- Author: Kathy Keatley Garvey
One potato, two potato, three potato, four...
You never know what will pop up in a pollinator garden.
Meet Mr. Potato Capsid, Closterotomus norvegicus, often found on nettle, potato, clover and cannabis.
We spotted him (or her) in a Vacaville pollinator garden, where there is no nettle, potato, clover or cannabis. But it also feeds on chrysanthemum, carrots and members of the sunflower family, Asteraceae.
It popped up on a chrysanthemum blossom. The insect is green and probably a nymph as the color changes, when it's an adult, to reddish brown.
It belongs to the family Miridae. Entomologists point out that this family is the largest of true bugs belonging to the suborder Heteroptera.
At first we thought it was a lygus bug, which is also a myrid and a serious pest of cotton, strawberry and alfalfa.
But no, a potato capsid, an insect originating in the Mediterranean region. It prefers to feed on flowers, buds and unripe fruit.
Same family, though.
- Author: Lauren Fordyce
Plentiful rainfall in California this spring created an ideal environment for many plants to thrive, including wildflowers, trees, and shrubs that desperately needed the water. However, other potentially harmful species also benefited from the unusually wet weather. Of particular concern are poisonous plants which are growing abundantly in parks and wildlands this year. These plants pose health risks to people, especially children, and pets. Being able to identify poisonous plants and understand available control options is critical for the safety of people who encounter them. While several poisonous plants grow in California, a few of the more common are detailed below along with information on how best to remove or manage them.
Poison Hemlock
Poison hemlock (Conium maculatum) is an invasive weed that thrives in disturbed areas but it can also invade native plant communities. It is commonly found in meadows, pastures, and fields, and may spread quickly after the rainy season. All parts of the plant are toxic to humans and animals when ingested. Touching poison hemlock may cause contact dermatitis for some people.
Poison hemlock can easily be mistaken for its relatives in the family Apiaceae, like carrot, parsley, parsnip, or celery, especially when plants are young. Leaves are triangular shaped, deeply lobed, and have opposite branching (Figure 1). Unlike invasive wild carrot (Daucus carota), poison hemlock lacks hairs on its leaves and stems. Poison hemlock has white, umbrella-shaped flowers, similar to those of native cow parsnip (Heracleum maximum). However, cow parsnip has much wider leaves that are arranged in threes and can measure up to 16 inches wide. You can also distinguish poison hemlock from similar plants by checking for purple streaks or spots along its hollow stems. Mature plants can reach almost 10 feet tall.
Poison hemlock is best controlled when young, before it sets seed. It releases seeds over several months, and copious amounts of seed can build up in the soil. Small infestations of poison hemlock can be managed by hand removal while wearing gloves or hoeing the area. The taproot must also be removed to prevent regrowth. Repeatedly mowing poison hemlock can deplete its energy and prevent seed production. Be sure to clean mower blades to avoid moving seeds to new areas. Herbicides containing 2,4-D, triclopyr, or imazapyr work best on seedlings. Glyphosate, chlorsulfuron, and metsulfuron are effective on larger, rapidly growing plants. Repeated herbicide applications may be required for several years until the seedbank has been depleted. Never burn poison hemlock as this can release its toxins into the air.
Poison Oak
Poison oak (Toxicodendron diversilobum) is a deciduous native plant that is widespread through California's coastlands, woodlands, rangelands, riparian areas, and urban parks and gardens. Poison oak, like its eastern relative poison ivy, contains an oil called urushiol that can cause contact dermatitis and itchy, weeping rashes on the skin of people who are sensitive to urushiol. The allergy-causing oils can persist on tools, clothing, and other objects for months or even years.
The old adage “leaves of three, let it be” often holds true for poison oak, but not always. Plants normally consist of 3 leaflets, but may sometimes contain 5, 7, or 9. Leaves are slightly lobed and occur alternately along the stem (Figure 2). They can vary in color and texture from glossy to dull, and thin to leathery. In open, sunny areas poison oak can grow to be a dense shrub. In more shaded areas it grows as a climbing vine. It can easily spread to cover large areas via seeds and rhizomes.
Poison oak can be removed through hand pulling and digging (including roots) with a shovel; wear protective clothing and gloves, and promptly wash or discard them afterwards. Removed plants should be carefully disposed of since the oils remain hazardous even after the plants have dried. Never burn or mow poison oak as it will release its oils into the air, posing an inhalation risk. Herbicides that contain at least 41% glyphosate or 61% triclopyr ester have been shown to provide effective control. Dicamba and imazapyr can also be used. Foliar applications should be made in the late spring or late summer, depending on the chemical used. Cut-stump treatments can be performed in the spring or fall.
Burning and Stinging Nettles
Unlike poison oak and poison hemlock which may only affect some people, burning and stinging nettles (Table 1) cause burning rashes to anyone who touches them. The rashes are caused by a toxin in the prickly hairs on the leaves and stems. Contact with burning and stinging nettles can cause blisters and red patches. Itching, burning, and tingling sensations may persist on the affected skin for several hours.
Burning nettle | Stinging nettle |
Found in disturbed sites, roadsides, orchards, and gardens; common along the coast | Found in unmanaged areas, riverbanks, moist wildlands, and roadsides |
Summer annual; blooms January to April | Perennial; blooms March to September |
Spreads by seed | Spreads by seed and rhizomes |
5 inches to 2 feet tall when mature | 3½ to 10 feet tall when mature |
Opposite leaves with toothed margins; ½ inch to 2 inches long (Figure 3) | Opposite leaves with toothed margins; 2½ to 5 inches long |
Burning and stinging nettles can be nuisance plants as well as health hazards. However, they are not considered invasive or noxious weeds. In fact, stinging nettle is native to California so control should only be performed if plants are causing economic or health concerns. Hand pulling while wearing gloves can be effective, but the underground stems (rhizomes) of stinging nettle must also be removed. Mowing close to the ground can prevent seed development and spread, but if done too early in the season the nettles will regrow rapidly from the rhizomes. The active ingredients 2,4-D, aminopyralid, dicamba, glyphosate, and triclopyr provide excellent control for both stinging and burning nettles.
To learn more about controlling these toxic weeds in landscapes and natural areas, see the Weeds page on the UC IPM website at ipm.ucanr.edu/PMG/menu.weeds.html or the Weed Research Information Center wric.ucdavis.edu. These and other weeds are described in the book Weed Control in Natural Areas in the Western United States, available from the UC ANR catalog anrcatalog.ucanr.edu.
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By Susanne von Rosenberg, UC Master Gardener of Napa County
It's May and everything is growing beautifully, including weeds. Even if your garden is exceptionally well-weeded, new invaders will creep in and demand attention. Our general reaction is to remove them as soon as we realize that we have them, and we think of a good, tidy garden as one that is free of weeds.
In general, until you are comfortable with weed identification, keeping your garden entirely free of things that you did not plant is a good approach. However, weeds can also provide some benefits, so learning about the different weeds can help you decide whether you just might let certain ones grow for a while. Over time, you may make friends with certain weeds and make them part of the cycle of your garden.
So what is a weed? Most commonly we consider something a weed if it is growing somewhere we don't want it to. Those California poppies you love in your flower beds just might be a weed if they start growing in your vegetable bed. I was surprised to learn that some people consider miner's lettuce, an edible California native that I carefully cultivated in my garden, a weed.
How can weeds actually be beneficial? Some weeds are edible, many can supplement your compost, and some help loosen the soil. They may provide erosion control and dust control. Some provide food or habitat for pollinators and other wild animals.
In addition, weeds can teach us about our soil. Certain weeds prefer specific soil conditions, so if you have those weeds, you can assume that your soil has those characteristics.
Common edible weeds include purslane, dandelion, lamb's quarters, nettles, fennel and chickweed. If you're not sure what you're looking at (you only know it's not something you planted), you can use the weed identification tutorials and information on the University of California Integrated Pest Management (UC IPM) site. If you're going to eat weeds (the ultimate revenge), use common sense. Never eat anything if you're not totally certain you've identified it correctly.
Many weeds make good additions to your compost or can serve as mulch. Annual weeds that have not developed flowers can be chopped up and left in place, although in winter and in moist areas of your garden, you have to make sure they don't re-root. You can also chop them and add them to your compost bin.
Those parts of perennial weeds that won't re-sprout can also be added to compost or used as mulch. With perennial weeds, though, it's important to know how they propagate so you don't inadvertently spread a problem. If a perennial weed has not flowered, you can also let it dry out completely (think completely crispy and brown) and then put it into your compost.
Some weeds improve soil by growing deep roots that break up the subsoil (the layer immediately below the topsoil). That allows the weaker roots of more delicate plants to access the water and nutrients there. Some common weeds with deep, strong roots include wild chicory, plantain, sow thistle and vetch, as well as lamb's quarter and purslane. Cut these weeds off at the soil surface before they start to flower. The roots will decay in place, adding organic matter to your soil. The tops can go into your compost. You'll get the most benefit if you keep these weeds fairly far apart; if they grow close together their roots won't penetrate as deeply.
Some weeds are great for attracting pollinators. However, you have to let the weeds flower. The mustard we see flowering in Napa Valley vineyards is one example. Fennel, wild radish and pigweed are other examples of weeds that are good pollinator plants. Pull them as soon as they have bloomed, and do not put the spent flowers in your compost.
Weeds can also act as living mulch. This feature can be particularly helpful in winter, if you are not growing vegetables or an intentional crop such as fava beans. Almost any annual weed can serve as living mulch. (You do not want to give perennial weeds the benefit of extra growing time.) Some annual weeds, such as chickweed and purslane, will form a mat as they grow and thus help suppress other weeds.
Finally, weeds give you clues about what is going on with your soil. Like other plants, weeds have specific soil preferences. Chicory, purslane and lamb's quarters are generally good news because they indicate rich soils. Thistles, wild turnip and bindweed, on the other hand, can indicate that you have compacted soil or a crusted soil surface. Poor drainage can be indicated by weeds such as sedges and Bermuda grass.
Research your weeds and learn what they tell you about your garden. Whether as indicators, food or soil improvers, weeds can be garden helpers, too.
Weed photo gallery list from UC IPM is here, a LIST OF ALL WEEDS. Find the common name to see a photo.
http://ipm.ucanr.edu/PMG/weeds_all.html
If you wish to ID the weed, use the UC IPM weed ID tool here:
http://ipm.ucanr.edu/PMG/weeds_intro.html
The UC Master Gardeners of Napa County are volunteers who provide University of California research-based information on home gardening. To find out more about home gardening or upcoming programs, visit the Master Gardener website (napamg.ucanr.edu). Our office is temporarily closed but we are answering questions remotely and by email. Send your gardening questions to mastergardeners@countyofnapa.org or leave a phone message at 707-253-4143 and a Master Gardener will respond shortly.