spotted wing drosophila

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A MONTH OF RECOGNITION

November 5, 2019/7 Comments/in Pests/by Lee Reich

Good in the Lab

National Fruit Fly Month — October — has drawn to a close. (That designation is my own, not the federal government’s.) Sure, a few still flit about here and there. But no longer do clouds of them hover over bowls of fruit in my kitchen. In case you haven’t experienced them, fruit flies, Drosophila species, are cute little (about 1/8 inch long) flies that feast on overripe and damaged fruit as well as other plant material.
Fruit fly
I, and perhaps you, were first introduced to fruit flies in middle school biology, raising them on some mix of banana and agar-agar. In those days, I got more intimate with them as part of a science project: My project was to test whether x-rays cause mutations. My dentist agreed to help. After raising a batch of flies, I went to his office and laid a vial of them on the dental chair whereupon Dr. Golden zapped them with a beam of x-rays. After the buggers and a similar vial of non-irradiated buggers had reproduced, I examined the offspring, especially their eyes and their wings. My experiment “proved” x-rays benign (as least as far as could be detected morphologically by a 13-year-old).

Fruit flies’ fecundity is what has earned them prominent positions in science. An adult lives for only about a month but during that tenure she may lay as many as 500 eggs. The courtship ritual of those little guys and gals is intricate, involving a kind of dance along with some instrumentation, provided by sounds from leg tapping, and some singing. Each gal gets involved with a number of guys.

Fun fact: Despite the small size of fruit flies, they have the longest sperm cells of any known organism — over 2 inches long for D. bifurca. Most of that length is the sperm’s tail. During mating, those tails are wound up in tightly tangled coils.

Not So Good in the Kitchen

Fruit flies are very interesting and useful in the lab but not in the kitchen. The flies lay eggs on the surfaces of fruits and vegetables. The eggs hatch into larvae which feed, in time turning the fruits and vegetables into a slimy mush. After molting twice, they morph into adults, who flit away to generate more offspring.

Growing up, I only knew fruit flies from the lab, never my mother’s kitchen. Why do they invade my kitchen? One possibility could be the smorgasbord my garden provides, more than ever spread on counters of that kitchen of yore. Also, refrigeration drastically slows the flies’ development but also can suppress or ruin flavors (tomatoes, for example) or speed wilting (lettuce, for example); I only refrigerate for longer term storage, not usually for fresh eating.

And being home grown, my fruits and vegetables need not aspire to the same cosmetic standards as commercial fruits and vegetables. Small wounds that I ignore or cut away provide access to fruit fly activity.

Still, I can’t let the flies run amok. Fortunately, fruit flies are easy to trap. And one of their favored baits, vinegar, is readily available. (Fruit flies have also been called “vinegar flies.”) Just put out a glass of vinegar and you’ll soon see a crowd of fruit flies flocking to it. That, of course, doesn’t trap them. Make that glass of vinegar into a trap by adding a little soap or detergent to the vinegar to decrease its surface tension so that, once in the drink, the fly can’t fly out.

Various kinds of vinegars are effective. Some people recommend apple cider vinegar. Or apple cider vinegar with a slice of banana thrown in. My preference is for balsamic vinegar. A mix of sugar, yeast, and water also works.
Fruit fly trap
Look on the web and you’ll see all sorts of more intricate — but none very intricate — traps for fruit flies. My method is to take a plastic carryout container with a lid, punch or drill a 1/8” wide hole in the lid, pour some balsamic vinegar into the container, then replace the lid.

A more Frightening Relative

Spotted wing drosophila

October isn’t the only month of prominence for fruit flies. They are out there whenever the weather is congenial and food is available. One of them, spotted wing drosophila (SWD) is fairly unique in that this species need not wait for a fruit to be overripe, damaged, or nearly rotting to attack. It threatens intact, even underripe, fruit such as raspberries, blueberries, and other fruits of summer.

SWD is a relatively recent arrival on the garden scene (2008 in California, 2013 in my garden). At first it seemed that was going to be the end of blueberries, my favorite fruit. Over the years, I’ve been able to mitigate damage. Early on, I tried sprays of Entrust and Neem, as per recommendations. But even though organically approved, for me these sprays take some of the enjoyment out of growing and eating the berries. Fine mesh covering over a whole planting has also been tried (effective, but not tried by me).
Netting for SWD
This year, and for the past few years, my blueberry planting has yielded its usual, good harvests utilizing a multi-pronged approach. For starters, I grow a dozen or so varieties that extend the season from late June until early September. SWD, here, at least, is inconsequential until early August, by which time our bellies and the freezer are almost full of berries.

In the latter part of July, I hang out traps, one per bush, that I’m helping test for Cornell’s Peter Jentsch. They are baited with raspberry essence laced with boric acid, which needs to be renewed by weekly spraying (of the trap, not the plants). After 3 years of testing, the traps seem to be effective.
SWD bait and kill trap
During summer, there’s always a bowl of freshly picked berries on the kitchen counter; by early August, fresh picked fruit goes into the refrigerator or, if the freezer’s quota still not yet filled, also into the freezer. Any larvae within fruit are killed after 3 days of refrigeration.
Bowl of blueberrires
Fruit flies and even SWD, despite their fecundity, aren’t about to take over the world. These pests have their pests, which include yellow jackets, ant, various other kinds of flies, and even smaller creatures, such as nematodes. Quoting Jonathan Swift, “. . . a flea, Hath smaller fleas that on him prey; And these have smaller fleas to bite ‘em, and so proceed ad infinitum.”

BLUEBERRIES GALORE, COMPOST TEA REDUX

July 15, 2015/19 Comments/in Fruit, Gardening, Soil, Vegetables/by Lee Reich

On My Knees for Blueberries

For the last few years, my blueberries have had a problem. Perhaps yours also. Rather than grow upright, the stems arch downward, some so drastically that they actually rest on the ground.

Blueberries galore

   A few years ago, I pinned blame on the weather. Not that it was evident just how the weather could be responsible, but it’s always convenient, in gardening, to blame things on the weather. But this explanation is hardly convincing. Spring and summer weather have not been consistent enough over the years to be able point my finger at too much rain and/or not enough sunlight (the combination of which could lead to those bowing branches).
   How about pruning or fertilization? Too much of either could promote lush growth that couldn’t support itself. Except that my pruning has been consistent over many years. And Dr. Marvin Pritts, berry specialist at Cornell, confirmed that he and others saw the same problem, without definitive explanation, a couple of years ago.
   I like the green thumb explanation best: That is, that I’m such a good blueberry grower that the branches can hardly support the prodigious crops I’ve coaxed from them. So I’m not really complaining. Just curious. And having to get on my knees to harvest low hanging fruit.

Remember Fruit Flies?

    There is one fly in the green thumb ointment. A fly, literately. A tiny fruit fly called the spotted wing drosophila or, quicker to say, which is necessary for this fly that’s getting a lot of buzz lately, SWD. The fly attacks many small fruit, starting the season with honeysuckle berries, then moving on to raspberries, blackberries, and . . . blueberries.
   Most fruit flies lay their eggs in overripe, or at least ripe fruit. Not SWD. She lays her eggs in unripe fruit. The eggs are small and what hatches from them are small; their being “maggots” sort of takes the appeal from the berries.
   SWD is a new pest, so new ways of thwarting them are being tried. Covering the plants with fine netting very early in the season is effective but would be very bothersome, for my planting, at least. Various organic sprays are another possibility: Entrust, which is derived from a soil bacterium, is effective if used STRICTLY according to directions; horticultural oil might prove effective. Traps are also under test.
   One way to bypass the problem is to grow only earlier varieties of blueberries. SWD has not showed up here and at many other sites until early August. Plenty of varieties — Duke, Earliblue, Toro, and Blueray, for example — are finished before then.
   But I want fresh blueberries on into September. Harvesting blueberries (or raspberries or other berries) and whisking them into a refrigerator at 34 degrees for 72 hours will kill eggs and larvae. Freezing, the destiny of about half our harvest, also kills the eggs and any hatched larvae. A little egg and meat boosts the protein content of the berries.

I Backpedal, Sort Of

It may be time for me to eat pie. Not blueberry pie, but humble pie. Regular readers of my words probably realize that I take a certain amount of pleasure in iconoclasm. And one recipient of my eye-rolling has been compost tea, something that many gardeners and farmers love to love even though there’s little theoretical or empirical support for its efficacy.

Compost tea, quick mix

“Little” but not “none.” A number of peer-reviewed articles describe benefits from using NON-AERATED compost tea to thwart root diseases. (The relatively recent interest in compost tea is for AERATED compost tea, often sprayed on leaves. Aerated compost tea, the brainchild and business of Dr. Elaine Ingham, is compost tea that’s bubbled with air for en extended period, often with molasses or other additions. Generally, experiments have not supported touted benefits of aerated compost tea.)
   For the past number of years, my pea crops have been failures, the plants yellowing and dying soon after harvest begins. Fusarium or some other root disease is the probable cause.
   In desperation, five times this spring, at about weekly intervals, I put a shovelful of compost into a 5 gallon bucket and filled the bucket with water. After one day of steeping, the tea was strained, put it into a watering can, and drenched on the soil beneath of my thirty foot, double rows of peas.
   Lo and behold: The peas look healthy and have been yielding good crops!

A healthy row of peas

I won’t say for sure it was the compost tea or what in the tea, if it was the tea, did the trick. But nothing else jumps out this year as the savior of my peas. For a more definitive tea endorsement, next year I should grow a row or two without the tea, and a row or two with the tea. I might try that, although it presents the possibility of my ending up with a row or two of unproductive vines.
For now, I’ll just have humble pie. And tea.

Plagues Come & Go, With Some Help, and Seattle-time

August 1, 2014/10 Comments/in Fruit, Gardening, Pests/by Lee Reich

Meet me in St. L . . . Seattle

Come hear me lecture on August 10, 2014 on “Luscious Landscaping, with Fruiting Trees, Shrubs, and Vines” at 1 pm in the Garden Room at Magnuson Park. For more information, go to http://www.brownpapertickets.com/event/755459.

Plague again; keep calm

Every year it seems some new plague is ready to attack plants. A few years ago, late blight of tomato moved to the fore. Emerald ash borer, threatening ash trees, was first found on our shores in 2002. (Figuratively; literally, the insect, native to Asia, was first noted in Michigan.) What’s next?

Perhaps a calmer outlook is called for. A decade or so garlic mustard seemed ready to take over our world. Not so, now, perhaps because it’s being crowded out by Japanese stilt grass, which itself seems now ready to take over our world. Garlic mustard is native over much of the northern hemisphere, except North America, and was introduced here around 1860 as a culinary herb. As for stilt grass, it hitchhiked here from China about a century ago, as packing material for porcelain. It’s deer-resistant, for what that’s worth.

Plant problems come and go. The best approach is to keep calm and, in some cases, plant something different, something plague resistant.

Bean Beetle Management

Green beans are a mainstay of my garden, of just about every garden. More than 20 years ago, Mexican bean beetles (a species of ladybug!) found my bean plants and have plagued them every year since.

The adults, with eight black spots over a red or yellow background, wake up late from winter sleep to lay eggs on bean leaves. I’ve come to despise the yellow, balled up spiny larvae that gorge on leaves and other plant parts.

Still, I have managed to grow good crops of beans over the years, not by killing the beetles or their larvae, but by growing a different plant. Sort of. Rather than grow pole beans, which reside in the garden all season long to provide a constant source of beetle food, I have been planting successive crops of bush beans. Bush bean plants tend to bear quickly and for about 3 weeks, then peter out, so a new planting in a new bed goes into the ground every 3 weeks from mid-May until late July.

Yield from a planting tapers off just as its resident beetle population is beginning a feeding frenzy. Then it’s time to pull up the plants, thoroughly clear the bed of leaves and old pods, and rush it all to the compost pile. Chopping the debris with a machete and burying it beneath straw and manure, and watering the pile, as needed, sends the temperature soaring, killing most of the beetles. Bean beetles are good fliers, so cooking the beetles in the compost pile doesn’t solve the problem, just keeps it under control.

Death to the beetles, with restraint

Something strange happened this year: As of this writing, only one beetle larvae has been seen. Last year I doused the bean plants a few times with one of two organic sprays, which gave good beetle control. It also gave me the confidence to try growing pole beans, as I did in my pre-Mexican bean beetle days. They got some bean beetles but we did harvest pole beans.

The sprays were Entrust and Azamax, both approved for organic agriculture. The active ingredient in Entrust is spinosad, a compound found in bacteria, Saccharopolyspora spinosa, that was isolated from soil collected inside an old rum still in the Virgin Islands. Although toxic to a range of insects, it is otherwise relatively benign. Still, the label requires waiting at least 3 days to harvest after spraying.

Azamax is an extract of the seed of the tropical neem tree, native to the Indian subcontinent. In that part of the world, this one tree has been used as human food, insect repellant, bird repellant, and an ingredient of soap. It degrades rapidly in soil or in water, and is harmless to earthworms, honeybees, and insect predators. Food crops can be harvested right after spraying Azamax.

Still, Azamax and Entrust are pesticides. Perhaps the bean beetle cycle has been broken here and sprays can be forgone in the future. I’ll keep calm. No sprays this year, yet.

SWD, go away

The same two organic sprays might be called upon for another pest, the spotted wing drosophila, unaffectionately known as SWD. Also an Asian import, this one has moved east since being first spotted in 2008 in California. It is hard to keep calm with this pest because it attacks blueberries, my favorite and heretofore my most reliable and abundant fruit crop. The pest is also fond of blackberries, raspberries, and — not that it matters to you or me, because we don’t eat them — honeysuckle berries.

Again, there are management options. Because SWD seems to blow in from more southerly locations, a fine net could exclude them. Prompt refrigeration of harvested berries for 3 days kills larvae within. Thorough harvest of sound and unsound berries also keeps populations in check.

And then there’s Entrust and Azamax (or some other neem product), any of which I consider a last resort. I’m setting up traps to monitor if and when SWD arrives. (For information on monitoring, see http://www.fruit.cornell.edu/spottedwing/monitoring.html.) Till then, and after, I’ll try to remain calm. Om. Om. Ah-oh-om.

Blueberry Challenge and Aromas Good and Bad

August 23, 2013/5 Comments/in /by Lee A. Reich

Book Giveaway: AND THE WINNER IS: Andrea Jilling. Andrea, please contact me about mailing out the book. Everyone, stay tuned for more book giveaways in future weeks.

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Blueberry-growing used to be so boring. Each autumn I’d spread soybean meal beneath the plants as fertilizer and top it with 3 inches of leaves, wood shavings, or other mulch. Late each winter I’d prune. In late June, netting would go over the top of the plants and from then on, into September, I’d harvest oodles of blueberries.

Earlier this year I knew things could get interesting. Spotted wing drosophila (SWD), a new pest fond of many fruits, showed up last year in the area and an encore was predicted. And then, starting in early August, my harvested blueberries began to soften quickly and were soon swimming in their own juice. The culprit, SWD, was here, in numbers, with plenty of enticing berries still weighing down the branches.

“Drosophila” might sound familiar from experiments in your high school biology class; it’s a fruit fly. SWD differs from other fruit flies in not waiting for fruit to be ripe or overrripe. This impatient bugger lays eggs in unripe fruit.

Blueberry harvest is an almost daily affair and my blueberries are organic, sustainable, green, artisanal, (very) local, etc., etc., so I couldn’t just start spraying any old pesticide. Fortunately, there is one pesticide, called Entrust (derived from a bacterium collected from the soil of an abandoned sugar mill in the Virgin Isles), that is “organic” and effective against SWD. I did spray and now, despite the mildness of this material, we have to wait 3 days for the spray to dissipate before harvesting berries. Restraint is needed with Entrust because one generation to the next for SWD can take less than 2 weeks, leaving ample opportunity for resistant strains to evolve, especially if the pest overwinters locally (which is not known at this time).

After two sprays of Entrust one week apart, I should and will try something else, in this case a 1% oil spray — also “organic” and relatively benign. In laboratory settings, at least, oil has been effective.

What about all the berries on the plant with SWD eggs in them that are and will hatch into adults? Harvesting them and whisking them into a refrigerator at 34° for 72 hours will kill eggs and larvae. Same goes, of course for freezing them. Another option is to immerse them in that 1% oil mix for 5 to 10 minutes.

The battle against SWD should not — does not — end there. Fine netting encasing the plants could keep flies at bay, as long as it’s put on before SWD arrives or, if resident ones exist, after an early spray of Entrust. Thorough cleanup of infested fruits will keep populations down. We’re throwing soft fruits into a bag which goes into the freezer, and then it’s a dish of fresh frozen eggs and larvae and blueberries for my chickens. Mmmmm.

You might detect some flippancy in my attitude towards this serious pest. That’s because we already have 69 quarts of sound blueberries in the freezer.

(Thanks to Peter Jentsch and Cornell’s Hudson Valley information for much of this information.)

UPDATE: Two sprays of Entrust and one spray of horticultural oil, each spray a week apart, seem to have brought SWD under control. Once the berry harvest is over, we’ll let our free-range chickens access into the “Blueberry Temple” too clean up fallen fruit and resident SWD larvae.

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Garlic has been harvested and, as usual, my yields and bulb sizes are nothing to brag about. “You should have cut off the scapes,” suggested more than one person, the scapes referring to the curly, bulbil-topped stalks that emerge from the centers of hardneck garlic plants.

I’m skeptical about scape removal. After all, that greenery does photosynthesize and, hence, help nourish the plant. And while seed development can drain a plant of energy, a scape is capped by small bulbils, not seeds.

A little research yielded widespread recommendations for scape removal, but hard data backing up that

recommendation was generally lacking. What I did learn was: 1) benefits of scape removal depend on the soil and variety of garlic; 2) benefits are greatest in poor soils; 3) benefits may be in terms of yield or bulb size. The most consistent reason to remove the scapes is that they are edible if harvested when just developing.

I don’t like the taste of the scapes so won’t bother removing them. I’m also not a big fan of garlic flavor so tend to plant them outside the garden in out-of-the-way locations where they’re never watered and the soil is not particularly rich. Hence, my poor showing of garlic.

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The garlic is now curing as it hangs from the rafters of my front porch where it, fortunately, keeps its aroma to itself. Along the path leading up to the porch are a few plants whose aromas are a lot more welcome on the way to the front door. Those plants have clustered there not by some grand plan of mine, but just by chance.

Let’s see, first on the way to the door is Jasmine ‘Maid of Orleans’ (Jasminum sambac) whose flowers emit a pure, sweet aroma. The plant has been blooming more or less all summer but you do need to put your nose right up to the flower to smell it. Next comes jimson weed (Datura spp.) and angel’s trumpets

(Brugmansia spp.), both vespertine plants with 6-inch long, trumpet-shaped blossoms that appear sporadically. I’m always enjoying rose geranium, mint, and rosemary, next in line, because its their leaves that are aromatic; a pinch can send me to olfactory heaven anytime I wish, day or night.

Nestled in among these last-named plants is one small pot of alyssum. Alyssum blooms nonstop through summer and into autumn so the honeyed scent can be enjoyed whenever I pass, as long as I stick my nose down into the flowers.