Scout for rice growth stage when you scout for rice diseases

• By Yeshi Wamishe •

kernal smut

Kernal smut — photo by Rick Cartwright

Preventative measures including land preparation, variety selection, seed treatment, timing for planting, nutrient and water management are key to suppressing most rice diseases. Implementing best cultural practices typically results in a healthy, flourishing crop. Under ideal growing conditions, the correct timing for management actions may be missed. Scouting for growth stages at the same time when you scout for rice diseases will help you save time and take timely disease management actions including fungicide applications.

When you scout, try to identify the growth stage at which a particular disease appears and determine how soon management actions should be taken. Also determine how far the crop is from harvest and predict the potential yield loss if left unmanaged or managed accordingly.

For instance, the “drain and dry” management decision to reduce hydrogen sulfide toxicity requires scouting and knowledge of growth stage either to completely drain and dry or just lower the water depth to mud or keep water depth shallow consistently.

Although we cannot scout for straighthead, kernel smut and false smut, growth stages are important to know for protective management actions. If a field has a history of these diseases and the variety is susceptible, the correct timing to manage straighthead is before mid-season.

The recommended timing for fungicide application to suppress kernel smut and false smut is between early to mid-boot. The fungicide application decision for these smuts is based on field history, varietal susceptibility and fertility management. Sheath blight and blast require scouting and growth stages are necessary to know to manage them.

Remember, rice benefits the most from fungicides in well managed fields if applied timely using adequate volume of water.

Please see the table below how growth stages are important to crop scouting. The major purpose of disease scouting is to be able to take timely management action.

rice disease scouting calendar

Dr. Yeshi Wamishe is a University of Arkansas Extension rice pathologist. She may be reached at ywamishe@uaex.edu.