher rate for field with high disease pressure history or field conditions favourable for disease development. Later application at first sign of disease (GS 29–37) or before head is half emerged (GS 49–55). Apply only the high rate on any application from GS 29–55. Maximum 2 applications/season. 45 days to harvest.

propiconazole – Bumper 418 EC

Comments (Days to harvest, label precautions, etc.)
Ground and aerial application. Apply at early signs of disease from the beginning of stem elongation (Zadok's 29-37). If conditions favourable to disease continue, apply again, if necessary, before head is half emerged (Zadok's 49-55). 45 days to harvest.

prothioconazole - Proline

Comments (Days to harvest, label precautions, etc.)
Ground application only. Use as a preventative when earliest disease symptoms appear on the leaves and stems. Recommended to be used with the registered non-ionic surfactant, Agral 90 or AgSurf at 0.125% vol/vol. Maximum 2 applications/yr with a minimum 7-day interval between applications. Do not apply within 30 days of harvest.

tebuconazole – Folicur 432 F

Comments (Days to harvest, label precautions, etc.)
Ground and aerial application. Only 1 application/year. Apply only up to flag leaf fully emerged stage (Zadok's 39). Do not apply at boot stage (Zadok's 47) and beyond. Use non-ionic surfactant such as Agral 90 or Agsurf at 0.125% vol/vol. 36 days to harvest.

Before using Folicur for wheat leaf diseases, consider that Folicur can only be applied once per year and has been traditionally used for Fusarium control, where applications are targeted at head emergence.

trifloxystrobin + propiconazole – Stratego 250 EC

Comments (Days to harvest, label precautions, etc.)
Ground and aerial application. Maximum 2 applications/year. Do not apply the second application within 14 days of the first. Apply only up to flag leaf fully emerged stage (Zadok's 39). Do not apply at boot stage (Zadok's 47) and beyond. Can be tank-mixed with Buctril M in wheat. 45 days to harvest.

Comments (Days to harvest, label precautions, etc.)
Use lower rate for applications at Zadok's 12-21 growth stage, when crop is in 3^rd leaf to tillering. Higher rate for applications at Zadok's 59 growth stage when head is fully emerged but prior to flowering. Maximum 2 applications/yr. 40 days to harvest. Do not graze crop or cut for hay.

Related links...

• Agronomy Guide for Field Crops - Publication 811
  • Cereal: Tan Spot
• Appendix G: Cereal Growth Stages
• Diseases
• Cereals