Weedy Rice Scouting and Reporting 2022

It is getting close to the time we need to scout for weedy rice. Our team will be scouting known infested fields that are planted to rice this year. Troy Clark, our Rice Junior Specialist, will be starting in the next few weeks, and will be reaching out to growers and PCA's. Like always, the more eyes on the ground we have, the better! So we are asking for everyone to please scout their own fields to look for suspicious plants.

For timing of scouting, the best time to start, is if you have applied all herbicides to control grasses, and you are still seeing what appear to be skips or misses in grass control. At that point, it is a good idea to go out and check the plants. If they do not have a ligule and auricle, then they are a grass species (not weedy rice) (Figure 1). If they have a ligule and auricle, then they are either rice, or sprangletop.

Figure 1. Ligule and auricle on a rice plant. Watergrass species do not have ligules and auricles.

Follow this key to help make the determination:

1. Does the plant have a ligule or auricle?
   1. If yes, does it have a white midvein down the leaf? (Figure 2)
      1. If yes → Sprangletop
      2. If no → Rice
   2. If no → Watergrass
2. If plant is rice (ligule and auricle), is it weedy?
3. Are the leaves smooth? (not rough)
   1. If yes → likely a variety
   2. If no → potentially weedy rice (call Farm Advisor to double-check)

Figure 2. White midvein on sprangletop leaf.

So far this season, we have had just a couple of calls about weedy rice (likely related to the reduced overall acreage), and thus far, all have been varietal contaminants. Thank you to everyone that has had us out to the field to check plants. The more vigilant we all are, the better we can tackle this weed.

Original source: Rice Notes newsletter :: July, 2022