- Author: Luis Espino
There are a couple of interesting issues I have noticed while looking at fields, mostly in the northern part of the valley. One is bakanae. Bakanae is a seed borne disease that is managed by soaking the seed in sodium hypochlorite or bleach. Levels are very low and is not going to affect yield. Affected plants are taller than the rest, tend to be lighter green and chlorotic. The tell sign that the problem is bakanae is the rotting of the crown. Affected plants will die before producing a panicle or will produce a blanked panicle.
Bakanae affected plant
Healthy and rotted crown caused by bakanae
Another interesting issue I found is young plants affected by aggregate sheath spot. Usually I don't see this disease being severe this early, but in this field a large patch seemed affected.
Young plant affected by aggregate sheath spot
Area affected by aggregate sheath spot. Notice the yellow leaves near the water.
I have heard blast is present in the Willows and Maxwell areas, but I have not seen any yet. Usually, a tell sign of leaf blast is burned circular areas near headlands, where N overlaps are. But make sure to inspect closely. In one field, the dead circles were not caused by blast, but most likely by rats or muskrats that had cut the rice and created a sort of nest.
Burned area caused by blast
Circular area damaged by rodents
- Author: Whitney Brim-DeForest
There are 6 so far:
- Fact Sheet #1: Nutrients in Rice Grain and Straw at Harvest
- Fact Sheet #2: Managing Potassium in Rice Fields
- Fact Sheet #3: Stem Rot and Aggregate Sheath Spot of Rice
- Fact Sheet #4: Kernel Smut of Rice
- Fact Sheet #5: Growing Season Water Use in California Rice Systems
- Fact Sheet #6: Managing Rice with Limited Water
- Author: Whitney Brim-DeForest
- Author: Roberta Firoved
The labeled weeds that RebelEX®controls are sprangletop, watergrass (both early and late), barnyardgrass, ricefield bulrush, Monochoria, redstem, ducksalad, California arrowhead, and water plantain. It does not have a water-holding period. The application timing begins from when the rice has one leaf or more, up to 60 days before harvest. Efficacy, as with most products, is better when the weeds are smaller. For flooded fields, it is important to have maximum contact, so it is recommended to lower the water in the field until at least 70% of the weed biomass is exposed, before application.
The product is “rainfast” (meaning it isn't affected by water) within 2 hours, so reflooding quickly is recommended. The label recommends restarting the flood at 3 hours after application, and to have the field completely reflooded within 24 to 48 hours at a maximum. Long drainage periods can encourage additional germination of certain weed species, including smallflower umbrella sedge, watergrass, barnyardgrass, and sprangletop.
Since RebelEX® also contains penoxsulam, it cannot be applied in the same season as Granite GR® or Granite SC®. Doing so will cause significant phytotoxicity to the rice, and will likely impact yields. Clincher® can be applied in the same season, but depending on the rate of RebelEX® applied, the Clincher® application rates will vary, so please refer to the label for rates and timings if planning to also apply both herbicides in the same season. For management of resistance, however, it is not recommended to apply Clincher® and RebelEx® in the same season, as both contain the same active ingredient, cyhalofop. Repeated applications of the same active ingredient (cyhalofop) will select for resistance in sprangletop, barnyardgrass, and watergrass (both late and early).
Remember to always follow all label instructions when applying any pesticide, as the label is the law. Make sure to pay particular attention to the Use Precautions and Restrictions. Consult your local Agricultural Commissioner's Office regarding buffer zones and aerial restrictions, before making any applications.
- Author: Bruce Linquist
This year we are conducting a study at the Rice Experiment Station to look at lodging differences between M-206 and M-105. There has been anecdotal evidence that M105 is more susceptible to lodging than M-206. We want to quantify this and see if we can manage N to reduce lodging if need be. Anyways, with this experiment, we have both of these varieties side-by-side in experimental plots. We used Cerano as part of the herbicide program. You can clearly see from the picture that M-206 is more susceptible to Cerano bleaching than M-105. Ray talked with Kent McKenzie about this and he also said he had seen similar findings. Anyway, we thought this might be interesting information for you.
- Author: Luis Espino
While checking traps recently, I noticed a lot of activity in the water in several recently flooded fields. A quick glance into the water might make you believe that tadpole shrimp is present in large numbers, or even perhaps that a treatment did not work. Make sure you look closely and don't confuse clam shrimp with small tadpole shrimp.
Clam shrimp are small crustaceans that look like a miniature clam; they are about a tenth of an inch and swim in the water slowly. Clam shrimp don't have the "tail" that tadpole shrimp have at the end of their shell. Most freshwater clam shrimp feed on algae and organic detritus. I am not sure what the ones in rice fields feed on, but they do not injure the rice. In the past, I have noticed that these clam shrimp come back after a tadpole shrimp treatment very quickly.
Clam shrimp close up
Large congregation of clam shrimp around decomposing rice roots
Tadpole shrimp are more problematic during seed germination. Once the seedlings have a well anchored root and the spike is green, tadpole shimp are less likely to injure them.