- Author: Josefa Price
As you drive through Fresno and other parts of the country, you may notice the Opuntia cacti, commonly known as the prickly pear cactus, adorning landscapes. Scientifically referred to as Opuntia ficus-indica and belonging to the Cactaceae family, these cacti play a significant role in our environment. Opuntias exhibit remarkable diversity and adaptability with approximately 150 to 180 species.
Opuntias hold cultural significance in many communities, particularly within the Hispanic/Latino population. Prickly pear cacti offer edible components - the prickly pears themselves (also known as tunas) and the tender new paddles (nopalitos). Prickly pears are a delight on their own or can be transformed into flavorful jams and juices. The common colors - fuchsia, orange, and green - each offer their own distinct flavors. Nopalitos, the young paddles, are a versatile vegetable used in breakfast dishes and salads.
However, a serious threat looms over the existence of these remarkable cacti - the Cochineal scale. The Cochineal scale is often mistaken for white mold, but these white-appearing furry scales on opuntias are insects that endanger the health of Opuntias. The scale insects feed on the cactus, causing chlorosis and, if uncontrolled, eventually leading to the death of the plant. Unfortunately, this infestation often goes unrecognized with the scale damaging or killing the plant and then spreading to neighboring Opuntias.
Detecting and combating Cochineal scale
Detecting a Cochineal scale infestation requires careful observation of your plant. Inspect the joints of the paddles, the spines, and even the prickly pear fruit for any white patches - a telltale sign of infestation. Proactive measures are essential to combat this threat. Pruning damaged pads is the first step and ensuring their proper disposal to prevent further spread. Second, forcefully spraying water on the plant can remove the scales' protective waxy layer, which then can be followed by applying insecticidal soap to the exposed bodies. Neem oil is an effective treatment to apply to the plant; however, caution should be exercised when using neem oil because applying it when external temperatures are above 70 degrees can damage the plant.
The Cochineal scale has both benefits and drawbacks. On one hand, it poses a clear threat to the health of Opuntias and must be actively managed to ensure their survival. On the other hand, there have been deliberate introductions of Cochineal scale as a biocontrol method to combat invasive Opuntia species. This approach helps restore balance to ecosystems by controlling the spread of aggressive plants and allowing native vegetation to flourish. Additionally, the Cochineal scale has been used to make carmine dye, natural red pigment #4, which has been used for coloring culturally and in economic markets.
Opuntias stand as resilient symbols of adaptability and utility within our landscapes. While the Cochineal scale presents challenges, it also showcases how a pest can be both a foe and a friend depending on the context. By understanding the complexities of this relationship, we can better appreciate and safeguard these remarkable cacti for generations to come.
References: https://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/cochineal.html
Opuntias: Nopales resilientes en nuestros jardines
Mientras viaja por Fresno y otras partes del país, puede notar los nopales Opuntia, comúnmente conocidos como nopal de tuna, que adornan nuestros jardines. Científicamente conocidos como Opuntia ficus-indica y pertenecientes a la familia Cactaceae, estos nopales desempeñan un papel muy importante en nuestro entorno. Las Opuntias exhiben una notable diversidad y adaptabilidad con aproximadamente 150 a 180 especies.
La cultivación de nopales Opuntia sirve para varios propósitos, que los convierte en una valiosa adición a nuestros alrededores. Su capacidad para prosperar en condiciones áridas, por ejemplo, las convierte en una opción ideal para el jardín tolerante a la sequía. Sus vibrantes flores amarillas no solo mejoran el atractivo visual sino que también atraen a polinizadores esenciales, incluyendo las abejas. Los nopales Opuntia también pueden servir como cercos naturales, disuadiendo a los intrusos que no deseamos que entren a nuestra propiedad. Sin embargo, uno de sus propósitos más destacados es en proporcionar sustento.
Sin embargo, una seria amenaza surge sobre la existencia de estos notables nopales: el insecto Cochinilla. La Cochinilla a menudo que se confunde como moho blanco, pero estos insectos de apariencia blanca en los nopales es un insecto que pone en peligro la salud de los nopales. La Cochinilla se alimenta del nopal, causando clorosis (hojas/pencas amarillas) y, si no se controlan, eventualmente provocan la muerte de la planta. Desafortunadamente, esta infestación a menudo no se reconoce como un insecto que daña o mata la planta y luego se propagan a los nopales vecinos.
Detección y combate de la Cochinilla
Detectar una infestación de la Cochinilla requiere una observación cuidadosa de su planta. Inspeccione las uniones de las hojas/pencas del nopal, incluso las espinas y la fruta en busca de manchas blancas, un signo revelador de infestación. Las medidas proactivas son esenciales para combatir este insecto. Apode las hojas/pencas dañadas es el primer paso para evitar una mayor propagación. En segundo paso, lave la planta con una manguera que tenga boquilla, luego puede seguir aplicando jabón insecticida a la Cochinilla. El aceite de neem puede ser un tratamiento efectivo para aplicar a la planta; sin embargo, se debe tener precaución al usar el aceite de neem porque si lo aplica cuando las temperaturas externas están a más de 70 grados de temperatura puede dañar la planta.
Insecto Cochinilla: ¿Amigo o enemigo?
La Cochinilla tiene beneficios e inconvenientes. Por un lado, representa una clara amenaza para la salud de los nopales Opuntia y debe gestionarse activamente para garantizar su supervivencia. Por otro lado, se han producido introducciones deliberadas de la Cochinilla como método de biocontrol para combatir las especies invasoras de nopales Opuntia. Este enfoque ayuda a restablecer el equilibrio de los ecosistemas al controlar la propagación de plantas agresivas y permitir que retoñe la vegetación nativa. Además, la Cochinilla se ha utilizado para hacer tinte de carmín, pigmento rojo natural #4, que se ha utilizado para colorear culturalmente y en los mercados económicos.
Las Opuntias son símbolos resilientes de adaptabilidad y utilidad dentro de nuestros jardines. Aunque el insecto Cochinilla presenta desafíos, también muestra cómo una plaga que puede ser tanto un enemigo como un amigo dependiendo del contexto. Al comprender las complejidades de esta relación, podremos apreciar y salvaguardar mejor estos notables nopales para las generaciones venideras.
- Author: Lauren Fordyce
It may be after Labor Day, but some of your plants may still be wearing white, breaking that long-standing fashion “rule”! While many of us don't adhere to this old rule for our wardrobes these days, you may care about white stuff on your plants this time of year.
There are several white colored pest insects and diseases that you could be noticing on your plants.
Scales
Several types of scale insects are white. Each has their own host preferences, or plants they feed on.
- Cochineal scales feed only on cacti, usually prickly pears. On the outside they are white and waxy but have bright red bodies. If you scrape them off, you'll notice a red stain left behind.
- Cottony cushion scale feeds on a variety of woody ornamental plants. Common hosts in California are citrus, cocculus, nandina, and pittosporum. Adult scales are elongated and fluted.
- Euonymus scale feeds on many different plants but can be a serious pest to Japanese Euonymus (Euonymus japonica). Immature males are white and elongated with a brownish-yellow area at one end.
See the UC IPM Pest Notes: Scales to learn more about these and other scales and how to manage them.
Mealybugs
Mealybugs are whiteish-gray, oval, wax-covered insects. They can be found on many different plants, from fruit trees to houseplants, often hiding in protected places like branch crotches.
Powdery mildew
Powdery mildew often appears as white powdery spots (fungal spores) primarily on the tops of leaves. It can infect fruits and fruit trees, vegetables, and landscape plants in shady conditions when temperatures are between 60 to 80 degrees.
Whiteflies
Whiteflies are tiny insects with white, waxy wings and yellow bodies. They feed in large colonies on the undersides of leaves and have a very wide host range, including trees, vegetables, houseplants, and flowers.
Hackberry wooly aphids
This introduced aphid species infests Chinese hackberry and other hackberry (Celtis) plants. Hackberry wooly aphid adults appear in white, fuzzy masses on shoot terminals and leaves.
Spittlebugs
Adult spittlebugs are often brown, but they produce a white, foamy excrement on plants that looks like spit. They are known to feed on just about any plant.
Mushrooms
Many fungi produce white fruiting bodies that may pop up in your lawn, mulched landscape beds, or on trees and stumps. Puffballs and other fungi in lawns are mostly just a nuisance. However fungi on trees can sometimes cause wood decay and harm trees.
For more help diagnosing a plant problem or identifying a pest, see the UC IPM Plant Problem Diagnostic Tool or contact your local UC Master Gardeners.
- Author: Kathy Keatley Garvey
Nicknamed the Biological Orchard and Gardens (BOG), it still contains the heritage fruit trees and mini-gardens, but one landscaped section that used to showcase phacelia, lupine, tidy tips, desert bell, baby blue eyes and other bee plants is now a haven for cacti and succulents.
"We just recently made a succulent garden," related Marlene Simon, curator of the UC Davis Botanical Conservatory and a UC Davis alumna. "We needed to move our large cacti collection and figured it would be nice for the public to see it. We plan to add more succulents such as agaves in the near future. It was going to be the Mediterranean section but we have moved that to the area next to the South African section."
BOG has been described as a living museum. The orchard contains heritage fruit tree varieties threatened with commercial extinction. They include the Gravenstein and Johnathan apples; the Suncrest peach; the Bleinheim apricot, the Mariposa plum and the Meyer lemon.
"Her home away from home is the magical UC Davis Botanical Conservatory...Here Marlene grows and cares for over 3,000 species of the world's most exotic/rare plants and flowers. In her spare time between appearing on Good Day Sacramento and work at the Conservatory, she guest lectures on all topics of organic gardening. As a fervent animal lover, Marlene donates her expertise to establish a wildlife garden at a regional non-profit wildlife center. When not immersed in the plant world, she can be found training daily for her next adventure, spanning from mountaineering to triathlon."
BOG is located in front (or back) of the Mann Laboratory on Kleiber Hall Drive, depending on which way you're going! If you park in Lot 26, off Kleiber Hall Drive, it's a short walk down the sidewalk to BOG.
![A garden in progress...A new addition to the Joseph and Emma Lin Biological Orchard and Garden at UC Davis is a cacti/succulent garden. (Photo by Kathy Keatley Garvey) A garden in progress...A new addition to the Joseph and Emma Lin Biological Orchard and Garden at UC Davis is a cacti/succulent garden. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/100700.jpg)
![Cacti are thriving in the Joseph and Emma Lin Biological Orchard and Garden at UC Davis. (Photo by Kathy Keatley Garvey) Cacti are thriving in the Joseph and Emma Lin Biological Orchard and Garden at UC Davis. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/100701.jpg)
![Marlene Simon, curator of the UC Davis Botanical Conservatory, answers a question during the UC Davis Biodiversity Museum Day, held on the Saturday of Presidents' Weekend. (Photo by Kathy Keatley Garvey) Marlene Simon, curator of the UC Davis Botanical Conservatory, answers a question during the UC Davis Biodiversity Museum Day, held on the Saturday of Presidents' Weekend. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/100702.jpg)
![UC Davis plant biology major Gabrielle UC Davis plant biology major Gabrielle](/blogs/blogcore/blogfiles/100703.jpg)
With our long, hot summers and drought seemingly becoming the norm, many home gardeners are on the lookout for water-efficient plants. Although often overlooked, the cacti found in North and South American deserts fit this purpose nicely, and as an added bonus most species have colorful, often spectacular, blooms. While there are also species of cacti found in cloud forests and even rainforests, these would not be appropriate for outdoor landscaping in the Northstate.
In the absence of leaves, the green stems of cacti have taken over the job of photosynthesis. In most plants, stomata (pores) on the leaves open during the day to allow for the uptake of carbon dioxide and release of oxygen during photosynthesis. This creates a problem for plants living in arid climates because whenever their stomata are open, water evaporates from them. Cacti and several other plant families have resolved this issue by utilizing a metabolic pathway known as crasssulacean acid metabolism (CAM). On the CAM pathway, stomates are closed during the day and open at night, limiting the loss of water. While their stomates are open at night, CAM plants take in carbon dioxide, store it in the form of malic acid, and then release the carbon dioxide from the malic acid the next day so that it is available for use in photosynthesis. This process requires the expense of a lot of energy, but since plants depend on solar energy, it is not an issue for sun-drenched desert plants like cacti.
Many cacti have shallow root systems that extend widely to quickly absorb as much moisture as possible from rare rainfalls. A cactus that is just a few inches tall may have roots reaching out several feet.
Cacti can be grown in any sunny, well-drained area. Smaller varieties can be kept as potted houseplants; hardy species can be grown as landscape plants, either in pots or in the ground. The best time to plant a cactus is in the late spring or summer, when its roots are actively growing. Always plant cacti bareroot. Let the soil in the pot dry out and then gently loosen the soil in the root ball and shake it off.
When planting a cactus, prepare a hole that is as deep as the plant's root ball and one and one-half times as wide. Place the cactus so that its stem is at the same depth it was before transplanting. Use heavy gloves and/or a thick layer of newspaper wrapped around the plant when handling a cactus. If your native soil is coarse textured and drains well, you can use it to fill in the hole and then pack it firmly around the root ball. If your soil is heavy and doesn't drain well, it would be wise to dig a deeper hole and backfill it with cactus mix. There are several cactus mixes available commercially, but if you want to make your own, a good recipe is three parts sand, three parts regular soil and two parts pumice or perlite. Planting cacti in raised or mounded beds is another work-around for slow draining, heavy soils.
If your cactus came from a lath house or outdoor greenhouse, protect it with a shade cloth for a couple of weeks. This will help it acclimate to the stronger outdoor sun and the cactus will be less likely to become sunburned while its outer skin toughens up. Once the cactus is in the ground, it should be watered until the soil is about as damp as a wrung-out sponge. While cacti require minimal care, their number one cause of death is over watering, so after the initial watering wait and don't water again until the top two or three inches of soil are dry. If your cactus looks a little shriveled, you may need to water it sooner. Cacti in pots usually need to be watered more often than those that are planted directly in the ground. Most cacti are dormant in the fall and winter, so they need little, if any, water then.
Cacti can be frost sensitive, but there are several genera that more cold-hardy. Cold-hardy genera include (but are not limited to): Opuntia, Ferocactus, Echinocereus, Escobaria, Corypantha and some species in the genera Cereus and Mammalaria. It is important to note that in many instances, “it's not the cold, but the wet” that can kill these cacti.
Opuntia cacti are also known as beaver-tail, or prickly pear cactus. Their stems consist of flattened, segmented pads. Most species of Opuntia have yellow flowers, but species with vivid purple, pink, red, or orange flowers are common as well. Opuntias can range in size from less than a foot to 15 feet tall. Their fruit is edible, but care must be taken to remove the spines before eating it. Young stems, called pads or nopales, are also edible and are an important part of Mexican cuisine.
Members of the genus Ferocactus are large, deeply ribbed, barrel-shaped cacti. Their “fishhook” spines often form an almost impenetrable armored web around the plant body. Their flowers can be pink, yellow, red, or purple, depending on the species. Ferocactus plants can range in size from less than a foot to over 12 feet tall, but most species are between one and four feet tall. Although these barrel cacti do contain water, it is not considered potable and is likely to cause diarrhea if it is ingested.
Echinocereus is commonly known as the hedgehog cactus. It is a relatively small, columnar cactus, with species seldom growing more than a foot tall. Although these plants are small, various species often produce masses of purple, red, pink or yellow flowers. Echinocereus spines can be tinged with pink, producing interesting color patterns on their stems.
Escobaria, commonly called pincushion cactus or foxtail cactus, is different from most other cacti in that it lacks ribs. Instead, Escobaria cacti have lobed protrusions called tubercles. Species in this genus are generally no more than six inches tall and can be columnar or globe-shaped. They can be solitary or grow in clusters and their flowers vary from yellow to pink, red and purple. Several Escobarias are extremely cold-hardy; this widespread genus is found from Mexico to Canada.
Coryphantha cacti, commonly known as beehive cacti, are very similar to Escobaria. To the layperson, they may look the same, but botanists have placed them in different genera because of significant differences in their seed coats. The Coryphantha genus is not as widespread as Escobaria and most species are uncommon.
Members of the genus Cereus are large, columnar, night-blooming cacti, but cereus is also used as the common name for several other night-blooming genera of cacti. Many members of the genus Cereus are frost-sensitive, but one Peruvian species, Cereus peruvianus, is hardy to 18° F! C. peruvianus, the Peruvian apple cactus, commonly grows to eight feet tall, but can reach heights upwards of 20 feet, making it an impressive focal point for a cactus garden. The flowers of the Peruvian apple cactus are large and white and last just one night; the petals wither in the morning sun. Its pollinator is a moth and if pollination is successful a large, red, spine-free fruit will develop. As its name implies, this fruit is edible. The flesh of the Peruvian apple cactus is crunchy and has been described as refreshingly juicy with a subtly tart sugarcane taste.
Plant Sale! The Master Gardeners will hold their Fall 2021 Plant Sale on October 30, from 9am to 1pm at the Demonstration Garden at Patrick Ranch (10381 Midway, Durham). Along with the Plant Sale, there will be two free workshops: “Gardening with Natives” at 10am, and “Berry and Grape Gardening” at 11am. No registration is required for these workshops; Covid safety protocols will be followed.
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu (preferred) or call (530) 538-7201.
- Author: Georgia Luiz
Lately, it seems I've been searching for hard to find cacti and succulents. This can become an interesting rabbit hole, leading to all kinds of eccentric people with passions for obscure species. Passions strong enough to get them to travel thousands of miles and go on expeditions for seeds in the wilds clear across the planet. This is what they do, it is how they roll, and once you get them started, just get comfy, because you'll be there a while. One of these meandering conversations led to the purchase of peyote seeds. No, not that kind. Lophophora williamsii, the infamous hallucinogenic is not legal for sale, which is fine by me, because I don't think I could bear to harvest it. These little cacti (Lophophora diffusa) are so cute. They look like green bellybuttons. And they are easily grown from seed. They popped up in 3 days. 5 out of 6 germinated. So if you're interested in an easy small indoor cacti any species of peyote cacti available for retail is a surprisingly easy choice.
![Lophophora diffusa. (painting by Georgia Luiz) Lophophora diffusa. (painting by Georgia Luiz)](/blogs/blogcore/blogfiles/13221.jpg)