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Rates and contents of fungicides for major rice diseases
Author: Yeshi Wamishe, Extension Rice Plant Pathologist

Although most of the rice in Arkansas was planted late in the spring of 2015, the weather currently appears to help the rice grow faster than a few weeks back. Favorable weather for the rice often means encouraging the growth and multiplication of rice pathogens that have been creeping around the crop. Varietal resistance is the best disease control measure. However, it is not always available to all diseases. Cultural management strategies are beneficial to reduce some rice diseases as long as the crop yield is not compromised. However, yield may be affected. For instance, cutting down nitrogen fertilizer reduce disease pressure at the same time affecting yield when applied below the recommended rate. As a result, use of fungicides to reduce disease pressure has become inevitable in our rice production system.

Pointers to Benefit the Most from Fungicide Application

  • »Fungicides applied at recommended timing and rate work best and maximize their benefit.
  • »Well managed fields benefit better from fungicide application.
  • »Fungicides mixed in adequate volume of water provide better coverage, particularly to fungicides applied on foliage.
  • »If tank mixing is required, check for the compatibility of the chemistries.
  • »To target more than one disease that require protective products, combination fungicides (Triazole + Strobi) work better (for instance, kernel smut, false smut and neck blast)
  • »To reduce resistance to fungicides, rotate chemistries with different modes of action.
  • »To cut expenses and also reduce resistance to fungicides, avoid automatic application. Apply fungicides when and where needed (scouting, previous knowledge of field history and variety resistance help to make the right decision).
  • »To reduce fungicide cost, products with different modes of action can be tank mixed by adjusting rates as required.
  • »To get maximum performance from fungicides, higher rates are usually preferred.
  • »Scouting for sheath blight in particular can help determine fungicide rate, timing and necessity.
    • »On assessment of the research from Dr. Rick Cartwright the following information have been extracted. Stratego at 16 oz provided 14-17 days control, whereas the 19 oz for 21-24 days. Quadris at 6.4 oz provided 10-14 days control while 9 oz for about 21 days. But the full rate 12.5 oz provided 28 days of control. Moreover, his research indicated, Azoxystrobin (Quadris) to be somewhat more effective on sheath blight than Trifloxystrobin (GEM)–but the difference was just slight.
  • »To suppress minor leaf and sheath diseases fungicide application may not be warranted. Broad spectrum fungicides such as strobulurin will provide adequate control if applied for major diseases such as sheath blight and blast and should be useful for minor diseases as well.






























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