By Jean R. Natter

Group and water containers

In an emergency, as in you were caught off guard, realize that container-grown plants are more sensitive to cold than the same kind of plants in the ground. It’s because roots are more sensitive to cold than top growth. Root are essentially exposed when in pots but are protected by the large soil mass in the ground.

The first things that need attention are container-grown plants. Set them pot-to-pot tight, in a sheltered place, then throw frost-blanket or an old blanket over the group. You can protect hanging baskets similarly, by setting each one on an up-turned pot or bucket. Then, too, a large cardboard box will shelter an individual specimen nicely. Such emergency covers can protect against several degrees of cold.

But don’t use plastic sheeting unless you prop it above the plants. The reason? When the freeze arrives, any plant tissue touching the plastic will die.

If you have sufficient time to think ahead, make certain all the containers are well-watered, even those you’re unable to move because of their size or weight. Even though it may be hard to believe, moist growing media is less likely to freeze than if it’s dry. (That’s true for all plants, whether in a container or the ground.)

And if you forget to set the plants in a sheltered site, you may still be able to protect them if you act just before dawn, the time when the lowest temperature occurs

The effects of a freeze

Frozen plant tissue turns dark and becomes soft to mushy. The reason, in most cases, is that ice crystals form inside the plant cells during a freeze and, then, perforated the cell walls. If you see minor freeze damage on a treasured plant early in the day, you may be able to limit potentially serious damage by shading the damaged area from direct sunlight. With shade, the intracellular ice crystals thaw slowly and will be less likely to rupture cell walls than if they thawed rapidly.

Some generalizations

• Get ahead of the game by adding several inches of mulch on the soil around cold-sensitive plants.
• In general, recently installed plants, even if a kind that’s normally hardy, are more likely to be frost-damaged than those planted a year or more previously.
• If a shrub or tree is seriously damaged during a freeze event, wait to remove damaged wood until after new growth begins in the spring. Then, cut at least an inch below the dead section. In the meantime, the damaged parts will provide a small amount of frost protection to the plant.
• If a hard frost, extended or not, is predicted, move sensitive plants into a shed or garage for the duration. Water, if needed, during their stay. (One year, several of my plants were still in good condition after 10 days in an attached garage with only one small window.)
• If a hard frost, extended or not, is predicted, move sensitive plants into a shed or garage for the duration. Water, if needed, during their stay. (One year, several of my plants were still in good condition after 10 days in an attached garage with only one small window.)

Resources

Winter Injury of Landscape Plants in the Pacific Northwest: (PNW Plant Disease Handbook; https://pnwhandbooks.org/plantdisease/pathogen-articles/nonpathogenic-phenomena/winter-injury-landscape-plants-pacific)

Abiotic Disorders of Landscape Plants (A copy of this book is in each metro MG office; pages 133-138 and 175-176.)

The following two Natter’s Notes have many images of cold damage but, unfortunately, are old enough that some of the listed references no longer exist:

Natter’s Notes: “Cold Damage – Lessons from the Garden” (In metro Mg Newsletter, January 2011. pages 4-5) http://www.metromastergardeners.org/files/news/January2011.pdf

Natter’s Notes: “December’s Cold Damage to Plants” (In metro Mg Newsletter, February 2010, pages 8-9) http://www.metromastergardeners.org/files/news/February2010.pdf

Freezing winter weather takes toll on home landscape plants: OSU eNews, (Reprinted in metro Mg Newsletter, February 2010, page 10) http://www.metromastergardeners.org/files/news/February2010.pdf

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Western Red Cedars Dying

Jean R. Natter, OSU Extension Master Gardener

Failing trees have been a persistent topic in MG Clinics and on the online Ask an Expert service during the past 6 or 7 years. Overall, it’s been an issue of continuing higher than normal temperatures combined with less than normal rainfall. Then, too, few homeowners realize that the continuing heat and drought affects their landscape trees in spite of being watered with the lawn sprinklers.

In order for trees to thrive, they should be irrigated separately from grass, with at least one watering to about 10 inches deep to the soil below the canopy every 3 weeks during our dry season. Indications of a water deficit is revealed by multiple signs and symptoms, among them wilted leaves; leaves with curled and/or dry edges; early fall color; leaf yellowing and early leaf drop.

Foresters have been puzzled by problems with Western Red Cedar (Thuja plicata) which normally do well on moist sites. The most recent thought is that these trees are finally succumbing to stress from many successive years of heat and drought stress.

Several recent Ask an Expert responses have noted “We are getting many reports of western redcedars dying this year, and the consensus seems to be that the combination of extreme heat and drought experienced since around 2013 through last summer is an important factor. Although this summer was mild, it often takes a year or so for a tree to show any signs of distress from drought.”

Another expert, in a response to a different client, said it this way: “Western redcedar are dying in some areas due to a complex of climate stress and other issues, with no clear primary agent of mortality.”

In general, the foresters responding through Ask an Expert are including a link to a publication released in April 2019: “Why is My Tree Dying? – Western Redcedar (Thuja plicata)” which, in summary, states:

Top-dieback, branch mortality, crown thinning and whole-tree mortality in all ages of western redcedar has [sic] been observed recently at lower elevations in the Willamette Valley and beyond. Although it is common to see ‘spiked’ or dead tops in older western redcedar, usually there are living lateral branches and a functional crown. No single factor has been identified in these more recent die offs, but a combination of poor or unsustainable growing conditions may be to blame. Redcedar may simply be growing in areas or within microclimates outside of their preferred range or areas that are no longer sustainable for long-term growth under current climate conditions.

Then, too, it suggests that alternate species for red cedar on generally dry sites include incense cedar, sequoia, and big leaf maple; on more moist sites which don’t dry out in the summer, western white pine, maple, alder, ash, or cottonwood.

Resources

– Abiotic Disorders of Landscape Plants” (#3420 UCANR); pages 51-59. A copy is in each of the metro MG offices.

– “Thuja plicata (Western Red Cedar)” outlines a basic description of this native conifer (50-70 feet, or more) which thrives in sun to part shade on moist soils, with numerous images of a healthy tree. https://landscapeplants.oregonstate.edu/plants/thuja-plicata

– “Why is My Tree Dying? – Western Redcedar (Thuja plicata)” – April 2019 – https://www.oregon.gov/ODF/Documents/ForestBenefits/TreeDeclinesRedcedar.pdf

– “Pruning Drought Stressed Shade Trees” encourages caution to remove as little wood as possible from a stressed tree, in part because it already has limited reserves, with precious little remaining to “spend” on otherwise unneeded wound repair. https://droughtresources.unl.edu/droughtpruning

Natter’s Notes

Found in OR: A Native Squash Bee

Jean R. Natter, OSU Master Gardener

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Fig 1: Female squash bee (above image); numerous pollen grains clinging to the scopa (pollen-collecting hairs) on hind leg of female squash bee; also notice her squared-jaw. (https://bugguide.net/node/view/1420105/bgimage)

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Thanks for the effective sampling goes to citizen scientists collecting native bees for a survey sponsored by the recently formed Oregon Bee Atlas (OBA). A second sample was acquired later on, again in southern Oregon. 

The Oregon Bee Atlas (OBA) represents the first steps towards gathering and organizing knowledge about our state’s native bees. The OBA’s mission (2018-2021) is to train citizen scientists (committed volunteers) to identify the many native bees known to reside in the state, and to seek new native bee records for the state. After a species checklist has been created, periodic follow-up surveys will be able to determine whether the numbers and health of Oregon bees is improving or declining.

As a result of finding these two bees, the OBA has issued a “squash bee call to action.”

Now that we “have two confirmed samples,” they say, “it would be great to get a map this year of the extent to which these bees have spread through Oregon – even negative results are welcome” In other words, OBA would like its volunteers start looking specifically for squash bees.

This is a project perfect for early risers. Volunteers need to go out early – dawn — before the flowers open, and manually unfurl the flowers.

[Currently, it’s thought likely that squash bees won’t be in the northern part of the Willamette Valley. But who knows? Nature may surprise us.]

The OBA Protocol for locating squash bees:

1. Early in the morning, open mature flowers of the larger flowered Cucurbita species and count the squash bees inside. These are male bees.

2. Only survey zucchini, pumpkin, and other large flowered squashes. Not cucumbers or small flowered plants. 

3. Take photos (clear, focused) of the flowers with squash bees.

4. Record how many squash bees you find in the flowers, collect the bees, then preserve them in rigid containers in your freezer until you contact me (j.r.natter@aol.com). I‘ll forward your documentation to the OBA.

5. OBA also requests you record the date and time of the collection; your name; the address; latitude; longitude; the flower (pumpkin; squash, etc.); and the number of squash bees in each.

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Fig 2: Female honey bee (above image), Apis mellifera, common in landscapes and gardens country-wide. (https://bugguide.net/node/view/1364844)

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Resources

Video: “Journey of the Squash Bees” (UC Davis) https://www.youtube.com/watch?v=pAQVNl0C-H0

Video: “Squash Bee Natural History” (UC Davis) https://www.youtube.com/watch?v=WobQObH4oDE

“The Bees in Your Backyard” (Wilson & Carril; Princeton University Press; 2016; pages 224-225.)

Images of squash bees, Peponapis pruinosa. (https://bugguide.net/node/view/83553/bgimage)

Natter’s Notes

Summer’s Challenges

Jean R. Natter, OSU Master Gardener

Ah, summer.  Thoughts of gentle breezes and abundant harvests. But, wait! Even as I write this, temperatures are soaring. Just how severely plants were damaged by the time you read this will depend upon how rapidly gardeners reacted. Or, better yet, were ahead of the game.

Just how plants are affected by high temperatures depends upon numerous factors, among them the extent and duration of the heat; the relative humidity; windy or not; soil moisture content; also, the kind of plant, its age, site, and general status when the heat hit. Sometimes leaves are only damaged superficially.  Other times, tissues die.

Tissue survival is most likely when the plant is fully hydrated well before the heat hits. After extreme heat arrives, stomates close, inhibiting water uptake by roots. So, whenever a heat wave is predicted, water the night before or early morning, between 2 and 6 AM.

Although sufficient and timely irrigation is important, so is temporary shade. Container-grown plants are especially vulnerable to damage during bright, hot weather. If possible, move them to a shaded site until the heat passes; if that’s impossible, rig temporary shade at least 18 inches overhead.

Avoid wilt

It’s critical to avoid wilting because wilted plants are permanently damaged even if the plant “totally recovers” after it is watered. Vegetables won’t produce the abundant yields gardeners expect.

Wilting is obvious with herbaceous plants, less so with woodies. In all cases, watch for subtle changes in leaf color. Early on, water shortages are signaled by an off-color, a somewhat blue- or gray-green.

Other effects of excessive heat include the following:

– Leaves droop, a plant’s temporary response to protect tissues from excess sunlight.

– Flower buds shrivel and dry instead of opening.

– Flowers scorch, especially at the petal edges.

– Fruits with insufficient leafy cover, may sunburn, and eventually spoil.

– Pollination fails, such as when immature summer squash doesn’t enlarge and, instead, rots at the blossom end. Or, when tomatoes stop setting fruit, resulting a harvest lull later on.

– Pollination is incomplete, as when summer squash resembles a billy club.

Blossom End Rot in tomatoes

Blossom end rot in tomatoes won’t be recognized by gardeners for a week or two. It’s caused by insufficient transport of calcium to the bottom of the fruit. (No; crushed eggshells in the soil won’t help.)

Early on, you’ll see a slight graying of the skin color on the blossom end. With continued stress, cells die, producing a black area which gradually enlarges and may permeate the entire fruit with a secondary infection (rot). Perhaps most frustrating is, even though damage isn’t visible on the exterior, the internal flesh has rotted. See “Blossom-End Rot of Tomatoes” (FS139; https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/fs139.pdf).

General guidelines for water

– Water early in the day so that your plants will meet the rising temperatures well supplied with a fully moist rootball.

– On scorching days, consider adding a second brief supplemental irrigation, perhaps up to half the usual amount, in the early afternoon to “top off” soil moisture.

–  Realize that the output of drip irrigation and soaker lines is in gallons per hour whereas sprinklers, in-ground or not, is gallons per minute.

Resources

– “Abiotic Disorders of Landscape Plants” (UC); pages 139 to 155.

– “Diseases of Trees and Shrubs” (Sinclair & Lyon, 2nd edition); pages 492 to 494.

– “How High Heat Affects Vegetables and Other Crop Plants” https://extension.udel.edu/weeklycropupdate/?p=3203

 

 

 

PDF Version Summer’s Challenges

Natter’s Notes

Brown Rot vs Bacterial Blight/Canker

Jean R. Natter, OSU Master Gardener

Two problems common to many fruiting and ornamental Prunus species are bacterial flower blight which often progresses into bacterial canker, and brown rot blossom blight and fruit rot.

Both diseases begin with very similar signs and symptoms. Flowers brown earlier than normal and collapse; the infection sometimes continues onto the attached twigs, where the affected leaves dry and cling to the branch; then, too, gumming or ooze may appear. Both diseases may kill branches, eventually the tree.

So, if you’ve been stumped now and then as to the correct diagnosis—brown rot versus bacterial blight – be heartened by the words of Jay Pscheidt, co-author of the PNW Disease Management Handbook: “Symptoms of the two will initially look the same. The big difference will be the development of signs – brown rot spores that give it that dull sort of gray coloration. So, if it has spores, it is for sure brown rot but, if they do not develop, we can’t really say for sure which it might be.” (Ed. comment: Ugh.)

A diagnostic option

As you know, MGs begin by obtaining a thorough history from clients. Another critical part of a successful inquiry is to examine suitable samples or images of much more than just one leaf.

Professional plant detectives visit sites where the troubled plants live; MGs don’t. Determining an accurate diagnosis is difficult, sometimes impossible while confined to an office.

But we must make every effort to resolve the issue before hand. One option is to pass the inquiry to the next shift or two via a Referral Form, another is to contact another of the metro MG offices during our shift.

Although MGs seldom submit affected tissues to the OSU Plant Clinic for diagnosis, we can do so. Insect ID is free; disease ID typically requires a fee. But, before submitting any sample from your MG Office, consult with one of the following persons: for Clackamas County: Jane Collier; for Multnomah and Washington Counties: Jean Natter.

Factors in both diseases

– Cold wet weather for Bacterial Blight; warm moist weather for Brown Rot. (This spring was perfect for brown rot.)

– Stressed trees are more susceptible.

– Some cultivars have tolerance while others are very susceptible

Cultural management of brown rot

– Remove and destroy infected twigs and branches in summer.

– Remove and destroy all affected fruit all dropped fruits as well as mummies that cling to the tree; don’t compost.

– Avoid wounding fruit at harvest and cool it immediately.

Chemical management of brown rot

– Apply fungicide during bloom; PNW Disease Handbook lists possible home gardener products.

– Realize that a product suited for application to ornamental flowering trees may be prohibited for fruiting trees.

Cultural management of bacterial flower blight

– Prune out affected tissues during dry weather; avoid the rainy months when bacteria may easily enter healthy tissues via leaf scars, the site of a mechanical injury, and/or pruning wounds.

– Disinfect pruners between trees with a 30-minute soak in 70% alcohol or in 10 percent bleach (9 parts water with one part of bleach)

– Consider replacing severely affected tree(s) with a tolerant kind. “Prunus sargentii ‘Rancho’ and P. yedoenis ‘Akebono’ appear to have some resistance. ‘Kwanzan’ cherries appear to be resistant when mature but not when young.” (https://pnwhandbooks.org/plantdisease/host-disease/cherry-flowering-prunus-spp-bacterial-canker)

Chemical management of bacterial flower blight

– No chemicals are listed for use by home gardeners.

– Client could hire a Certified Arborist to spray. It’s helpful to request on-site evaluations from 3 or more Certified Arborists. (Use zip code to search for nearby Certified Arborists at www.treesaregood.org.)

– Use of copper is discouraged because of bacterial resistance problems, also that it may increase disease intensity.

Resources

Bacterial Flower Blight and Canker:

— PNW Disease Handbook: https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-bacterial-canker

— Bacterial canker – http://ipm.ucanr.edu/PMG/r105101511.html

Brown Rot Blossom Blight and Fruit Rot:

— PNW Disease Handbook: https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-brown-rot-blossom-blight-fruit-rot

—  Brown rot – http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/DISEASE/aprbrownrot.html

PDF Version Brown Rot vs Bacterial Blight

Natter’s Notes

Noctua pronuba, the Winter Cutworm

Jean R. Natter, OSU Master Gardener

Winter cutworms, also known as Large Yellow Underwings, were first identified in Oregon about 2001. Since then, they have raised a ruckus in home gardens, lawns, pastures, and agricultural fields during the winter. The larvae (caterpillars) feed on a wide array of plants at night, whenever the air temperature is 40F or more. So, it’s critical that the damage is differentiated from that of slugs and snails which, by the way, don’t always leave a slime trail.

ID characteristics

Both the adult and larvae are seen in several color forms. Among the adults (moths), the wing coloration ranges from light tan to quite dark brown. But certain characteristics are constant, among them the 2 dark, kidney-shaped spots on each forewing.

To ID the larvae (caterpillars), look for a brown, inverted-Y on a light-colored head capsule. And, along each side of the body, you’ll see a row of dark dashes, each one underlined with a slightly shorter, light colored dash. Newly molted caterpillars are bright green. And, as is usual for Lepidoptera, the larvae will also have prolegs and 3 pair of true legs.

Life cycle

During the growing season, the adults rest in the shelter of leaves on low-growing plants. Now and then, it’s likely you’ll flush one out while working in the garden during the summer.

The flash of orange on each hind wing of a brown moth is an easy field ID character. (See https://bugguide.net/node/view/9821.)

The life cycle follows complete metamorphosis. The several hundred eggs are laid in large patches on the host plant, arranged in neat side-by-side rows. Larvae (caterpillars) hatch in 2 to 4 weeks. They’ll feed in the fall and continue through the winter, at night, whenever the temperatures are above 40F. During the day, the larvae rest just under the soil surface, quite close to the stem of the victimized plant.

Because caterpillars are chewing pests, plant parts disappear. Winter cutworms commonly align with leaf edges and eat inward, creating larges scallops. Or they may chow down somewhere within the leaf blade.

The caterpillars pupate in the soil. Likely you’ll find a number of them as you prepare your flower and veggie beds this spring. A fun project is to rear out the pupae to verify which particular caterpillar species you have.

To rear a pupa, place it in clear container and cover with a breathable lid, perhaps paper toweling held in place with a rubber band. Set the container somewhere you’ll see it often, but not in the sun, then wait for the adult to emerge. Adult moths are always easier to ID than are pupal cases you find in soil.

Common victims

Favored host plants are numerous, among them flowers and vegetables; Pacific coast iris; and the great common mullein, Verbascum thapsus, the latter considered a weed here in Oregon. During 2015, they specialized in “mowing” grasses at their bases.

 Damage

Because damage occurs during winter, be certain to differentiate damage from that caused by slugs and snails which, by the way, don’t always leave a slime trail. Then, too, before you suggest treatment, determine if damage is current and possibly ongoing. Or is it old damage? In that case, the pest is long gone.

Management

The PNW Insect Management Handbook discusses home garden management of caterpillars in the section Horticultural, Landscape, and Ornamental Crops: Common Landscape Pests.

Take your choice of physical methods, among them to handpick; feed to the birds, drop into a nearby spider web; flick into soapy water; cut in half or stomp. Bacillus thuringiensis (Bt) is an organic ingredient useful against caterpillars on both ornamental and edible plants; always apply according to label directions.

Resources

1172. Large Yellow Underwing A New Cutworm in Idaho includes images of several very similar species, most of which are more common in agricultural sites than in home gardens; http://www.cals.uidaho.edu/edComm/pdf/CIS/CIS1172.pdf.
1173. Winter Cutworm: A New Pest Threat in Oregon contains close-up views of the larvae [page 3] as well as chemical recommendations for both home and commercial users; https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9139_1.pdf.
1174. Large Yellow Underwing moth and cutworm caterpillar, Noctua pronuba has excellent images of eggs, larvae, pupae, and adults; http://www.wildlifeinsight.com/british-moths/large-yellow-underwing-moth-and-caterpillar-noctua-pronuba/.

PDF Version Noctua pronuba

Natter’s Notes

Fertilizing Garden Plants

Jean R. Natter, OSU Master Gardener

As we discussed last month, the cue to start fertilizing seedlings of seasonal flowers and vegetables is by using a commercial trick: Apply a liquid fertilizer at half, or quarter, strength as soon as the cotyledons (seedling leaves) change position from vertical to horizontal. An early fertilization such as this will give your seasonal flowers and vegetables a running start toward the abundant harvests you expect. (Fertilizing Seasonal Vegetables and Flowers; Metro MG Newsletter; February 2019: http://blogs.oregonstate.edu/mgmetro/?cat=1179565)

A brief overview

Fertilizer deficiencies in landscape plants are uncommon in our region’s clay-based soils. Typically, potassium (K), phosphorus (P), and magnesium (Mg) are present in sufficient quantities for most plants.  Even so, it’s worth knowing that nitrogen is the element most often in short supply because it is water-soluble.

Nitrogen deficiency is characterized by pale and/or stunted growth; oldest leaves that turn yellow and may also dry and shrivel; along with dark green tip growth. (That’s true only if the plants received appropriate amounts of light and water for their kind.)

Growing in containers may complicate things. The soilless planting mixes used in containers, combined with a severely restricted root space, offer plenty of opportunities for plant problems. Here’s where a commercial potting mix premixed with a bit of fertilizer will come in handy for at least the first season to maintain woodies.

Eventually, though, container gardeners must periodically add fertilizer elements needed for growth, more often than in a ground bed. Even so, nitrogen will be the most common nutrient deficiency. The frequent watering required to maintain container-grown plants readily washes out nitrogen because of its high solubility.

Then, too, long-lived container plants become rootbound after a number of years in the same container. Roots have filled all the cracks and crevices in the potting mix such that nothing gets through, not roots nor water, or even fertilizer. Roots aren’t able to function. Sometimes it’s too late to re-pot.

Samples of effective fertilizer programs

Seasonal flowers or vegetables in pots: Mix a slow-release fertilizer into the potting mix, then sidedress about 4 weeks later. If needed during the season, use a dissolve-in-water product to perk up the annuals. Don’t bother adding a high phosphorus fertilizer in the hopes it will encourage flowering. Seasonal plants must absorb the required phosphorus very early in their brief lifetime.

Seasonal flowers or vegetables in the garden: Rake a starter dose of granular fertilizer into the conditioned soil. Immediately after setting the transplants, settle the soil around their roots with a diluted fertilizer solution. Sidedress about 4 weeks later. (Again, high phosphorus isn’t needed for bloom.)

Herbaceous perennials in the garden: Proceed as for seasonal flowers the first year. If needed, sidedress in each successive year. (With ornamental grasses, consider skipping the starter fertilizer because the plants may grow too soft and flop; also consider minimizing, or skipping, any sidedressings.) With experience, you’ll learn how to “read” your plants.

Lawns: Choose from fertilizing programs for high-, moderate-, or low-input lawns. Complete details for planting and maintaining lawns are in “Practical lawn care for western Oregon” https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1521.pdf.

Shrubs and trees in the landscape:

Contrary to popular opinion, established landscape shrubs and trees seldom need fertilizer, especially if they are supplied with an organic mulch such as bark dust or wood chips out to the dripline. Bark chips, 3 to 4 inches deep, are recommended for trees or use bark dust, but to only 2 inches deep. That sort of program is similar to following nature’s lead: Maintain an organic mulch around the base, both to slowly fertilize the trees and shrubs as the mulch degrades in place, also to conserve soil moisture and to minimize fluctuations of soil temperatures. (Yes, you’ll still have to weed now and then.) The main undesirable effect of fertilizing long-lived landscape trees and shrubs is that doing so increases the frequency for pruning.

If you think that you absolutely must fertilize woodies, apply granular nitrogen after the new leaves have fully expanded. Then, they’re able to put fertilizer to good use while they photosynthesize. (Broadcast it underneath the canopy, out to the dripline.) Fertilizing at other times of year may produce new growth but the tree must use its own reserves, not the fertilizer, to do so.

This, by the way, brings an important caution to mind: Never fertilize a stressed tree because it needs all its reserves to survive the stress.

Blueberries would be notable exceptions to the take-it-easy guidelines for landscape woodies, simply because you want them to fruit well. See Growing Blueberries in Your Own Garden – https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1304.pdf.

Roses are another exception to laid-back fertilizing because, this time, the desired yield is abundant flowers for outdoor display and probably also as indoor cut flowers. Obtain a “rose fertilizer” from a large garden center or use one of the formulations available from the Portland Rose Society, then apply according to directions. (http://www.portlandrosesociety.org/fertilizer.html) Don’t bother with homemade concoctions.

Resources

– Soils and Fertilizers (chapter 2 in Sustainable Gardening, the MG handbook)

– Fertilizing Shade and Ornamental Trees https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/fs103.pdf

The PDF Version:
Fertilizing Garden Plants

Natter’s Notes

Fertilizing Seasonal Vegetables and Flowers

Jean R. Natter, OSU Master Gardener

When it comes to fertilizing plants, common myths may risk your plants’ health.  The general guideline is to start early and supplement as the season proceeds. So, let’s look at the facts, while focusing on growing annual flowers and vegetables.

Synthetic or organic?

It’s important to know that many brands and forms of fertilizer work well. Whatever your choice, organic or synthetic, liquid or solid, the goal is to produce abundant yields of flowers and/or edibles. It’s also possible to use a combination of organic and synthetic. For instance, you might plant a cover crop, then follow with synthetic fertilizers at the appropriate times. (See Cover Crops for Home Gardens; FS 304; https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/fs304.pdf.)

In order to obtain the same end result, synthetic products are less costly than organics, are applied in small amounts, and act rapidly. Organics cost more, in part, because they require larger amounts as well as considerable labor to haul and apply. Then, too, organics react relatively slowly because they rely on soil organisms to release the fertilizer elements. Perhaps the greatest value of the bulky organics (manure), is that a small percentage of fertilizer elements remains to be released during subsequent years. Thus, avoid overloading the soil by applying the full amount of manure for 1 to 3 years, then apply a smaller amount during successive years. (See EC 1503, page 7.)

Soil tests

A professional soil test is useful before beginning a new garden to identify possible excesses and deficiencies in the soil. Then, when repeated every several years, the test will note changes and suggest adjustments in fertilizer applications. Fall is a good time for a test because lime and possibly other remedies can be applied in a timely manner.

Here, in the metro counties, we typically suggest the nearby A&L Soil Lab, 503-968-9225. Call them to ask how to sample and how to deliver the soil. Request a general test, with recommendations, for a home garden in which you will grow annual vegetables, or whatever else you are interested in, perhaps lawn.

Fertilizing seasonal plants in the garden versus in pots

When it comes to fertilizer deficiencies in our region with its clay-based soils, the most common in home gardens is nitrogen. (Nitrogen deficiency is revealed in pale and/or stunted growth; oldest leaves turn yellow, then dry and may drop; new tip growth is dark green.)  So, for the most part, you can forget about using any of those various fancy deficiency charts when growing seasonal plants in the garden. In most instances, a general fertilizer with nitrogen (N), phosphorus (P), and potassium (K) will do the job for seasonal flowers or vegetables, presuming, of course, that the plants receive appropriate amounts of light and water for their kind.

Growing in containers is where things may become complicated. Fill them with a commercially-prepared potting mix because the coarse components will allow good drainage in the shallow depth available in most pots as long as it has drain holes. (Avoid adding coarse stuff in the bottom because, contrary to popular opinion, it impedes drainage.) Find a potting mix that works for you and your watering habits, then always use the same stuff in your containers.

It’s worth knowing that commercial potting mixes enriched with a bit of fertilizer will need additional fertilizer if your seasonal plants are expected to achieve the expected abundant yields. Always use a general purpose product designed for container-grown plants.

Wherever a seasonal plant is growing, in the ground or a pot, don’t bother adding a high phosphorus fertilizer to encourage bloom. A plant absorbs what it needs when it needs it. More important yet, adequate phosphorus must be available in the first quarter of the plant’s life.

Starting seasonal flowers and vegetables from seed

If you seed directly into the garden, begin by digging to the depth of a garden fork, remove weeds and debris, mix in several inches of compost, then level the soil. Next, rake in a starter dose of granular fertilizer, then seed and, finally, settle the soil by gently watering.

As soon as the cotyledons (seedling leaves) change position from vertical to horizontal, apply a liquid fertilizer at quarter strength. Follow up with a side-dressing at about 4 weeks. (Or follow the package directions!)

Similarly, when seeding into a container, fill it with slightly moist potting mix, seed, then water lightly to settle the seed and potting mix. When the cotyledons become horizontal, apply a liquid fertilizer at quarter strength.

Set your transplants, either home-grown or purchased, into their final growing place when they are several inches tall, then water with quarter-strength fertilizer to settle the soil. It won’t be long until you can start harvesting.

Useful Resources

– Growing Your Own (EM9027) provides a rapid overview especially useful for gardeners, including those new to our region. Particularly helpful is the chart of planting dates for vegetables. (We’re in Region 2.) https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9027.pdf

– Soils and Fertilizers (chapter 2 in Sustainable Gardening, the MG handbook)

– A Guide to Collecting Soil Samples for Farms and Gardens https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec628.pdf

– Fertilizing Your Garden (PNW 1503) includes the use of wood ashes. https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1503.pdf

– Fertilizing with Biosolids (PNW 508) https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/pnw508_0.pdf

PDF Version:
Fertilizing Seasonal Vegetables and Flowers

 

 

Natter’s Notes

Helpful Books & Websites

Jean R. Natter, OSU Master Gardener

Research-based information underlies everything Master Gardeners do. But it’s challenging to keep up with all that when you’re scrambling to know where the information is. When you’re searching online for data, adding “site:edu” (without the quote marks) will limit the results list to information from educational institutions. Unfortunately, “site:edu” doesn’t guarantee accuracy, because people aren’t perfect. (Believe it or not, mistakes happen.)

Right now, you may be wondering who, or what, can you believe? Well, to increase the likelihood of passing on accurate information, always review and compare at least 3 of the search responses. If disparities exist, continue searching and/or ask someone who may be able to provide additional insights. Your goal is a “Teachable Moment” during which you accurately inform the public. No home remedies, even if one was suggested in a university publication.

To begin your research, realize that each metro MG Office has a list of pre-approved resources in the “Master Gardener Office Information” binder under Tab L, Helpful Books and Websites. Begin with the list’s Table of contents. Each section generally lists books first, then websites. Most cited books are in each MG Office.

Following is a brief sample from the final page: Five very common, annoyingly weedy plants that tend to run rampant in the northwest. Some have been declared invasive, others are on a watch list.

Arum, or Lords and Ladies (Arum italicum) Herbaceous perennial; green leaves marked w/ white; deep fleshy root w/ offsets; prolific seeder https://www.portlandoregon.gov/bes/article/486580

Lesser Celandine (Fig buttercup; Ranunculus ficaria; formerly Ficaria vicaria; Ficaria verna)

• The Undesirable Beauty of Lesser Celandine https://conservationdistrict.org/2018/undesirable-beauty-lesser-celandine.html
• Lesser Celandine (USDA) https://www.fs.usda.gov/naspf/sites/default/files/naspf/pdf/lesser_celandine.pdf

Pokeweed (Phytolacca americana) An escaped shrubby herbaceous perennial with poisonous berries https://www.fs.fed.us/wildflowers/plant-of-the-week/phytolacca_americana.shtml

Spurge laurel (Daphne laureola) A woody Daphne escapee; seeds freely in northwest woodlands https://weedwise.conservationdistrict.org/2018/november-weed-month-spurge-laurel-2018.html

Tree of Heaven (Ailanthus altissima) Large, rapid-growing, a profuse seeder, with many root sprouts

• How to ID Tree-of-Heaven https://www.portlandoregon.gov/parks/article/570659

Tree of Heaven http://www.docs.dcnr.pa.gov/cs/groups/public/documents/document/dcnr_010311.pdf

PDF Version:
Helpful Books and Websites

Natter’s Notes

A New Spider; Trellis Rust

Jean R. Natter, OSU Master Gardener

A new spider in Oregon: The Brown Widow Spider

Almost everybody loves to hate spiders. Especially during the late summer and fall, when the males are dashing around the house searching for females.

Well, let me introduce the Brown Widow Spider, Latrodectus geometricus, a relative of the black widow. Now, people have another spider to worry about. (The western black widow, L. hesperus, is scarce in western Oregon, more abundant in the south and east sections.)

A first-ever record for Oregon, the brown widow was found in Oregon City earlier this year. It resembles an adult-sized version of an immature black widow, a variable combination of off-white, brown, tan and black. It can be challenging to differentiate between the 2 species until they’re more than half-grown. Finding an egg sac makes it easier; the brown widow’s is “spiky” whereas the black widow’s is smooth.

 

 

 

 

 

 

 

Resources: Spiders

– Oregon Spider Facts, a livestream video, with the main topic the recently identified Brown Widow Spider (ODA 2018-10-01; Entomologists Jim LaBonte and Josh Vlach, ODA Insect Pest Prevention and Management Program; https://www.facebook.com/ORAgriculture/videos/1704791909648978/)

– “How to Identify the Brown Widow Spider” (R. Vetter; UC Riverside) –https://cisr.ucr.edu/identifying_brown_widow_spiders.html.

– “Brown Widow Spider: Facts from Entomologist Josh Vlach” (video; 2 min 35 sec; https://www.facebook.com/ORAgriculture/videos/2151585361748105/)

– “Oregon Spiders” contains basic information and numerous links –  https://www.oregon.gov/ODA/programs/IPPM/Pages/OregonSpiders.aspx.

– Overview of potentially venomous spiders in Washington (and Oregon): https://www.doh.wa.gov/CommunityandEnvironment/Pests/Spiders.

– “How to Identify the Hobo Spider” and the giant house spider (Eratigena atrica) – https://s3.wp.wsu.edu/uploads/sites/408/2015/02/PLS-116-How-to-Identify-or-Misidentify-the-Hobo-Spider.pdf. The final verification step: Examine the male palps (p.7) or the female epigyne (p.9).

Trellis Rust on Pear

An alert client submitted images of Trellis Rust on 3 y.o. pear trees to the Clackamas County MG office last month (October 2018), a disease first identified in Oregon during 2016. Signs, symptoms, and the alternate host (juniper) are quite different from those of the more common Pacific Coast Pear Rust (alternate host incense cedar).

The MGs reported the infection to Jay Pscheidt, the OSU Plant Pathologist. Here’s his response:

Looks like we have this disease on pear in Benton, Marion, Clackamas and Multnomah counties. I have not heard of any other places. No one has made mention of it on Juniper which is interesting in itself.

From our experience this year in the Corvallis area it has not been too severe on pear. A few leaves on a few trees. In the home landscape, leaf removal seems a viable option for the moment.

I suspect chemical management may help but timing is everything. Bonide Fruit Tree and Plant Guard RTS is registered for pear but also contains an insecticide in addition to a group 7 + 11 fungicide. It should have some activity on both scab and rust. But we don’t need to be spraying pear trees now as the spores are heading to the juniper alternate host. Infuse Systemic Disease Control is registered for juniper and may have some activity to prevent infection of rust. In other words, spray pears in the spring and junipers in the fall if you want to use chemical protection.

Separation of the hosts will be the best method.

Resources: Trellis Rust on Pear

– Trellis Rust (PNW Handbook; – https://pnwhandbooks.org/plantdisease/host-disease/pear-pyrus-spp-trellis-rust-european-pear-rust)

– Pacific Coast Pear Rust (PNW Handbook – https://pnwhandbooks.org/plantdisease/host-disease/pear-pyrus-spp-pacific-coast-pear-rust)

– “Pear Trellis rust, a new disease” (Natters Notes; 2017-10 – http://blogs.oregonstate.edu/mgmetro/index.php?cat=1179565&paged=2.)

– “Pear Trees: Rust, times 2” (Natters Notes; 2018-06 – http://blogs.oregonstate.edu/mgmetro/2018/06/01/pear-trees-rust-times-2/)

PDF Version:

Natter’s Notes Spiders and Trellis Rust PDF