You may have noticed swarms of flying insects landing on your roses, calla lillies, hydrangeas, and other flowers. If you look closely, you'll see the insect inside the flower, and the chewing damage on the petals. These pests are hoplia beetles, but are often misidentified as Japanese beetles or rose chafer beetles.

Beetles are the most plentiful of all insects on the planet, so it's understandable to get a few of them confused. Let's compare photos and other details about each of these beetles, and also mention the green June beetle, a beetle that is commonly mistaken for the Japanese beetle.

Japanese Beetles

Japanese beetles do not have an established population in California. The California Department of Food and Agriculture* (CDFA) maintains traps for detecting this pest throughout the state. When Japanese beetles are found in California, they are targeted for eradication (complete elimination). Read more about this invasive species on the UC IPM website at https://ipm.ucanr.edu/Invasive-and-Exotic-Pests/Japanese-Beetle/ 

Green Fruit Beetles

Green fruit beetles are a dull green color and much larger than Japanese beetles. You may notice them in late spring and summer as they zoom around your garden. Fortunately, they are rarely a pest. https://ipm.ucanr.edu/PMG/GARDEN/FRUIT/PESTS/grfruitbeetle.html 

Rose Chafer Beetles

The rose chafer beetle resembles the hoplia beetle, however, this pest is not found in California. You can read more about these beetles on this informational page from University of Minnesota https://extension.umn.edu/yard-and-garden-insects/rose-chafers 

Hoplia Beetles

Hoplia beetles are small, brown, and their undersides look like they've been dusted in gold. If you hold one in your hand, they will “play dead” and not move, making it easy to examine them.

The best way to manage hoplia beetles is to regularly handpick or shake them off flowers into a bucket of soapy water and then dispose of it. This can help reduce beetle populations in the future. You can also fill white, 5-gallon buckets with water and a few drops of detergent. The white color may attract the beetles which will fall into the bucket and drown. Luckily, hoplia beetle populations begin to dwindle in June. Using a pesticide to spray the beetles is not recommended. You can read more details about managing hoplia beetles in the UC IPM Pest Notes: Hoplia Beetles.

*it's important that we help prevent invasive pests from taking hold in our communities and threatening agricultural crops. You can help by saying "yes" when asked if the Agricultural Commissioner's Office can place traps in your landscape.

 

Recently I had the pleasure of sipping a delicious margarita made with hibiscus juice. A tropical plant, hibiscus plants produce large, showy blossoms. Generally grown for ornamental purposes, the flower is also known for its culinary applications, one of which is making a refreshing juice, like the one in my margarita!

Hibiscus are one of many flowers that are edible. Edible flowers can be used to add color, fragrance, flavor, and texture to foods. They can be added to soups and salads raw, used in entreés or desserts, make tea or flavored water, candied, breaded, or fried. They have the benefit of often being healthy while providing few calories.

This is the first part of a two-part article. This article will focus on ornamental edible flowers. The second half to be published next week, will feature edible flowers from vegetable and fruit plants, and weeds.

Precautions 

Before consuming edible flowers, one should always proceed with caution. As with any new food item, slowly introduce specific flowers to the diet to see if any allergic reactions occur. The flowers should come from your garden or trusted source that has not been sprayed with pesticides. Do not use flowers from plants or bouquets that have been purchased from a floral shop, nursery, or garden center, as they may have been treated with pesticides. Many flowers share common names, so always look for the scientific name (genus and species) to ensure you have the right flower.

Harvesting

Choose flowers that have just fully opened, harvesting in morning right after the dew has dried. Flowers need to be carefully washed out, and in many cases, remove the stamens, styles, pistils, and sepals (the parts that hold the pollen and the green stems that hold petals together). Use as soon as possible for maximum flavor.

So Many Flower Choices!

Ornamental edible flowers are generally grown in gardens as ornamental plants, but they also can have a place on our plates. They come in a wide array of sizes, shapes, and colors suitable for virtually any occasion. Here is a very small sampling:

Nasturtiums: these flowers have a delicious, peppery taste similar to watercress and their colorful blooms look lovely in summer salads. 

Pansies: come in a wide range of colors with a mild lettuce-like taste which makes them popular for salads. The entire flower can be used.

Marigolds: some varieties have better flavors than others, so experimenting is a must. French marigolds have a bright, citrus-like flavor and a colorful addition to salads. The petals can be cooked in dishes and are sometimes referred to as “poor man's saffron.” Dried petals of African marigolds can be used to make a tea.

Dianthus or pinks: Their petals can be steeped in wine or sugared for use in cake decorations. The petals are unexpectedly sweet, if the bitter white base of the flowers is cut off.

Honeysuckle blossoms, as the name suggests, have a honey-like flavor. They bring a fragrant sweetness to jams, jellies, cakes, candies, and other sweet treats.

Roses: are often used in Middle Eastern dishes in the form of rose water which can add an intense flavor to a dish. The petals can also be sugared or used as garnishes.

Lavender: not only smells wonderful, but English and French lavenders have a sweet flavor used in a wide range of baked goods, ice creams and other recipes. However, use sparingly, as the flavor can be overpowering. 

In recent years edible flowers have become popular in restaurants and home kitchens. If you want to explore expanding your cuisine with edible flowers, there are a number of edible flowers books available which will give you many suggestions regarding preparation and recipes. Your local library can help you find one! Meanwhile, I'm going to learn how to make hibiscus juice to put in a margarita!

 Denise Godbout-Avant has been a Stanislaus County Master Gardener with UC Cooperative Extension since 2020. 

 

UC IPM's online courses for 2023 are now available!

All of UC IPM's courses can be accessed for free. However, if you need Continuing Education Units (CEUs) and a certificate of completion, most courses require payment. From now through October 31, 2023, we are offering 50% off the regular price when you use code ipm50 at checkout.

Certain course certificates are offered for free this year, such as Urban Pyrethroid and Fipronil Use: Runoff and Surface Water Protection and Providing IPM Services in Schools and Child Care Settings.

All courses must be completed by December 30, 2023 if you need CEUs. Upon course completion, be sure to download the Certificate of Completion (PDF file) to receive your CEU credits. Certificates will not be available for download after December 30th. 

Visit the UC IPM website to see all the courses that we offer for CEUs by the California Department of Pesticide Regulation (DPR). Many of our courses are also accredited by the California Structural Pest Control Board (SPCB), Certified Crop Adviser (CCA), the Western Chapter of the International Society of Arboriculture (WCISA), and the Arizona Department of Agriculture.

2023 Pesticide Instructor Training via Zoom

If you are looking to become a certified trainer, this is the workshop for you. Participants who complete this training will become qualified to provide pesticide safety training to fieldworkers and pesticide handlers, as required by California state regulations and the EPA revised Worker Protection Standard. This training is approved by the California Department of Pesticide Regulation (DPR). Each participant will receive a certificate and CE is available. All workshops run from 8am to 4:30pm. 6.5 CEUs (Laws & Regulations) from DPR are pending. Registration is now open. 

Please contact psep@ucanr.edu with any questions.

This blog article is for readers who may have heard of subsoil, but don't really know what it is, or how it may or may not affect their gardening efforts. 

What is subsoil?

There are several layers (also known as “horizons” to soil scientists) that can be found when we dig deeper and deeper down into the soil. We can imagine all the individual layers of a soil stacked one on top of the other like a layer cake, this is called the soil profile. The surface soil is the uppermost layer of the soil profile, and the one we are most familiar with, because this is where most of the action takes place. Soil mixing with tillage, compost and fertilizer application, irrigation, plant root growth, and animal activity (including microbes) are mainly concentrated within the soil's surface layer. Additionally, decomposition of plant and leaf litter occurs most rapidly in the surface soil, this eventually leads to the formation of new soil organic matter. In comparison, the subsurface soil, or subsoil, is composed of one or more soil layers that lie below the influence of surface soil activities. There is not a consistent depth at which every surface soil layer changes into the subsoil layer(s), rather the subsoil occurs at a different depth from place to place depending on numerous factors, including some of the factors mentioned previously. This is the reason why it is difficult to determine where the subsoil layer begins in the soil profile.  

What does subsoil contain?

Subsoil is found deeper in the soil profile and does not directly experience a lot of the processes that occur in surface soil. As a result, the subsoil has less soil organic matter, less insect and animal activity, slower air and water movement, and a slower rate of decomposition compared to the surface soil layer. However, the subsoil underlies the surface soil and is indirectly influenced by the activities that occur at or near the soil surface. Therefore, the subsoil layer(s) has the excess fertilizer nutrients, herbicides, pesticides, and other dissolved salts that were lost from the surface soil due to heavy rainfall or irrigation. As surface soil begins to erode and age, the water moving into the subsoil can also have a lot of clay that accumulates in distinct regions of the subsoil.

What does subsoil look like? 

It is possible to identify subsoil by recording when and where you notice distinct changes in color, texture, and/or structure of the soil. The surface soil is often enriched in organic matter, giving it a dark appearance, typically dark brown or black. The movement of smaller soil particles from the surface soil into the subsoil increases clay content. The subsoil also lacks many of the rooting channels and biological pores that help build and support soil structure due to the limited presence of plant roots and animal activity. Therefore, as you dig deeper in the soil profile, if you see the soil color begin to fade from a dark brown or black to lighter shades of gray or brown, you notice it becomes harder to dig deeper into the soil, and/or you notice the soil is no longer loose and crumbly but becomes denser and lacks plant roots and worm channels, it is very likely you have reached the subsoil layer.    

What is subsoil used for? 

In general, the subsoil is a less suitable medium for plant growth compared to surface soil because of some of the factors mentioned previously. There are properties of subsoil however that make it suitable for other uses such as a source of “fill soil” for “cut-and-fill” construction operations, as a source of clay for building materials, and as an absorption layer for on-site wastewater disposal.

What can home gardeners do to keep their subsoil in great shape year after year?

Healthy soils are effectively balanced among the chemical, physical, and biological processes that allow soil to function properly and achieve a desired outcome, such as being an optimal medium for plant growth. Therefore, to build or support healthy subsoil, it is important to consider each of these processes, keeping in mind that what occurs in the surface soil layer can, at some point, be reflected by what is observed in the subsoil. With this in mind, to encourage soil health in the subsoil it is important to recognize that certain plant nutrients move with rainfall or irrigation water, such as nitrogen, and may be enriched in the subsoil. Effectively balancing plant nutrient fertilization to avoid excesses can limit the amount of plant nutrients transferred from the surface to the subsoil. The subsoil often has a poorly developed structure due to the lack of plant rooting channels and animal activity (including microbes). Growing a diverse group of plants that have distinctly different rooting depths, ranging from shallow- to deep-rooted, can encourage the formation of rooting channels that extend into the subsoil. The burrowing activity of earthworms also creates channels that deep-rooted plants can easily use and follow into the subsoil. Additionally, the presence of actively growing plant roots acts as a food source in the subsoil that stimulates microbes. The physical structure of subsoil can be improved with deep-rooted annual or perennial plants. As soil structure improves and more of these biological pore spaces are created, the rate of water and air movement into the subsoil layer will increase, helping sustain the balance among chemical, physical, and biological processes.           

What is the substratum layer of soil? Does that layer affect gardening at all, and if so how?

Stratum is a term that is commonly used to identify a distinct layer of rock or soil. Substratum then is a term used to indicate the relative underlying position of a distinct rock layer within stratified rock formations or a distinct layer of soil that lies below the surface soil. The substratum layer of soil has some of the same properties that are common to the subsoil. Although, many of the chemical, physical, and biological processes are further diminished in the substratum layer compared to the subsoil. Specifically, growing roots are not likely to be found in the substratum, so the properties of the substratum layer are unlikely to directly influence plant growth. The limited amount of water and air in the substratum layer will however help breakdown larger solid rock fragments, forming a loose and very coarse structure that closely resembles the mineral composition of the underlying layer(s) of the soil profile.      

What is the bedrock layer? Does that layer affect gardening at all, and if so how?

Bedrock is the bottom layer of the soil profile layer cake. The bedrock layer consists of solid rock that has not yet been exposed to the chemical, physical, and biological processes of the surface soil and subsoil. In some places, bedrock is the foundation from which the overlying soil layers developed, while in other places, the bedrock layer may have become “buried” by windblown sand or sediment. Bedrock does not directly influence plant growth, but it can determine the type of clay minerals found in different layers of the soil profile. 

Dr. Anthony Fulford is the Area Nutrient Management and Soil Quality Advisor for Stanislaus, Merced, and San Joaquin Counties.