Natter’s Notes

Jean R. Natter, OSU Extension Service Master Gardener

Once again, the annual Gardeners’ Itch is surging. That’s in spite of the mid-February snow storm that likely afforded one last browse through catalogs, or possibly created a faint cloud of apprehension as you wondered why you bought so many seeds.

Start your project with new containers or thoroughly wash used ones. Just about anything will do as long as it’s at least two inches deep and has drainholes. Plastic containers are a good choice as they slow moisture loss. Consider multi-celled propagation trays; 6-packs you’ve saved from previous years; individual small pots; or use 4- or 5-inch pots as community pans, each one with a different kind of seed.

If you’ll use individual peat pellets, pre-soak well prior to seeding. Then set them side-by-side, one pellet touching the next, thereby increasing moisture retention a bit. After the seeds sprout and begin to develop roots, the pellets will dry rapidly. You might consider a multi-cell tray with individual units the perfect size to hold just one pellet.

The method using individual peat pots is similar. Pre-soak the pots, fill with seeding mix, plant the seeds, then water to settle the mix. But when you transplant to the garden, strip off the peat pot to allow the roots unhindered access to the garden soil.

Fill your containers with a sterile, fine textured growing medium. Do it the easy way with a commercially-packaged seed-starting mix because they’re formulated to drain well in shallow pots. A bonus: The mix is sterile, that is, as long as you don’t set the filled pots on the ground.

Instead of scooping potting mix to fill the pots, use a professional trick to ensure the media remains light and airy, two qualities which guarantee good-sized air spaces that, in turn, allow excellent drainage.

To do so:

a. Set your containers in a group, the sides touching each other.

b. Slightly moisten the media: Add hot water and toss gently to combine, until the media is barely moist throughout.

c. Pour the barely moist media into the containers.

d. Level off excess media with the side of your hand. 

e. Pick up each container and gently tap it onto a hard surface 3 times from a height of 4 inches.

f. Lightly tamp the surface of the media in each container, just enough to level the surface.  (An excellent “tamping tool” is the bottom of another container that matches the available surface area.)

Sow your seeds on the surface of the mix.  Drop one or two seeds onto the surface of each of the smallest units.  If you’re using 4-inch pots, sparsely sprinkle about 20 seeds over the surface. With still larger containers such as a nursery flat, first create shallow rows, then seed. 

Cover the seeds with moist media, the depth to match the diameter of the seed.  Large seeds – such as beans, corn, radish, and squash – are best sown directly into the garden but, for these, wait until the soil is warm enough for rapid germination. Corn and basil planted early will fail.

Water each container thoroughly by setting it in water. Remove when the surface glistens with moisture, allow to drain, and set in a bright, moderately warm place. Alternately, group the pots in a nursery flat and use a gentle spray, moving it back and forth, to thoroughly moisten the media.

Create a mini-greenhouse, of sorts, for your seeds by slipping its pot into a clear container of some sort.  Match the “greenhouse” to the size of your project.  Use what you have at hand, perhaps a clear plastic bag which rests on bamboo sticks to allow head room; or clear plastic storage boxes such as those for shoes and sweaters.

Set the ‘greenhouse’ in a warm but not sunny place. If needed, lift the cover briefly to vent excess moisture that accumulates on the insider.

Seedlings require bright light! As soon as the seeds sprout, the main challenge is to provide enough light to develop sturdy seedlings.  Sunny windowsills rarely provide adequate bright light for seedlings.

Some folks use a commercial light stand but you can substitute a 2-tube fluorescent fixture suspended 2 inches above a workbench holding the plants. Suspend the fixture on chain so that you can adjust the height as the plants grow. My old-school strategy of one cool white and one warm white tube works well. The plantlets will thrive with 16 hours of light a day.

Seedlings will also benefit from a slightly lower temperature at this stage. On average, daytime temps of 65 to 70°F and nighttime temps of 55 to 60°F are adequate. Then, too, if seedling roots dry out, they die! Watering from the bottom is a gentle method, but dump the excess within 20 minutes.

Seedlings also require fertilizer! Begin fertilizing when the cotyledons ( seedling leaves) are flat out. Use fertilizer-enriched water at half-strength for every other irrigation. And always transplant seedlings, either to a larger pot or to the garden, when the first set of true leaves expand.

Always transplant seedlings when the first set of true leaves expand. But recall that you’ll need to harden off the seedlings prior to planting outdoors. Hardening off means to prepare tender, indoor-grown plants for a harsher life outdoors. (See “Sustainable Gardening.”)

And finally, be aware of the potentially unhappy side of gardening: Herbicide carryover in manure compost. And that’s true whatever the source, free or commercial. I recently responded to an Ask Extension inquiry from a gardener whose vegetables were affected during 2020. (See resource list for online links.)

Resources

• “Sustainable Gardening” – Your trusty, research-based MG Handbook.
• “Growing Your Own” – A free tabloid with an extensive planting chart for vegetables (Page 7 and various helpful gardening information. The metro counties are in Region 2. (https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9027.pdf)
• “Herbicide Carryover in Manures,” an overview – https://puyallup.wsu.edu/soils/clopyralid/
• “A Simple Bioassay for Herbicide Carryover” is an easy test to ensure safety for your plants. – https://s3.wp.wsu.edu/uploads/sites/411/2014/12/PDF_Clopyralid_Bioassay.pdf
• “What to do about Herbicide Carryover in the Garden” clearly outlines remediation. –https://pesticides.montana.edu/reference/contamination.html

Natter’s Notes

Jean R. Natter, OSU Master Gardener

In case you haven’t been outdoors recently, you need to know weeds are growing in spite of the soggy soil from all the recent abundant, rainfall. So, let’s review a few strategic management strategies for successful weed control in gardens and landscapes. As you may know, the PNW Weed Management Handbook (see resource list) has a thorough overview of the subject.

Annual weeds are classified as warm-season or cool-season plants, with each kind genetically destined to germinate (sprout) in the appropriate season, then survive for a year or somewhat less. The same categories are assigned to perennial weeds but these are considerably more long-lived, persisting for 3 or more years.

As a result, gardeners must be vigilant year-round.  

Several key principles limit weed populations in gardens and landscapes, among them these:

– Kill weeds when they’re young; ten fingers are always at hand.

– Don’t allow weeds to set seed.

– Annual weeds will die when cut just below the crown.  Use a knife, or any one of various hoes – standard garden hoe, diamond hoe, or a scuffle hoe.

– Perennials will re-grow when cut off, even if covered with mulch  Vigorous kinds will make it through a lasagna garden; and may lift landscape fabric and/or polyethylene sheeting. 

– To kill perennial weeds, you must starve the roots; to do so, remove all green growth every week for as long as it takes, very likely several years.

– Herbicides are rarely a “once-and-done” remedy.

Gardeners can make good use of creating a “stale seedbed” before planting a flower or vegetable bed, or even a lawn. The reason?  Hundreds of dormant seeds — termed the “Soil seed bank” – have been deposited in the soil during years and years of poorly managed, or unmanaged, weeds. Whenever soil is disturbed, some of those seeds are brought near the surface where they germinate because they are exposed to light, also appropriate temperatures and moisture.  

Start a stale seedbed a month or so prior to the desired planting date, thereby allowing for a cycle or two removing weed seedlings.  Do everything needed to prepare the planting bed: dig; remove obstructions and weeds; amend the bed; level the soil; then moisten the soil to settle it and allow for germination.  As soon as a good stand of young weeds about inch tall is present, destroy them using your preferred method: hand, hoe, flamer or, if you must, herbicide. 

The earlier a stale seedbed is started, the more germination cycles possible, the fewer weeds will be present to steal water and light from the desired crop.  Next, seed or transplant your veggies or flowers with minimal disruption of the soil, and deal with any seedling weeds promptly.

With perennial weeds, choose among these destructive techniques:

1. Dig it out; repeat as needed.

2. Cut it off; repeat as needed.

3. Herbicides are effective if the right kind is used according to label directions; repeat as needed for re-growth and/or use #1 and #2, above.

Tools to help limit weeds:

– Hands

– Hoes

– Herbicides, organic or synthetic: Contact products kill only top growth (fine for annual and seedling weeds); systemic products translocate (move) into other plant parts, sometimes into roots.

– Mulch, with the understanding that new weeds, in the form of seeds, will continue to arrive via clothing; muddy boots; new plants; birds; hitchhikers on mowers; or may be blown in.

– Flamer

Some trees are known to put up root suckers after they are cut down, among them are such broadleaf trees as ash, aspen, cottonwood, flowering cherry and poplar.  Conifers won’t re-sprout, even if the roots remain in the ground.

To limit root sprouting after a broadleaf tree is removed:

– Cut down the tree as soon as the new leaves have fully expanded in spring. 

(Principle: The tree used most of its reserves for new foliage, thus the stump/roots will put up fewer sprouts than if the tree is removed later in the season.)

– Immediately after the tree is cut off, paint a 2-inch-wide band of the other edge of the cut surface with an herbicide such as triclopyr or 2,4-D, following label directions.

– Remove new shoots as soon as they’re seen:

       – The more often new greenery is removed, the better the chances of decreasing the roots’ reserves; once a week is a good plan.

       – The longer new growth remains, the more reserves it sends to the roots, thereby extending the battle. 

– Be persistent and you will win; pause for a season and you lose.

Resources

– Sustainable Gardening (your MG Handbook)

– Weeds and Your Garden: https://ecommons.cornell.edu/bitstream/handle/1813/43859/weeds-in-garden-bro-NYSIPM.pdf;sequence=1

– PNW Weed Management Handbook: Online at  http://pnwhandbooks.org/weed/horticultural/home-garden-landscape-management  

– PNW Weed image gallery (from the 2010 Weed Handbook): Organized by common name, each weed with 1 to 3 images: seedling, flower and/or mature.  http://uspest.org/pnw/weedimages?weeds/id/index.html

– Weeds and other unwanted plants (text and images)  http://ipm.ucdavis.edu/PMG/menu.weeds.html

Natter’s Notes

Jean R. Natter, OSU Master Gardener

Early in 2020, a new pest of mason bee, Cacoxenus indagator, was identified in Washington State for the first time. It’s often referred to as the Houdini Fly because of the unique way it escapes from the mason bee’s nesting cell. It’s also nicknamed the Red Devil due to its large red eyes, or just Devil Fly. It’s presence in Oregon is suspected to but not yet verified.

The arrival of the Houdini fly is suspected to be an unfortunate example of moving bees without carefully inspecting them and their nests prior to the move. “In New York, the first two records were in 2011, although it may have arrived there earlier. It had presumably come there from Europe, probably someone moving an unclean nest block,” said Josh Vlach, from the Oregon Department of Agriculture during an interview by Andony Melathopolous during PolliNation Podcast #154 (2020).

What damage does the fly cause?

“The flies don’t actually attack the bees; they’re kleptoparasites,” continued Vlach.  “The fly is in the same group as Drosophila fruit flies that fly around a bowl of over-ripe fruit.” They closely resemble their fruit fly cousins – about the same size, with large red eyes, but otherwise a dull brown color. They move rather sluggishly, and are often seen near the entry to a nesting tunnel.

After the mother bee leaves the nesting tunnel, the Houdini fly enters the tube, lays eggs on the pollen ball, then quickly exits. After the nesting cell is closed by the mother mason bee, the fly larvae hatch and eat the pollen ball. As a result, the mason bee larva starves.

 How to recognize an infestation

Telltale signs of these kleptoparasitic flies are sticky clusters of small white maggots in a nest cell. The bee larva is dead or missing. [Note: Kleptoparasite may be spelled with a “c” as in cleptoparasite.] But beware! Another pest, a parasitoid, produces a similar cluster of small white larvae.

Be aware of a look-alike infestation by tiny wasps

Unfortunately, to the untrained eye, the white larvae of Monodontomerus wasps could be mistaken for Houdini fly maggots. These small black wasps – sometimes referred to as ‘Mono’ wasps – are much more active than adult Houdini flies. The adult wasps erratically flit about. They’re parasitoids which lay multiple eggs in a single mason bee larva. However, the end point is the same as with the Houdini flies: Dead mason bees.

Management suggestions for Houdini flies (WSDA Pest Alert)

–  Harvest mason bee cocoons – Open mason bee nesting materials before they emerge in the spring and destroy Houdini fly maggots.

– Control adult mason bee emergence – If you cannot open nesting materials, place your nesting materials in a fine mesh bag and close tightly. As the bees emerge, release the mason bees daily and kill any Houdini flies.

– Only use nesting materials that allow you to open, inspect, and harvest cocoons. Visual inspections can greatly reduce Houdini fly populations. (Ed. note: Kill the larvae on sight.]

– Before purchasing mason bees, ask the provider how they harvested and whether they inspected the cocoons for Houdini fly.

– Only purchase pest-free mason bee cocoons.

A few final words

– WSDA suggests: “Please do not unnecessarily move bee blocks or boxes around.”

– If you’re having sizeable losses of healthy mason bee cocoons, seriously consider modifying your materials, methods, and procedures.

– A viable alternative to using clustered artificial housing for native bees is a healthy environment with modest-sized patches of suitable flowering plants that provide a year-round succession of bloom

– Perhaps the best habitats for native bees are patches of bare soil, along with naturally-occurring tubes, among them spent plant stems and old holes from boring beetles, all in a pesticide-free location.

Resources

– PolliNation transcript #154 – An interview with Josh Vlach, ODA. (https://extension.oregonstate.edu/podcast/pollination-podcast/154-josh-vlach-invasive-pests-pollinators)

– “Parasitoids and Cleptos”- https://ento.psu.edu/research/centers/pollinators/resources-and-outreach/disappearing-pollinators/parasatoids-and-cleptos [Caution: “. . .artificial bee nests and hotels may be preferentially used by introduced bee species and native wasps, rather than native bees]

– Video: Houdini fly, a kleptoparasite of Osmia –  https://nurturing-nature.co.uk/wildlife-garden-videos/cacoxenus-indagator-a-cleptoparasite-of-red-mason-bees-video/

– Video: Life cycle of Montodontomerus wasp – https://www.youtube.com/watch?v=_bwhBipHktI 

– “How to Manage the Blue Orchard Bee”- An overview. https://www.sare.org/wp-content/uploads/How_to_Manage_the_Blue_Orchard_Bee.pdf

– “Orchard Mason Bee” (10-Minute University) — Orchard Mason Bees (wordpress.com)

 – Pest Alert WSDA// https://agr.wa.gov/departments/insects-pests-and-weeds/insects/apiary-pollinators/pollinator-health/houdini-fly  Houdini fly found in Washington; images and 2 videos:

Video: How does Cacoxenus escape?; Video:Devil fly on nesting tubes. “The accompanying fauna of Osmia cornuta and Osmiarufa” – Pests of Osmia in Europe, with images – http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.598.9947&rep=rep1&type=pdf