Watch Out, for Black Walnuts

Citizen scientists (that could be you and me), look up! At black walnut’s leaves. At the recent meeting of the New York Nut Growers Association (, Karen Snover-Clift of Cornell University went over the ins and outs of “thousand cankers disease of walnut.”
    Like Dutch elm disease — it pretty much wiped out American elms, once valued for creating a cathedral effect as their branches arched over tree-line streets — thousand cankers disease is spread by an insect. But the walnut twig beetle is only part of the problem. When it bores into the bark, it spreads a fungus that clogs up a tree’s “tubes.”
    With Dutch elm disease, once a tree is infected, the fungal culprit spreads within the tree to kill it. Not so with thousand cankers disease. With this disease, death comes from fungal infection that follows thousands of dark, dead cankers of insect feeding.
    Who cares about black walnuts? I do. Each fall the trees bear an abundance of nutritious and delicious nuts. (Not delicious to everyone; the strong flavor does not appeal to everyone. But no reason any food should appeal to everyone unless you’re MacDonald’s.) And, quoting from The Tree Book, written in 1914 by Julia Rogers, “The black walnut is majestic as a shade tree — a noble ornament to parks and pleasure grounds. It needs room and distance to show its luxuriant crown and stately trunk to advantage. Then no tree excels it.”

Walnut twig beetle

Walnut twig beetle

    And finally, black walnut yields among the most beautiful of woods for furniture and gun stocks. Again quoting Ms. Rogers, the wood has “silvery grain, rich violet-purple tones in the brown heart wood [and] exquisite shading of its curly veinings.”
    Thousand cankers disease moved into southwestern U.S. from Mexico (would a wall keep them out? will Mexico pay for it?) and has remained mostly in that region. Black walnut is native to eastern U.S., but the tree has occasionally been planted out west. More importantly, the disease has recently reared its ugly head at a few locations in the east. If infected trees can be identified, the disease can be contained to check its spread.

Thousand cankers

Thousand cankers

    Any tree with an infected branch is usually dead by the end of the season!
    So look up, scan the tops of any black walnut trees for limbs that are dead or show flagging foliage. Your job, and my job, is to look for these trees and then report them.
    For a more thorough treatment of thousand cankers disease, as well as reporting guidelines, see A good start in confirming the disease would be to take some good digital photos and send them to the state diagnostic laboratory, the county Cooperative Extension office, or department of environmental conservation.

Chipmunks, Still Cute Here

    I find chipmunks cute, as I’m sure everybody would — except for anyone for whom chipmunk is a garden pest. This year, for some reason, an especially good crop of chipmunks are scurrying about. I see them everywhere, except on my farmden. Their absence here could be attributed to my dog friends Sammy and Scooter, and my cat friend Gracie.
    I would not tolerate chipmunks if they were to eat my blueberries, my filbert nuts, my . . . pretty much anything I’ve painstakingly planted and nurtured. Besides dogs and cats, traps also are effective.

No, I’m Not a Strawberry Pest

    As if plants didn’t have enough pest problems. I recently attacked my strawberry bed with my scythe, swinging the sharp blade low enough to cut off every last leaf from the plants. No, I’m not just another plant pest, trying to kill plants; I was “renovating” the bed, preparing it for next spring.
    Shearing off the leaves not only removes leaves, but also disease spores on the leaves that inevitably find their way into any strawberry bed. Obviously, I raked up the old leaves and carted them over to the compost pile.
    The next step in renovation was to pull out any weeds in the bed. The major weed in the bed was  . . . strawberries. Strawberries spread by creeping stems along which grow new plants that take root, making them usually their own worst weed. Each plant needs about a square foot of elbow room to realize its full potential of one quart of berries per plant.
    So I ruthlessly ripped out enough plants so that my 3-foot-wide bed was left with a double row of plants spaced a foot apart. Older plants get decrepit with age, so those were the first to go.Spreading compost in strawberry bed
    Finally, icing on the cake. I laid a 1 inch depth of compost all over the bed and tucked up to each of the remaining, leafless strawberry crowns. A little fertilizer and straw, pine needle, wood shavings, or any other weed-free organic material would be almost as good.
    It’s been a few weeks and already new leaves are sprouting. The plants are on their way to a healthful and healthy crop of sweet, juicy berries next spring.Strawberry plants, a few weeks after renovation


Small Plants

Weeding. Planting. Harvesting. Making compost. Spreading compost. Staking. Pruning. Mowing. These are some of the activities I share with my plants this time of year. But, as Charles Dudley Warner wrote in his 1870 classic, My Summer in a Garden, “Blessed be agriculture! If one does not have too much of it.” Which prompts me to weed, plant, harvest, etc. most efficiently.

Bush cherry, 1 month after planting

Bush cherry, 1 month after planting

    Let’s take a look at some of the trees and shrubs I’ve planted this spring: Romeo and Carmen Jewel bush cherries, aronia, Grainger shellbark hickory, Great Wall Asian persimmon, Rosa canina, and Hidcote St. Johnswort. Just getting all those plants through their first season could entail lugging around many buckets of water. But it doesn’t.
    Large plants of any of these could possibly be sourced but I chose small plants. And that was the first step to making sure that, paraphrasing C. W., I wasn’t overburdened with my agriculture.
    With smaller root systems, small plants establish more quickly than large plants. In fact, establishing more quickly, smaller plants usually outgrow their larger counterparts after a few years.
    A tree or shrub with a two-foot diameter root ball might require 3 gallons of water weekly until enough roots foraged out into surrounding soil to make the plant self-sufficient water-wise. Two cups of water weekly is enough to keep my newly planted Romeo bush cherry alive since its move from the 4-inch-diameter pot it previously called home.
    By the end of this growing season, all these small plants will be firmly established and pretty much water independent. They’ll get supplemental water only if there’s any extended dry spells in their second season.

Small Planting Holes

    Water for these young plants isn’t all about watering per se.
    Site preparation is also important. Not that, as older gardening books used to suggest, it’s “better to dig a $50 hole for a $5 tree than a $5 hole for a $50 tree,” the dollar amounts reflecting the size of the tree and the hole. No need for such heroic measures. Digging that large a hole breaks up the capillary channels in a large volume of soil, leaving large air gaps in the soil through which water just runs down and out. Capillary channels can move water, down, up, and sideways.

Shellbark hickory, 1 mo. after planting

Shellbark hickory, 1 mo. after planting

   Better — and easier — is to dig a hole only twice as wide as the spread of the roots or root ball (if potted), and only as deep as needed so a plants sits at the same depth as it did its pot or the nursery.
    With few exceptions, no need to add compost, peat moss, fertilizer, or anything else to the soil in the planting hole. After all, the expectation is for roots to eventually extend well beyond the planting hole. Create excessively posh conditions in the hole and roots have no incentive to leave. Then roots grow only in their planting hole, not beyond.
    All soil goodies are best lathered on top of the ground. My first choice is for compost. Nutrients and beneficial soil organisms within the compost, over time, meld with the soil below. Compost also softens impact of raindrops so that water can percolate down into the ground rather than running off in rivulets — lessening my need for watering.
    A mulch is the final icing on this layer cake. I’ll top the compost with wood chips, leaves, straw — any weed-free, organic material. This top layer further softens the impact of raindrops, keeps compost moist and vibrant, and slowly decomposes to nourish soil microorganisms and then  the tree or shrub.
    Yesternight’s rain or 1.25” did a week’s watering for me. A good rule of thumb is to apply one-inch of water once a week, or, equivalently, three-quarters of a gallon per estimated square foot spread of the roots. Potted trees and shrubs need that one-inch of water spread over 2 or 3 days of the week for a couple of weeks after being planted, until their roots begin to spread into surrounding soil. Larger tree and shrub transplants need more water, more frequently, for a longer period of time.

Followup on Drastic, and Less Drastic Pruning

    I recently wrote of “renovating” my old lilac shrub, a no-brainer as far as pruning. You just lop each and every part of the plant right to the ground. My fears that such drastic pruning might also kill the plant were unfounded. Already, new sprouts are growing from the sawed off remains of the plant as well as from some distance away. All that’s needed now is to choose which sprouts to keep to grow into a whole new shrub.

Lilac regrowth from stump

Lilac regrowth from stump

    My blueberry shrubs also received more drastic pruning than usual. To lower their height and to encourage and make space for younger, more fruitful stems, I lopped a few of the oldest stems of each bush right to ground level. Like the lilac, new sprouts soon rose from ground level.

Blueberry, new sprouts

Blueberry, new sprouts

    Late next winter, I’ll save the most vigorous of these new sprouts and lop the rest of them all the way to the ground. And, of course, again lop to ground level some of next year’s oldest stems.
    Such pruning (covered in my book The Pruning Book) keeps blueberry and lilacs perennially renewed, without any stems that are too old to flower or fruit well as well as plenty, but not too many, young replacement stems for the future.


Reader Alert: Invasive Plant

    The sweet scent practically bowled me over. My friend, walking with me along the nearby rail trail, characterized the aroma as citrus-y rather than sweet. Either way, the aroma was delicious and welcome. Too bad the source of the scent, autumn olive (Elaeagnus umbellata), is a plant so reviled.Autumn olive blossoms
    “Too bad” because the plant also has other qualities. The olive-green leaves lend a Mediterranean feel to any setting. Microorganisms associated with the shrub’s roots garner nitrogen from the air to enrich the soil. And come early fall, the plants are loaded with delicious and nutritious, small, red (sometimes yellow) berries.
    Alas, this non-native plant grows too easily, frequenting fields and waysides. It’s deemed invasive, which it is . . .  but?
  Autumn olive fruit  (Autumn olive is often confused with Russian olive, E. angustifolium, a close relative that is more tree-like, less invasive, and with sweet, olive-green fruits. Another equally attractive, fragrant, tasty, and soil-building plant is gumi, E. multiflora, not well known but closely related to the other “olives.”)

And Yet Another Invasive

    Soon, by the time you read this, the rail trail and elsewhere will be suffused by another pleasant aroma, that of honeysuckle. These flowers are also followed by red berries, but they’re not edible. (Other honeysuckle species do yield edible berries, an up and coming fruit called haskaps.)Honeysuckle flower
    How could anyone not like a plant with a name like “honeysuckle?” A lot of people don’t like honeysuckle because it too, despite its qualities, is invasive.

You Call This Renovation

    Before anyone attacks me for heaping praise on invasive plants, let’s sidle off the rail trail and back to the home front, where yet another delicious scent fills the air. This one wafts from a plant that, unlike autumn olive, Russian olive, and gumi, is not invasive and is truly in the olive family: lilac (Syringa vulgaris).
    Actually, for years now, my lilac bush has not been perfuming the air as much as it should. The plant is old, my guess is over 50 years old. Not that age alone is responsible for its poor showing. Lilac, like other shrubs, have long-lived root systems. No stem ever develops into a permanent, long-lived trunk and — important for all flowering and fruiting shrubs — after a certain age stems can’t keep up the flower production of its youth.
    The way to prune any flowering or fruiting shrub is by a renewal method. You cut down some of the oldest stems that are no longer performing well. And then you thin out — that is, reduce the number of — some of the youngest stems so that each can develop to its fullest potential without being crowded.
    How long an old stem is worth keeping and how many new stems spring up each year from ground level depends on the kind of shrub and the growing conditions. A highbush blueberry stem, for example, retains its youthful fecundity for about 6 years; a raspberry, for two years.

Young lilac, old lilac, renovated lilac

Young lilac, old lilac, renovated lilac

    I’ve pruned my lilac over the years, but — I have to admit — never cut the old stems close enough to the ground nor thinned out the many young stems sufficiently. (My excuse is that the dense crowding of 5-inch-diameter stems made cutting difficult, the difficulty made more so by the haven they provided for poison ivy vines.)
    A non-blooming lilac shrub isn’t worth keeping, so drastic renovation was in order. This treatment can be applied to any old, decrepit shrub. It’s easy. All that’s needed is to cut everything to the ground. Which I did.
    My lilac’s stumps gave evidence to the shrub’s poor showings over the years with their many thick yet half-rotten, old stubs. Shrubby stems, as I wrote, just aren’t meant to live that long, and over time can’t support good flowering.
    If all goes well, new sprouts should soon poke up from ground level, vigorous new sprouts because they’ll be fueled by a large, old root system. It’ll be a few years before any of those sprouts get old enough to start flowering. But I’ll make sure to thin them out so each has room to develop. I promise.

Win a Copy of My Book

A few weeks ago my plum tree was in full bloom, actually only part of it was in full bloom. Winter’s wacky weather? Spring’s wacky weather? Plum, blossoming branchOffer an explanation and, if correct, you’ll be in the pool of readers, one of whom, randomly selected, gets sent a free copy of my book Grow Fruit Naturally. Respond by midnight, May 31st.
GFN Front Cover


Henry IV Method of Pruning

   Deb get’s a little nervous every time a go into the garage for some pruning tools this time of year. Not because she’s afraid I might hurt myself but for what I might do to the plants. Today it was so-called “renovative pruning” of the St. Johnswort ‘Sunny Boulevard’ shrubs that line the western edge of the brick terrace. I approached the shrub with some unconventional pruning tools.
    Let’s first backtrack and put everyone at ease. A shrub is a shrub because it’s shrubby; that is, it’s always growing new shoots at or near ground level rather than developing a permanent, upright trunk off which permanent limbs and new shoots grow. Some shrubs — most shrubs, in fact — get congested with too many new and older shoots rising from their base and too many old shoots that no longer perform well, in this case performance meaning a good show of flowers. An old stem can put on a good show for only so many years before becoming decrepit.

St. Johnswort, pruned

St. Johnswort, pruned

    The obvious solution to the above two problems with shrubs is to, first, limit the number of new shoots arising low in or around the plant. It’s a matter of judgement for how many to leave. (Pruning is art and science, and my book, The Pruning Book, attempts to make readers better artists and scientists, when pruning, at least.) As far as those old stems, they should be cut down near ground level once they’ve overstayed their welcome.
    So much for maintenance pruning. Sometimes a shrub has gotten too out of hand for all this detail work. Enter renovative pruning. It’s very easy: You just lop everything down to the ground, which is what I did to ‘Sunny Boulevard.’ I started out using a chain saw, my Stihl pole chain saw. This saw has a smaller blade and a long reach, which allowed me to get to the base of the plant without battling all the arching stems. After that, I sawed back stems arching over the hypertufa wall edge of the terrace with a Porter Cable sawzall powered by a 20 volt battery. Final cleanup was with my Fiskars Powergear lopper and Felco pruning shears. (That’s a lot of product recommendations, but I highly recommend all of them.)

All’s Well That Ends Well (in Pruning)

    So what was I left with when I was done pruning? Nothing. Nada. Zip. Well, not really; the roots were still alive and in the ground. And I’m banking on those roots sending up new sprouts. And because ‘Sunny Boulevard’ is slated to start blossoming in July on buds that form on new shoots, I’m also banking on blossoms on those new shoots. Because they’re beginning growth way down at ground level, blossoming might begin a bit later than usual.
    Shrubs that blossom early in the season, such as forsythia, lilac, and mockorange, form their flower buds a year before they actually open. Hence, the best time to prune these shrubs, if you want a full show of blossoms, is right after the blossoms fade. Prune them before blossoming and you cut off potential blooms.
    Still, having a clean slate after a dramatic renovative pruning is appealing, sometimes even with a sacrifice of blooms. Deb is now nervous about the lilac bush, which also needs some renovation. I’m planning to do a less dramatic renovative pruning on it, and I’ll probably wait until after it blossoms.

Onions’ Size Matters

    Big onions or medium-sized onions or small onions, what to grow? The choice is mine (and yours). Much depends on planting distances.
    I’m opting for medium-sized onions, about 3 inches in diameter. Yesterday I set out about 250 transplants grown from seed I sowed in early February in a tub of potting soil: Three varieties: Ailsa Craig, an heirloom from 1887, for sweet, mild onions that need to be used early because they don’t store well; New York Early, a nonhybrid variety selected over the years by New York onion growers, for medium term storage; and Copra, a rock-hard, hybrid onion that stores very well, all the while maintaining some sweetness.  In a 3-foot-wide bed, I planted 5 rows of onions, with about 4 inches between rows and about 4 inches between onions in each row.
Onions, planted    Planting distances are not the end-all for onion size. Variety also figures in; given enough space, In northern areas, such as around here, long-day varieties, which form bulbs when daylength is 14 hours or more, get largest because they grow the most leaves before bulbing begins. More leaves means bigger bulbs, which also a reason to plant as early as possible. (Note to myself: Plant onions earlier next year, in mid-April.)
    Even among northern varieties of onions, potential sizes vary. Ailsa Craig onions have the potential grow quite large, which is why they’re grown for exhibition at state fairs and the like. I’m banking on the close spacing keeping them from growing too big, 5 pounds or more by some accounts.
    Of course, good growing conditions also make for more leaves sooner. Got that. I spread compost an inch deep over the already mellow soil and drip irrigation lines are poised to quench the plants’ thirst.