There have been numerous calls of late about Loyant herbicide injuring rice.
A few things we know from working with this herbicide over the past few years:
- Hybrids are most sensitive to injury from Loyant; medium-grain varieties are less sensitive than hybrids; and long-grain varieties are least sensitive.
- Rice that receives excessive rates of Loyant are more prone to show injury – such as doubled-up ends or edges.
- Other herbicides which can cause injury to rice can compound the injury effects of Loyant.
Injury symptoms from Loyant are typically very mild if observable at all soon after the flood is established. However, 14-21 days after application and flooding, injury symptoms can begin to show up.
In many cases this is primarily associated with more erect, upright plant structure (Fig. 1) with some “onion-rolling” of leaves and “buggy-whipping” where the leaves catch at the collar rather than releasing (Fig. 2, 3). In some more extreme cases we’ve observed this year, we’re seeing bunched nodes inside the stem (Fig. 4, 5, 6) and occasionally they begin to blow out of the side of the boot (Fig. 7, 8).
If injury is relatively mild it may be best to reduce the flood level to help the rice overcome the stressful conditions. Under situations with severe injury, it may be best to completely remove the flood. Loyant is most active under flooded conditions, so allowing some drying of the soil may be necessary to help rice overcome situations with severe injury.
It should be noted that not all injury observed may be due to strictly Loyant, but the combination of Loyant activity and other herbicides – we have observed a great deal of herbicide injury this year in the absence of Loyant and some of these combinations may simply be too much for rice in an extremely hot year with rapid rice growth.
Drying fields is not an easy call at this time with hot, dry conditions and considerations should be made for time to re-flood and rice growth stage. We need to avoid drought stress conditions to reproductive stage rice to ensure that we do not reduce yields by causing drought stress at this time, particularly at 1/2” internode elongation.
Call us if you have additional questions.