- (Focus Area) Agriculture
- Author: Kathy Keatley Garvey
Oh, there ain't no bugs on me
There ain't no bugs on me
There may be bugs on some of you mugs
But there ain't no bugs on me
You can hear it on YouTube.
UC Davis distinguished professor James R. Carey of the Department of Entomology and Nematology, drew national news media coverage in 1991 when he declared that the medflies are "established" here, that the "recurring outbreaks" are not caused by tourists continually bringing infested fruit to California in their airline baggage.
Today Carey says that California's fruit fly invasion is in "crisis mode."
The professor will present a Department of Entomology and Nematology seminar on "California's Fruit Fly Invasion Crisis" at 4:10 p.m., Monday, June 3 in Room 122 of Briggs Hall. It also will be on Zoom. The Zoom link:
https://ucdavis.zoom.us/j/9 5882849672.
"After seven decades of near-continuous outbreaks in scores of California cities, tephritid fruit fly invasions (e.g., Mediterranean, oriental, peach, and Mexican fruit flies) are reaching critical mass, with many of the annual eradication programs morphing into below-the-radar, never-ending fruit fly control programs," Carey says in his abstract. "Permanent establishment of any one of these tropical species has the potential to shut down the multi-billion dollar domestic and foreign markets for hundreds of California fruit and vegetable crops."
"I will present an overview of the long-developing crisis, discuss lessons learned from analysis of fruit fly detection databases, and argue that, in order to have any chance at stemming this ever-rising tide, CDFA and the USDA urgently needs to switch from their historic, ad hoc eradication strategy to a new one that is evidence-based and far more scientific."
Carey served on the CDFA's Medfly Scientific Advisory Panel from 1987-1994, testified to the California Legislature "Committee of the Whole" in 1990 on the Medfly Crisis in California, and authored the paper "Establishment of the Mediterranean Fruit Fly in California" (1991, Science 258, 457).
Carey is a fellow of four professional societies: the Entomological Society of America, the American Association for the Advancement of Science, the California Academy of Sciences, and the Gerontological Society of America. He is former director (2003-13) of a 11-university consortium funded by the National Institute on Aging (NIH/P01) on the evolutionary ecology of lifespan.
- Author: Luis Espino
I received several calls and comments about issues with tadpole shrimp this spring. While this pest is well known to growers and PCAs, it can still be difficult to manage during planting time. Mistiming of insecticide application can result in shrimp damage. Tadpole shrimp develop fast, and really fast when it is warm. This spring was warmer than last year during mid to late May, when most of the rice was being flooded and planted. If a field takes long to flood and seed, the shrimp have more time to develop and may injure seedlings as soon as they start germinating in the field. What shrimp size can injure rice? If you can see the shrimp, they can injure rice. However, larger shrimp will cause more injury than smaller shrimp. The figure below shows how, in a field infested with TPS, the stand is reduced more the later the field is seeded after flood (DAF).
Some of the fields where shrimp injury occurred this year are fields where pyrethriods do not control shrimp anymore. In these fields, Dimilin is working well. However, remember that Dimilin may take a few days longer to clear up the shrimp than pyrethroids and copper, especially when the shrimp are large.
When shrimp injury occurs soon after seeding, they will feed on the emerging coleoptile and radicle, completely consuming these tissues. When this happens, seeds won't recover. If only some of the tissue is consumed, seedlings may be able to continue growing once the shrimp is controlled. The picture below shows seedlings where the coleoptile and radicle have been consumed compared to two uninjured seedlings at the bottom of the picture.
If a field is damaged by tadpole shrimp, reseeding is an option. Some trials conducted a couple of years ago by Bruce Linquist showed that the optimum stand is about 25 plants/ft2. Rice plants can compensate when the stand is reduced. For example, when the stand is reduced to 12.5 plants/ft2 (half the optimum), yield is reduced only 10%. In general, reseeding should be considered when the stand is reduced to 10 plants/ft2 or less. Draining the field before reseeding increases the likelihood of establishment of the reseed, but it may not be possible in all cases. When reseeding, use a higher seeding rate to increase the chances of establishment and make sure the shrimp have been controlled. As a grower told me a few years ago, remember that reseeding is a bit of a gamble.
- Author: Ben A Faber
Rely® 280 Herbicide Available for Use in California Avocado Groves
The California Department of Pesticide Regulation has approved the herbicide Rely® 280 (glufosinate-ammonium) for use in avocado groves in California. Rely® 280 is a post-emergence broad-spectrum herbicide for use against broadleaf and grassy weeds. Glufosinate-ammonium is an excellent alternative to glyphosate, especially for those weeds that have developed glyphosate resistance.
The California Avocado Commission provided funding for Dr. Peggy Mauk, extension professor for subtropical horticulture at the University of California-Riverside, to conduct efficacy trials with glufosinate-ammonium and the IR-4 program provided funding for the required phytotoxicity (crop safety) trials. “Glufosinate-ammonium is an effective broad-spectrum herbicide,” said Mauk. “The weed that is the biggest problem here in Riverside is mare's tail or hairy fleabane ( Erigeron bonariensis). Glufosinate will kill it depending on the application timing and size of the plants. Treating for weeds is also going to be seasonal…the spring is usually worse because spring rains bring a lot of weeds, especially this past year.”
Currently, growers must have a copy of the DPR approved supplemental label in their possession when using Rely® 280. The DPR-approved label has a stamp on it with the wording "LABELING ACCEPTABLE State of California Department of Pesticide Regulation Pesticide Registration" and can be downloaded here. This supplemental label expires on December 1, 2025, and BASF, Rely® 280's manufacturer, anticipates that all old product will be used by that date and new product with avocado listed on the package label will be fully in the supply chain by that date.
Dr. Mauk's phytotoxicity trials found minimal damage, assuming sound application practices are followed. “Spray applications should not be made when there is a breeze,” Mauk emphasized. “If the wind carries the herbicide onto the plants, there can be some leaf discoloration. The discoloration appears as occasional purple spots on the leaves. There is not widespread damage. We also never saw any discoloration on the avocado fruit.”
General questions about this registration can be directed to CAC's Research Director Dr. Tim Spann at tim@spannag.com or 423-609-3451. For specific questions regarding the use of Rely® 280 growers should contact their Pest Control Advisor.
- Author: Kathy Keatley Garvey
The katydid nymph did.
It did appear in May.
The UC Statewide Integrated Pest Management Program (UC IPM) tells us that katydid nymphs appear in our gardens in April or May.
This little nymph was right on time, barely, as it surfaced in our Vacaville garden on May 28.
The nymph, a leafeater, is usually so camouflaged in the vegetation that we don't see it--unless it's hanging out on a California golden poppy blossom or a neon pink rock purslane. The adult katydid can be an economic pest when it feeds on such crops as mandarins.
Frankly, it can look quite comical as it "walks the walk," its long threadlike antennae probing the way as it descends a stem in the early evening.
- Author: Patricia Lazicki
- Author: Neil McRoberts
General situation
Temperatures over the past few weeks have been in the 80s and 90s, ideal conditions for thrips development. The hot weather coming up is also expected to accelerate thrips development and activity. I'm seeing some TSWV infection in nearly every field in Yolo and Solano counties that I visit, though generally at low (<1%) incidence.
Thrips population and outlook
We're in generation 3, with adults predicted to peak in the next week or so and generation 4 adults to peak in early July. Generations 3 and 4 represent the major risk of TSWV getting into crops before fruit set, so if you're planning to use insecticides to knock down thrips numbers, the next month or so is an important period. TSWV is only likely to reduce yields when infection occurs during or before fruit set, so all but very late-planted fields should be far enough along by Generation 5 (predicted to come towards the end of July) to shrug off any new strikes.