• Agribusiness & Markets
  • Agribusiness
  • Agricultural Economics
• Animal Health
  • Chemicals
  • Diseases
  • Parasites
• Animal Welfare
  • Department's role in Animal Welfare
  • Reporting Animal Cruelty
  • Useful Links
  • Your Responsibilities
• Crops
  • Barley production in Western Australia
  • Bridging the Yield Gap in higher rainfall environments
  • Canola and Oilseeds
  • Engineering
  • GM Crops
  • Lupins and Pulses
  • Nutrition
  • Oats
  • Speciality Crops
  • Storage
  • Wheat
• Environment & Climate
  • Climate Change
  • Climate weather and crops
  • Land Use Sustainability
  • Rangeland Management
  • Regional Resources and Support
  • Resource Planning and Management
  • Salinity
  • Salinity Case studies
  • Soil Land & Water Regulations
  • Soil and Landscapes
  • Sustainability
  • Vegetation
  • Water
• Farm Systems
  • Drought Reform Pilot 2011-12
  • Organic Farming
  • Seasonal Update
  • Sensitive Sites
  • Small Landholder Information Service (SLIS)
• Food
• Gardens & Households
• Horticulture
  • Engineering
  • Floriculture + Nursery
  • Fruit and Nuts
  • Vegetables
  • Viticulture
• Invasive Species
  • Invertebrate Pests
  • Vertebrate Animal Pests
• Livestock
  • Agribusiness Livestock and Sheep Updates
  • Beef Cattle
  • Dairy Cattle
  • Engineering
  • Fertiliser Action Plan
  • Goats
  • Honey Bees
  • Livestock identification and brands
  • Other Livestock
  • Pork Group
  • Poultry
  • Sheep and Lambs
• Pastures
  • Annual pastures management
  • Annual pastures species
  • Australian Trifolium Genetic Resource Centre
  • Forage crops / Fodder conservation
  • Perennial pastures
  • Saltland pastures
• Plant Health
  • Chemicals
  • Parasites and Nematodes
  • Post-border biosecurity
• Quarantine WA
  • Export requirements
  • Freight and cargo
  • Import requirements
  • Intrastate requirements
• Weeds
  • Declared plants in Western Australia
  • Herbicides
  • Integrated Weed Management
  • Major Weeds
  • Research Projects
  • Weed Publications and Links
  • Weed Watcher

Crop Updates - Rate response to fungicide for cereal leaf diseases

Rate response to fungicide for cereal leaf diseases
R. Loughman and J.S. Bhathal, Plant Pathology, Agriculture Western Australia, South Perth, Plant Pathology, Agriculture Western Australia, Geraldton

SUMMARY

Greater opportunities are being recognised for economic control of wheat leaf disease using single fungicide sprays applied around flag leaf emergence. Registered rates for triazole fungicides such as Folicur®, Impact® or Tilt® are generally in the range 62-125 g ai/ha. Triazole fungicides also exhibit activity at rates lower than 62 g ai/ha. Lower rates may have a role in disease control where disease is not very severe and long duration of control is not required.

BACKGROUND

Triazole fungicides have become more cost effective in the last 5 years. Costs are now around $20-25/ha including application for a standard 62 g ai/ha treatment. Experiments have shown the possibility of providing cost effective disease control at lower rates and cost depending on circumstances of disease pressure and crop yields.

RESULTS

A randomised replicated experiment at Badgingarra in 1997 examined the effect of varying rates of triazole fungicides for control of septoria nodorum blotch. Disease development was low to moderate resulting in an average 10% yield increase with fungicide. Five fungicides (Folicur®, Impact®, Tilt® and two unregistered products) were evaluated at 4 rates of application (38-125 g ai/ha). Folicur® and two unregistered products were marginally more effective at controlling septoria nodorum blotch than Impact® or Tilt® in this experiment. All fungicides were equally effective at increasing yield. All rates of fungicide were equally effective at increasing yield and only the 125 g ai/ha rate showed superior disease control compared to the lower rates (Table 1).

Table 1. Effect of rates of triazole fungicide on grain yield and leaf disease of wheat affected by septoria nodorum blotch, Badgingarra, 1997

In contrast, a randomised replicated experiment at Badgingarra in 1993 developed severe septoria nodorum blotch resulting in a 97% yield increase with high rates of fungicide. Under this severe disease pressure disease control and yield were significantly improved with increasing rates of fungicide (Table 2).

In 1997 the response of disease control to increasing rates of fungicide applied as single sprays varied in 7 fungicide experiments (Figure 1). While there was some apparent increase in yield with higher rates of fungicide at some locations (Figure 2) treatment at 125 g ai/ha did not significantly increase yield at any location compared with lower rates of application.

DISCUSSION

Improved response to increasing rates of fungicide application can sometimes be demonstrated under situations of severe disease pressure but at other times different rates of fungicide have no significantly different effects on yield. A standard treatment of 62 g ai/ha costing around $20-25/ha is moderately effective at controlling disease, improving yield and providing economic returns. For circumstances where disease pressure is lower, such as lower rainfall areas, adequate short duration control may be achieved with lower rates of fungicide.

Previous work examining rates of fungicide and spray volumes indicated that disease control achieved with 31gai/ha could be sub-optimal at spray volumes less than approximately 50 L/ha.

Table 2. Effect of rates of Tilt® 250 fungicide on grain yield of wheat affected by septoria nodorum blotch, Badgingarra, 1993

Figure 1. Response of disease to increasing rates of fungicide applied as single sprays in seven fungicide experiments

Figure 2. Response of yield to increasing rates of fungicide applied as single sprays in seven fungicide experiments.

ACKNOWLEDGEMENTS

This research was supported by GRDC. The trials were managed by plant pathology staff in conjunction with Badgingarra, Geraldton and Wongan Hills Research Support Units of Agriculture Western Australia. The cooperation of various property owners is acknowledged.

Return to Crop Updates 1998 Weeds Index Page