- posted by: Yvonne Rasmussen
- Author: Monica Finigan
This summer, the Napa County Master Gardener help desk received many calls about peach leaf curl, a fungal disease that affects the leaves and shoots of peaches and nectarines. It causes distorted, reddened leaves that eventually fall off the tree. See UC Integrated Pest Management page for photos and further descriptions of the disease.
Symptoms normally appear about two weeks after leaves emerge. The first signs are red spots on the leaves, which soon become thick and puckered. Whitish spores appear on the leaf surfaces, then leaves turn yellow and drop off. Healthy new leaves do emerge to replace the fallen ones unless subsequent showers cause the disease to spread to the new leaves.
If healthy leaves replace the damaged ones, why should a gardener be concerned? Because peach leaf curl affects the vigor of the tree. In severe cases, the disease can significantly reduce fruit production and tree growth. If peach leaf curl builds up and the tree is left untreated for several years, the tree may seriously decline and need to be removed.
Unfortunately, there are no effective treatment options between spring, when the symptoms appear, and summer, when the tree bears fruit. Although some gardeners pull off the diseased leaves, this technique has not been proven effective.
Taphina deformans, a fungus, causes peach leaf curl. Periods of cool, wet weather when leaves are beginning to unfurl create a favorable environment for the fungus. Maximum infection develops when the trees are wet for two or more days during this vulnerable period. Our spring weather pattern over the past three years has provided the conditions this fungus loves.
To control peach leaf curl, treat peach and nectarine trees with a fungicide in fall after leaves have dropped. In the past, the disease could be successfully treated with either lime-sulfur fungicide or a fixed copper fungicide with a copper compound containing at least 50 percent copper. Unfortunately, the most effective products have been removed from the market by the manufacturer. The only fungicides left for treating peach leaf curl contain lower levels of copper and copper soap.
You can make the copper ammonium complex products more effective by adding horticultural oil to the treatment mixture. The oil, which should be one percent of the mixture, also helps control some insects that affect the trees. Spray your trees twice, the first time in late November and the second time in early February. A handy trick for remembering those dates is to spray right after Thanksgiving and just before Valentine's Day. Spray trees until they are dripping.
Alternatively, you can prepare what's known as Bordeaux mixture. This treatment is effective against peach leaf curl, but it is not available for sale and you must mix the ingredients just before application. It takes longer to prepare and requires more knowledge and safety equipment both in the preparation and the application. Contact the Napa County Master Gardener office if you would like information on preparing and using Bordeaux mixture.
Another way to reduce peach leaf curl is to plant trees that are resistant to the disease. Resistant peach varieties include Frost, Indian Free, Muir and Q-1-8. Although frost is resistant, it does need fungicide treatments the first two to three years after planting.
In fact, all of the resistant varieties still benefit from spraying. While resistant, they are not immune, especially during years when the conditions are particularly favorable for the disease. My son, Sean, and I have both grown the Indian Free peach tree and found this heirloom to be vigorous as well as resistant to leaf curl. However, it is not self-fruitful, so it needs to be planted near another peach or nectarine tree for pollination. The nectarine variety‘Kreibich is also resistant to peach leaf curl.
If you experienced problems with peach leaf curl this year, consider pruning the tree this fall prior to applying fungicides. This practice can reduce the number of spores overwintering on the tree. Remove all pruning debris and dispose of it in the municipal yard-waste container. Do not water the tree with overhead sprinklers, as this could spread the spores. And don't forget to spray around Thanksgiving and shortly before Valentine's Day.
Napa County Master Gardeners (cenapa.ucdavis.edu) answer gardening questions Monday, Wednesday and Friday, 9 a.m. to noon, at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 253-4221.
- Posted by: Yvonne Rasmussen
October 27, 2012 - By Pat Hitchcock, U. C. Master Gardener
Lovely October! Nighttime temperatures are dipping into the forties, daylight hours are shrinking, and the tomatoes we adored in August are just not as tasty now, if in fact there are any left on the vines. If you haven’t done so already, now is the time to get some winter vegetables in the ground so you will have something fresh to eat in the cold months to come.
Among the easiest vegetables to grow are cool-season greens. You can eat them at any stage, from just barely sprouted to large and mature. Some greens, like lettuces and chicories, can be served raw in salads, and most of them can be boiled, steamed or braised. Many greens not only prefer the cooler temperatures of fall and winter, some of them actually improve in flavor if they experience light frost.
The easiest lettuces to grow are the loose-leaf types. If you are starting lettuce from seed, look for varieties labeled as cold-hardy. Local nurseries have many types available as seedlings, to give you a head start. Some nursery six-packs include a mix of types, a good choice if you like variety in your salad.
Chicories are related to lettuces and include endive, escarole and radicchio. Appreciated for their crunch and pleasant bitterness, these greens need to be grown in cool to cold weather to keep that bitterness in check. These hearty greens can be braised or enjoyed raw in winter salads with sliced persimmons or pears and toasted walnuts.
The Brassica family includes greens related to turnips and cabbage, such as arugula, collards and kale. Leafy mustards, bok choy and napa cabbage (Chinese cabbage) also belong to this family. Leaves from these plants add a lot of flavor to salads when picked young and tender. As plants mature, the greens are better suited to cooking. Brassicas are hardy and easily withstand the frosts of typical Napa Valley winters.
Also consider planting chard, beet greens and spinach this fall. These vegetables grow well in cool to cold weather. Ideally, you should start them in late summer to get them launched in warm soil, but you can still plant seedlings until the end of October. Place them in the sunniest location you have; winter days are so short that your vegetables will need as much sun as possible.
Before planting, add two to four inches of compost to your garden bed, digging it into the top few inches of soil. The organic matter in compost improves soil drainage and texture.
Consider adding fertilizer of some sort, especially if you grew summer vegetables in the same bed. Most compost is low in nitrogen and the other nutrients that growing plants need. If you are not sure what to add, go with an all-purpose formulation labeled for vegetables, and follow package directions. Too much fertilizer can harm seedlings and add unwanted chemical salts to your soil.
When transplanting seedlings, follow the recommended spacing on the plant tag. Consult a garden book if you aren’t sure. In general, place seedlings far enough apart so that they will touch only when full grown. Place leaf lettuces, arugula and spinach 8 to 12 inches apart; more vigorous greens, such as chard and cabbage, will need 12 to 18 inches between them. Handle plants carefully to minimize trauma to them, which can stunt them and reduce your yield. Plant them in moist soil, and do not let them dry out.
Water regularly until rain arrives. Often the first few storms do not bring enough moisture to wet the soil deeply, so monitor often and water as needed. Assuming a typical wet winter, your greens should not need watering unless we get a dry spell lasting more than a couple of weeks.
Common pest problems include aphids, slugs, snails, imported cabbageworm and cabbage loopers, as well as birds and deer. Watch for aphids and spray them off with water to keep them from establishing colonies. To minimize the caterpillar pests, protect your young plants with row cover. This lightweight garden cloth allows air and water through but keeps flying insects from reaching plants and laying eggs. Monitor for slugs and snails; pick them daily when they first appear to reduce their numbers and minimize their damage. Exclude birds and deer with row cover or bird netting.
Most greens grow relatively fast. In ideal conditions, lettuces and arugula reach full size in four to six weeks. But with the cold weather and reduced daylight of late fall and early winter, growth will be much slower. Pick outer leaves at any stage and leave the inner ones to keep growing to extend your harvest.
If your plants seem to grow slowly, don’t give up on them. Roots will still be developing
underground. These laggards may surprise you with a burst of growth in January or February after other plants have finished producing.
I can’t promise that you will enjoy your sweet and spicy winter greens as much as your summer tomatoes, but your harvest will be fresher and more nutritious than any greens you can buy.
Workshops: Napa County Master Gardeners conduct workshops throughout the year see our wesbite for details and registration information. http://cenapa.ucdavis.edu
- Posted by: Yvonne Rasmussen
- Author: Denise Seghesio Levine
Every year, I try to grow something I have not grown before. Loofahs were my experiment this year.
Some people mistakenly think that these scratchy, buff-colored scrubbers are a cousin to sea sponges. Often found in natural food stores and spas, loofahs are actually a member of the Cucurbitaceae family, along with squashes, cucumbers, melons and gourds. “Sponge gourd” is a common name for loofah (also spelled luffa).
Six species of loofah have traditionally been used for food and sponges. Although all species have edible blossoms and fruit that is edible when immature, before it becomes fibrous, only two species are generally cultivated. Luffa acutangula, sometimes called Chinese okra and occasionally seen on Asian menus, is long and ridged.
For the table, it is harvested young, like a summer squash. Maybe next year I will try that one.
But this year, I grew Luffa aegyptiaca, the sponge loofah, because the seed packet intrigued me. It showed a beautiful green vine with small, shiny, dangling melon-like fruits. An image of the harvested loofahs made them look like they would easily fit in your hand, just the right size for scrubbing dishes. Visions of homegrown loofahs tied with bright bows for holiday gifts filled my imagination.
The size of the seeds should have given me a clue. They were shiny and dark, like extra-large watermelon seeds. For one of the loofahs growing in my garden to fit in my hand, I will have to cut it into five pieces.
Loofahs need a long growing season, so I started the seed in April. I soaked the seeds for a day, then planted them in small pots rather than directly in the ground as I knew these heat-loving plants would need a jumpstart. I watered them every few days to keep the seedling mix moist but not soaking wet.
When the first true leaves appeared, it was time to transplant. I took care to be gentle. Although the plants are still small, their roots can be up to six inches long and do not like being disturbed.
In early May, I chose a spot in the garden that got full sun and worked compost into the soil there. I erected a tall wire cage and planted the seedlings about a foot apart all around the cage. I mulched with compost and installed drip emitters. I protected the seedlings from slugs and birds until they were established, but after that, the plants were relatively pest-free.
Loofahs grow quickly into rambling vines with rapidly developing leaves and tendrils. Large, bright yellow blossoms soon appear. Our garden pastime this year was watching the shiny black bumblebees and carpenter bees diving into the golden pollen in the center of the abundant loofah flowers. With so much pollinating activity, we were surprised that it took so long to finally see a baby loofah.
That first loofah quickly grew to resemble a long cucumber. The surprise was that, unlike a firm cucumber, this fruit was squishy and soft.
Like their cucurbit relatives, loofahs are annuals. They perform much better supported by high trellises or cages than sprawled on the ground. Trellising keeps them cleaner and away from some pests, and the loofahs grow straighter than they do without a trellis.
Over the next few months, my loofah vines continued to fill in and flower abundantly, attracting more and different bees, wasps and flies. But it took a long time before more fruit appeared. Just a few weeks ago, we started noticing more “babies.”
Now that the weather is turning, we have several mature loofahs, a good selection of probably harvestable sponges, and a bunch of babies that are clearly not going to mature before the season ends. Maybe we will cook a few of those.
Loofahs are harvested when the peel is easy to remove from the spongy skeletal fibers beneath. Pick them when they start to feel light and turn from green to tan or yellow. The skin should feel loose and thin and peel off easily. Shake out the seeds. Leave sponges whole, or cut them smaller. If you harvest them before the autumn rains arrive, they will be a lighter and more regular color. Rain can darken and discolor them.
I plan to grow loofahs again next year, but for now, I am looking forward to peeling the skin from this year’s fruits and revealing the sponge within.
- Posted by: Yvonne Rasmussen
- Author: Denise Seghesio Levine
October 12, 2012 5:27 pm • DENISE SEGHESIO LEVINE
This is your chance to find plants that are native to the county, and the diversity may surprise you.
This year, the Native Plant Society has more than 1,000 different varieties of plants for sale. Whether you are looking for winter color, drought tolerance, deer resistance or another manzanita for your collection, you will probably find suitable choices at Skyline Park this weekend.
So how to decide? Native Plant Society member Kendra Baumgartner, a plant pathologist with the UC Davis, has grown many natives in her garden and has several favorites.
Bumblebees and hummingbirds are attracted to the bright red blossoms of California fuchsia (Zauschneria californica). This plant produces abundant trumpet-shaped flowers, does well in full sun, spreads easily by roots and is very drought tolerant.
Another colorful, drought-resistant bumblebee favorite that performs well in sun is flannelbush (Fremontodendron californicum). Flannelbush has big, tropical-looking yellow flowers, and it matures into a small tree. At the Martha Walker Native Habitat Garden in Skyline Park, you can see what flannelbush and other native plants look like and how large they grow.
To attract wild and domestic honeybees, consider wild or California lilac (Ceanothus spp.), which flowers in white, purple or blue. For a drought-resistant ground cover in a spot with full sun, choose C. gloriosus porrectus or C. prostratus. Blue beauties like C. ‘Frosty Blue’ and C. ‘Dark Star’ reach six feet tall or more. If you have a large garden, consider C. ‘Ray Hartman,’ which grows up to 18 feet tall.
Looking for color in a shady spot? For red blossoms in full or partial shade, Kendra suggests spice bush (Calycanthus occidentalis). Spice bush needs more water than some natives, since its natural habitat is normally in riparian areas. In addition to its unique, dark red blossoms in spring, spice bush offers the benefit of its spicy fragrance, which the thick, dark green leaves release when brushed or crushed.
Blue-eyed grass (Sisyrinchium bellum) is an herbaceous plant, but it is called a grass because it has blade-shaped leaves that grow in tufts. It spreads by roots, does well in full to partial sun and is drought tolerant. The plant takes its name from its little blue flowers with bright yellow centers, which appear in spring and summer.
Deer grass (Muhlenbergia rigens) is a big bunch grass that grows up to two feet tall. It can be hacked to the ground in winter, and it appreciates regular trimming during the growing season to keep it from looking too wild. In Kendra’s garden, dragonflies perch on the upper leaves, while sparrows take shelter under the canopy of leaves that drape to the ground.
Snowberry (Symphoricarpus albus) is another riparian woodland shrub that matures into a low bush with pretty, delicate leaves and tiny pink flowers. Snowberry produces large white berries in winter, an important food source for birds.
The Native Plant Society has at least nine different manzanita varieties available, from Arctostaphyolos uva-ursi ‘Pt. Reyes,’ a ground cover that stays below two feet in height, to A. ‘Dr. Hurd,’ a manzanita that can grow 10 feet tall. Manzanita is a popular plant in Napa County, for good reason. It has beautiful bark in red, tan and brown and tiny pink or white bell-shaped flowers in spring.
If you have room for a medium to tall tree in full or partial sun, take a look at the blue oaks for sale (Quercus douglasii). Blue oaks have beautiful blue-gray leaves that they drop in winter to reveal draping branches that are a favorite perch for songbirds (and, as Kendra warns, for the Cooper’s hawks that eat them). Blue oaks are drought tolerant once established.
Studies show that fall-planted perennials develop more drought resistance. They get off to a good start in warm soil and then have all winter to develop a deep, strong root system. While most plants need to be watered diligently during their first growing season, fall-planted perennials typically need less water for less time than their spring-planted counterparts.
The California Native Plant Society, Napa Chapter, sale took place Saturday, October 13, 2012 and Sunday, October 14, 2012 from 10 a.m. to 4 p.m. both days. While you are at the sale, pick up some information about the California Native Plant Society. This organization is an excellent resource for information about plants in our area. Consider becoming a member so that you can learn through working with them. Getting to know the plants around us and understanding their natural habitat adds richness to our lives in Napa County.
- Author: Cindy Watter, UC Master Gardener of Napa County
I never had luck growing lavender until I moved to Napa County. I had lived in fogbound areas with lots of rain, lots of redwoods and soil that didn't drain well, and those are exactly the conditions that prevent lavender from thriving.
Napa Valley, with its Mediterranean climate, is perfect for lavender. I began planting it in my yard and was rewarded with beautiful, healthy, fragrant plants that attracted bees and butterflies galore.
Lavender belongs to the Labiatae plant family, also called Lamiaceae. Many culinary and medicinal herbs belong to this family; some, like mint, have square stems. Its genus, Lavandula, contains 28 species.
English lavender, with its spires of florets, is Lavandula angustifolia. Hedge lavender is Lavandula intermedia. French lavender is Lavandula dentata, which refers to its toothed leaves. Spanish lavender, or Lavandula stoechas, is easily recognized. Its bloom is shaped like a fat bumblebee, with four petals that look like rabbit ears.
Lavender comes in a range of colors, from white to dark red—and, of course, lavender. Julie Thompson, a Napa County Master Gardener, and professional lavender grower, particularly likes ‘Opal Rain,' a pale pinkish-white lavender, for its fragrance. She also recommends ‘Folgate' because, she says, “it is a jack-of-all-trades,” good for hedges, bushes, containers, and cooking. Both are of the L. angustifolia type and are edible.
Speaking of edibility, lavender plants contain linalool, a compound that is poisonous to dogs and cats if ingested in large quantities. The key word is “if.” A pet would have to eat a lot of lavender to become sick, and the fragrance of lavender isn't enticing to cats or dogs.
Over thirty years, neither feline nor canine has betrayed the slightest interest in the lavender in my yard. The only way my pets would eat lavender would be if I poured bacon fat on it.
As for the rest of us, lavender has many culinary uses, and the best lavender for those purposes is English lavender. Other types contain camphor and just don't taste that good. Of course, you should only ingest lavender that has not been sprayed with pesticides.
Lavender prefers sandy, well-drained soil and six hours of sun a day. It enjoys spring rain but can survive the summer with very little water.
If you have clay soil, you can add compost (always a good idea) or plant your lavender in raised beds or containers. Thompson suggests growing lavender in raised mounds if your soil doesn't drain well or planting it on an incline.
Lavender appreciates pea gravel or decomposed granite for mulch, rather than organic matter. It also likes good air circulation. If you want to feed it with an organic fertilizer early in the growing season, go ahead. But beware that too much nitrogen fertilizer will encourage abundant leaves, but not flowers.
I usually have a few lavender plants in containers. In the past, I would repot them after a couple of years, but now I put them in the soil and put new ones in the pots. I think lavender reaches a point where it just wants to stretch out.
Many gardeners are so thrilled to have a healthy blooming plant that they hesitate to prune it. Thompson said English lavender loves to be trimmed. Hedge lavender should be trimmed on top, not into the plant.
I let some lavender plants get too leggy, so I sheared them back by half. Now, a year later, they are fat and full of flowers.
Sunset's Western Garden Book says if a lavender plant gets woody and open in the center, take out a few of the older branches, and remove more as new growth occurs. If that doesn't work, ditch the plant. (Master Gardeners call this “shovel pruning.”)
When working with lavender, wear garden gloves to avoid possible contact dermatitis. Actually, gloves are a good idea when working with any plant.
Lavender oil is said to have some health benefits. The National Institutes of Health website confirms that it has antimicrobial properties. Tests have shown that some dental patients relax in response to lavender fragrance.
Several years ago, the UC Master Gardeners of Napa County hosted a speaker who recommended planting lavender (and other herbs) in groups of three, with groupings dispersed over the yard so that bees and butterflies will fly back and forth over the property.
Once some friends came over for a backyard dinner, and one guest couldn't stop watching the bees and butterflies traversing the yard, searching for nectar in lavender, salvia, and Mexican marigolds.
“Did you plant everything this way on purpose?” the guest asked. Yes, I did, and I was thrilled someone besides me was enjoying the effect.
Library Talk: Join UC Master Gardeners and Napa County Library for “Melons for Summer Sweetness” on Thursday, May 2, from 7 pm to 8 pm, via Zoom. Many varieties of melons thrive in backyard gardens with enough space to let them spread. Get tips for choosing varieties, managing soil and irrigation, and learning how to tell when they are ripe. Register to receive the Zoom link.
Workshop: Join the UC Master Gardener of Napa County Rose Team for a workshop on “Summer Rose Care” on Saturday, May 4, from 10 am to noon, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa (rear entrance). After the first spring blooms have faded, many rose bushes begin to show stress. Do you have black spot, rust, mildew or aphids? The Rose Team will provide research-based answers about all aspects of rose care. Attendees will be invited to join a hands-on workshop at Fuller Rose Garden in Napa on May 9 to practice what they have learned. Registration required.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions on Mondays and Fridays from 10 am until 1 pm at the University of California Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa. Or send your questions to mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description.
