Cereals: Wheat: Septoria Leaf Spot (Septoria tritici)

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

Table of Contents

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

Description

Septoria leaf spot attacks only leaves, whereas Stagonospora glume blotch appears on the leaves and glumes. Initial infections from Septoria leaf spot appear as small, light green-to-yellow spots between the veins of the lower leaves. These spots elongate to form irregular reddish-brown lesions. Embedded in these lesions are small, dark brown-to-black fungal bodies (pycnidia) that can be seen easily with the use of a hand lens.

Septoria leaf spot appears as small, light green-to-yellow spots that elongate to form reddish-brown lesions.

Integrated Pest Management Options

Wet, windy weather and moderate temperatures favour disease development. Destroying volunteer wheat, reducing crop residue and crop rotation also help reduce risk. Use less susceptible varieties.

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

Foliar Treatment

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. Tank-mixing with insecticide is not recommended, as this fungicide could affect insecticide efficacy.

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). Maximum1 application/season. 45 days to harvest for grain and straw. Do not harvestfor forage. When disease pressure from stripe rust and wheat leaf rust is expected to be high, use the higher application rate of 1 L/ha.

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 one 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.

Comments (Days to harvest, label precautions, etc.)
Use lower rate for applications at Zadok's 12-21 growth stage, when crop is in 3rd 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
  • Septoria Leaf Spot Stagonospora (Septoria) Glume Blotch
• Appendix G: Cereal Growth Stages
• Diseases
• Cereals