SEEKING TRUTHS

(The following is adapted from my most recent book, The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden, available from the usual outlets or, signed, from here.)

OBSERVE AND ASK

Charles Darwin did some of his best work lying on his belly in a grassy meadow. Not daydreaming, but closely observing the lives and work of earthworms, eventually leading to the publication of his final book, The Formation of Vegetable Mould through the Action of Worms. He calculated that these (to some humans) lowly creatures brought 18 tons of nutrient-rich castings to the surface per acre per year, in so doing tilling and aerating the soil while rendering the nutrients more accessible for plant use.
Darwin and worms
We gardeners can also take a more scientific perspective in our gardens without the need for digital readouts, flashing LEDs, spiraling coils of copper tubing, or other bells and whistles of modern science. What’s most needed is careful observation, an eye out for serendipity, and objectivity. 

Observation invites questions. How many tons of castings would Darwin’s earthworms have brought to the surface of the ground in a different soil? Or from soil beneath a forest of trees rather than a grassy meadow? 

And questions invite hypotheses, based on what was observed and what is known. Darwin’s prone observations, along with knowledge of soils, earthworms, plants, and climate, might invite a hypothesis such as “Earthworms would bring a greater amount of castings to the surface in a warmer climate.” Is this true? How can we find out? 

MAKE A HYPOTHESIS

Gardens are variable and complex ecosystems, which makes growing plants both interesting and, if you want to know why a plant did what it did, frustrating. Many gardeners do something — spraying compost tea on tomatoes to reduce disease, for example — and attribute whatever happens in the ensuing season to the compost tea, ignoring the something else, or combination of things, that might also have made contributions to whatever happened. 

Enter the scientific method, a way to test a hypothesis. You put together a hypothesis by drawing on what is known and what can be surmised. In spraying compost tea, your hypothesis, could be based perhaps on the idea that beneficial microbes in compost tea could could fight off pathogens, just as they do in the soil. (Many gardeners do, in fact, recommend compost tea for plant health. Do I? See https://leereich.com/2015/03/compost-tea-snake-oil-or-plant-elixir.html.)

Less disease on your sprayed plants would strengthen the case for further study. Why further study? Because the response of plants in a given season at a given location is not sufficient to make a general recommendation or make a theory. 

The way to truly assess the benefit of the spray is to subject it to scientific scrutiny: Come up with a hypothesis, such as “Compost tea reduces tomato leaf diseases,” and then design an experiment to accurately test the validity of the hypothesis. 

DESIGN AN EXPERIMENT

A well-designed experiment would need more than just one treated (compost tea sprayed) plant and one control (water sprayed) plant. Grow ten tomato plants of the same variety under the same conditions and some will grow a little more than the others, some a little less. With too few test plants, natural variation in growth from plant to plant might overwhelm any variation due to a treatment (spraying with the tea in this example). Given enough plants to even out the natural variations in, say, disease incidence, the effects of a treatment can be parsed out. Greater natural variations would require more plants for the test. 
Variability in plant populations
A garden experiment might have additional sources of variation. Perhaps one side of your garden is more windy, or the soil is slightly different, or basks plants in a bit more sunlight than the other side. Rather than have all the treated plants cozied together growing better or worse because of this added effect, even out these effects by randomizing the locations of treated and control plants. 
Experimental design
Now we’ve got an experiment! All that’s needed is to spray designated plants with either the compost tea or the water, and then take measurements. Plug those measurements into a software program for statistical analysis and a computer will spew out a percent probability, based on variability within and between each group of plants, that the tea was responsible for less disease. A test with 90% or 95% probability is usually considered sufficient to link cause and effect. You can then answer “yea” or “nay” to the hypothesized question; you now have a theory, or not. 

IS IT SIGNIFICANT?

A good test could involve a lot of plants and a lot of measurements, more than most of us gardeners are willing to endure. A danger exists, as Charles Dudley Warner so aptly put it in his 1870 book, My Summer in a Garden: “I have seen gardens which were all experiment, given over to every new thing, and which produced little or nothing to the owners, except the pleasure of expectation.” Then again, setting up something less than a full-blown experiment could be fun and, while not proving something to a 95% confidence level, still suggest a possible benefit. 

Knowing what’s involved in testing a hypothesis also increases appreciation for all that can affect plants. Perhaps your tomato plants’ vibrant health wasn’t from your compost spray. Knowing something of the scientific method can help you assess, whether observed in your own garden or a friend’s garden, or reported in a scientific journal, the benefit of the spray. 

So go out to your garden and look more deeply into Nature, perhaps, like Darwin, lying on your belly. Understanding some of the science at play in the garden takes it to the next level. And you’ll find that the real world, neatly woven together, is imbued with its own poetry, with science being one window into that poetry.

Me mulching, even as a beginning gardener

Me mulching, even as a beginning gardener

FRUITS OF ISRAEL

Olives Galore

Now I feel foolish buying olives. I recently returned from visiting Israel where there were olive trees everywhere. Irrigated plots of greenery thrived in the broad expanses of the otherwise grays and browns of the desert. Trees popped up here and there in backyards and front yards of homes in streets lined with apartment buildings as well as along cobblestone streets in rural areas. Trees were even prominent in city parks, either as self-sown wildings in less tended areas or as formal plantings.
Woman harvesting olives in Jerusalem park
And oodles of ripe or ripening olives were clinging to branches or littering the ground. Need some hand lotion? Just pluck a ripe olive, squeeze it gently, and spread out the fresh oil that drips onto your hand. 

Want some olives for eating? Not so fast. Fresh-picked ripe or green olives are extremely bitter (due to oleuropein). That bitterness is removed with brine, multiple changes of water or lye solution followed by fermentation. My favorite olives are “naturally, sun-cured,” which, I imagine, means left hanging on the tree a long, long time. The dried, ripe olives I found still-clinging to branches tasted awful!
Green olive fruits
I was tempted to harvest some olives to bring home. A few other people had similar ideas, as evidenced by one woman on a ladder in a park in Jerusalem. Of course, these people were only miles or less from home; I was 5,000 plus miles from home. I let the olives be.

I actually grow olives here in the Hudson Valley, in a large container that spends summers outdoors basking in sunlight and winters in my cold basement near a large window. I should say that I grow an olive tree, rather than olives. My maximum harvest has been a half-dozen olives — which I did let hang for a long, long time, at which point they tasted delicious.
My potted olive treeMy olive harest-3 fruits
Olive fruits are borne on one-year-old shoots. This year, before moving my tree to the basement, I pruned more severely than usual. That should stimulate more one-year-old shoots this spring, to, I hope, yield more fruit.

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Another of my favorite Mediterranean fruits also growing in abundance in as many guises as olive in Israel was pomegranate. Unfortunately, I just missed the harvest of this fruit. All that remained on wild plants were a few red arils still clinging to darkened portions of skins.  Fruits must have been ripe somewhere because ripe fruits and fresh squeezed juice were available in markets and and street carts everywhere. 
Pomegranate espalier, IsraelPomegranate display, Israel
I, of course, also grow pomegranate, similarly to olive except that, being deciduous, this plant does not need light in winter. It spends those months in a dark, walk-in cooler. 

Sad to admit, my yields of pomegranate fruits have been even less than my yields of olive. As in zip, zilch, zero. The plants flower every spring and with a small brush I’ve transferred pollen from the anthers of male blossoms to the stigmas of female blossoms. (Plants each have separate male and female blossoms.) Bases of female blossoms begin to swell hopefully. Then they drop.

Every year I threaten my plant with a walk to the compost pile — to no avail.

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The third plant of the triumvirate of my favorite Mediterranean fruits is, of course, figs, which I saw in abundance in Israel mostly in wild settings. The plants lacked fruit, except for a few with small, green figlets that will either drop or ripen next spring. Fig is rather unique in its fruiting habit, able to bear fruit on one-year-old wood as well as on new, growing shoots, and the latter crop just keeps forming and ripening as long as growing conditions are to its liking.
Wild olive tree in Israel
One old tree growing in a courtyard in charming town of Sfad was hosting an old friend  — or, rather, enemy — of mine, fig scale insects. I’ve battled it one my greenhouse figs.

Figs were available in the markets but I was reluctant to even try them knowing that figs must be dead ripe to taste good. At that, stage they can hardly be transported more than arm’s length from hand to mouth.
Figs for sale, Israel
Figs are one Mediterranean fruit that I grow with great success, both in my greenhouse (minimum winter temperature 37°F) and, wintering in my walk-in cooler and summering outdoors, in pots like my pomegranate. Figs are generally easy to grow because of their unique bearing habit, their lack of need for pollination, and their general tolerance for abuse.

My last day I broke down and, against my better judgement, bought some figs. Mine are better.
Me eating one of my figs

MORE AUTUMNAL NEATENING

An Upbeat Closing

I don’t know about you all, but I have a great urge to tidy up my garden this time of year. Partly it’s because doing so leaves one less thing to do in spring and partly because, as Charles Dudley Warner wrote in My Summer in the Garden in 1889, “the closing scenes need not be funereal.” All this tidying up is usually quite enjoyable.
Pulling creeping charlie
Moist soil – and not too, too many weeds – make weeding fun. Creeping Charlie (also know as gill-over-the-ground) has sneaked into some flower beds. Its creeping stems are not yet well-rooted so one tug with a gloved hand and a bunch of escaping stems slithers back from its travels forward from beneath and among flower plants and shrubs. What remains are occasional tufts of grassy plants, especially crabgrass, easily wrenched out of the ground or coaxed out with my Hori-Hori garden knife.

This tidying is intimate work: me, the soil, weeds, and garden plants at close range. While I’m down there on hands and knees, I’ll also cut back some old stalks of perennial flowers. When everything is cleaned up, I’m going to spread a blanket of chipped wood (free, a “waste” product from arborists) over all bare ground.

The one thing not to do this time of year, as far as tidying up, is pruning. Better to prune after the coldest part of winter is over and closer to when plants can heal wounds.

A Real Crocus, Now

A few weeks ago, I, along with anyone visiting my garden, was wowed by autumn crocuses then in bloom. As I pointed out, they weren’t not true crocuses (they were Colchicum species), they just acted like crocuses – on steroids. Then, a couple of weeks later, I noticed that my true autumn crocuses (that is, the ones that are true Crocus species) were in bloom.
autumn crocus
And I did really have to stop and notice them after that most flamboyant show of fake autumn crocuses. These true crocuses (crocii?) are dainty plants, just like spring crocuses, and their colors are subdued: some are pale violet and some are white. In contrast to the fake autumn crocuses, which multiplied like gangbusters, the real autumn crocuses look about dense as when I planted them. Both kinds of crocuses wait until spring to show their leaves.

It’s fortunate that the part of my garden that’s home to autumn crocuses, real and fake — the mulched area beneath the dwarf apple trees — is free of weeds. Otherwise, the real autumn crocuses, being so dainty and lacking a supporting role of leaves, would be swallowed up, visually or for real.

Weed? Perhaps.

Back to weeds . . . I’m trying to see the positive side of all that creeping Charlie I’ve been pulling. Bits of it that have insinuated themselves in amongst the bases of stems of woody shrubs, especially thorny ones like the Frau Dagmar Hastrup rose, are not that much fun to weed out. So what’s good about creeping Charlie?
creeping charlie
For one thing, with shiny, round leaves of a deep, forest green color, it’s not a bad looking weed. The flowers are an attractive, purple color although neither big nor prominent enough to make a statement. The otherwise excellent reference book Weeds of the Northeast (Cornell University Press) erroneously states that “the foliage emits a strong mint-like odor when bruised.” That would be nice except that I’ve never noticed that odor and didn’t even when I just ran outside to crush some leaves check up on this statement.

Creeping Charlie grows well in sun or shade, so well that when I worked in agricultural research for Cornell University, I considered the plant as a possible groundcover to replace the relatively sterile herbicide strips in apple orchards. It grows as such beneath my dwarf pear trees.

Creeping Charlie beneath trees

Creeping Charlie beneath my pear trees

The plant could even be a somewhat ornamental groundcover, making up for any lack of great beauty with its capability to rapid fill in an area and grow only a couple of inches high. You couldn’t ask much more from a plant – except to keep out of some of my flower beds.

A MONTH OF RECOGNITION

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

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.”