Hi Don,

I was browsing your website and noticed that St. John's wort can't be sold in Yolo and was wondering why. I have some seeds of another Hypericum (punctatum) and want to know if I should worry about planting them or not, since it seems like a similar species.

Thanks!

H. perforatum is considered a noxious weed threatening rangeland in California, and sale in Yolo County is forbidden by the County Agricultural Commissioner. Management of weeds in that category is at the discretion of each county's ag commissioner, so other counties may allow them. You are not restricted from growing a different species; there are many other species of Hypericum that can be sold (and are not considered invasive). For example, H. perforatum and H. canariense are on the invasive plants database. Your species is not.
Here is a reference link: cal-ipc.org

Here is an article about true invasives and mere garden thug
Don

Common Landscape Errors

or ... It Isn't The Plant's Fault!

If April showers bring May flowers, what do May showers bring?

Written for the Davis Enterprise, May 26, 2011
Click on any image for a larger version

Fungus!

Last May I wrote a column which began,

"What's up with this weather? ....
Below average temperatures every month ... by as much as 10 to 15 degrees. If we complete May without breaking 90 degrees, it will be the first time since 1971. Pleasant as that may be for gardeners, the weekly rain and cool temperatures have played havoc with plants and crops."

Well, deja vu.
For the record, we did finish May 2010 without breaking 90 degrees. So far this year, other than a brief spate of windy, dry, warm weather May 3 through 5, temperatures have been below average as well. Mild temperatures and high humidity lead to disease problems, and rain in March left many fruit trees nearly fruitless.

So we get questions ...
There are dead branches on my apple tree!

Fireblight on an apple tree.

Fireblight is a bacterial disease that attacks blossoms, young fruit, and tender shoots of apples, pears, and related trees and shrubs. It is specific to members of the pome branch of the rose family. Ornamental pears and crabapples, loquats and pyracantha can also be affected. Symptoms are rapid dieback of short shoot. The affected parts look burnt, as if by fire.

Fireblight infects within a temperature range of about 55 to 80 degrees and very high humidity, so normal hot dry weather stops the spread. But it can do a lot of damage in a short period of time. Prune out affected portions, cutting down into healthy green wood, and throw away the prunings. Contrary to older advice, it is not necessary to clean your pruning shears between cuts. The disease is transmitted by bees, and by spores during periods of very high humidity.

The tomato plant I bought a couple of weeks ago is not looking good. It is losing leaves and has black spots on most leaves (fungus?). I would think it is the cool weather and especially that crazy hail we had. The top part of the plant looks okay. Will it heal itself, or should I buy a new plant?

Early blight is a leaf-infecting fungus on tomato seedlings. It was most likely on the plant when you bought it. Normally we don't have to worry about it here, because the fungus can't sustain low humidity. Cold temperatures have slowed the growth of the seedling, hail has made points of entry on the leaves, and rain has continued to splash the fungus upward. It will likely outgrow the problem.

Why is there hardly any fruit on my apricot, plum, peach, or nectarine?

European honeybees are finicky workers. They won't fly when the weather is cold, windy, overcast or rainy. We had 14 days of rain in March when the stone fruits were flowering. So some varieties got good pollination, but most didn't.
Apricots were hard hit by brown rot fungus again this year. The disease attacks and kills blossoms and developing fruit, sometimes spreading into the branch. Plums, and peaches and nectarines, also show dieback and fruit loss due to brown rot. Prune out the dead twigs as best you can, and mark your calendar to do a dormant spray next winter. Brown rot is the major factor limiting success with apricots here.

What is causing the holes on ...

... the leaves of my plum and pluot?

Shot hole fungus on a plum

Shothole fungus causes small areas of the leaf to die, and then the dead tissue falls out, leaving a small hole. It looks as though something has been eating the leaf. Not very harmful, but it does increase over time. The dormant spray noted above will help prevent it.

... the petals of my roses?

Earwigs like to crawl up rose bushes and feed on the thrips that are hiding among the rose petals. That is helpful, but unfortunately they also like to eat rose petals. Earwigs can be trapped with any fragrant cooking oil, left out in shallow bowls.

Katydids have just hatched out, and can be found here and there feeding on soft green leaves and rose petals. Their damage is transitory, and they move on quickly, so control is not necessary (or feasible).

What is causing the spots on the leaves of (1) my citrus; (2) my persimmon?

Spots on persimmon caused by environmental stress.

If you want to impress people, tell them the leaves have oedema. That is Greek for "spots." On thick-leaved plants oedema occurs during conditions of high or low temperatures, low humidity, and wind, It is an environmental stress and is not harmful to the tree. In the summer oedema can make Eastern redbud leaves (Cercis canadensis) unattractive.

Why are the flower buds of my gardenia falling off without opening?
Cool weather. Gardenia wants even, warm temperatures all the time. The plants will initiate flower buds at any time of year, but if the nights are cooler than about 55 degrees the buds will drop without opening.

If I plant hot peppers near my sweet peppers, will it make my sweet peppers hot? or vice versa?
If I plant a lemon near my orange, will it make my orange sour?
No, and no. The only time cross-pollination in the garden affects the part of the plant that you eat is when you are eating the seeds. So certain types of corn need to be isolated from each other, because you are eating the seed; never plant sweet corn near field corn or popcorn, or many of the kernels will be very chewy!
Oranges may be sour because the tree isn't getting enough sun. More commonly it is because you are harvesting too early. Many citrus turn color before they turn sweet.
The heat in peppers is caused by capsaicin, which is present in varying quantities in hot peppers and not present in sweet peppers. Hot peppers vary in their heat due to genetics (the type and seed strain of the pepper), environment (hotter in hot climates), and watering (reducing water concentrates the flavor, including the heat). Most of the hot pepper varieties we grow are open-pollinated seed strains, so their genes are more variable than hybrids. If your "sweet" pepper turned out to be hot, it was mislabeled. If your hot peppers aren't hot enough, try watering less.

Cross-pollination in the garden can affect the seed you save. If you carefully save seed from your favorite squash plant, but had a pumpkin nearby, you can get some very strange results in the next generation.

What are these dragon-looking bugs on my salvia?!?
Those are the larvae of ladybird beetles, aka ladybugs. The larvae eat aphids even more voraciously than their parents. You will also find an intermediate stage between the larva and the adult. Other beneficial aphid-eaters in the garden right now include leatherwing beetles and the larvae of lacewings. It is rare for us to need to spray for aphids once we have a resident population of beneficial insects. Sprays often kill the beneficials. So let nature run its course, and learn to recognize the good bugs.

Ladybird beetle (ladybug) larva.

Ladybird beetle pupa

Ladybird beetle adult

All the stages!

---

© 2010 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616

www.redwoodbarn.com

Feel free to copy and distribute this article with attribution to this author.

Lavenders!

What's that purple flower?!?

(Click on any image for a larger version)

You'd be surprised how often I get that question. In winter, it's rosemary or lilac vine (Hardenbergia). In spring, California lilac (Ceanothus) blooming in the Arboretum draws admiring visitors and bees. Thanks to the City of Davis, some of our roadsides have low-growing shrubs with vivid purple flowers right now: Spanish lavender (Lavandula stoechas Otto Quast).

Lavandula stoechas 'Otto Quast' in mid-street planting

Otto Quast is one of the Arboretum All-Stars, and for good reason. Lavenders in general are tough, drought-tolerant shrubs. What sets Spanish lavender apart is that it blooms early, often starting in February and continuing into the summer. The shrub has a low spreading habit.

Unlike other lavenders, it also has a set of showy petals atop the bloom spike. These act as a 'come hither' for pollinators, so Spanish lavender is less fragrant than other species. Breeders have introduced new forms with stronger or softer colors and some have even longer petals than Otto Quast, which will probably supercede it in the nursery trade.

What do lavenders want?

Lavenders are from the Mediterranean, so they are perfectly adapted to our climate of hot sunny days and dry summers. Growers in areas with summer rainfall struggle to keep them alive because of their sensitivity to crown rot. Commercial lavender production has been tried in many parts of the U.S., and the limiting factors are winter cold and high summer humidity, neither of which is an issue here.

Lavender farmers are advised to take extensive measures to improve soil drainage. From one publication: “Beds must be worked down 18 to 24 inches. It is best to raise the bed about 6 inches above ground level and mix in 1/3 sand, 1/3 loam, and 1/3 clay soil.” [ATTRA*]

A mixed bed of lavenders in June. The English lavenders are in full bloom, and the lavandins (hybrid lavenders) are just beginning to spike. Blooms will continue through the summer, even into the fall. Lavender plants like full sun and dry soil.

Well, folks, add one more advantage to living in California. We don't have to do any of that to grow lavender here. Just plant the shrubs elevated so water never stands around the stem: a raised bed is fine, but a slight mound or furrow is fine. Water should drain away from the plant. Water every few days to get the plants established. Then lavenders can be irrigated deeply and very infrequently.

I water my mixed lavender planting every 3 to 4 weeks with a drip irrigation system that runs for several hours or overnight. Established plants can survive the summer without any watering, though that may truncate the bloom season. In any case, never water them more than once a week unless they are in containers.

Gardeners get perplexed about what to do with lavender shrubs after a few years. The nature of the plant is that it sprawls and tends to lose foliage in the center. Light trimming with shears after bloom can encourage a bushier growth habit. Or you can just let them slowly fall apart, try cutting them back hard after a few years (sometimes this kills the shrub), or simply replace them. A new plant will bloom in the second year; often in the first.

In sum: lavenders love sun, tolerate extreme heat and wind, and prefer dry soil. There are a lot of different kinds!

Which smell best?

Traditional lavender for sachets and potpourri is English lavender (L. angustifolia). Hybrids between English and Portuguese lavender (Lavandula spicata) are called lavandins, and they are the oil producers. (Just for the record, English lavender is not native to England; it came from northern Spain.)

There are several chemicals in lavender flowers that make up the aroma, and the exact constituents vary between species, as well as what part of the plant contains the most of each. Portuguese lavender contains more camphor than English does. Some varieties have aroma compounds in the leaves, others in the flowers. French lavender has especially fragrant leaves.

The English flowers are sweeter, the others more acrid but with longer-lasting scent. So lavender products often contain both. Spanish lavender smells slightly sharp, sort of like turpentine, but the oil is used in air fresheners and insecticides.

Which look best?

Most have grey-green leaves. Some are nearly silver, and a few are variegated. French lavender has toothed leaves (dentate), and the Arboretum All-Star hybrid called Goodwin Creek inherited those. A number of varieties are more compact growers, making them better for small gardens.

When do they bloom?

English and hybrid lavenders start blooming later than Spanish does, mostly beginning in May. Lavandins bloom for much longer than most references describe, making them some of our best garden choices. I have found these often continue blooming into the fall.

A gallery of lavenders

click to enlarge

Lavandula stoechas 'Dedication'

Lavandula stoechas 'Passione'

Lavandula officinalisEnglish lavender bloom spike

Lavandula pinnata

Lavandula x 'Grosso'

Lavandula 'Warburton' has variegated, fragrant foliage

Bees love lavender flowers!

Here is a summary of the types,

including just a few of the many varieties available in nurseries:

Lavandula angustifolia ENGLISH LAVENDER

Bloom earlier than Lavandins; shorter spikes, darker flowers. The strongest sweet lavender fragrance. Very seasonal bloom (May - June here), and they often don't flower heavily until established.

o Hidcote Compact, very tight growth to 1-2 feet tall and wide, with darkest purple blue buds and flowers. Foliage varies from green to very gray.

o Lavender Lady Similar to Munstead, this seed-grown strain blooms the first year. The only lavender available in six-packs.

o Munstead-To 2 feet tall, spreading, with light purple flowers. Foliage usually green, but may be gray-green.

Lavandula dentata FRENCH LAVENDER

Big 4 x 6 shrub with green, toothed leaves (there is a gray version, L. dentata candicans) Showy purple flowers spring through fall. Foliage is fragrant but flowers aren't. Not common in the trade. Notable as a parent of the Arboretum All-Star:

o _L. x 'Goodwin Creek' -- 3 x 4 shrub with soft, densely woolly gray green leaves with coarsely serrate margins. Grown for great, gray leaves and attractive habit, with a continuous display of very dark purple flowers in spring, summer, and fall. Medicinal scent.

L. x intermedia LAVANDIN

Bloom later than English lavenders; longer flower spikes, fatter flowers. Originally grown for lavender oil. Later cultivars were selected for showiness. Flowers June through summer here, often into fall.

o du Provence To 3 feet tall, spreading wider, with lots of flowers over a long season. Very fragrant, very popular garden variety.

o Dutch Mill To 2 feet tall, 3 feet wide, with flower stalks to 18-24 inches long. Rich deep purple flowers are extremely fragrant.

o Grosso Compact growth with thick spikes of dark purple buds and purple flowers. Commercially grown for oil. Very fragrant. One of the best.

o Twickel Purple More violet-purple than Grosso. Very fragrant. Sometimes listed as a form of English lavender.

Two more are worth mentioning for their extraordinarily long bloom season, and frost tenderness. Often sold alongside hardy types, leading to consternation when winter arrives and they may be killed. Flower spikes are great for cutting, though they aren't fragrant. Worth growing for the abundance of bloom and intensity of color.

o L. multifida FERNLEAF LAVENDER

2 x 3 shrub with soft, ferny green foliage. Blue-violet flowers. Always in bloom. Tender; grown as annual here.


o L. pinnata buchii

3 to 4 feet tall and wide with feathery gray-green leaves and stalks of dark purple flowers which open spirally along the cluster through the summer. Tops are frozen back at 25 degrees; usually grown as annual here.

References:
*National Sustainable Agriculture Information Service, ATTRA

For more information about the Arboretum All-Stars, visit their website, and see our Davis Enterprise article from December 2009.

Written for the Davis Enterprise, April 28, 2011

© 2010 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616

www.redwoodbarn.com

Feel free to copy and distribute this article with attribution to this author.

Easy Edibles!

Written for the Davis Enterprise, March 24, 2011

Click on any image for a larger version

We get questions.

I have never planted a living thing before. I have a patio and I want to plant some edible things.
Which fruit trees do you have to spray for bugs?

There are lots of new gardeners these days planting fruit trees and vegetables. Many express concern about the amount of time or expertise they'll need. Bottom line: many of you want to grow food without fuss.

My definition of easy: a plant that gives good food without any special fuss! No routine spraying needed. Simple pruning, if at all. Tolerant of a range of soil and water conditions. Here are a dozen or so easy edibles.

1. Strawberries

Garden strawberry (Fragaria chiloensis)

Easy? They flower within weeks of planting and set fruit right away.

Grow strawberries in half or full-day sun, in soil that you've added compost to, and where you can water them frequently. Plant Sequoia for best flavor, day-neutral varieties to extend the season.

Hint: Protect the fruit! Spread coarse bark around the plants just as they begin to flower. They'll set their fruit above the ground, away from sowbugs and slugs. Plants live 2 - 3 years.

Alpine strawberry (Fragaria vesca) is very different. The plants do not produce runners; great for the herb garden or even in pots. Produce small very sweet berries throughout the summer.
Prefer some shade. Plants live many years.

2. Some easy Citrus

Kumquat (Fortunella species)

The hardiest citrus. Full sun or light shade. Not fussy about soil, but like regular feeding.

Peel is sweet, flesh is tart. Ripen year-around. Fragrant flowers in summer.

Nagami has bright orange fruit shaped like an olive. Very ornamental; best-known type. Meiwa has sweet, round fruit.

Hybrid kumquats gain some cold-hardiness from the kumquat parentage. Calamondin is a prolific producer of round, tart fruit that are used in drinks and as garnish. Limequat is hardier than lime, but has similar flavor.


Lemons (Citrus x limon)

Full sun or light shade. Somewhat frost tender, especially when young.

Meyer Lemon is said to be a cross between a lemon and a mandarin. Compact plant to about six feet, easily kept lower. Can flower, set, and ripen fruit year-around.

True lemons (Lisbon and Eureka varieties) grow much larger and have thorns.


Mandarins (Citrus unshiu)

Full sun for best flavor. More cold-hardy than other citrus.

Owari Satsuma is the hardiest, best-known mandarin, ripening November - January. Other varieties extend the harvest season through spring. See our article on mandarins from December 2010.


Oranges (Citrus sinensis)

Full sun for best flavor. Young plants may need frost protection; established trees survive cold weather.
Navel and blood oranges ripen in winter. Other varieties ripen in spring. Valencia oranges, used mostly for juice, ripen in spring and summer.

3. Mediterranean and Asian fruits

Figs (Ficus carica)

Tolerant of nearly any soil. Can live without any summer watering; very heat tolerant. Produce a small crop in spring and a large crop over several weeks in late summer and fall. The sheer quantity of fruit can be a problem.

Black Mission and Brown Turkey are the common backyard varieties. Gourmet figs also do well: white (Conadria, Kadota), striped ones (Panache), and more. Slow-growing variety called Blackjack can be kept under 10 feet.


Mulberries

Easy? Indestructible.

Morus alba is the white mulberry. The fruitless male is used as a huge shade tree. Teas Weeping is a fruiting type easily kept below 10 feet tall; cute garden accent or playhouse for young kids, with mild, sweet fruit that stains everything. Reseeds.

Morus nigra is the black mulberry, including Russian, Persian, and Pakistani varieties. Slow-growing small trees to fifteen feet, easily kept lower. Large, soft, juicy, intensely sweet-tart fruit resemble giant blackberries. Birds love them. Fruit stains fingers, sidewalks, and clothing. Does not reseed.


Persimmons (Diospyros kaki)

Tolerate drought or garden watering. Beautiful chartreuse foliage in spring; showy fruit in winter. Grow at moderate rate to thirty feet by twenty feet, but can be pruned for size. Produce dozens to hundreds of fruit. The trees drop fruit steadily all season, including lots of unripe fruit as the tree thins itself. Birds will enjoy what you don't harvest.

Fuyu is the flat-bottomed variety you eat while it is still firm. Hachiya has elongated shape and is puckery-astringent until squishy-soft.


Pomegranates (Punica granatum)

Probably the most heat and drought tolerant fruit species. Showy red flowers in late spring; nice yellow fall color, then bright red fruit in fall and winter. Attractive large shrub can be trained as a small tree.

Look for Wonderful, Granada (earlier-ripening), Angel Red (more juice. A number of other varieties are becoming available.

4. Plums

Many stone fruits need careful pruning and spraying. Plums are nearly foolproof. Take partial shade or full sun, average watering.

Japanese plums (Prunus salicina)

Tangy-sweet flavor. These listed are self-fruitful, meaning you only need one tree. Good thing: they're very productive. Santa Rosa produces prodigious quantities of fruit (hundreds) that ripen all at once. Emerald Beaut, Howard Miracle, and Nubiana have fruit that hangs on the tree for a couple to several weeks, remaining firm and of good quality.

European plums (Prunus domestica)

Maybe if we stopped calling these "prune plums" more people would grow them. The fruit, fresh off the tree, is firm and very sweet.

5. Guava-like fruit

Chilean guava (Ugni molinae) and Pineapple guava (Feijoa sellowiana, now Acca sellowiana) are hardy ornamental shrubs with edible fruit (and edible flowers in the case of Feijoa).
Tolerant of sun or light shade, and drought.

6. Some easy vegetables

Anyone gardening with kids should plant radishes and sunflowers; quick to sprout, easy to grow. Full sun.

Gypsy pepper is the most productive sweet pepper I grow. Each plant produces at least a dozen pale yellow-green fruit which ripen red very quickly.

Small-fruited tomatoes are reliable, heavy producers. Choose Juliet hybrid, Sungold hybrid, or two popular heirlooms: Currant, and Yellow Pear.

Finally, kitchen herbs are very easy to grow in the ground or in containers, an excellent choice for novice gardeners. Mix several types in a container, preferably in at least part-day sun (full is best).

Some are long-lived garden perennials or shrubs, while others are annuals. Basil is in the latter category. If you are limited for space, plant Spicy Globe bush basil, a compact one-foot plant with extra-pungent leaves.

7. Also-rans

My Davis Enterprise columns are supposed to be 1000 words. That is a good thing, as it keeps me focused and makes me assess my criteria more carefully. Here were the ones that ended up on the cutting-room floor.


Pie Cherries

Bright red, pretty fruit on very productive, ornamental little trees. Rich flavor. All are self-fruitful and ripen later than sweet cherries, perhaps avoiding the main infestation period of the Spotted wing drosophila. Until we know better how much of a problem that pest will be, these are 'provisionally' easy.

Varieties:

English Morello

Blood-red juice, red flesh, bright red skin, very tart pie cherry. Late June, early July.

Montmorency

Clear juice, white flesh, bright red skin, less acidic pie cherry. Mid to late June.
Hint: long ripening period.



Jujubes (Zizyphus jojoba)

Pretty little trees with shiny foliage are very tough, easy to grow. Produce loads of fruit in early fall that look like little elongated brown apples. Sweet as dates when dried.



Quince (Cydonia oblonga)

Tolerant of heavy soil, lawn watering, or drought. Trees, often multi-trunked, grow to ten feet or more.

Smyrna Quince is the best-known variety, with several dozen very hard, lemon yellow fruit that have rich perfume and wonderful flavor, used in cooking and preserves. Ripen in fall.

Fragaria vesca

Alpine strawberry

'Nagami' kumquat

'Meyer' lemon

Navel orange

Black (Persian) mulberry fruit

'Hachiya' persimmon

'Santa Rosa' plum

Ugni molinae

Chilean guava

Feijoa sellowiana

Pineapple guava

'Juliet' tomato

'Sungold' tomato

A bowl of mixed basil

Top of Page

© 2011 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616

www.redwoodbarn.com

What's That Tree?

Written for the Davis Enterprise, February 24, 2011

Click on any image for a larger version

Overheard at the UC Davis Arboretum, Feb. 20: "This is why I moved here from Michigan."



I was standing in the Eric E. Conn Acacia Grove, trying to get a close-up of the daffodil-yellow clusters of blooms. February is still technically winter, and we've had more than our share of dreary weather this season. But on a sparkling sunny February day recently, folks were outside enjoying the early flowers.

Acacia dealbata Silver wattle

Trees blooming in February? Of course. The almond blossoms began a week ago. Flowering pears a week before that, and flowering plums have already passed their peak of bloom. The earliest flowering cherries such as Okame are in flower. In the family orchard the first peaches have broken dormancy. Back in the arboretum, a little further down the path from the acacias, Western redbuds are showing bud color; expect blooms in a week or so.

Almond blossom in February

I am accustomed to getting inquiries about the early-blooming trees and shrubs. Folks who move here from real-winter climates can't seem to believe that this is normal. From the other end of the spectrum, folks like me who moved here from milder climates don't recognize them. Deciduous flowering trees and shrubs need a certain amount of winter chilling to break dormancy and flower properly. Coastal southern California doesn't get enough cold for that.

I do remember an old Acacia baileyana tree in our yard in San Diego; old by acacia standards, that is. Mostly subtropical trees or shrubs, fast-growing acacias tend to have weak wood and poor branch angles, so many fall apart after 20 years or so. I can't really recommend most species for residential landscapes, and nursery availability is very limited. Fast-growing, low-demand trees tend not to be popular with wholesalers; some may be available at arboretum sales. But the arboretum collection is a winter delight, and thanks to a donation from Dr. Conn there are now paths, benches, and signs identifying the species.

So what is blooming in February? More-or-less in order of bloom:

Flowering pear (Pyrus kawakami).


The first to bloom, these can be seen along F Street. In Southern California they are called Evergreen pears; down there, they get enough chilling to bloom, but don't drop their leaves in fall. Here they are usually deciduous. Drawbacks: odd flower odor; leaf-spot fungus, bacterial fireblight.

Almonds (Prunus amygdalus).

Almonds grow in a narrow climate range around the world, with California's Central Valley producing 80% of the world's supply. Commercial types get fifteen to twenty feet tall and broad, and two varieties are necessary for cross-pollination. The dwarf variety Garden Prince is self-fruitful and grows to about ten feet.
Almonds are not real fussy about soil. Water deeply every week or so during summer. Disease and pest problems are not significant.

Prunus blireiana Flowering plum

Flowering plums.

Prunus blireiana is first to bloom with semi-double soft pink flowers. Foliage emerges bronze-red, then turns dark green by summer. Fruitless. Prunus cerasifera varieties are next, and are popular for the purple-red foliage. Krauter Vesuvius has become the most widely-planted type because it is nearly fruitless. Older varieties had copious fruit.
Plums aren't fussy about soil, and can even tolerate lawn watering. Leaf color is more intense in full sun. Leaf-spot fungus and aphids can be a nuisance but are manageable.

Prunus 'Okame'

Flowering cherries

Most varieties bloom in March, but Okame (Prunus hybrid) is an early-flowering cherry with February blossoms. Ornamental cherries have diverse growth habits. This one is upright and round-headed.
Cherries are fussy about soil, requiring good drainage and at risk of crown rot if watered too often. Don't plant in the lawn!

Note: almonds, pears, plums, and cherries should have their trunks painted with an interior white latex paint at the time of planting to prevent sunburn and borers.

Magnolia?

Walking further to the west in the arboretum, past the Putah Creek Lodge and uphill toward the gazebo, I suddenly found a tulip tree in full bloom. Huh? Magnolia soulangeana blooms in early March, but this variety is ahead of schedule. Varieties range from dark to light pink, with other deciduous magnolias available that are pure white.
Magnolias are not drought tolerant, and the foliage can burn during extremely hot weather. The slow-growing trees reach ten to twenty feet or more tall with equal spread, depending on variety.

Prunus 'Okame'

Flowering quince

Chaenomeles japonica. A non-descript deciduous shrub the rest of the year, quince suddenly bursts into bloom as early as January with blossoms opening for several weeks. Varieties range from three to ten feet in height, usually with an angular spreading habit. Flowers are pink, red, or white; in the case of variety Toyo Nishiki, all three colors occur on the same plant. The shrub has a tight clump of multiple shoots rather than a single trunk. It can be planted and pruned as a hedge. Very tough, carefree, they are tolerant of any soil, sun or light shade, and either regular watering or drought. Some set hard apple-like fruit, which is very aromatic and makes wonderful jam.

Chaenomeles japonica

A few other notable February bloomers:

Chaenomeles japonica 'Toyo Nishiki'

Lilac vine
(Hardenbergia violacea 'Happy Wanderer'): vigorous vine to 15 feet or more with royal purple flowers in February. Full sun is best; partial shade o.k. Freezing weather nips the flower buds some years.

Oregon grape
(Berberis aquifolium, formerly Mahonia aquifolium). More yellow flowers in the arboretum. Note: yellow flowers attract beneficial insects. Oregon grape can be a scruffy-looking shrub, and the leaves are prickly. But the shiny foliage and early winter bloom, plus bird-attracting fruit, make it a good background shrub in a wilder landscape. It is tolerant of sun or shade, regular watering or considerable drought.

Winter daphne (Daphne odora 'Marginata')
Folks admire the specimens blooming right now in the Ruth Risdon Storer garden at the west end of the arboretum. There are also some pure white-flowered daphne nearby in the Shields garden. The fragrance of daphne is astonishing. Unfortunately, they are easy to kill, requiring perfect drainage and careful water management.

Dormant spray recommendations.

Always read and follow label instructions!
For the products we sell, mix together in each gallon of spray:
2 oz LiquiCop (= 4 Tbsp)
2.5 – 3.5 oz spray oil
(= 5 – 7 Tbsp, or 1/8 to <1/4 cup)

You can use a hose-end sprayer** if you use the lower amount of oil (you will barely add any water to the concentrated mixture). Otherwise, use a tank sprayer.
Spray the tree thoroughly, to the point of runoff.
It will probably take about two gallons of spray to cover a medium-size tree with conventional training and pruning; one gallon of spray to cover a summer-pruned backyard orchard tree.
Spray peaches and nectarines while they are still dormant.
You can spray other fruit trees such as apricots. plums, and cherries with the same mixture.
Many fruit species such as figs, persimmons, and pomegranates need no spraying. Citrus are sprayed only as needed for specific pest and disease problems.
Dormant and bloom sprays don’t control the worms that get into apples and pears, or the new fruit-fly larvae that are attacking cherries. For those we use growing-season sprays.

The diseases we are concerned about are:
• peach leaf curl, which only affects peaches and nectarines. Sprays are only effective before the buds break. If they show color (green or pink) it is too late.
• brown rot, which primarily affects apricot (and almond) blossoms. See note*. Sprays are only effective when the trees are in bud and bloom. Plums and cherries, as well as peaches and nectarines, can also get brown rot, but it is much less common.
• This spray mixture also helps control shothole fungus, and the oil helps to reduce over-wintering insects.

Notes:
MicroCop (copper sulfate) and Polysul (lime sulfur) are no longer available, so we are now recommending the liquid copper spray. It is less effective for leaf curl, unfortunately, but easier to apply. The problem is that the final spray solution, following label rates, is lower concentration than you were applying before. We cannot recommend that you exceed the label rates.

** You cannot apply both products at the same time in a Dial-A-Pro hose-end sprayer. Apply each at the label rate, 24 hours apart.
* Copper is not effective for brown rot on apricots, and there is no organic or low-toxicity alternative available to homeowners. Chlorothalonil is available, but is very toxic; read and follow label instructions carefully if you choose to use it. Note non-chemical suggestions for control measures at ipm.ucdavis.edu:
Prompt removal and destruction of fruit mummies and diseased plant parts prevents the buildup of brown rot inoculum and helps keep rot below damaging levels. Prune trees to allow good ventilation. Furrow irrigate or use low-angle sprinklers to avoid wetting blossoms, foliage, and fruit. Plant varieties that are least susceptible.

Product information:

LiquiCop

Spray Oil

draft Jan 14 2011