Soil is brown, right? Usually. But perhaps you have also seen gray soil, whitish soil, red soil, black soil or even kind of a bluish soil. What does it all mean?
Delving into my Master Gardener references, I found some answers in the University of California Division ofAgriculture and Natural Resources Leaflet 2280.
Although color does not influence how productive a soil might be, it is an indicator, and we can learn a lot about the quality of the soil from that one observation. Color is one of the most useful characteristics in the classification and identification of soils.
We can usually determine what color soil is just by looking, and generally this observation is sufficient. But if a color description is required for analysis or communication, the exact shade can be matched to the Munsell Soil Color Chart, which provides a standard method for describing soil color.
In Napa Valley and throughout most of California, brown and gray soils comprise the largest swaths of landscape. Although these soils are moderately low in organic matter and often high in clay, they include some of our most productive alluvial soils.
Alluvial soils are created on valley floors by the movement of water. One property owner's erosion is another lucky person's alluvial soil. Nearly all the soils in the central and coastal valleys, including the Napa Valley, are alluvial and extremely useful for growing intensive crops.
Soils in the Central Valley tend to be gray. On the west side of the valley,soil texture is coarse to medium from granitic alluvium. The east side of the valley features medium- to fine-textured soil due to layering with sedimentary alluvium.
Still, color is only one indicator. These two areas show wide variation in productivity and other important characteristics.
Black soils are usually high in organic matter, but high is relative. Some black soils test relatively low in organic matter and relatively high in mineral content. Others occupy the other end of the spectrum—squishy black muck that can contain up to 50 percent organic matter. Peat bogs fit this description.
Black soils often have a strong granular structure. In coastal valleys, they can form on top of native grasslands. In other areas, black soils form under poorly drained conditions and range from peaty to mostly clay in texture. With proper identification and good management, these soils can be highly productive for vegetables and field crops.
Red soils can be beautiful but are often deficient in nutrients needed for healthy plant life. Usually lacking in nitrogen, essential for strong leaf development, red soils are also frequently deficient in zinc, sulfur and phosphorus. These nutrients are all necessary for the proper development of plant leaves, roots and fruits, so anyone attempting to garden in red soil will probably need to amend generously.
Why are red soils so problematic for gardening? Generally they are older soils that have gone through intensive weathering. Some of that rich alluvial gold in the valley soil probably came from old red bluffs that were robbed of their riches. This explains why bluffs with exposed edges and timberlines that have been exposed to hot summers and drenching rains are often red hued. The soil has been washed away by wind and rain down to clay pans or hard pan.
White, light gray or gray soils usually have a preponderance of sand or lime. If you rub these soils through your fingers, they feel gritty and sandy. While these soils often drain freely, they can have difficulty holding water and nutrients long enough for your plants to absorb them. In some chalky or sandy soils, iron deficiency can be a problem. This deficiency is a common problem for orchard crops but can also be problematic for other food and ornamental crops.
And then there is the blue or blue-gray mucky soil that smells bad and can have a sewer- like odor. Often this condition is the result of poorly aerated subsoil. Organic matter doesn't have enough oxygen to completely breakdown the materials.
These incompletely digested soils are not healthy for plants. Dissolved materials and gases in these soils are toxic to plant roots. To rehabilitate blue, smelly soil, extensive aeration is needed to complete biodegradation and provide a healthy environment for plant growth.
Most of the soils in Napa County are predictably brown. But the occasional pockets of different colors now speak to me in a different way. And now I understand what they are saying.
Workshops: U. C. Master Gardeners of Napa County will host a workshop on “Home Vineyard: Part 1” on Saturday, February 27, from 9:30 a.m. to 2:30 p.m. at the University of California Oakville Experimental Station, 1380 Oakville Grade Road, Oakville. What to do, what to look for, and what to plan for in the vineyard between February and August. Workshop will be presented in two parts. The morning (9:30 a.m. to 11:30 a.m.) will be classroom discussion. The afternoon (12:30 p.m. to 2:30 p.m. will be a field trip to a local vineyard. On-line registration (credit card only); Mail-in/Walk-in registration (cash or check only).
U. C. Master Gardeners of Napa County will host a workshop on “Irrigation Hands On” on Saturday,February 27, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension office, 1710 Soscol Avenue, Napa. Learn how to modify your current irrigation system to make it more efficient and effective. There will be demonstrations and hands-on learning about irrigation controllers, sprinklers, drip systems, rain water capture and grey water systems. For the hands-on segment, bring garden gloves to protect your fingers and a pair of scissors or garden shears .On-line registration (credit card only); Mail-in/Walk-in registration (cash or check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
Vines throughout the valley are progressing through a process called veraison. Veraison is a French word signaling the start of the ripening process.Changes occur throughout the vine during this phase, but most importantly, veraison is when berries begin to ripen.
During veraison, berries become soft and take on the characteristic colors of the variety.Cabernet Sauvignon and Merlot grapes begin to change from green to red. From veraison until harvest, the berries will increase in size, weight and sugar content.The canes change from green to a woody brown,developing the strength needed to carry the weight of the grapes.
While veraison progresses, commercial and home growers take steps to protect the crop before harvest. Beginning with bud break in the spring, grape growers must constantly manage powdery mildew (Uncinulanecator) and botrytis (Botrytis cinerea).
In many vineyards, the spores that cause powdery mildew and botrytis are ubiquitous.A powdery mildew infection appears as a blue fungus on individual berries or bunches. Botrytis affects the internal tissues of the berry or the entire bunch. Berries split and fungal spores can proliferate. In both cases, home gardeners should remove and dispose of infected bunches to prevent wind from spreading the spores to healthy fruit. Spores of both diseases can also over-winter on vine bark and infect grapes the following year.
Grapes need leaves and sunshine to ripen. Monitoring the amount of leaves, their placement and their health is referred to as canopy management. Growers remove leaves at the base of the canes surrounding grape bunches to allow for light penetration and airflow. Then they continue to observe weather conditions and how the vineyards are oriented to the sun. They may do limited leaf removal on the west side during July and August. Over-exposing the crop can cause sunburn and bunch rot.
Home grape growers need to observe their microclimates and placement of buildings when determining how to manage the canopy. Irrigation is another way to manage canopy health. The goal is to keep the canopy healthy without promoting too much growth. During the final stages before harvest, growers mustmake irrigation decisions based on the size of the canopy, the weather, the age of the vineyard and the available soil moisture. Overstressed vines can lose leaves needed to complete ripening.
Pest management is always top of mind for growers. Vertebrate pests are a constant concern, but as ripening progresses, vineyard managers begin looking to the sky for other pests that enjoy ripe, sweet berries. Birds can devastate an entire crop. Growers use noisemakers and reflectors to deter them, but those methods may have limited or only short-term benefits. Netting may be used if bird pressure is high.
Bird netting is positioned on both sides of the vine row, protecting the fruit zone throughout the vineyard. It must be installed early, before hungry birds sense that the crop is sweet. If it is installed too tightly, birds can pierce the grapes while hanging onto the netting.
In the weeks preceding harvest, growers also mow or disk the vineyard floor to minimize weed seed production and to improve access by picking crews. This constant attention to detail protects our valley's most valuable crop and gets the winemaking off to a promising start.
Garden Tour: The Master Gardeners of Napa County invite you to attend their sixth garden tour, “Down the Garden Path,” on Sunday, September 13. On this self-guided educational tour, you will see seven gardens owned by Master Gardeners in and around the City of Napa. These gardens illustrate how Napa County Master Gardeners use University of California research-based horticultural information to develop and maintain their own gardens.Tickets: $30 advance / $35 day of event. Purchase tickets here: http://bit.ly/1fqLJZe. Or you can purchase tickets at the Master Gardener office (address below). For more information, call 707-253-4143.
Workshop: Napa County Master Gardeners will hold a workshop on “Home Vineyard: Part 2” on Saturday, August 15, from 9:30 a.m. to 2 p.m. (with a 30-minute lunch break. Learn what to do and what to look for and how to plan for harvest and crush in the vineyard, testing the must, managing the vines after crush, and preparing for winter and the next growing season. Master Gardeners with home vineyards will present this workshop, and answer your questions.Please bring a sack lunch, comfortable clothes and shoes for walking through the experimental vineyard. Location is the University of California Oakville Experimental Station, 1380 Oakville Grade Road, Napa. Online registration (credit card only)Mail-in registration (cash or check only)
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
While the calendar says spring is several weeks away, by the end of the month the earliest fruit trees and their ornamental cultivars will also begin to bloom, especially the almonds and plums. In our pleasant valley, the seasonal change is happening ahead of the spring equinox.
What should you be doing in the garden? Top of the list is to finish the winter tasks. Roses should be pruned before they start their vigorous growing next month, and fruit trees before the buds break. In general, any winter-dormant tree or shrub should be pruned before it blooms or puts out leaves, but wait to prune spring-blooming ornamentals like camellias and azaleas until after they have bloomed.
If your peaches and nectarines suffer from peach leaf curl, February is the last month to effectively spray for this fungal disease. According to University of California IPM, our statewide integrated pest management program, the safest effective products available for backyard trees are copper soap (copper octanoate) or a fixed copper fungicide. You can get detailed information about peach leaf curl at http://www.ipm.ucdavis.edu/QT/peachleafcurlcard.html.
There is still time to plant bare-root plants, including fruit trees and roses. Nurseries may also have strawberries, artichokes and cane berries, such as blackberries and raspberries, to plant now.
You might notice that the leaves of your citrus trees are yellowing. In our climates, many citrus suffer from iron deficiency in winter as wet soils and cool temperatures affect the ability of the roots to access iron in the ground. This iron chlorosis may be treated with a foliar spray of chelated iron, available in nurseries. It is tempting to fertilize with nitrogen as well, but hold off until the weather is warmer. Nitrogen fertilizer could stimulate new growth, which is especially sensitive to frost damage. Our frost season will not be over until late spring.
Slugs and snails are rainy-season pests that may be active in your garden now. Chemical baits alone won't solve the problem. Regular handpicking is the preferred method for controlling them. You can trap them by setting out boards or inverted flower pots in the evening. Prop up the boards or pots by about an inch to allow slugs and snails easy access. Turn the boards over and destroy the gastropods every morning when you do your rounds.
If you are persistent, after a few weeks you should notice significantly fewer of these pests in your garden. If you do choose to use chemical bait, look for one with iron phosphate as its active ingredient. These baits are safe for use around children, pets and wildlife. Avoid baits containing metaldehyde, as this ingredient is particularly poisonous to dogs and cats.
In the flower garden, remove spent blossoms regularly to keep your fall-planted annuals looking good. You can still plant more cool-season flowers such as pansies and snapdragons. Visit a local nursery for more ideas. Clean up fallen camellia and azalea blossoms to prevent petal blight, a fungal disease promoted by rainy weather.
In the vegetable patch, you may be harvesting fall-planted favas, kale, chard, carrots and beets. These cool-season vegetables tolerate some frost. In February you can begin planting these crops again to harvest in late spring before setting out summer veggies. You can direct-sow seeds of chard, lettuce, beets, radishes, and spinach into previously prepared garden beds. You can transplant starts of all the brassicas (cabbage, kale, Brussels sprouts, broccoli and cauliflower) as well. Looking ahead to the warm season, early February is the time to start tomato, pepper and eggplant seeds indoors for transplanting later.
February should be a rainy month. If your soil is wet, you should not handle it. Walking on or digging in wet soil destroys its structure by compacting it, eliminating the air and water pockets that are a significant component of healthy soil. Wait for dry weather before planting, and don't plan to do major soil preparation until later in the spring.
If rainy weather prevents me from getting everything done this month, I don't mind. Every gray, wet day means more water in the soil bank for the next season. Besides, yellow blossoms look especially bright silhouetted against a cloudy sky.
Workshop: Join Napa County Master Gardeners on Saturday, February 7, for “Home Vineyard: Part 1.” Learn what to do, what to look for, and what to plan for in the vineyard between February and August. A follow-up workshop will be held in August. Location: U. C. Oakville Experimental Station, 1380 Oakville Grade Road, Oakville. Classroom discussion from 9:30 a.m. to 11:30 a.m. Discussion moves into the vineyard from 12:30 p.m. to 2:30 p.m. Online registration (credit card only)
Mail-in registration (cash or check only)
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
Thanks to December's rains, I can breathe a sigh of relief that my fall-planted cover crops are growing, unlike last year. Now I look toward pruning and preventing Eutypa dieback, a fungal disease, from invading my grapevines this winter.
Pruning is one of the most important tools in my toolbox to manage vine growth. I can control the size of the vine by pruning to a set number of buds, or potential shoots. If I leave too many buds, I may end up with too much fruit, not enough shoot growth and an over-cropped vine that can't mature all its fruit. If I leave too few, I may create too much vigor, causing excessive shading, not enough fruit and fruit of poor quality. It is a balancing act. When I prune, I assess each vine individually.
Eutypa dieback comes from a pathogen that causes cankers, resulting in vine decline and a huge economic loss for growers due to lower yield and treatment costs. This pathogen is prevalent on the North Coast and infects more than 80 plant species worldwide. Some of the hosts in our area include grapes, apricots, cherries, almonds, pears, apples, crabapples, willows, big-leaf maples, oleanders, California buckeye, ceanothus, blueberries and kiwifruit.
Pruning wounds are infected with Eutypa by wind- or rain- driven spores. It maybe several years before symptoms show up. Ultimately, the disease kills the vine. When a vine is five to six years old, you may begin to see the symptoms: stunted shoot growth or no shoot growth. If you looked at a cross-section of the vine, you would see a wedge-shaped canker.
These symptoms are easier to see in spring before the canopy grows too large, so spring is the time to flag diseased vines for removal later. You can combat Eutypa by cutting out the infected area until you see only healthy tissue and no cankers. Make sure to dispose of all infected material.
I try to manage Eutypa in several ways. One strategy is to prune as late as possible, after spore concentrations peak. Pruning wounds, which remain susceptible for up to six weeks, are less susceptible when temperatures are warming. The wounds heal much more quickly and might be colonized by beneficial microbes that grow over the pruning wounds and prevent infection. I also try to avoid creating large wounds and instead make smaller cuts, which heal faster and have less surface area for spores to land on.
Double pruning is also an option, especially if you have many vines to prune. This is a common practice in our valley. For the first pass, the vine is cut 10 to 12 inches above the spur; final pruning happens later in winter or spring when conditions are less conducive to transmitting the fungus. That second pass can move much more quickly, and the chance of infection is minimized.
Wound protection is another option, by organic or conventional methods. You can view photos of Eutypa and recommendations for control at http://www.ipm.ucdavis.edu. Search for Eutypa dieback.
Napa County Master Gardeners are offering a home vineyard workshop on Saturday, February 7 (information below), which will address these topics in more detail.
Workshop: Join Napa County Master Gardeners on Saturday, February 7, for “Home Vineyard: Part 1.” Learn what to do, what to look for, and what to plan for in the vineyard between February and August. A follow-up workshop will be held in August. Location: U. C. Oakville Experimental Station, 1380 Oakville Grade Road, Oakville. Classroom discussion from 9:30 a.m. to 11:30 a.m. Discussion moves into the vineyard from 12:30 p.m. to 2:30 p.m.
Online registration (credit card only)
Mail-in registration (cash or check only)
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
It is about that time of year when any of us who have a small home vineyard or acres of vineyards anticipate bud break. By now we have all done our pruning on the dormant vines and are waiting for the first signs of a new vintage.
But we are also aware that with bud break come all the other concerns in managing our vines: frost protection, rain at the wrong time and powdery mildew. And more powdery mildew. The last few years have taught us to be flexible and not anticipate what nature has in store.
Managing the vineyard is less stressful if we know we have done all we can to improve the chances of a successful fall harvest. Powdery mildew is the most serious and widespread disease in California vineyards in terms of cost of control and losses in yield. Wine quality can be affected when as few as 3 percent of the berries are diseased; severe mildew may cause berries to crack, allowing rot-promoting organisms to enter. Surprisingly, powdery mildew is not the same mildew we get on roses.
All succulent tissues on a grapevine are susceptible to mildew, and the fungus begins to show shortly after bud break. Usually within one week of the first spring rain you can see colonies on the underside of leaves. The fungus forms a white, web-like mat over the leaf tissue and draws nutrients from the plant tissue. This leaves develop a dusty appearance as the spores spread.
How does mildew get started? It cannot grow on dead or dormant grape tissue. It survives the winter under infected buds; or when autumn rains wash the spores off of leaves and shoots and onto the bark of upper trunks and cordons. In the spring, rain and sprinklers release the spores and wind blows them onto newly emerging shoots and leaves. If you had a lot of mildew the previous year, you might see red, stain-like scarring on vine canes. This is dormant mildew. Buds near this scarring will start to be infected.
In mild weather, spores germinate in less than five days. Mildew really loves temperatures between 70°F and 85°F. High temperatures kill the spores. And temperatures above 95°F for 12 continuous hours cause the mildew to stop growing. Temperature plays a larger role in the disease development than moisture and humanity. Rain, dew and irrigation water can actually cause poor germination of the mildew spores, and they can sometimes even be washed away. Powdery mildew is spread by windborne spores and they can travel a long distance.
The infection in the fruit can continue until certain sugar levels are reached in the grapes. The damage can cause stunted berries, decreased yield, delayed ripening, scarring and off flavors in the wine. Some varieties are more susceptible to mildew, including Chardonnay, Cabernet Sauvignon, Carignane and table grapes.
To control powdery mildew, it is best to apply preventatives and keep applying them. It is difficult to eradicate and you need to start early. Many materials can be used. For advice, visit www.ipm.ucdavis.edu/PMG/crops-agriculture.html.
Protect vines and new buds and leaves before your vines become infected. Fungicides will inhibit spore development and germination. Sulfur is an effective and economical control and in most years provides adequate protection. Other options are also available.
New vines do not need treatment, but in the second year, you should monitor for mildew on leaves. After year two, start the regimen.
To summarize, if you grow grapevines, you will have to treat for mildew every year. The control is a preventative. Some products provide longer protection than others. Be sure to watch the weather.
Workshop: On Saturday, April 6, from 9:30 a.m. to noon, Napa County Master Gardeners will present a workshop on “Small Home Vineyards” at the Yountville Community Center. The fee is $15. Call 707-944-8712 to register or register online at www.townofyountville.com/index.aspx?page=274. Call the Master Gardener office for more information at 707-253-4221.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners (http://cenapa.ucdavis.edu) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions?