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PROTECTING YOUR HOME AGAINST WILDFIRE

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published August 7, 2016

Kudos to our firefighters for their hard work in fighting the recent wildfires and successfully protecting local homes. Since they do their part in keeping us safe, local home owners should help in the protection of their properties with fire-resistant landscaping. In the short term, there are some easy steps you can take to provide some protection to your home. If your home is situated in an area vulnerable to wildfire, the longer term actions of designing and creating a fire-resistant landscape should be undertaken.

Mulches: Many of you know I favor bark mulches in the landscape because they add organic matter to the soil as they decompose, conserve soil moisture, control weeds, and keep the soil cooler than rock mulches. However, when working to create a fire-resistant landscape, the use of bark or wood chips should be eschewed in favor of non-flammable gravel or rock mulches. Gravel or rock mulches are best especially when mulching any areas that are close to buildings, fences, wood decks, or other wooden structures.

Raised Beds: Raised beds are a big trend in gardening right now, but they are predominantly constructed out of wood. In fire-vulnerable areas, it is better to build raised beds with bricks, concrete blocks, rocks, corrugated metal, or other non-flammable materials.

Landscape Maintenance: While not everyone craves a neat and tidy landscape, yard cleanup and the removal of plant litter is one way to reduce fuel for potential wildfires. So get busy now raking up the layers of dead pine needles and arborvitae foliage beneath these evergreens, dry leaves that have piled up in nooks and crannies around the yard, or bunches of dry plant litter anywhere else. If pines or other needled evergreens are situated close to your house, regularly remove their litter that accumulates on the roof and in gutters.

Keeping potential sources of fuel in mind, be sure to store any firewood 30 to 100 feet away from structures and also keep vegetation away from area. Eliminate any piles of plant litter, such as grass clippings, you may be accumulating. Also, remove dead shrubs and tree branches in your landscape. Cut down weeds and brush in areas of your property that are not landscaped.

Lawns: In regions like ours where the supply of irrigation water is a constant concern, limited areas of lawn are advocated to conserve the amount of water needed to keep grass green during the heat of summer. However, green lawns do resist fire well and efforts should be taken to maintain this green space around your home. However this is not a license to apply water heedlessly. You should still water more deeply, less frequently to save water and promote a healthy green lawn.

Trees: Because I like trees and appreciate the cooling value of their shade, I have ten trees in my yard. If I was in a fire-vulnerable area, I would need to consider pruning off the lower limbs of my trees to remove this ladder fuel. Ladder fuel is plant vegetation, green or dry, that permits fire to ascend into the tops of trees. Pruning off limbs from 6 to 15 feet up is recommended. For the health of the trees, this is best done with proper pruning cuts when the trees are young.

Landscape Design: Creating a well designed “firewise” landscape is very important if your home is situated where it is vulnerable to wildfires, especially if in the wildland-urban interface area. You can help defend your home with sound firewise landscaping. For information on firewise landscape design, go to the University of Idaho’s publication “Protecting and Landscaping Homes in the Wildland/Urban Interface” available at http://www.treesearch.fs.fed.us/pubs/22257. For a list of firewise landscaping plant materials go to: http://www.co.chelan.wa.us/files/public-works/documents/firewise_landscaping_materials.pdf

TOO MUCH COMPOST?

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published July 31, 2016

While both new and experienced gardeners know that garden soil may benefit from the addition of compost, they do not know about the problems that can arise when from adding too much or using poor quality compost. Let’s take a little time to chat a bit about the pitfalls of adding compost to garden soil.

While good quality compost is considered the holy grail of garden organic matter, there are no set standards for compost. The quality of compost varies with the types of materials composted and the composting processes used. Mature compost is one where the organic materials are fully broken down into stable organic matter. Quality compost is mature compost that is not high in salts, contains no contaminants from industrial waste, has few weed seeds, and can provide plant nutrients.

You can not discern quality compost by looks. If purchasing commercially made compost, ask the seller for a copy of the laboratory analysis provided by the compost producer. Look for the carbon to nitrogen ratio (C:N) that indicates the stability of the organic matter (OM). A ratio between 12:1 to 15:1 is an indication that the OM is stable. If the ratio is less than 10:1, it is an indication that it contains organic materials that are still in the process of decomposing. A ratio above 25:1 indicates that the compost contains high carbon materials that break down very slowly and will tie-up available nitrogen as it decomposes, depriving garden plants of nitrogen and hampering plant growth.

On the analysis look for the EC or electrical conductivity of the compost. This is a measure of the soluble salts in the soil. High soluble salt levels are harmful to plant roots. Compost with an EC above 8mmho/cm are high in salts and should be avoided. It is better to purchase compost with an EC that is between 0 and 4 mmhos/cm.

Also, pay attention to the percent (by dry weight) of organic matter in the compost. If the percentage is lower than 30 per cent, it means that soil or sand have been added to the mix. If higher than 60 percent, it is unfinished or immature compost containing undecomposed organic materials.

Be aware that each batch of compost that a producer makes varies in its analysis. One time the salt levels may be acceptable and the next time they may be too high, so check the analysis each time you purchase compost even if it comes from the same supplier or producer.

While local soils often benefit from the addition of quality compost, it is possible to over do it. Too much compost can cause problems including excess nutrient levels, especially nitrogen and phosphorous, high soluble salts, and excessive levels of organic matter. (Levels of organic matter above 5% to 8% by weight are too high.)

The general rule of thumb when adding compost to the soil in vegetable gardens or annual flower beds is to add no more than 2 to 3 inches of quality, low-in-salt compost to garden. The compost should be thoroughly incorporated into the top 6 to 8 inches of soil before planting. Done annually, the level of organic matter in your soil will increase. To avoid excessive levels of organic matter, reduce the amount of compost you are adding to only 1 inch after three years or get a soil test to determine the level of organic matter in your soil. As with so many things in life, too much of a good thing can be bad. The same goes for compost.

Garden Hint: How much compost do you need to apply one inch to the garden? Three cubic yards will cover 1,000 square feet to a depth of one inch.

ROOT WEEVILS IN THE GARDEN

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published July 24, 2016

This week I was out weeding in my garden and noted considerable notching caused by root weevils on the leaves of various plants. Root weevils are a common pest in area home gardens but the adult weevils are seldom brought to the Extension office for identification. That is because they are nocturnal, feeding late at night and hiding during daylight hours on the undersides of leaves or beneath debris on the ground. However, you do not have to see one of the critters to know that they are at fault. Root weevil feeding causes characteristic scalloping or small semi-circular irregular notches along the leaf margins.

While some insects feed only on certain species of plants, roots weevils are not as selective. In home gardens they tend to show a preference for rhododendron, lilac, forsythia, peony, rose, euonymus, Japanese holly, blueberries, and strawberries, but they will chow down on over 100 other species of plants. Along with their distinctive notching, another sign of their presence are black fecal deposits found on the undersides of notched leaves.

Because there are at least 16 species of root weevils found in Washington, adult weevils vary in size from 1/8 to 1/2 inch long and in color from black to brown or gray. Based on research done by Sharon Collman, WSU Extension Entomologist, black vine, obscure, and strawberry root weevils are very common in western Washington, but the lilac root weevil is dominant in eastern Washington landscapes and gardens.

So what makes a weevil a weevil? Weevils are a specialized type of beetle. They are somewhat oblong in shape and have hard, crunchy outer wings. What sets them apart from beetles is their elbowed antennae and their specialized mouth parts that look like an elongated snout. Also, the inner wings of most weevils are not well developed, leaving them unable to fly.

So what makes a root weevil a “root” weevil? The creamy-white C-shaped legless grubs or larvae of root weevils eat plant roots. They start out by feeding on fine roots and then may move onto larger roots and even the crown or base of plants. Leaf notching caused by adults is primarily just cosmetic damage, but heavy feeding on the roots by larvae can kill plants.

One control strategy is to avoid introducing root weevils into your garden and landscape by inspecting plants before you buy and avoiding any with the characteristic notching. Root weevils cannot fly. To get from here to there they have to walk or hitch a ride on infested plants, soil, or plant litter.

Once root weevils get started in a yard or garden, it is hard to get rid of them. There are some home garden insecticides available for control of the adults, but generally these materials are not very effective. If you do try chemical control, apply sprays at night between nightfall and midnight when the adults are feeding.

WSU Extension recommends that gardeners manage root weevils by hunting them down after dark. No, I am not kidding. Place sheets or box tops under your infested plants and then go out late at night and shake the branches. The weevils will drop onto the sheet where you can collect and dispose of them. Do this on successive nights until you are not getting any adults dropping off the plants. (You may want to warn your neighbors about this so they do not call the police.)

Another method of control is the application of beneficial nematodes to the soil when the larvae are present. The nematodes are applied as a drench to moist soil when the soil temperature is above 55 degrees. Because of climatic conditions in our regions it may be difficult to effectively control root weevils with nematodes, but some local gardeners indicate they have worked for them.

For more information on the biological, cultural, and chemical control of root weevils go to: http://insect.pnwhandbooks.org/small-fruit/strawberry/strawberry-root-weevil.

HARVESTING AT THE RIGHT TIME

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published July 17, 2016

Vegetable gardening is a lot of work, but it is worth it to be able to pick fresh nutritious produce right from the garden. However, not everyone knows when or how to harvest vegetables at the “peak of perfection.” Since many warm season vegetables are starting to become ripe, let’s talk about harvesting and care of just-picked veggies.

Summer Squash: Zucchini and yellow summer squash are best harvested when they immature and only 4 to 7 inches long. To pick the fruit, cut them off the vine using garden shears or a knife. If allowed to grow larger and more mature, their skin gets tougher and the seeds get bigger and harder. After harvesting wash the fruit with clean water and then use immediately or store in vegetable bin of the refrigerator. They will only store for a week or less.

It is important to harvest your fruit as soon as they reach the right stage because it promotes the production of more fruit. However, you and I know there is always one zucchini on the plant that hides and grows to gargantuan proportions. Sometimes these are thrown out or given away, but creative cooks will remove the hardened seeds and stuff the fruit for baking, chop it up for use in soup, or grate it for adding to zucchini bread or tomato sauce.

Onions: Dry onions are ready to harvest when most of their tops have fallen over. When this happens, it means the onions are done bulbing and will not get any bigger. To harvest, carefully pull them out of the ground and shake off as much soil as possible. In heavier soils the onions may not pull easily so lift them out of the soil using a spading fork. Then “cure” or dry the harvested bulbs in a shaded location with good air circulation. Once their roots are dry and the skins become dry and papery, cut the tops off about two inches from the bulb and store them in mesh bags under dark, dry, cool (32 to 40 degrees) conditions. Keep in mind that sweet onions, such as Walla Walla Sweets, do not store well. Yellow onions store the best, followed by red and white onions. Of course, you do not need to worry about curing or storing the onions if you want to eat them immediately.

Both the green stems and immature bulbs of green onions or scallions are harvested whenever they reach the desired size. Wash green onions thoroughly with cool, clean water before eating. Because they are immature, green onions do not store well and should be kept in the refrigerator and used within a week of harvest.

Cucumbers: Like their summer squash cousins, cucumbers are harvested when they are immature and before their seeds fully develop. Cut them off the vine leaving 1/4 inch of stem attached to the fruit. The correct size for harvesting depends on the cultivar and their intended end-use, with pickling cucumbers tending to be smaller than those cultivars for salads and fresh eating. Check the cultivar seed packet or catalog to find out the correct size for harvesting. Mature cucumbers are undesirable because they have tough skin, bigger seeds, and often a bitter flavor. Harvest your cukes regularly to promote continued bloom and fruit production. After harvesting, wash the fruit and then store them in the refrigerator for a week or less.

Harvesting melons can be tricky, so we will tackle that topic another time.

THERE ARE NO PERFECT TREES

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published July 10, 2016

I am often asked what the best trees are for planting in our region. However, this query typically includes certain criteria that make my answer more challenging. Homeowners want a tree that does not get too big, does not produce messy fruit or seeds, does not have insect or disease problems, or does not have invasive roots or surface roots. Their ideal tree also has pretty flowers in the spring and attractive fall color, grows quickly, and tolerates our local soils and climate well.

If you are waiting for a list of the trees that meet these criteria, you will have to keep waiting. There are no perfect trees. Every tree has one or more characteristic that is objectionable in some way.

Leaf Litter: If you own a mature sycamore or silver maple, you know that large trees with large leaves produce large volumes of leaves, creating a raking and disposal nightmare in the autumn. Mature large trees can be magnificent. However, when studying what type of shade tree to plant you, may want to consider trees, such as little leaf linden or river birch, with smaller leaves that produce a smaller volume of fall foliage.

Seed and Fruit Litter: Generally, trees are going to produce litter in the form of seeds or fruit. I frequently hear complaints about the massive amounts of seeds produced by some maples and Siberian elm, as well as the seed balls of sycamore and sweet gum trees.

The fruit of ornamental plums, crab apples, and cherries can provide food wildlife, but this fruit can be very messy when ripe and mushy, especially if the tree located close to pavement. Some fruit trees, even ornamental fruit trees, are subject to attack by the cherry fruit fly or the codling moth. County law requires that these pests be controlled even in ornamental fruit trees. This requires regular pesticide applications.

Gingko fruit smells like dog manure and mulberries will turn white tennis shoes permanently purple. Catalpa, Kentucky coffee tree, and honeylocust can create an abundance of bothersome litter with their seed pods.

When selecting trees, look for seedless and fruitless cultivars. For example, the Autumn Blaze maple is a hybrid cross between red and silver maple. It is seedless or pretty much seedless. If you find those spiny seed balls of sweetgum trees a problem, look for ‘Cherokee’ or ‘Rotundiloba’, both virtually seedless sweetgum cultivars. If you like gingko trees like I do, be sure to purchase a male tree, as only female trees produce the stinky fruit. If you like mulberry trees but want to skip the fruit, find Morus alba ‘Fruitless’ that does not produce berries.

Bark and Twig Litter: Some trees, like sycamore, have bark that sloughs off and in some years they can create considerable annoying bark litter. However, this does create an attractive mosaic bark pattern. Siberian elms and birches have a tendency to drop twigs all the time that must be cleaned up before mowing. Since river birch is one of my favorite trees, I am willing to tolerate this annoying tendency.

Nut litter: Mature nut trees, such as walnut, horsechestnut, Chinese chestnut, and oak all produce fairly large hard or spiny fruit. Before planting nut trees, be sure to consider the fruit that will eventually be produced.

There are no perfect trees, but some research before you buy and plant a tree will help you avoid trees that create a mess and more work for you.

FLOWERS ATTACKED BY DASTARDLY INSECTS

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published July 3, 2016

It is simple, I grow flowers in my garden because they are pretty and colorful. It is very disappointing when insects damage or destroy these blossoms. Here are three dastardly pests that are significantly impairing beautiful blooms in my garden.
Thrips: Western flower thrips cause damage to roses and a variety of other flowering perennials. Thrips are very tiny, straw-colored insects that feed on flower petals, often before the buds even open. They use their rasping mouths to scrape at plant tissues and suck up the liquids that ooze out. Their feeding causes streaks and blotches on the petals. If damage is severe, the flower buds may fail to open.
Thrips are difficult to control because their populations build up very quickly. Prune off and dispose of badly infested flowers and buds. Eliminate plant litter and weeds in and around the garden. Avoid using pesticides that kill thrips predators, like lady beetles and lacewings, or that harm bees visiting the flowers. If you decide to apply an insecticide, apply it directly the buds and blooms. Repeat applications are likely to be needed. For effective insecticides, go to: http://hortsense.cahnrs.wsu.edu/Search/MainMenuWithFactSheet.aspx?CategoryId=1&SubCatId=2&PlantDefId=33&ProblemId=568
Tobacco Budworm: The tobacco budworm is devouring all the buds on my petunias, including my beloved Wave petunias, before they even have a chance to open. Aargh! The few flowers that are able to open, are riddled with holes. The adult of the tobacco budworm is an unremarkable greenish-brown moth about ¾ inch long. Like many moths, it is nocturnal, flying, mating, and laying eggs at night starting in late spring to early summer.
On petunias the moths typically lay their eggs on the leaves, but on geraniums they deposit them directly on the flower bud clusters. As soon as the eggs hatch, the little larvae immediately get to work eating flower buds. They will also eat holes in leaves, especially when there are not many flower buds left. Along with the obvious holes in flower petals, buds, and leaves, they deposit their telltale small black frass (poop) on the leaves.
The larvae are hard to detect because young larvae are yellowish-green in color and blend in well with the foliage. More mature larvae vary in color from green to brown, tan, or purple. During the day, the larvae tend to hide in the soil at the base of the plant and then venture out at dusk to feed. When using hand picking for control, look for them at dusk.
As their name infers tobacco budworm is a pest of tobacco, but it also feeds on many other hosts, such as roses, snapdragon, zinnia, verbena, chrysanthemum, marigold, and sunflower. However, its preferred hosts are petunias and geraniums.
Sunflower Moth: The larvae of the sunflower moth also attacks garden flowers. Its hosts are sunflowers and other members of the same family such as daisies, zinnia, coneflower, and cosmos. The larvae of the sunflower moth feed on the flower centers, eating the developing seeds and leaving webbing and frass .
Most home garden insecticides are ineffective against both the tobacco budworm and the sunflower moth. For effective insecticides go to: http://hortsense.cahnrs.wsu.edu/Search/MainMenuWithFactSheet.aspx?CategoryId=1&SubCatId=2&PlantDefId=171&ProblemId=827
When using insecticides for control of tobacco budworms, apply them as soon as feeding damage is noticed. For sunflower moths, apply them when the flowers start to bloom.
I do not like using insecticides in my garden, especially on flowers that are visited by bees and other pollinating insects. As a result, I have switched to plants planted for the colorful foliage, like coleus and sweet potato, but I just cannot give up my petunias!

PICKING STRAWBERRIES

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published February 14, 2016

Let’s talk about picking strawberries, not harvesting those delicious red berries but selecting which varieties to grow. There are three main types of strawberry varieties, or more correctly cultivars or cultivated varieties. There are June-bearing, everbearing, and day-neutral cultivars.

June-bearers form their flower buds (that turn into the berries) in the fall and produce their one main crop of berries in spring or early summer, depending on the cultivar. Everbearers form their flower buds in the fall and again during summer and produce one crop in spring or early summer and a second crop in late summer or early fall. Day-neutral strawberries form their flower buds all through the growing season, producing a continuous crop of berries with production slowing during the heat of summer.

June-bearers tend to have the largest berries and produce the most fruit over a relatively short period of time. This makes them a good choice for gardeners growing strawberries with the goal of preserving them by freezing or for making jam. Day-neutrals generally produce smaller berries with great flavor over a much longer period, making them a good option for fresh eating.

Another consideration in selecting strawberry cultivars is their winter hardiness. The plants need to be able to withstand the cold of winter in the region they are grown. Some cultivars are very popular in other parts of the country or even other regions in Washington, but may not perform well here. Look for hardy cultivars recommended for growing in the inland Northwest. Here are some of them:

When it comes to June-bearing cultivars, there are a number of possible choices. Benton and Hood are long-time favorites. Hood produces large fruit early in the season and is good for fresh eating or making jam, but does not stand up well to freezing. Benton produces smaller, medium-size berries in late mid-season. They are good fresh and fair as frozen berries. Two other recommended June-bearers are Rainier and Shuksan. They are judged to have the best flavor for fresh eating and are good to excellent for freezing, although Rainier’s berries turn dark rapidly in hot weather.

Popular everbearers recommended for eastern Washington are Quinault, Ogallala, and Fort Laramie. None of these have great size and the fruit is generally not as firm as that of other types.

Day-neutral strawberries are my favorites. Tribute, Tristar, Albion, and Seascape are all recommended for our region. Tribute and Tristar have been around a long time and are dependable. They only have medium-size berries, but their excellent flavor makes up for this. Seascape, a California strawberry, has larger berries with good flavor but the plants are very susceptible to verticillium wilt. This disease can be a problem in local gardens and will shorten the life of a planting. Fern, another day-neutral sometimes seen for sale, is also susceptible to verticillium wilt and has not been tested for production in Washington.

If you want to grow strawberries, now is a good time to start planning what cultivars to plant. Check with your local nursery to see what cultivars they plan to offer this year. Purchase dormant, certified virus free plants for planting in early spring. For more information on growing strawberries in your garden, refer to “Berries for the Inland Northwest” at http://cru.cahe.wsu.edu/CEPublications/MISC0253/MISC0253.pdf and “Growing Strawberries in the Inland Northwest & Intermountain West” at http://www.cals.uidaho.edu/edcomm/pdf/bul/bul0810.pdf They provide information on site selection, planting, and care of garden strawberries.

WIND IS TOUGH ON GARDEN PLANTS

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published June 26, 2016

The weather this spring has certainly been erratic going from calm and sunny to windy and stormy and back again. These winds have created havoc for outdoor events and celebrations, but they have also impacted our yards and gardens.

Wind beats plants up. The wind flails leaves about, tearing the tissues and creating small holes in young, tender leaves. As the leaves grow bigger, the holes get bigger too, looking very much like chewing insects are doing the damage. When the wind is severe, some leaves may actually become shredded.

The leaves of squash, melon, and cucumber leaves are very bristly. When beaten about by wind, these bristles puncture leaf surfaces. This leads to small crusty patches that resemble a plant disease instead of typical wind injury. In sandy areas, the wind combined with fine sand particles can “sandblast” the stems and leaves of seedlings or transplants. This sandblasting abrasion can seriously damage young plants or outright kill them.

Desiccation is another problem that occurs as a result of windy weather. Wind increases the loss of moisture through plant leaves. Even if the soil is adequately moist when a wind event occurs, the plant roots may not have grown enough to absorb all the water needed to keep up with what is being lost through the leaves. The result can be brown, crispy leaf margins or similarly necrotic spots between the veins on the leaves.

The drying effect of wind can also cause the desiccation of flowers, leading to a lack of fruit set. In addition, the activity of bee and other pollinating insects decreases when it is windy, also leading to a decrease in the number of fruit that develop.

Severe winds and hail can cause wounding and bruising of fruits and vegetables. Bruising is usually worse when the fruit is ripe or nearly ripe. If the fruit is soft, these injuries can easily provide entry to bacterial rot organisms. Remove and dispose of fruit with significant large bruises or soft spots so that potential rot diseases will not spread to healthy, unblemished fruit.

Herbicide injury is an unnatural consequence of winds. When a gardener applies an herbicide spray in their yard, even a very slight breeze can pick up the spray droplets and move the herbicide to unintended nearby plants or even plants much further away.

The phenoxy herbicides, such as 2,4-D, dicamba, and mecoprop, commonly used for killing broadleaf weeds like dandelions are often the cause of herbicide damage found in local yards and gardens. These materials distort plant growth, causing twisted stems, cupped, feathered, or distorted leaves, and curling of growth. The best way to avoid this type of damage is to use these herbicides only if needed, apply them when the wind is calm, and use a sprayer that applies large droplets instead of a fine mist.

It is interesting to point out that while wind can cause damage to our garden plants, slow their growth, and reduce production, some wind stress can be helpful. Researchers have found that light wind, less than five miles per hour, can lead to plants with stronger, stockier stems. We can only hope we have seen the last of the extreme winds for this season, but what are the chances of that?

BROWN AND DEAD EVERGREENS PART 2

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published June 19, 2016

Last week I covered the top two factors contributing to the browning and dieback of many area needled evergreens. While it is no surprise that heat and drought stress could cause problems, some of you might wonder why we are just becoming aware of the severity of the situation.

It is easy to tell when a tomato or squash plant is suffering from drought or heat stress. They wilt. This is not the case with trees, especially conifers. Browning needles and excessive needle-drop are telltale signs of stress, but a conifer may not exhibit browning until some time after the damage from stress has occurred. Why is that? Conifer needles have a very waxy coating that slows their drying out, delaying browning, diagnosis, and preemptive action.

I will also point to the cumulative stress from three successive years of extraordinarily hot summers and minimal winter precipitation. Many of these conifers have been declining over that time, but the additional stress year after year has pushed them past the tipping point.

So what about trees that are turning brown despite their owners watering correctly, keeping the top 18 inches of soil moist and mulching to keep the roots cooler? Restricted or girdling roots, the result of improper planting, are often involved in helping push trees over the edge.

Container grown plants are frequently pot-bound with circling roots or very dense, matted root masses. If these roots are not properly cut and loosened at planting time, the roots will not move out into the surrounding soil where they have access to moisture and nutrients. Eventually the roots will girdle or Achoke@ the plant, preventing the uptake of water, and killing the tree. The signs will be that same as signs of drought and heat stress.

A similar problem occurs with balled and burlapped trees that are grown in the field, dug, and their root ball wrapped in treated burlap. In our dry climate, the burlap does not decay quickly enough to allow for good root growth out of the original root ball. University horticulturists, landscape professionals, and The American National Standards Institute (ANSI) all indicate that the burlap should be removed before planting.

Also, the soil in the root ball is commonly very different from the native soil where the tree is being planted. This can lead to difficulty in keeping the soil in the root ball and surrounding soil moist, but not excessively wet.

Soil compaction restricts root growth and can contribute to a tree=s demise. This is because compacted soil has less air available for the roots and roots need air to function. In addition, soil compaction physically impedes root growth. In older landscapes, soil becomes compacted over time from traffic and even sprinkler irrigation. In newer landscapes, the soil may be highly compacted due to the use of heavy construction equipment during building.

Where trees are growing in lawns, periodic aeration can help relieve some of the compaction. However, if the compaction is severe, a certified arborist may recommend more extreme measures. When planting a new landscape, the soil should be properly prepared with tilling before planting.

This week and last week I have mostly focused on the browning and dieback of conifers in our area, but we are also seeing dieback on some local deciduous trees and shrubs. Depending on the plant=s situation, this decline may be attributed to the same factors causing the browning on conifers. I sure hope this summer is cooler. How about you?

WHY ARE THE EVERGREENS DYING?

GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published June 12, 2016

I noted earlier this year that our last three summers have been abnormally hot with record breaking heat. Even before I started getting calls about dying arborvitae, pines, cedars, and other conifers, I predicted that the stress caused by extreme heat and inadequate watering practices was going to lead to the decline of many area trees. We can not do anything about the weather, but we can try to avoid the same problem in the future by reviewing the contributing factors.

Before we do that, let’s talk about the needles on conifers. While we call trees with needles “evergreens,” they do shed or drop their oldest needles ever year. Evidence of this is the bed of needles underneath pine trees. This is not a problem for healthy trees that are producing a new set of needles each year. These new needles persist on a tree for a year or more. Depending on the species, pines will hold their needles for two or more years and spruces for five years or more. However, if a conifer is stressed or its health is compromised by insects or disease, the production of needles will be reduced or stop altogether. This stress can also lead to the browning and shedding of more than just the oldest needles. As a result, a tree will have fewer and fewer green needles, a sign of its decline.

Drought: We are in a region with very limited precipitation, making adequate irrigation essential to growing healthy trees. Many homeowners assume that their trees are getting enough water, but they do not check the soil moisture in the tree’s root zone to make sure.

The water absorbing roots of most landscape trees are within the top 12 to 18 inches of soil. It is this zone that should be kept moist with deep watering. Watering trees just with the lawn for 15 to 20 minutes once or twice a day may not be enough to moisten the soil to the needed depth. It of course depends on how much water is being applied, weather conditions, and the type of soil. The only way you will know if the soil is moist enough is to use a trowel to dig down and check.

It is also important to moisten the soil where the water absorbing roots are located. They are not close to the trunk or under the canopy of mature trees. They are located at and beyond the canopy or outermost spread of the branches called the “drip-line.” It is to this area that water should be applied.

Heat Stress: We can not offer much relief from the heat to established trees, but when planting new trees we should consider planting trees that are well adapted to hot summer weather. If you plant a species that is not well suited to our climate, select the site carefully to provide it with protection from sun, heat, and wind. On younger and smaller trees, mulch the root zone with three or four inches of wood chips or bark to keep the roots cooler and to maintain soil moisture.

Oh my, I have come to the end and I have not had the chance to talk about soil compaction and other factors contributing to local conifers turning brown. More next week…

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