It's hot. Tomatoes like heat, right? Actually, tomatoes like warm weather, between 65 and 85 degrees. When temperatures soar past 95, tomatoes stop growing. In that kind of heat, their flowers fail to pollinate and instead they dry up and drop off, putting a pause on the production of new fruit. Tomatoes that have begun to color will halt at orange and fail to turn red.

We can't control the sun, but there are a few things we can do to help tomatoes stay productive in our hot valley summers. In the first place, plant tomatoes in a spot that gets sun in the morning and filtered sun in the afternoon. If tomatoes are sitting in the blazing sun all day, create afternoon shade for them with a sheet of row cover material or shade cloth clipped to the west-facing side of the support structure on which the tomatoes are growing. Arrange the cloth over the tops of the plants to protect from mid-day sun as well. Leave the east side of the plants free for morning sun and air circulation, and to allow pollinators to reach plants. Clothes pins or binder clips can be used to secure the row cover material or shade cloth and are easy to take off to allow access to harvest. Use of shade cloth can drop the ambient temperature by as much as 10 degrees and is often sufficient to keep tomatoes in that sweet spot of productivity.

If your tomato plant has good green leaf color, is flowering and has fruit developing, but its leaves are curling up, you are experiencing a common summer problem for tomatoes in our area. The culprit again is most likely heat. Tomato leaves transpire water from the undersides of their leaves. When a tomato plant can't take in as much water as it is losing, its leaves will curl up. This occurs when the soil is too dry, the temperature is too hot, or it's too windy. Check soil moisture by poking a finger an inch into the soil. If it's dry, it's time to water. Leaf curl is the tomato's way of reducing leaf surface area to reduce water loss. Curling up will not affect fruit production or the health of the plant.

Upward leaf curl can also result from overwatering. Too much water can cause roots to rot. Rotten roots will not be able to pull in moisture and, though water is abundant, the tomato plant can be dying of thirst. Again, a finger into the soil will tell you if the soil is too wet. The plant will not recover from root rot.

There is one further thing to rule out before you rest in the tranquility that upward leaf curl requires no action on the gardener's part: pests. Check a few leaves to be sure the curl isn't harboring an insect or caterpillar cocoon. No caterpillar, no problem. Your tomatoes are fine in their self-protective upward curl.

A two- to three-inch layer of mulch around tomatoes will help the soil retain moisture and stay cooler. Straw, wood chips, chopped leaves, and grass clippings are all fine mulches for this purpose. Mulch also helps keep moisture around tomato plants more even; this can keep the fruit from cracking and help to prevent blossom drop.

Ever wondered how to encourage sweeter tomatoes? Here temperature and sun are your friends, to a point. Ninety degrees and lots of sun will give you a sweeter tomato. At 100 degrees, fruits develop color on the outside, but stay green on the inside: not tasty. So when temperatures soar, pick tomatoes that have begun to color and allow them to ripen indoors. Remember: never refrigerate a tomato.

For the health and beauty of your tomatoes, give them a bit of protection in the heat of summer. Mulch and a bit of shade will help in maintaining happy plants that produce delicious tomatoes.

For more information see ANR Publication on Growing Tomatoes in the Home Garden.

The 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.

Continuing our focus on select species of Eriogonum (wild buckwheat), this week's discussion features California buckwheat (E. fasciculatum).

First, here is a quick review of characteristics common to all of California's wild buckwheats. They are hardy colonizers of tough soils and dry ecosystems, such as coastal scrub and chaparral. They can live at the edges of deserts and up to high elevation tree lines. Their blossoms are important to pollinators such as bees, butterflies, and hummingbirds, providing them with flowering food long after other natives have gone dormant. Buckwheat flowers have tall, slim, delicate anthers that seem to float above the flower mass, creating their signature lacy or frilly look. Because they hybridize indiscriminately, at last count there were over 250 species to explore and enjoy.

Species Focus - California Buckwheat

Eriogonum fasciculatum, best known as California buckwheat and sometimes called eastern Mojave buckwheat or flat-topped buckwheat, is found primarily on dry slopes and canyon washes in the American West, including Nevada, Utah, and Arizona, in addition to California and reaching as far as Mexico's northwest. In California it is the most widespread of the shrubby buckwheat species, found in abundance in the southern half of our state. It is less common in the Central Valley and northern reaches, although it has proven to be a successful a landscape plant in Butte County. Its adaptation to our Mediterranean climate allows it to survive on as little as seven inches of rain annually.

This buckwheat species is evergreen and blooms from May through October. It can grow to nine feet high and six feet wide (almost as big as its largest family member, the giant buckwheat), but usually reaches around four feet in height and width. E. fasciculatum is a very pretty plant when flowering – its many small, frilly white or pink flower clusters are held aloft on flexible, slender stems above rafts of narrow green leaves. The blossoms turn rusty or burnt orange in color as they dry late in the season, adding muted fall colors to the landscape. Leaves are fuzzy on the underside, and either smooth or fuzzy on top.

According to California Native Plants for the Garden (an excellent resource for gardeners looking to shift from traditional thirsty landscaping to a yard that conserves water and sustains pollinators), the hairs on E. fasciculatum's leaves contribute to its ability to withstand the dry and harsh conditions of the ecosystems it inhabits. Hairy leaves provide insulation from heat and protection from direct sunlight as well as a boundary air layer that reduces water loss.  

Its genus name, fasciculatum, comes from the Latin word meaning “bundles,” used in botany to refer to the growth habit of plant leaves. It shares this genus name with many other plant species.

California buckwheat makes excellent honey, and the plant is billed as the most important native source of honey in the state. (Honey made from yellow star thistle may be just as delicious, but that plant is an aggressive and invasive intruder!)

Native American peoples in the west and southwest used different parts of the California buckwheat for nutrition and medicine. The Cahuilla tribe of what is now the greater Palm Springs area used this plant in many ways: they treat headaches and stomach pains with tea made from its leaves; treated colds and sore throats with tea made by steeping its roots; and applied poultices made from pounded roots to wounds. Cahuilla peoples also treated heart problems with tea from the dried flowers and dried roots of E. fasciculatum. Modern science has verified that a chemical compound common to several plant species including Eriogonum can be beneficial to hearts (USDA Plant Profile).

The Natural Resources Conservation Service, a division of the US Department of Agriculture, identifies and experiments with natives and other plants for their conservation value - primarily their ability to protect soils from erosion, revegetate burn scars, and provide habitat and sustenance to wildlife as an aid in controlling agricultural pests. Their experiments with California buckwheat show that it has superior value in all three of these categories. The USDA Plant Profile for E. fasciculatum classifies its performance as a conservation plant on critical areas and problem soils as “excellent.” It receives another “excellent” mark for providing “nectar sources for beneficial insects when planted next to crops as part of an (IPM) Integrated Pest Management program.” They recommend the use of its seeds in seed mixes introduced to burn scars for revegetation. Finally, California buckwheat gets USDA bonus points because it is “ideal for environmental enhancement uses” (government-speak for “beautiful in the landscape”).

If you plant E.fasciculatum in your yard, be sure to locate it away from regular irrigation sources and in soil that drains well. It will be happy if you give it problem soil (rocky, alkaline, etc.). Make sure it has room to expand or even take over, because it can become invasive. It is an attractive and valuable addition to any drought resistant, native pollinator garden.

A number of buckwheat species, including a large lovely California buckwheat, are thriving in the Butte County Master Gardener Demonstration Garden at Patrick Ranch (located just south of Chico on the Midway). At this time of year, they are abuzz with bees, and visited often by butterflies. Due to our current safety measures, no human visitors are allowed, but we look forward to seeing you there in the future, so you can appreciate the fascinating buckwheat family and our gardens in general.

For more information on E. fasciculatum, see the following sources:

Calflora

United States Department of Agriculture, Natural Resources Conservation Service, Plants Database

Carol Bornstein, David Fross, and Bart O'Brien, California Native Plants for the Garden (Cachuma Press, 2005)

The UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system, serving our community in a variety of ways, including 4H, farm advisors, and nutrition and physical activity programs.  Master Gardeners bring practical, scientifically-based knowledge directly to our community. For help with gardening in our area, visit our website. If you have a gardening question or problem, call the Master Gardener Hotline at (530) 538-7201 or email mgbutte@ucanr.edu.

We often experience ants in our homes when weather conditions change. They are typically looking for food, water, warmth, and/or protection from extreme weather conditions. Ants belong to the insect order Hymenoptera and are close relatives of bees and wasps. The most common outdoor ant found in California is the Argentine worker ant. The Argentine worker ant is approximately 3mm long, dark colored and does not sting. They have no natural enemies. Their colonies have multiple queens and only the queens lay eggs. An ant's life cycle moves from egg to larva to pupa to adult. Their nests are normally found in moist soils, under debris or along sidewalks and driveways. Argentine ants are drawn to sweet foods but will also feed on protein (e.g. dead bugs). The Argentine ant will venture up to 100 feet away from the nest to find food, water and shelter inside buildings. Once inside, if ants find food, they will continue to invade until the food source is removed and/or the entryway sealed.

While it is not realistic to eradicate all ants from your backyard, you can effectively reduce the number of ants entering your home by following a 3-Step integrated approach as follows:

Minor Indoor Problem (small trail of ants observed infrequently). Prevent further intrusion by:

1) Identifying the location where the ants are getting into the house. Inspect baseboards, floors, electrical outlets, vents, pipes, drains and walls for any entryways and seal them off (caulk is good for this). Destroy any nesting sites found close to the house. Cut back trees, shrubs or wooded material touching the house and clear away mulch or debris that is next to the house.  

2) Clean up food and water sources in the home. All sources of “attractive” food should be removed or securely sealed. Use soapy water to kill ants and eliminate their trails.

Moderate (trails of hundreds of ants) and Severe (several hundred to thousands of ants continue to invade for weeks or months). Supplement steps 1 and 2 above with the addition of bait stations as follows:

3) Install bait dispensers around the outside of the house (UC Researchers have had success using bait dispensers such as KM AntPro Liquid Bait Dispenser). Baits are more effective and less toxic than traditional pesticide treatments for ants. Baits are insecticides mixed with materials that attract worker ants. The advantage of a bait station over an insecticide spray is that the spray only kills the worker ant while the bait station allows worker ants to take the bait back to the colony to feed and kill the colony ants, including the queen ant. When all the queens die, the colony is destroyed. Continue to refill dispensers regularly with liquid borate-based bait until the ant problem ceases. It is critical that you select the right bait/attractant for Argentine ants (liquid baits with 1% or less borate are suggested). Install at least one dispenser on each side of the house, next to structures where ants are trailing (but at least 5 ft. from any nest). Keep ant bait stations out of direct sunlight.

Following the 3-step approach above should correct home ant invasions. For more information see the UC IPM Pest Notes on ants.

The 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 or call (530) 538-7201.

Is there an area in your garden where you are battling noxious weeds or other invasive plants? If so, soil solarization is a solution that avoids the use of herbicides and saves you from the on-going work of pulling up the invaders. Our hot summer months are the ideal time to employ this method.

Soil solarization is a simple, non-pesticidal method for controlling diseases, nematodes and weeds that is ideal for the Central Valley of California. Placing clear plastic sheets over wet soil during hot summer temperatures for 4 to 6 weeks will kill most diseases, pests and weeds. In addition, research has shown that this method speeds up the breakdown of organic material in the soil and aids in the release of soluble nutrients such as nitrogen. Plants grown in solarized soil often grow faster and produce greater, better-quality yields.

Solarization most effectively controls soil-borne fungal and bacterial plant pathogens such as those causing Phytophthora root rot, Southern blight, Verticillium wilt, Fusarium wilt, damping off, crown gall, tomato canker and potato scab.

Nematodes can be controlled but not completely eliminated by solarization, because they are mobile and can move through the soil. Control is most effective in the top 12 inches of soil.

Most annual and perennial weeds can be controlled by solarization. It is particularly effectively in controlling winter and summer annuals. Perennial weeds are more difficult to control because roots and rhizomes can be buried deep in the soil. Solarization is not effective in controlling field bindweed, or yellow and purple nutsedge.

While solarization kills many soil pests, beneficial soil organisms either survive or recolonize the soil rather quickly. Earthworms can retreat to lower depths. Beneficial fungi such as mycorrhizal fungi and bacteria that parasitize plant pathogens quickly reestablish themselves.

Solarization is most effective when days are long, temperatures are hot, skies are clear, and winds are mild. June to August is therefore the most effective time in the Central Valley. Prepare the soil by removing weeds, rocks or other debris. Break up dirt clods and create a smooth soil surface.

Saturate the top 12 to 24 inches of soil. Wet soil conducts heat the best and is more effective in killing soil organisms. Cover the soil immediately after irrigation. Usually irrigation is not needed again, but very light or sandy soils may require a second irrigation. If needed, drip lines can be installed under the plastic.  

Use clear plastic to snugly cover the smooth soil surface. Lay the plastic as close as possible to the soil surface so there are few air pockets. Thin clear plastic (1 millimeter) provides the greatest heating potential but is more susceptible to tearing. Slightly heavier plastic (1.5 to 4 millimeters) may be best. The type of drop cloths used in painting work well. The plastic sheeting should be slightly bigger than the area to be solarized. Dig a trench around the area. Cover one edge of the plastic with soil to hold it down. Pull the plastic tight across the soil and bury the opposite edge. Do the same with all sides. Keep the plastic as close to the soil surface as possible.

After 4-6 weeks the plastic can be removed. Treated soil can be immediately planted or left fallow until the next growing season. Additional information can be found in the UC IMP Pestnote, Soil Solarization for Gardens & Landscapes.

The 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, call the Hotline at (530) 538-7201 or email mgbutte@ucanr.edu.