- Author: Luis Espino
We are seeing severe armyworm infestations in the field. Moth numbers have stayed relatively constant in a few locations, still on the increase in Sutter and Yolo counties. This means that egg laying may continue and we may have more worms coming up.
I have gotten several reports of pyrethroids not controlling worms. Dimilin (diflubenzuron) has been working well. However, remember that Dimilin has an 80 day pre-harvest interval. Intrepid (methoxyfenozide) received a Secion 18 today and can now be used.
The infestation is not over yet, so don't stop scouting. If you detect small worms, consider a treatment. Armyworms get their name form the fact that they move "like an army", in large numbers all at once. Worms may move from areas with severe infestations to unaffected areas of the field.
Here's a few of the pics I have received from several areas of Colusa, Glenn and Butte counties.
- Author: Whitney Brim-DeForest
It may be a bit early in the season to start thinking about herbicide resistance, but in just a couple of weeks, most rice growers will have put out their last herbicide applications, and it will be time to start scouting.
University of California Cooperative Extension, in collaboration with the Agronomy Research and Information Center at UC Davis, has produced a short video which explains how to collect seed to make sure that if you do submit weed seed for testing, you get back accurate results. The form which must accompany any submitted weed seeds can be found on the UCANR Rice Website: http://rice.ucanr.edu/files/263785.pdf.
- Author: Whitney Brim-DeForest
Over the past year, weedy rice has become a top issue in California rice, both for individual growers and for the industry as a whole. Working together, the University of California Cooperative Extension and the California Rice Commission have come up with a set of tools to assist in getting control of this pest. Of course, none of it would be possible without the input and cooperation of the Pest Control Advisers (PCAs) and California rice growers, who are the first line of defense in dealing with weedy rice. Additional assistance in material development and funding have come from the California Rice Research Board, the California Crop Improvement Association and the staff at the California Rice Experiment Station.
A new website, www.caweedyrice.com, contains all of the most up-to-date information regarding weedy rice in California. The website covers identification, management, and weedy rice sample submission.
An identification pamphlet was mailed out by the California Rice Commission a couple of weeks ago to most growers and PCAs. If you need additional pamphlets, they are available at your local UCCE office. Identification posters will be distributed to Agriculture Commissioner's offices, PCA offices, and rice mills and distributors in each county in the next few weeks. They are also available at your local UCCE office upon request.
To report an infestation of weedy rice, a new app is also available for download from the Google Play and ITunes stores.
The "Weedy Rice Reporter" app will let you send up to six pictures and aGPS location taken with your phone toUCCE RiceAdvisors so that we can confirm or rule out weedy rice. OnlyUCCE RiceAdvisors will be able to access any app submissions. We hope that the app will help us identify infestations early so that management actions can be implemented to eliminate weedy rice from the fields.
- Author: Whitney Brim-DeForest
I went out on a few farm calls in the past week, and have noticed a trend. Due to the unusually wet weather this spring, some of the weeds are already producing seed out in the field! This occurs when the field was moist or wet in the spring, and was not tilled or sprayed prior to planting.
If you have weeds that are already setting seed, follow the steps below:
1) First, make sure to get proper identification of the weed species. Some weed species will produce seed and that seed can germinate and send up a second flush of weeds, in the same season! They are:
- Smallflower umbrella sedge
- Mexican sprangletop
NOTE: There are two types of sprangletop: Mexican and Bearded. Only the Mexican sprangletop will set seed that will germinate this season. Bearded sprangletop seed is dormant and won't germinate until the 2018 season.
2) If you have one of the above-listed species that is already setting seed, it is important to make sure that your follow-up herbicide application will control this second flush of germinating seeds. Otherwise, the amount of seed produced and deposited into the seedbank will be exponentially higher than in a normal year, because there will be two generations of plants that set seed in the same season!
3) If you have a weed species setting seed that is NOT listed above, you will likely not be able to do much this year, as the weeds are likely too large to control with herbicide and any impacts on yield have already occurred. Plan to have an aggressive program for next year (2018)!
- Author: Luis Espino
I have received reports of significant defoliation due to armyworms from several areas: Glenn, Colusa, Butte and Yolo counties. In most areas the defoliation is severe but the area affected within fields still small.
I inspected a field in Glenn County. The defoliation was severe along levees and in near borders, and worms were about 5th instar. Population was high, similar to 2015.
Severe defoliation along levee.
Severe defoliation along border of field.
Fifth instar armyworms in Glenn County field, 21 June 2017.
The degree day model predicted 5th instar armyworms will start showing up June 22. The heat from last week sped things up, but the model was really close.
Remember that worms feed the most during 5th and 6th instars, and it will take them 10 days to complete their cycle after reaching the 5th instar. This means that there is plenty of time for them to cause more injury and move to other areas of the field. Keep a close eye and consider a treatment if the worms are still present. Do not wait until worms get bigger, they are harder to kill with any insecticide. It's starting to look like 2015.
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