By Yeshi Wamishe, Extension Rice Pathologist
Field history is a major factor when considering using 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 solaniis is prevalent. Remember grape colaspis damage, and cold or herbicide damage can enhance the complexity of seedling diseases.
April 17, 2019, 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. 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, 2019, we took stand count and seedling height.
Experimental results showed:
- 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.).
- In such a severe disease situation, treatments with only insecticide were not good enough.
- Seedling stand counts appeared to be a better parameter to evaluate differences in efficacy between product mixes.
- The fungicidal product mixes with higher efficacy appeared to last for more than two weeks under repeated rain conditions.
- Gimini 214 CL appeared to be as susceptible similar to Diamond to R. solani AG-9.