Category Archives: plant diseases

Methods for controlling plan diseases

About Roses

Roses are the flower of love. Many of us have fond memories of favorites in our motherís garden or of a beautiful bouquet given or received on Valentineís Day. Itís dormant season for roses which is good for both pruning and adding a few to the garden.

David Austin rose

As a designer I have clients who have inherited roses and want to keep them as a remembrance. Others want to create a cutting garden filled with roses and other perennials. Donít feel guilty for growing those beauties in your own garden. They use less resources than you think and there are many ways to grow them sustainably.

Roses, whether bush types, climber or ground cover carpet varieties, use a moderate amount of water in order to thrive according to the latest Water Use Classification of Landscape Species (WUCOLS) list. This amount of summer irrigation is the same as many of the plants on the list of Scotts Valley Water Districtís 800 Approved Low Water-Use Plants for lawn replacement. Plants such as Emerald Carpet manzanita, Joyce Coulter ceanothus, Siskiyou Blue fescue grass, Pacific wax myrtle, butterfly bush, yarrow hybrids and Tapien verbena have similar water requirements.

Since now is the time to prune your roses here are a few tips.

Strike it Rich hybrid tea rose

Prune shrubs moderately to keep them compact. The goal is to keep the center of the plant open for good air circulation aiming for a vase-shaped bush with an open center. Cut out canes that cross, appear weak or are diseased, spindly or dead. Healthy canes appear green or reddish while old and dying canes are brown. Cut back the remaining stems by about one third. When pruning, cut canes at a 45-degree angle just above an outward facing leaf bud or a swelling on the cane. Clean pruners after every use to prevent the spread of disease and keep your pruners sharp.

Prune heirlooms roses such as David Austin and other old antique garden roses less because their open look is part of their charm.

Same goes for climbing roses. Cut out extra stems if there are too many and also cut back long established canes to about the place where they are slightly thicker than a pencil. Then cut each side stem down to several inches. This will make the cane flower along its complete length for a beautiful spring display.

Zepherine Drouhin climbing rose

Pluck off and rake away any old leaves. They can spread fungal spores. Consider spraying dormant plants with a combination of organic horticultural oil and copper soap or lime-sulfur. If you usually only have problems with black spot you can use a mixture of 1 teaspoon baking soda with a few drops of light horticultural oil in 1 quart water and spray every 7 to 10 days during the spring.

Prune your roses throughout the growing season, too. Deadheading, or cutting off spent flowers, encourages plants to re-bloom. Mulch around your roses to conserve water and encourage soil microorganisms.

Don’t worry whether you’re pruning job is perfect. Roses are super forgiving and you can always trim them up again later.

The Best Dogwoods & How to Grow Them

Alluvial_Terrace_wholesale_nursery
Alluvial Terrace Nursery

Thereís nothing like learning about trees from someone who has discovered for themselves what makes a winner and how to grow it. Recently I had the opportunity to tour a small wholesale nursery near Corralitos. Jon Craig has evolved from Silicon engineer to a propagator of plants and trees and heís all the happier for it. He laughs when he says he has loved plants for a very long time starting with his first job mowing lawns. As a former engineer itís all about the research and the plants he grows showcase his success.

His very favorite tree is the dogwood. Not just any dogwood but the ones that bloom with the largest flowers for the longest time. There are four main species of dogwood trees. From the Himalayas in China comes cornus capitata, Korea is home to cornus kousa. Cornus florida grows on the east coast and the west coast is home to cornus nuttallii or Western dogwood.

Jon_Craig_with_Mountain_Moon.1600
Jon Craig with cornus capitata ‘Mountain Moon’

We are all familiar with the Eastern dogwood that blooms early in the spring. Itís beautiful but rain and wind can cut short the flowering season many a year and the root system is prone to disease. Our Western dogwood is prone to leaf spot fungal diseases. The Kousa dogwood is a more drought tolerant, disease resistant and a tougher plant all around. Large, showy flowers open after the tree has leafed out and remain for a long time. This makes it good for hybridizing with other varieties.

The Stella series is a mix of a florida on kousa dogwood roots. Vesuvius series is a cross of our native nuttallii with a florida as is Eddieís White Wonder. There is also a nuttullii-kousa cross called Venus that displays huge flowers and gets its disease resistance from the kousa roots. All these cultivars strive to produce a tree with superior disease resistance and huge, long lasting blooms.

cornus_capitata_Mountain_Moon_closeup
Mountain Moon

Deciduous dogwoods donít like wet feet especially in the winter. Thatís how they develop fungal disease. But thereís an evergreen dogwood that can handle moisture all year round. That tree is Jon Craigís very favorite. With a name like Mountain Moon you can just picture it blooming high in the Himalayas. Huge flowers up to 6Ē wide can last from late spring into early summer. After flowering, the fruits begin to form and grow into red balls about the size of large strawberries. This is the reason is it also known as the Himalayan Strawberry Tree. They are edible but bland and tasteless to us. The birds love then though and they remain on the tree while woodpeckers and robins have a feast.

Cornus capitata ‘Mountain Moon’ is a tough tree that can handle strong winds and isnít bothered by any pests or diseases. They enjoy lots of organic matter as do all dogwoods. Many people think of dogwoods as an understory tree but this location is often too shady. Grow them in a full or partial sun location that gets afternoon shade after 4pm. Add a couple of extra drip emitters or inline drip tubing to your irrigation system and theyíre happy.

cercis_Ruby_Falls.1600
Ruby Fall redbud

Besides enjoying the hundreds of blooming dogwoods, I learned about a redbud that is not as fussy as the lovely Forest Pansy. Ruby Falls and Merlot promise to be more reliable in the garden and more heat resistant.

Jon will try his hand growing just about any plant that he thinks others will also enjoy. A fine crop of Alice oakleaf hydrangea grew near a block of Michelia ‘Inspiration’ getting ready to flower and scent the air. The lilacs had finished blooming but the peonies were just starting their show. Jon shared a tip about tree peonies he learned recently from a well-seasoned Japanese gardener. He followed her advice and cut back the tree peony stem in the dormant season forcing it to produce new stems. Voila- they are now loaded with flowers.

peony
peony

Jon grows many other types of dogwood and also Copper beech, magnolia macrophylla, Royal Raindrops crabapple , Sheriís Cloud nyssa and even a Purple-leaved hazel. I could only fit a couple of 5 gallon cans in my car so a beautiful smoke bush in full bloom and a Black Lace elderberry now call Bonny Doon home. But I have my eye on one of those spectacular Mountain Moon evergreen dogwoods for the back garden.

Pruning Roses for Bloom & Vigor

rose_pink_cabbageIn the spirit of practicing what I preach I set out to do a little pruning around the Ďol homestead last week. Since I cut back the hydrangeas pretty hard last year this time round I did only a bit of shaping. The fuchsias havenít gone totally dormant this year but as they bloom on new wood I cut them back by a third. Then I looked at the roses. I have a few climbers and several shrub roses. This is how Iím going to get the best rose show ever this year.

I want my roses to produce lots of roses on a compact shrub and not just a few OLYMPUS DIGITAL CAMERAexhibition size blooms so I prune my shrubs moderately. My goal is to keep the center of the plant open for good air circulation aiming for a vase-shaped bush with an open center. Iíll cut out canes that cross, saving the better of the two, prune spindly and diseased stems and dead wood. Iíll also prune canes that appear weak or broken. Healthy canes appear green or reddish while old and dying canes are brown. Cut back the remaining stems by about third. When pruning, cut canes at a 45-degree angle just above an outward facing leaf bud or a swelling on the cane. Slant the cut away from the bud to encourage growth outward. Clean pruners after every use to prevent the spread of disease and keep your pruners sharp to make clean cuts.

rose_Hot_Cocoa.2048Heirlooms roses such as David Austin and other old antique garden roses require less pruning because their open look is part of their charm.

Same goes for climbing roses. Cut out extra stems if there are too many and also cut back long established canes to about the place where they are slightly thicker than a pencil. Then cut each side stem down to several inches. This will cause the cane to flower along its complete length for a beautiful spring display.

My roses still have many of last yearsí leaves and are pushing new growth rose_Icebergalready. I know those old leaves will spread fungus spores and possibly infect the new growth so Iíll patiently pluck them off. If you have a huge climber this might not be possible and spraying with fungicide may be your only option if youíve had disease problems in the past. Rake up the debris beneath the plant and discard to eliminate overwintering fungus spores. It’s a good idea to spray the bare plant, coating the trunk, branches and twigs and the surrounding soil with a combination organic horticultural oil to smother overwintering insect eggs and a dormant spray like lime-sulfur or copper soap to kill fungus spores. If you usually only have problems with black spot you can use a mixture of 1 teaspoon baking soda with a few drops of light horticultural oil in 1 quart water and spray every 7 to 10 days during the spring.

Pruning intimidates some gardeners but when you understand the reasons for making the cuts, pruning becomes less daunting. The reasons to prune are for health, appearance and to control size.

Prune your roses throughout the growing season, too. Deadheading, or cutting off spent flowers, encourages plants to rebloom. Every time you cut a rose bloom to bring it indoors or deadhead a fading rose, prune the stem down to shape the plant at the same time. Prune to a spot that has at least 5 leaflets. Roses grow from the point where they are cut, so consider the overall shape of the plant as you snip.

Don’t worry whether you’re pruning job is perfect. Roses are super forgiving and you can always trim them up again later. Roses are like redwoods -you can’t kill one- they’re the energizer bunnies of the plant world.

Dogwood in the Santa Cruz Mountains

dogwood_RoblesEarlier this year the flowering plums were the first trees to welcome the beginning of spring. Then came the flowering cherries, crabapples, pears, redbuds and lilacs. But now the flowering dogwoods take over as the stars of the show. They are blooming everywhere I go. Whole neighborhoods, lined with dogwood trees, are coming to life.† I† know of several beautiful specimens along Hwy 9 that bursts into bloom this time of year covered in snowy white, pink or rosy blossoms. There are many types of dogwoods and every garden has the perfect spot for at least one. What better way to honor Earth Day 2014 than to plant a tree?

When thinking about where to plant your dogwood tree consider what role you want cornus_florida_closeupthe tree to play in your garden. You might place it where it becomes the main focal point especially during the spring flowering season but also where you can enjoy the brilliant fall foliage. Maybe one located at the back of the garden would be nice drawing the eye along a path and the flowering shrubs growing along the edges.

Dogwoods need good drainage. If your garden has heavy clay soil plant your tree in a raised bed. They make excellent understory trees in high filtered shade if the air circulation and drainage are good. With 2-3″ of mulch dogwoods thrive in full sun, too. The fungal disease anthracnose is not usually a problem here in our summer dry area if drainage is good. Hybridizers have successfully crossed the Japanese dogwood, cornus kousa, with the eastern dogwood, cornus florida, to create the wonderful disease resistant Stellar series. Also the native Pacific dogwood, cornus nutalli, has been crossed with the eastern variety to produce Eddie’s White Wonder. Both are good choices.

cornus_florida_closeup2The beautiful flowers of the dogwood are actually bracts, a leaf-like structure surrounding a flower. The colorful bracts of poinsettias, the magenta bracts of bougainvilleas and the bracts of the dogwood are often mistaken for flower petals. No matter what you call them, the blossoms are spectacular.

Dogwoods attract a variety of wildlife. All sorts of critters use this tree for food and shelter. The giant silk moth and several species of butterflies favor dogwoods as host plants. The spring flowers provide nectar to bees and other pollinating insects. Robins and sparrow are just two of the bird species than build nests on the horizontal branches and many others seek shelter in the leaves. The high calcium, high fat, fleshy red fruits are eaten by 35 species of birds including titmice, juncos and waxwings.

The fruit of flowering dogwood is poisonous to humans but the root bark was used by Native Americans as a fever reducer, skin astringent, an anti diarrhea agent and as a pain reliever for headache and backache relief. It was also use to counteract the effects of many poisons and as a general tonic. The flowers were infused to reduce fever and relieve colic and several plant parts were used as medicine for blood diseases like malaria.

Because dogwood leaf litter decomposes more rapidly than most other species it has been planted on abandoned strip mines and used for urban forestry projects. The wood is hard, strong and shock resistant, making it suitable for wood products that need to withstand rough use like tool handles, roller skate wheels, golf club heads and knitting needles and spools.

Dogwoods look so great in our area because we get some winter chill.† Some of cornus_capitata_closeupmy favorite varieties include cornus capitata also known as Evergreen or Himalayan Dogwood. It’s a slow growing tree which will reach 20 ft tall after about 25 years and has large white blossoms.

Other common favorites with rosy flowers are Eastern dogwood, Cherokee Chief and Cherokee Brave. Their leaves turn glowing red in fall with fruit lasting well into winter. There are lots of white blooming varieties also and this tree is the parent of the exceptional hybrid Eddie’s White Wonder and the anthacnose-resistant Stellar Pink.

The Japanese dogwood, cornus kousa, starts blooming several weeks later than the Eastern varieties and continues for 5-6 wks. The flowers open along with the leaves which is different than its relatives. This dense multi-stemmed tree grows to 20 ft tall.† With raspberry-like fruits that persist into winter and leaves that turn yellow or scarlet in autumn it’s a beautiful addition to the garden.

Remember a mature leafy tree produces as much oxygen in a season as 10 people inhale in a year. Trees clean the soil and air of pollutants, act as windbreaks and can muffle noises.

Gardening Tips for August & IPM

I go out into my garden and look around daily. I pick basil for tonight's bruschetta, parsley for the potatoes and a few Sungold cherry tomatoes that don't make it into the kitchen but are eaten on the spot. I count 10 hummingbirds around my 3 feeders, the Ruby-crowned kinglets are scouring the trees for spiders and other bugs and the Wilson's warblers have found the thistle sock.

But what's this? Some of the fuchsia leaves and buds are curled, there are notches in the impatien balfourii and I see white furry things on the trunk of the crabapple.  The weather is hot one day and foggy the next. Better adjust my watering schedule, too. Whether you're seeing some of these same problems in your garden or have different issues that you don't know how to handle, here are some tips to help you decide what you can live with and what you can't.

Integrated pest management or IPM is a fancy name for common sense. By planting the right plant in the right place you can prevent most pest infestation. Pick your battles.Take action against insects only when they pose a significant threat to your plant.

Plants can usually survive with a little bug damage. Insects that are natural predators often will eventually arrive and handle your bug problem.  Picking them off by hand or spraying them off with water often works, too. Some vegetable plants may need to be protected with insect barriers or row covers. Simple traps for earwigs, slugs and snails are effective, too. Vacuuming is another method of controlling pests. Tilling the soil often disrupts the breeding cycle of insects like the rose slug. Encourage beneficial insects to visit your garden by planting a variety of plants. Use natural biological insecticides like Bt and nematodes that have minimal environmental impact.

If you feel you must spray for soft bodied insects like mites, choose insecticidal soap. This may sound strange but by not killing all the pests there will be some left in the gene pool that are not resistant to the organic or chemical sprays. Those left will dilute any resistant genes that appear.

Regular monitoring is the cornerstone of IPM. This is where that daily walk in your garden with a beverage comes in. You can see if a problem is getting out of control or not.

The fuchsia gall mite is one problem that I keep tabs on or the hummingbirds aren't happy. If your fuchsias aren't blooming and the leaf tips look curled up and deformed, your plants are infested with fuchsia gall mite.  First discovered on the West Coast in 1980 it is often mistaken for a disease because of the way it distorts and twists fuchsia leaves and flower buds.  The damage caused can be debilitating.  The leaves curl and distort so much that normal photosynthesis is disrupted and weakened plants fail to bloom  Infested plants usually recover if further mite damage is controlled.

Prune off all distorted foliage and buds.  This may be the best method of control as petroleum oil or insecticidal sprays need to be made every 4-7 days to disrupt the mite life cycle and will result in the mites becoming resistant. Neem oil is not recommended for use on fuchsia flowers.

There are several gall mite-resistant fuchsias, both hanging and upright, that are every bit as showy as the traditional fuchsia varieties.  if you have been plagued by fuchsia mites, try growing one of these instead. A list from Crescent City Fuchsia growers is available at http://www.ccfuchsia.net/ccfuchsia5.htm.

If you have a problem in your garden and don't know what to do, feel free to email me. I'm always happy to help a fellow gardener.

 

Sudden Oak Death Syndrome ( SOD )

InDay Lilypreparing for a consultation for another site under native oak trees at risk for SOD I found the latest host list published by the Sudden Oak DeathTask Force . The new list updated March 2008 also lists plants naturally infected and lots of information re. spreading the fungus as well as tips on sanitation. The latest information on prevention and keeping the immune system of your trees up if also available. I did find that a few of the plants that I was going to recommend for homeowners with oaks on their property have now been listed as vectors. They are coffeeberry, toyon, berberis aquifolium, manzanita and some varieties of ceanothus. This is important information for all of us to know.