- Author: Lauren Fordyce
Healthy Soils Week (Dec. 4-8) is a week-long initiative by the California Department of Food and Agriculture (CDFA) to highlight the importance of soil health throughout California.
Healthy soils can improve crop yields, sequester carbon, reduce erosion, and increase biodiversity. In addition, they can reduce pest problems and pesticide and fertilizer use. Healthy soils lead to healthy plants which are less susceptible to pest attacks and can better tolerate and recover from pest pressure.
In integrated pest management (IPM) we promote the use of cultural control methods to improve soil and plant health, making an environment less conducive for pests to establish, reproduce, and cause damage.
Here are some cultural tips for creating healthy soils and reducing pests:
- Improve soil drainage to avoid oversaturated, water-logged soils. Moist, compacted soils can attract earwigs, slugs, and nematodes and encourage damping off, Phytophthora, and other diseases to develop.
- Use mulch. Mulches can moderate soil moisture and temperature, reduce compaction, and suppress weeds. But use them carefully as improperly selected or applied mulches can damage plants and attract pests.
- Clean up fallen fruit and leaves. Good sanitation is essential for preventing pests from establishing and spreading. Removing infected fruit, leaves, and branches can prevent insects and pathogens from overwintering in the soil.
- Fertilize appropriately. Too much or not enough nutrients in the soil can result in plant stress. Stressed plants are more susceptible to pests and diseases. Applying too much fertilizer (especially nitrogen) can result in excessive plant growth which often attracts pests like aphids and psyllids.
- Dethatch lawns. Thatch includes pieces of grass stems, roots, and rhizomes. It is slow to decay and can build up on the soil surface making it difficult for water to reach the roots. Several turfgrass pathogens can also survive in thatch.
- Solarize the soil as needed. Soil solarization uses heat from the sun to kill pathogens, nematodes, and weed seeds in the soil.
- Author: Elizabeth J Fichtner
- Author: Mel Thayer
- Author: Robert Van Steenwyk
Walnut scale (Figure 1) is an important economic pest of walnuts in California. High populations of walnut scale may affect tree vigor as well as predispose trees to diseases caused by several plant pathogenic fungi and possibly flatheaded borer damage. Historic UC Pest Management Guidelines emphasize the efficacy of insecticide applications at the crawler stage of insect development (late April to mid-May); however, with the introduction of new pest management tools such as insect growth regulators (IGRs), new studies have been conducted to evaluate the efficacy of these products at earlier times during the insect lifecycle. Both walnut scale and frosted scale overwinter as immature nymphs; therefore delayed-dormant application of IGRs has the potential to inhibit maturation and subsequent reproduction of these pests.
In 2023, UC ANR and UC Berkeley researchers initiated a new collaborative study investigating the efficacy of four products applied at various rates and times (Table 1). Two insect growth regulator products, Esteem® (IRAC Group 7C) and Centaur® (IRAC Group 16), were included in the study, with both delayed-dormant (February 8, 2023) and crawler-stage (April 26, 2023) application timings. Centaur® was also investigated at two rates. Crawler-stage applications of Senstar® (a combination of spirotetramat and pyroxifin) and Assail 20SG® (a neonicitinoid) were also included in the study.
Delayed dormant IGR applications inhibit maturation of walnut and frosted scale. Delayed-dormant application of Centaur WD® at either 34.5 oz/acre or 46 oz/acre reduced walnut scale survival by 81% of that of untreated control treatment by April. Both Esteem and Centaur reduced populations of mature frosted scale observed in late April by the over 85% of that on untreated trees (Figure 2).
Crawler populations affected by IGRs and conventional insecticides. All treatments suppressed the rates of crawler emergence over time in comparison to the untreated control (Figure 3); however, delayed dormant applications of both IGR treatments (Centaur® and Esteem®) resulted in the highest suppression of the first-generation curve (Figure 3). Both rates of Centaur® applied during the delayed dormant period resulted in similar suppression of crawler emergence. Crawler stage application of Centaur® at the higher rate resulted in similar levels of crawler suppression as the delayed dormant IGR treatments (Figure 3). Moderate suppression of first-generation crawlers was observed with crawler stage treatments with the low Centaur® rate, Esteem®, and Assail® 30SG (Figure 3). Crawler stage application of Senstar® suppressed first-generation crawler emergence (Figure 3) and resulted in modest suppression (45%) of total crawler populations across the season as compared to the untreated control (Figure 4). All IGR treatments, regardless of the rate or timing, performed similarly with regard to total crawler populations across the season (Figure 4). The range in total crawler suppression across treatments of similar statistical significance was 88.2% (Centaur, 46 oz/acre, delayed dormant) to 54% (Assail, crawler stage), illustrating the variability in crawler counts in the orchard system (Figure 4).
Summary. Delayed dormant applications of either of the insect growth regular products, Centaur® or Esteem®, offer excellent suppression of walnut scale and frosted scale populations. Delayed dormant applications may offer similar efficacy at lower product rates due to the opportunity to achieve better coverage prior to leaf-out. Additionally, delayed dormant applications of these products may inhibit maturation of nymphs into adults, thus limiting sexual reproduction and subsequent laying of eggs.
In prior studies, the efficacy of crawler stage Assail® application became apparent the year following application. Based on this background information, the populations of adult walnut scale will be evaluated across all treatments in April 2024 to fully capture the efficacy of these products over time.
Additionally, future studies are planned to further determine the value of dormant versus delayed dormant applications of IGR treatments for management of walnut scale. The results of the current study, however, do demonstrate a need for updating the current UC IPM guidelines for management of walnut scale. To date, the UC IPM guidelines only recommend crawler-stage applications of IGR products while the current study demonstrates the value of IGR applications earlier in the season.
The holiday season is fast approaching! With many people traveling and visiting new places during this time, it's important to understand how to check for bed bugs and prevent them from coming home with you.
Regardless of what type of lodging you choose–hotel, motel, cabin, or other type of rental–no place is immune to bed bug introductions or infestations. Follow these tips for a bed bug-free holiday.
When settling into your room
- Before putting your luggage down on the bed, couch, or floor, do a quick bed bug check. You can either leave the luggage in the hall or place it in the bathtub, where bed bugs are not likely to be.
- Thoroughly inspect the bed, nightstand, upholstered furniture, and closets. You can use a flashlight or a phone light to help you look for bed bugs, shed skins, or fecal spots. Look along mattress seams, under covers, around the box spring, behind headboards and picture frames, and along baseboards.
- Watch this video to learn how to do a bed bug inspection: https://www.youtube.com/watch?v=oWCc3Mngo7E&t=2s
After you return home
- Before bringing luggage inside your home, inspect it for any signs of bed bugs that may have hitched a ride. Store luggage away from the bedroom to prevent potential introductions.
- Launder all the clothes from your trip on the hottest settings to kill bed bugs or their eggs that may have gone unnoticed. For items that cannot be washed, freezing them for several days will also kill all stages of bed bugs.
With Thanksgiving and its generous tradition of sharing coming up next week, the California Department of Food and Agriculture (CDFA) is urgently reminding Californians in fruit fly quarantine zones that they should not be moving homegrown produce off their property.
There are seven different fruit fly quarantines currently active in California, in the counties of Los Angeles, Ventura, Sacramento, Riverside, San Bernardino, Contra Costa and Santa Clara. These invasive fruit flies can be spread to new areas on fruits and vegetables so the movement of these products is forbidden in quarantine areas.
If you live in a fruit fly quarantine zone:
- Do not take fresh fruits and vegetables off of your property.
- Adopt the principles of “Don't Pack a Pest” to help prevent future introductions of invasive pests and diseases while traveling.
- Fruits and vegetables must be consumed or processed (i.e., juiced, frozen, or cooked) at the property of origin.
- To dispose of fresh fruits and vegetables, double-bag and seal prior to placing them in the trash–not in your green waste or compost bin.
- Allow authorized agricultural workers access to your property to inspect fruit, check fruit fly traps, or conduct fruit fly eradication activities.
- Report any suspected fruit fly maggots that you find inside of your backyard produce by calling the CDFA Pest Hotline: 1-800-491-1899.
Quarantine maps, restrictions, and other information is available online at: https://www.cdfa.ca.gov/plant/pe/InteriorExclusion/quarantine.html.
Revised from the California Dept. of Food and Agriculture (CDFA) blog post on November 15, 2023.
Peach leaf curl is a fungal disease that only affects peach and nectarine trees. The fungus causes distorted, reddened leaves to appear on the tree in the spring. While many peach and nectarine trees don't begin to show obvious symptoms of peach leaf curl until the spring, the time to manage the disease is in late fall and winter.
If left untreated for several years, trees can decline and need to be removed. In some cases, peach leaf curl can affect the quality of fruit too.
To effectively control peach leaf curl, spray an appropriate fungicide in the fall or winter, after leaf drop but before flower buds swell in the spring. The fungal spores overwinter on peach and nectarine twigs and flower buds. If left untreated, the spores will germinate in the spring, especially in years with heavy rainfall. In Northern California you can usually treat trees starting in late November. In Southern California you can usually start in early January. A single treatment while the tree is dormant is generally advisable, but in areas that get a lot of rainfall, you may want to spray again later in the dormant season.
Numerous copper-based fungicides are available to effectively treat peach leaf curl when used according to label instructions. Always read the product label before buying or using a pesticide. Use only the rate listed on the label to avoid fungicide resistance and avoid making applications before it rains.
For more management information, see the UC IPM Pest Notes: Peach Leaf Curl and Pesticides: Safe and Effective Use in the Home and Landscape.