Fungicide seed treatments are worth it if seedling diseases are present

• By Yeshi Wamishe •

rice seed fungicidal treatments

Fig. 1: This photo shows the efficacy of different seed dressing fungicide treatments against Rhizoctonia solani AG-9 in an experimental field at the Rice Research and Extension Center near Stuttgart, Arkansas.

Field history is a major factor when considering to use fungicide seed treatments. If your field has a history of seed rot and seedling diseases (mostly blight and seedling death), it is highly possible you’re dealing with a seedling disease complex caused by fungi and other microbes, of which Rhizoctonia solani is part of.

Remember grape colaspis damage and cold or herbicide damage can enhance the complexity of seedling diseases.

April 17 we planted seeds of Diamond and Gimini 214 CL, treated/untreated with insecticides or fungicides. We used Rhizoctonia solani AG-9 to inoculate plots. The seeds took 17 days to grow and emerge.

rice seed fungicide treatment results

Fig. 2

Conditions on several days were cold and rainy until emergence and even after until data were collected. Twenty seven days from planting on May 14, we took stand count and seedling height.

Experimental results showed:

1. Considerable differences among the seed treatments showing the importance of R. solani AG-9 in causing severe seed and seedling disease in rice (See Fig.1, Fig. 2, Fig. 3.).

2. In such a severe disease situation, treatments with only insecticide were not good enough.

3. Seedling stand counts appeared to be a better parameter to evaluate differences in efficacy between product mixes.

gemini's response to fungicide seed treatments

Fig. 3

4. The fungicidal product mixes with higher efficacy appeared to last for more than two weeks under repeated rain conditions.

5. Gimini 214 CL appeared to be as susceptible similar to Diamond to R. solani AG-9.

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