Seed

“It is remarkable how closely the history of the apple tree is connected with that of man.”
—Henry David Thoreau

Born on the Silk Road, the domestic apple, Malus domestica, has implanted itself into human civilization like no other fruit. Forbidden, mystical, golden, magic, fair, and evil, the apple graces the writings of Homer to Thoreau, the paintings of Caravaggio to Magritte, and the religious traditions of Germanic pagans to Christians.

Wild apple trees bearing big, sweet fruit evolved several million years ago in temperate Eurasia. Glacial fingers of the Ice Ages then isolated their genetic material into distinct regions, producing unique wild apple species. The fossil record from Western Europe to China shows that humans collected wild apples for food as early as 10,000 BC. However, it was not until the establishment of trans-Eurasia trade routes in the first millennium BC, known as the Silk Road, that these wild apples were brought together through hybridization to develop the domestic apple.

The modern apple contains the genetic material of at least four wild apple species with origins in Europe and Asia. Much of the genome originates from Malus sieversii, a wild apple still found in the Tien Shan Mountains of Kazakhstan. It is generally thought that this large, sweet apple was carried east and west along the Silk Road, where it came in contact with hardy European wild crab apples and hybrids from Siberia and Iran. Because of the hundreds of thousands of years of genetic isolation, these wild apple hybrids may have shown robust growth and sizable, sweet fruit, attracting the attention of orchardists throughout Europe and Asia.

But apples are victims of their own genetic creativity; they are incredibly heterogeneous, like humans, and produce offspring that may have little resemblance to the parent trees. Domestic apples cannot self-pollinate or even pollinate from the same variety. Therefore, an apple grown from seed will not “come true,” looking and tasting nothing like the fruit from which it came. Most of these seedling trees will produce undesirable wildling apples. Only one in ten thousand seedlings will have new apples worthy of further regard. Genetic variation is favorable for creating new cultivars with new tastes and textures and flourishing in new environments but frustrating for apple growers who want to preserve a favored variety. The answer to this problem came thousands of years ago from China with the art of grafting, whereby a scion (twig) from a chosen tree is inserted into the rootstock of another. The resulting tree will produce the desired fruit. All modern apples known today are exact clones of others born by chance.

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Blight

“Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree.”
—Martin Luther

William Denning noticed sweet sap oozing from a canker on the cracked bark of a quince tree in his prized New York orchard overlooking the Hudson River valley. He noted this in his journal; the year was 1780. The Northeast was recovering from the most severe winter in the eighteenth-century, and the Continental Army had just suffered a significant defeat by the British at the Siege of Charleston. Two weeks later, the leaves and fruit on an entire branch wilted and eventually turned brown and died as if they had been scorched with fire. Over the next fourteen years, as his young country struggled with its formation, Denning watched the destruction of his entire pear and quince orchard, one branch, one tree at a time. He could see no external cause of the “malady” but surmised it must be from an insect, a “stem borer.” However, his similarly affected farming neighbors concluded their trees had been “blasted by lightning.” By 1817, fire blight, as the condition was then referred to, was felt to arise from “the rays of the sun operating on the vapor, or clouds, floating in the atmosphere, either by concentration or reflection.”

It would take almost seventy more years before scientific inquiry conclusively determined bacteria caused fire blight, the first known contagious plant disease. Four years later, M. B. Waite showed insects spread the disease, the first such example of any plant pathogen, either microbe or virus. By then, germ theory had been well-established and proven in the animal kingdom, but many botanists still resisted extending this concept to plants.

The bacteria Erwinia amylovora, responsible for fire blight, is indigenous to the American Northeast and can infect all members of the rose family, such as hawthorn, wild crab apple, serviceberry, and mountain ash. With the introduction of European apple, pear, and quince trees to the American colonies in the 1600s, fire blight had a new host. The disease spread rapidly with fruit cultivation through the Ohio River Valley and the Southeast. California and the West initially escaped the disease because the Spaniards brought Western fruit directly from Europe to California via Mexico, bypassing the Northeast endemic. The Western settlers grew fruit trees throughout the Pacific Coast for over one hundred years before fire blight eventually spread across the continent in 1887 and destroyed a third of the Californian pear and apple crop between 1900 and 1910.

Fungicides and insecticides had no effect on the bacteria. Treatment remained reactive—prune and destroy infected branches as they became visible. Fire blight favored recent growth and water shoots, so farmers starved heavily diseased orchards of fertilizer and forced dormancy until they could prune out the infection. Fire blight could destroy a tree in one season and an entire orchard in a few. Because insects, birds, and even tools spread the bacteria, neighbors cut and burned fallow and abandoned orchards to protect their own. In the end, perhaps the British orchardists of the English Isles, while hearing of the plight of their American counterparts after their revolution, had the last laugh.

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Scale

“Time ripens the substance of a life as the seasons mellow and perfect its fruits. The best apples fall latest and keep longest.”
—Amos Bronson Alcott

When James Lick died of a stroke in his San Francisco hotel on October 1, 1876, he was the wealthiest man in California, possessing vast real estate throughout the West Coast, including the entire island of Santa Catalina. After arriving in the then-sleepy town of San Francisco in 1848 from South America, he capitalized on the emerging gold rush by selling 600 pounds of Peruvian chocolate to would-be-miners with pockets flush with cash. This led to the first of his three notable lifetime achievements: convincing his one-time neighbor in Lima, confectioner Domingo Ghirardelli, to come to the Golden State.

Lick was an avid astronomer and philanthropist, establishing the world’s first permanently occupied mountaintop observatory—The University of California Lick Observatory—on Mt. Hamilton, southeast of San Francisco. A thirty-six-inch refracting telescope mounted at the site made the first new moon discovery on Jupiter since Galileo’s time—his second notable achievement.

An amateur botanist and lover of plants, Lick imported ornamental and fruit trees worldwide for his manor house in San Jose. In the early 1870s, workers found a tiny scale-like insect on one such tree. This pest scattered throughout his orchard and neighboring groves of apple, pear, apricot, plum, and other deciduous stone fruits. Within twelve years, the scale had spread to all significant fruit-growing regions of the Pacific coast, causing extensive crop loss and economic damage. The Department of Agriculture determined James Lick unintentionally imported the San Jose scale, as they labeled it, on a peach tree from a remote area between Peking and the Great Wall of China—Mr. Lick’s third and most significant notable achievement, albeit destructive.

For several years, the scale was confined to the West and unknown to have infected the important pear and apple orchards in the Middle and Eastern states. However, in 1893, the scale was identified in a Virginia nursery, brought over on a California plum tree, and spread throughout the region. Soon, the scale emerged over the American Northeast and South, Europe, Japan, Hawaii, and Australia. The scale first appeared in Northwest Arkansas in 1903 on mail-order peach trees.

The San Jose scale weakened the leaves on recent growth and caused purple-red blemishes on the fruit. A lime-sulfur-salt wash and oil emersion spray, applied in the winter, could control but not eliminate the pest. To offset the increased cost of spraying, California farmers began short-pruning and shaping their trees to facilitate insecticide application, a practice not adopted in Arkansas for decades. In the early 1890s, the San Jose scale was the first insect observed worldwide to develop resistance to an insecticide. Hyped-up national and global attention to this tiny bug led to the first of many interstate and international regulations controlling the distribution of orchard fruit and nuts.

In Japan and China, traveling research entomologists discovered an Asiatic ladybird beetle dined on the scale, controlling damage and allowing local farmers to cultivate their crops. In 1902, scientists shipped hundreds of these beetles back to the East Coast in an unsuccessful attempt to introduce them to American orchards.

The female San Jose scale is a soft, yellow, immobile insect without legs or wings and lives under a hard cap. It sucks sap from branches, leaves, and fruit, robbing vigor and stunting growth. In the late spring, short-lived males emerge with legs, wings, and antennae and fly from tree to tree to mate with females. After mating, the female produces about 400 crawlers that travel short distances to attach themselves to the tree and create their own hard cap. Two to three adult generations can occur each season in Arkansas and destroy an apple tree in just a few years if left uncontrolled.

At the turn of the century, renowned entomologist C. L. Marlatt appropriately petitioned his colleagues to refer to this pest as the Chinese scale. But alas, the moniker San Jose scale had already villainously attached to the South Bay orchard of James Lick, the man who also introduced America to the sweetness of Ghirardelli chocolate.

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Moths

“For when man migrates, he carries with him not only his birds, quadrupeds, insects, vegetables, and his very sward, but his orchard also.”
—Henry David Thoreau

John Chapman (a.k.a. Johnny Appleseed) began his legendary spread of apple trees to the frontier wilds of Ohio, Pennsylvania, Illinois, Indiana, and Ontario in the early 1800s. He carried seeds, seedlings, and shoots from one farm to the next, planting orchards and nurseries along the way. Undoubtedly, he spread the destructive codling moth as well.

The codling moth has followed apple cultivation from Asia Minor to Europe and worldwide for thousands of years. Its name derives from the frequent infestation of codlin apples, small, firm, green apples first grown in pre-Victorian England. These apples required parboiling (coddling) before they were edible. By the early 1700s, the moth was well-established in American apple orchards, having arrived on European fruit stock.

Moments after hatching from tiny white eggs on the surface of apple leaves and twigs, the codling moth caterpillar, one-eighth of an inch long, makes its way to the calyx (bottom of the fruit where the flower once was) and bores its way into the pulp. Once inside, it seals its entry with scraps of apple skin, pulp, and excrement. The worm works its way to the seminal chamber of the fruit, where it consumes the seeds, thus halting the growth of the fruit and causing premature ripening and dropping.

After three to four weeks of feeding, the worm exits the apple and finds a protected location in the tree bark or under fallen leaves to spin a cocoon. The adult moth, one-half inch long, soon emerges, mates near the tops of the trees at twilight, lays eggs near the developing fruit, and dies. Arkansas orchards could see three generations of codling moths in one season, each more extensive and damaging than the preceding.

Control of the codling moth in the 1920s was difficult and often ineffective. Farmers collected and destroyed dropped apples. They wrapped trunks with burlap to discourage larvae from using the rough bark to shelter a cocoon. Last, they sprayed lead arsenate on the developing fruit, giving partial protection from caterpillar infestation. Spraying was costly, especially on the tall trees of Arkansas, where the damage was worse at the top. Fruit sprayed with lead arsenate required acid-washing to remove the pesticide residue before market. After washing, packers waxed and polished the apples to show they had been cleaned. Consumers came to associate waxing with purity, and the practice persisted long after growers stopped using lead arsenate.

Indeed, John Chapman helped spread the codling moth westward by planting seed nurseries for local farmers to tend. Because he shunned grafting, his seedling apples, contrary to popular folklore, were not especially edible and primarily used for hard cider. By supplying means for “drink,”—a Bacchus of the wilderness—he was welcomed by pioneers on every farm in the expanding frontier.

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Rust

“It was from out the rind of one apple tasted, that the knowledge of good and evil, as two twins cleaving together, leaped forth into the world.”
—John Milton

In the late nineteenth century, French winemakers pressed renowned botany professor Pierre-Marie-Alexis Millardet of the University of Bordeaux to solve an urgent problem affecting local vineyards. A downy mildew fungus, accidentally introduced from America into the premiere Bordeaux wine-growing region, was causing extensive economic damage and tainting its stellar reputation.

Millardet visited the expansive Château Dauzac, growing exclusive wines, once classified by Napoleon as one of the eighteen Cinquièmes Crus of Bordeaux. He noticed that though the fungus affected vast swaths of Cabernet Sauvignon and Merlot, it spared thin strips of the vinery along public roads. Speaking directly to the caretakers, he learned workers routinely sprayed a solution of copper sulfate on the fruit closest to the road to temporarily impart a bitter taste and discourage theft by passersby. This led Millardet to begin a series of experiments at Château Dauzac. He learned copper ions inhibited the germination of fungal spores and halted the spread of the infection. In 1885, he developed a blend of copper sulfate and quicklime, nicknamed the “Bordeaux mixture,” that proved highly effective in controlling fungal diseases, including the cedar-apple rust native to North America.

On the first warm, wet spring days from Maine to Louisiana, round galls (Gymnosporangium juniperi-virginianae) on the branches of the eastern red cedar swell and extrude dozens of bright orange gelatinous horns like a postmodern medusa. The tendrils release millions of microscopic fungal spores (basidiospores) into the wind, drifting for several miles.

Spores landing on the moist leaves or fruit of native crab apples or cultivated apples will attach, germinate, and embed. Infection takes only a matter of hours. Yellow-orange rust spots with a bright red border enlarge to a quarter inch over the next few weeks. The center becomes stippled with black pimple-like bodies, exuding a sticky substance to attract insects. Aphids, flies, and ants unwittingly carry spermatia from one rust spot to another, fertilizing the fungus. The lesion soon grows to extend through the leaf, emerging on the underside with reproductive bodies called aecia. Apple leaves react to this invader by thickening and cupping the aecia, but to no avail. The leaf becomes deformed and weakened, no longer capturing the sun’s energy to perform photosynthesis—the magic of making sugar from carbon dioxide and the foundation of all life on earth.

By mid-summer, the aecia free millions of aeciospores into the air. These new spores are harmless to apples but must land on an eastern red cedar to continue the life cycle. In the fall of the first year, small green-brown galls form on infected cedar needles. Eighteen months later, after a few warm spring days, the tiny galls mushroom in size to two inches in diameter and explode into flowering tendrils of two-celled teliospores, releasing the airborne cedar-apple rust spores once again. This is one of nature’s most complex life cycles, requiring two different host plants, four different spore types, and two years to complete.

For the red cedar, the fungal damage is slight. For the apple, it can be devastating. Heavily infected leaves will turn yellow and drop in mid-summer. Fruit will blemish, under-develop, and deform—becoming unmarketable. Once the rust spot is visible on the leaf, the damage is irreversible for the season.

In 1922, the United Fruit Company introduced Millardet’s Bordeaux mixture to South America, where locals nicknamed it “Perico” or “Parakeet” for it could turn exposed farmworkers blue. Overuse of the mixture polluted water and soil, killing fish and livestock. Despite this, farmers throughout North America adopted copper sulfate and lime because it was highly effective against many agricultural fungal diseases. They sprayed the mix in the early spring on apple trees throughout the twentieth century to prevent cedar-apple rust damage. The bitter-tasting mix would remain on the leaves and fruit for several weeks before eventually being washed off by rain.