For two years in a row I have received a report from a PCA in Yuba County of conchuela stink bugs on rice. This is very unusual; I have never seen these stink bugs on rice before, and I'm not very familiar with them. A quick on-line search shows that they are common on the western US; they can be a pest of cotton, alfalfa seed and sorghum, but it has a wide host range. Our UC IPM webiste only lists them as a pest of apple and pear, so I don't know how prevalent they are in agronomic crops in the Sacramento Valley.
Last year they did not affect yield or quality in the field where they were detected. I am not considering these bugs a pest; just incidental at this point. I'd love to hear from other PCAs or growers if they have noticed them in their rice.
Every year we see some off-types in our public varieties that have a genetic mutation we call elongated upper internode. This mutation causes the internode below the panicle to elongate, resulting in panicles that stick above the canopy. Some have confused this abnormality with weedy rice.
It seems that the occurrence of this abnormality may be related to weather - some years we see it more often than others. In any case, the frequency with which it occurs is so low that it does not affect yield.
- Learn how to identify weedy rice
- Learn to differentiate weedy rice from other grassy weeds
- See what weedy rice looks like in the field
UCCE Rice Farm Advisors will be at two weedy rice locations to show growers, PCAs and other interested parties how to spot and identify weedy rice before it is headed. Weedy rice samples will be available for inspection and comparison with other weeds. We will observe infested fields from the field's edge, so no boots required.
Stop by any of the locations below between 8:00 and 10:00 am. Looking at samples and fields will take about 20 minutes.
Dates and locations:
Time: Between 8:00 and 10:00 am
- Author: Whitney Brim-DeForest
As many of you are aware, many of our grass species in California rice are resistant to multiple herbicides. Late watergrass aka "mimic" (Echinochloa phyllopogon), early watergrass (E. oryzoides) and barnyardgrass (E. crus-galli) are among some of our most competitive weed species, causing large yield reductions when uncontrolled.
One of the last remaining chemicals that our grass species are not yet resistant to is pendimethalin. Commercial formulations for pendimethalin registered for California rice are Prowl H2O and Harbinger. Prowl H2O is a delayed pre-emergent herbicide applied onto dry, drill-seeded fields. Harbinger is also a delayed pre-emergent herbicide, but the Harbinger system can be used in fields that are seeded by air. Both are viable uses of the chemical, and which one you choose will depend on your available equipment. For more information on how to apply, refer to the product labels.
Although I have used Prowl H2O in field trials and have a pretty good idea of its efficacy, I was curious to see how Harbinger looked in the field, since I have not yet had the opportunity to use it in a trial. I recently visited Rice Researchers, Inc., a rice breeding facility in Glenn County, where they are using a Harbinger-based program, for the second season. The photo (below) shows the rice at about 30 days after seeding. No weed species were present in the field. This is after one delayed pre-emergent Harbinger application.
It is too late to utilize pendimethalin this season, but for help incorporating pendimethalin into your herbicide plan for 2018, talk to your PCA, or give one of the UCCE Rice Advisors a call. Especially for growers that have herbicide resistant grasses, it can be a valuable tool in reducing grass populations.
Moth catches have come down considerably. Looks like the worst of the infestation has passed. There are still worms out in the field; keep an eye on late planted rice.