Posts Tagged: Agriculture

A New Topics in Subtropics Newsletter!!!

Hot off the internet, a new edition of Topics in Subtropics, articles from UC subtropical horticulture folks

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Pendimethalin Use in California Rice: Clarifications and Updates

At our last meeting, we had some questions about the approved uses of pendimethalin in California rice. There are several products labeled for use on rice with pendimethalin as the active ingredient. As of June 2024, pendimethalin registered products (on...

The unintended consequences of clean fuel policies

How policies affect emissions, land use, and the prices of fuel and vegetable oils

Over the last two decades, both the federal government and state governments have enacted policies to reduce greenhouse gas (GHG) emissions in the transportation sector. In a new Special Issue of ARE Update, University of California agricultural economists explore how these federal and state renewable fuel policies have affected biofuel production for motor and aviation fuels and consider how these policies have affected land use and food prices. Their research shows that as U.S. demand for renewable diesel began to outpace supply, consumer prices for vegetable oil—which is used as a feedstock for renewable diesel—surged.

The national Renewable Fuel Standard (RFS) and California's Low Carbon Fuel Standard (LCFS), implemented in 2006 and 2011, respectively, have led to an increase in the amount of biofuels consumed and produced in the United States. While the RFS mandates that a minimum volume of renewable fuels be blended into U.S. transportation fuels, the LCFS sets an annually increasing targeted reduction in transportation-related carbon emissions. The LCFS set a 2030 target date to reduce GHG emissions by 20% through the development of a carbon trading program that requires refiners who produce ‘dirtier' fuels to buy credits from those who produce cleaner (e.g., renewable) fuels.

The authors show that after 2020, whenLCFS credit prices (i.e.,biofuel subsidies) were high, California saw an increasing volume of motor fuel coming from renewable diesel — which previously only made up around 5% of the state's diesel blend. Currently, the retail diesel blend in California is 35% conventional diesel and 65% renewable diesel.

By 2023, renewable diesel was the most consumed renewable fuel in California and also generated the most credits under the LCFS. Because renewable diesel is a perfect substitute for “conventional diesel,” it does not need to be blended with conventional diesel, unlike biodiesel which is chemically different from renewable diesel.

The agricultural inputs used to make renewable diesel can be used not only in the production of motor oil, but also in the development of sustainable aviation fuel (SAF). Additional tax credits set forth in the 2021 Inflation Reduction Act aim to bring about a 100-fold increase in the production of these fuels by by the end of decade. However, the authors of the second article show that current incentives to produce SAFs are not large enough to overcome the opportunity cost of instead using these fuels for on-road use.

After the drastic increase in demand for renewable diesel (up 500% over the last five years), a higher percentage now comes from edible vegetable oils. This increased demand almost certainly plays a role in increasing inflationary pressure on foods such as cooking oils.

“From 2018 to 2024, food-at-home inflation was 24%, but over the same period, fats and oils inflation was 83%,” said UC Davis professor and co-author Jens Hilscher.

The increased demand for these oils from the United States has also led to booms in production in countries such as Brazil and Indonesia, and some of the land conversion into these vegetable oil crops could result in deforestation. Greenhouse gas emissions are a global challenge. The authors show that local biofuel mandates often succeed in moving U.S. consumption of these fuels from one product or region to another without necessarily decreasing emissions at the national level. Their research emphasizes the importance of a coordinated effort to target emission reductions with a careful eye to the indirect consequences that inevitably result from ambitious policies.

To learn more about how federal and statewide renewable fuel policies have affected the demand for biofuels, read the full Special Issue of ARE Update 27(5), UC Giannini Foundation of Agricultural Economics, online at https://giannini.ucop.edu/filer/file/1719507310/21010/.

ARE Update is a bimonthly magazine published by the Giannini Foundation of Agricultural Economics to educate policymakers and agribusiness professionals about new research or analysis of important topics in agricultural and resource economics. Articles are written by Giannini Foundation members, including University of California faculty and Cooperative Extension specialists in agricultural and resource economics, and university graduate students. Learn more about the Giannini Foundation and its publications at https://giannini.ucop.edu.

Ettamarie Peterson: The Queen Bee Who'd Rather Be a Worker Bee

Ettamarie Peterson, fondly known as "The Queen Bee of Sonoma County," will be displaying a bee observation hive at the Vacaville Museum's Children's Party on Thursday, Aug. 8 but the life of a queen bee is not for her. "I have decided I...

Encouraged by the workshop instructor to hold newly emerged bees, Ettamarie Peterson shows a handful of bees at the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis. (Photo by Kathy Keatley Garvey)

Encouraged by the workshop instructor to hold newly emerged bees, Ettamarie Peterson shows a handful of bees at the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis. (Photo by Kathy Keatley Garvey)

Ettamarie Peterson stands next to Miss Bee Haven, an eight-foot-long ceramic-mosaic sculpture of a worker bee at the UC Davis Bee Haven. It is the work of Donna Billick of Davis. (Photo by Kathy Keatley Garvey)

Ettamarie Peterson stands next to Miss Bee Haven, an eight-foot-long ceramic-mosaic sculpture of a worker bee at the UC Davis Bee Haven. It is the work of Donna Billick of Davis. (Photo by Kathy Keatley Garvey)

Ants and Mealybugs?

Managing citrus mealybug – does ant control help?

Sandipa Gautam, Sanjeev Dhungana, and David Haviland

UC Co-operative Extension

Starting 2019/20 season, pest control advisors started noticing citrus mealybug infestations in multiple citrus varieties that continued to increase in acreage in the San Joaquin Valley. Although present in the citrus systems, mealybugs were considered to be a minor pest and kept well under check by natural enemies until recently.

What are mealybugs?

Mealybugs are soft, oval, flat, distinctly segmented insects whose body is covered in white mealy wax. Citrus mealybug, Planococcus citri is the most common species associated with citrus. Females lay ~600 eggs in egg sacs loosely held by white cottony flint. Crawlers are yellowish, and can move or be carried by ants, birds, or the wind to start new infestations. Crawlers feed by sucking sap using straw-like stylets and soon develop a waxy covering (Fig. 1C). Like California red scale, females molt and stay as third instars until mated by a male. Males go through a pupal stage and emerge as adults with wings that fly to seek a mate.

Mealybugs prefer the inside canopy of the tree and can be found under dense leaves, between clusters of fruits, or in other cryptic places where they can be difficult to find, especially when the population is low. As the season progresses and the tree flushes, blooms, and fruit develops, mealybugs move to the parts of the tree where nutrients flow. Ongoing research on seasonal phenology suggest that there are 5-6 generations in the San Joaquin Valley. The first generation starts from overwintering adult/egg populations in late March/early April. The second-generation crawlers/nymphs move to fruit in June/July. The remaining generations each year primarily feed and multiply on the fruit.

Mealybugs produce nutrient rich honeydew that is an attractive food source for ants. Ants have been reported to defend insect colonies from predators and parasitoids. In an early infestation, ant trails can be used as an indicator to locate mealybug infestations or other sap sucking pests. Managing sugar feeding ants in citrus orchards has shown increased biocontrol of sap sucking insects. It is plausible that loss of chlorpyrifos as an ant control tool may have aggravated ants thereby aiding to increase mealybug pressure in recent years.

As mealybugs have become a reoccurring pest in citrus orchards, University of California researchers-initiated studies to work towards developing strategies to manage this pest. Research funded by Citrus Research Board and led by Gautam lab is investigating biology, field ecology, and management of mealybugs. During field visits, our observations have shown that various ant species of were present throughout the growing season attending mealybug colonies.

Does managing ant help suppress mealybug?

UC researchers have documented that managing sugar feeding ants increases biocontrol, thereby reducing the pest pressure of sap sucking insects. When ant densities are were reduced >90%, there was ~90% less mealybug on twigs and complete elimination of mealybug was reported from fruit. However, managing ants has been a challenge since the use of chlorpyrifos was banned. To address this need, UC researchers have worked to develop and test different types of hydrogel beads for delivering insecticide products to sugar-feeding species of ants.

Research led by David Haviland has focused on the experimental use of commercially-available polyacrylamide hydrogel beads for large field-scale applications. In 2023 a large-scale field trial was conducted in a 20-acre grapefruit block in Sanger, California. Two applications of hydrogel beads laced with insecticides were made on Aug 2 and August 30, 2023. Post-treatment evaluations for ant density were done on 24 trees/plot by counting the number of ants that passed through a graft union for 15 secs weekly for 4 weeks after each application. The effects of ant suppression on mealybug densities was evaluated in October 2023 by counting the number of fruits infested with mealybugs (presence/absence) on 30 fruits from the inside canopy. Insecticide treatments had variable results on ant density, with lowest ant density consistently found in plots treated with thiamethoxam. Similarly, plots treated with thiamethoxam had the lowest populations of mealybugs.

There's a lot more to this story:

https://ceventura.ucanr.edu/Com_Ag/Subtropical/?newsletteritem=100493

 

 

 

 

mealybug stages

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