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DOING SOMETHING ABOUT (MICRO)CLIMATE CHANGE

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Microclimates, Here, There, and Everywhere

    Mark Twain wrote that “Everyone complains about the weather but nobody does anything about it.” I’m going to step up to the plate and do something about it — not the climate but the microclimate. “Microclimate” is the very local weather. And I do mean “very local,” as, for example, right around a particular plant.
    Different microclimates exist all around my property — and yours. Near the south wall of my brick house for example, winter low temperatures don’t plummet nearly as low as they do, say, 30 feet away from the wall. The bricks are very good at absorbing the sun’s heat, then let it slowly ooze out after nightfall. Near that wall is where I’m planning to plant out a Kadota fig tree now dormant in my basement. (Come late fall, after harvest, I’ll dig up the tree with a good root ball and return it to winter quarters in the basement.) 

'Surround', a white clay, sprayed on apples

‘Surround’, a white clay, sprayed on apples

    On the other side of my house, where sunlight can’t fall in winter, days and nights are colder than the general temperatures, and remain colder from spring through fall. Near that north wall, then, would be a good place to plant an apricot or peach tree to delay unfolding of their blossoms, which otherwise open so early that they often succumb to subsequent spring frosts. Dead blossoms mean no crop for that season.
    Apricots and peaches, like most fruits need sunlight to fuel the most flavorful fruits. Although areas near the north wall are shaded — and hence cooler — in winter, from spring through early fall the sun wraps enough around the sky from the northeast to northwest corners to cast its light there.
    Other influences on microclimate include fences, land sloping in various directions, paved areas, plant or built windbreaks, and changes in elevation.

(Micro)Climate Modification

    Much of what I have planted, including many fruit plants, are nowhere near fences or paving, and my land is mostly flat. It is lowland, in a valley, and cold air, which is heavier than warm air, collects in this low spots, to threaten the blossoms on my fruit plants with late, killing frosts.
    Mark Twain notwithstanding, I’m going to try doing something about the weather — the microclimate, in this case — on plants nowhere near walls, fences, or paving.
    Enter ‘Surround’, the trademark name for a special formulation of kaolin clay. This product was developed about 30 years ago mostly as a nontoxic way to thwart insect pests. It’s especially useful for controlling plum curculio, a pest of plums, peaches, apples, and some other fruits; curculio isn’t easily controlled by other organic methods.
 

'Surround' spray on blueberries

‘Surround’ spray on blueberries

   Kaolin is white, so when a sufficiently thick coating of ‘Surround’ is built up on branches, they appear white. Old Sol’s rays just bounce off white surfaces, the surfaces, in this case being the buds of fruit plants. So the buds stay cooler, delaying bloom, hopefully until after threat of frost has past.
    I’ve already given the plant a couple of coats of ‘Surround’, and they already have a sun-drenched, gray-cast, Mediterranean look to them. A couple more coats will make the visual effect more dramatic, both to me and Ol’ Sol, and will get a jump on curculio control.

Awake too Soon

    Downstairs, in the basement, things are not as quiescent as hoped. That’s where the figs, pomegranates, and mulberries are spending winter, the cool (45°F) temperature holding back growth. Or so I thought.
    One plant, Pakistan mulberry, has decided to awaken. This mulberry is a species of white mulberry (Morus alba) that differs markedly from the white mulberries you see here. Pakistan is only about as cold-hardy as fig (which is why they share winter quarters in my basement) and bears a very delicious, dark purple fruit up to three inches long!

'Pakistan' mulberry

‘Pakistan’ mulberry

    Pakistan evidently has a low chill requirement, that is, it does not take much cold for it to feel like winter has ended so it can begin growing. Different plants have different requirements for the number of hours of chilling, which is temperatures between about 30 and 45°F., they need to be exposed to before they can begin growth for the season.
    I may have to move the budding plant into the greenhouse where it really is spring, with temperatures at least into the 70s on this sunny day.

A Moon Landing?

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Anyone visiting my garden a few days ago might have thought they happened upon a moon landing or extraplanetary explorer. A two-legged creature was wandering around in bright blue pants and a bright blue, hooded jacket (actually, rain gear) with goggles and a respirator and 4 gallon tank strapped to its back. Periodically, an engine whine was accompanied by a cloud of mist (a jetpack)?
The creature was me and I was doing what was necessary to put myself on the road to a harvest of delicious apples (especially the variety Hudson’s Golden Gem) and plums (especially the variety Imperial Épineuse). I was dolled up for what looked like a moon landing because I was spraying pesticides on my

trees. In this part of the world, sad to say, that’s generally what’s necessary to get a decent — sometimes any — crop of apples or plums.

Some years I grow these fruits organically; some years I grow them, as some commercial growers say, ecologically or biologically. My organic approach is to spray a special formulation of kaolin clay, called ‘Surround’, and sulfur, a naturally occurring mineral. ‘Surround’ keeps insects at bay; sulfur does the same for some diseases. To be effective, ‘Surround’ must be maintained as a dust-like, white coating on the trees. This laid-back Mediterranean look to the trees necessitates a not very laid-back 3 sprays, before bloom, to build up a base layer, and followup sprays every week or following as little as 1/4 inch of rainfall. Even then, in my experience, control is marginal.
My ecological/biological approach is to spray the horrible sounding material, Imidan, with, again, sulfur. Imidan is a chemical pesticide, but one that has a relatively low toxicity both to humans and to beneficial insects. A perfect year would require only 2 to 3 sprays, the first right after petals drop and the others before mid-June. Re-spraying is usually not needed until after an inch of rainfall. Between rainfall washing off spray, sunlight degrading it, and dilution due to fruit growth,

‘Surround’ on apples

fruits are essentially squeaky clean by harvest time. (After the end of June, approaches other than sprays thwart remaining major pests.)

Back to my moon suit . . . The suit is necessary no matter what I spray. Getting doused with, or breathing, even something as benign as kaolin clay is not good.
And the jetpack? That’s my backpack sprayer. Spraying anything is no fun. Fortunately, except for the apples and the plums, spraying is almost never needed here on the farmden. Also fortunately, my sprayer makes easy work of the job. It’s a Stihl, gasoline-powered backpack sprayer that always starts right up, gives good coverage, and lets me, in less than a half an hour, mix the spray, apply it to about 2 dozen trees, and thoroughly clean it.
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Spraying pesticides, organic or otherwise, is not the only approach to keeping plants healthy. Any insect or disease problem can gain a toehold only when there’s a plant susceptible to the problem, an organism that can cause the problem, and a suitable environment in which the problem can develop. So, I beef up my plants’ defenses by paying special attention to the soil, making sure drainage is perfect, and by applying

Good soil, organic matter added from the top down

mulches of compost, wood chips, hay, and other organic materials. The mulches feed the plants as well as worms, fungi, and other “good guys” in the soil. Above ground, pruning lets branches bathe in sunlight and air, both of which make for better fruit and conditions less conducive to insect and disease problems. If my plants are thirsty, they get water.

What I do not do to make my plants healthy is apply compost tea, biochar, or any other potions, or, along the same lines, click my heels together three times and repeat, “There’ll be no pest problems.”
For apples and plums in this part of the world, all three requirements for pest problems — pest presence, susceptible host plant, and environment suitable for the problem to develop — are generally fulfilled. Hence, the necessity of sprays. Still, using a minimum of carefully selected sprays and needing to “ship” my fruit no more than 200 feet from the trees to my mouth (or kitchen) makes for a minimum affront to the environment.
People too often equate “fruit growing” with growing apples. That should not be the case because there are plenty of other fruits, and plenty of them can be grown with hardly a thought to pest control. Pears, for instance. I have about 20 pear trees; none require spraying. The same could be said for blueberries, raspberries, persimmons, cornelian cherries, blackberries, pawpaws, hardy kiwifruits, gooseberries, currants . . . I could go on. In some cases, such as grapes, choosing a disease-resistant variety is the way to avoid having to spray.
As I emphasize in my recent book, Grow Fruit Naturally, choosing plants adapted to your site is a very important part of growing fruit naturally, as is providing optimum growing conditions. 
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Winter cold, Winter chill, & Late frosts

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I’ve tended the same plot of ground for about 30 years, and this is the oddest winter and spring yet. 
In almost every year past, the nearby Wallkill River has swelled its banks in early April, then overflowed for a few days to stop traffic on my road. This year, the water level is so low that I’m hoping for some rain. Well, almost hoping for rain. I’m still recovering from last August and September’s record rains that made waterfront property of my home and back gardens.
Apple buds in “tight cluster”
If rainfall hasn’t been whacky enough, just look at temperatures over the past few months and especially over the past few weeks. Here in the Hudson Valley — throughout the Northeast, in fact — winter temperatures have been the warmest in decades. In years past, temperatures plummeted each winter to minus 25 degrees F, less so in more recent years. This winter, temperatures here never went below a balmy pus 5 degrees F. Plants know it: Bamboo (Phyllostachys aureosculcata) stayed green all winter, Chester thornless blackberry was unscathed by cold, and trifoliate orange (a citrus relative!) seedlings did not die back at all. A few more winters like this and I’ll be tempted to try growing southern magnolia (‘Bracken’s Brown Beauty’ is one of the hardiest) and camelias (Sasanqua camellias, which bloom in autumn, are the hardiest), which are among the few plants for which I bemoan living this far north.
If the relatively balmy winter was not enough wackiness, how about early spring temperatures? March’s string of daily temperatures in the 70s coaxed blossoms from such plants as Nanking cherry, saucer magnolia (Magnolia soulangiana), and forsythia more than 3 weeks ahead of schedule. Towards the end of March, apple buds were swelling and pears almost popped open.
The average date of the last spring frost around here is May 15th. Which is to say is that I’m worried about my fruit crop this year, a worry that has just been propped up the the forecast for a low of 24 degrees F. for tonight (March 26).
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Whether or not cold kills a fruit bud depends on the depth of cold as well as the speed and stage of bud development. Recent warm weather speeded up bud development, making buds more susceptible to cold.
Bud development on fruit plants is divided into self-descriptive stages: apples, for example, go from silver tip to green tip to half-inch green, tight cluster, first pink, full pink, first bloom, full bloom, and, finally, post bloom. Charts are available(http://www.hrt.msu.edu/faculty/langg/Fruit_Bud_Hardiness.html) that give approximate killing temperatures for each stage. For apples, the critical temperatures for the various stages are, respectively, about 15, 18, 23, 27, 28, 28, 28, 28, and 28 degrees F .
So fruit might still be in the offing even after tonight’s predicted freeze. But there’s still many weeks to go before mid-May! What to do?
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The easiest course to follow now is to just relax and hope for the best. There’s always next year.
The green center of this cut bud shows that it’s still in good shape.
My trees, even my older ones, are mostly dwarf in size, made that way by special rootstocks. In year’s past, I’ve scurried outside to drape blankets and other coverings over my trees. Coverings add a few degrees of cold protection, mostly for the kinds of freezes (radiation freezes) that occur on still nights with clear skies, by bouncing back downwards the heat that’s being radiated from the earth skyward. I’ve got too many trees to cover.
Someone asked me about sprinkling water on their fruit plants to fend off cold. That works, and is sometimes done by commercial growers, if water is applied continuously until it finally melts. The water releases heat of fusion as it freezes. Of course, all that water and ice can lead to limb breakage and saturated soil.
Given my number of fruit plants, I’m going with option number one. Well, almost. I have one peach tree, now in full bloom. It’s growing in a pot. Into the garage it will go, protected from cold.
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The next morning: As predicted, temperatures dropped to 24 degrees F. All plant seem happy but there are still weeks of potential frost damage in the offing. 
‘Surround’ controls insects and delays bloom — I hope.
My new tack is to slow bud development. This afternoon I sprayed fruit trees, bushes, and vines with ‘Surround,’ which is nothing more than kaolin clay, an effective organic insecticide. The ghostly white coating on the stems should reflect sun’s rays, keeping branches and buds cooler to delay flower bud development.
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Two gardening workshops in the offing:
On April 22nd, I’ll be hold ing a pruning workshop, covering the why, when, with what, and how of pruning.
On April 28th, I’ll be holding a grafting workshop, covering the how, why, and when of grafting. In addition to a hands-on demonstration, participants will graft and take home their own pear tree.
Both workshops will be held at my “farmden,” run from 2-5:50 pm, and cost $55. Pre-registration is necessary. For information o registration, 845-255-0417 or