Plum

Leaf-curl plum aphid and mealy plum aphid are the species here, and they are more of a problem on plums than on most other fruit trees - heavy early colonies curl and yellow the leaves and can stunt young shoots. Dormant oil in winter smothers overwintering eggs where it recurs.

Dense clusters of tiny insects packed onto shoot tips, flower buds, and the undersides of young leaves. Curled, cupped, or distorted new growth that never opens properly. A sticky shine on the leaves - and on whatever sits under the plant - that later goes black with sooty mold. Tiny white cast skins left behind where a colony has been feeding. Ants running steadily up and down the stems, which is often the first thing you notice. Mottled, streaked, or misshapen leaves that do not grow out can mean a virus the aphids brought with them rather than the feeding itself.

Knock the colonies off with a hard jet of water and repeat every few days - on most plants that alone ends it. Pinch out or prune off the worst-infested tips rather than treating the whole plant. If colonies keep rebuilding, spray insecticidal soap or horticultural oil directly onto the insects, covering leaf undersides, and repeat weekly until they are gone; treat early or late in the day, and never spray a wilted or heat-stressed plant. Avoid broad-spectrum insecticides - they kill the ladybugs, lacewings, and parasitic wasps that were about to solve the problem for you, and aphid numbers usually come back worse afterward. Anything you spray must be labeled for the plant you are treating; follow that label and observe its pre-harvest interval. On anything you eat, wash leaves, heads, and buds well before use, since aphids hide down in crowns, folds, and tight growth.

Go easy on nitrogen: the soft, lush growth that heavy feeding produces is exactly what aphids breed on. Check new growth once a week through spring and early summer so you catch colonies while they are still small, and rub the first few out with your fingers. Leave flowering plants nearby and skip broad-spectrum sprays - ladybugs, lacewings, hoverflies, and parasitic wasps do most of this work for free, and they only stay if there is something for them to eat. Keep ants off the plant where you can, since they protect aphids from those predators. Water steadily so plants are not stressed, and check any new plant over before you bring it home or move it indoors, since aphids usually arrive on something else.

Aphids are small soft-bodied sap-suckers - green, black, gray, pink, or waxy white, and mostly wingless - that gather in dense colonies on the tenderest new growth: shoot tips, buds, and the undersides of young leaves. They breed extremely fast in mild weather, so a few can become hundreds inside a week. Their feeding curls and distorts soft growth, and the sticky honeydew they excrete coats everything below and turns black with sooty mold. Ants often farm and defend the colonies for that honeydew. A few aphids are normal on almost any plant and a healthy plant shrugs them off; only dense, persistent colonies do real damage, and some aphids also spread plant viruses as they feed.

Because plums ripen in a short window, a few days of unchecked bird and squirrel pressure can take a big share.

Fruit disappearing from the outermost, most exposed parts of the plant first, and from the top of a tree where you cannot reach anyway. Single neat pecks and gouges in ripening fruit, with several fruits sampled rather than one eaten through - the classic sign that it was birds rather than an animal. Heads of grain or seed going visibly lighter and emptier as they ripen, with hulls and chaff scattered underneath. Freshly sown seed vanishing off the surface of a bed before it germinates. Bird traffic in and out of the plant picking up as the crop colors, and birds waiting on nearby wires and branches. Wasps arriving at the pecked and split fruit shortly afterward.

There is no treatment once a crop is being taken - only protection and timing, so the answer is to get netting on and to pick what is ready. Reflective tape, flash ribbon, spinners, and decoy predators do work, but only for a few days at a time: birds habituate fast, so move and rotate them and never rely on them as the main defense for a crop you care about. Cut and gather grain or seed heads a little early, at firm dough, and finish drying them under cover instead of leaving them standing for the flocks. Plant a little extra, or a decoy crop the birds prefer, and accept sharing anything that crops heavily. On a wild or foraged patch, fruit going to birds and small mammals is the point of the plant rather than a problem to solve.

Net, and net early. Bird netting draped over a frame or hoops so it stands off the fruit, with the edges closed at ground level, is the only thing that reliably works at harvest scale - and it has to go on before the crop starts to color, because once birds have found the food they are far harder to displace. Keep fruit trees small enough that netting them is actually feasible; that decision gets made years earlier, at planting. Bags of mesh, organza, or paper slipped over individual heads, clusters, or prize fruit protect a small crop without netting the whole plant. Then shorten the exposure: pick promptly and completely rather than leaving ripe fruit hanging as a lure, clear split and dropped fruit that draws birds and wasps alike, and where a crop can finish off the plant, harvest a little early and ripen or dry it under cover. Rake in or cover broadcast seed so it is not lying in plain view.

Birds find ripening fruit and seed before you do. Robins, waxwings, starlings, catbirds, jays, sparrows, finches, blackbirds, and doves all work a garden, and the pressure arrives in a narrow window - the last days before harvest, when sugar rises, color changes, and the crop softens or the grain hardens. A flock can strip a small planting in a day or two, and birds that only peck rather than take whole fruit still leave wounds that rot or draw wasps. Squirrels, chipmunks, and other wildlife usually turn up on the same crop at the same time. This is competition rather than disease: the birds are not harming the plant, and a big tree or a heavy-cropping bush often has enough for everyone - but on a small planting it can be the difference between a harvest and none.

A few weeks of feeding rarely hurts an established tree, but they also chew ripening fruit - net or otherwise protect the fruit during peak beetle flight.

Clusters of shiny metallic beetles massed together on the upper, sunniest foliage and down inside open blooms, heaviest on warm sunny afternoons from around late June. Leaves reduced to lace, with the veins left intact and the tissue between them gone - unmistakable, and quite different from the ragged chewing of a caterpillar. Ragged, chewed petals and blooms that never open properly. Beetles that let go and drop straight to the ground when you disturb the plant. Feeding damage on ripening fruit, on the plants they also take fruit from. Whole branches going brown and lacy at the top of a plant while the shaded lower growth stays untouched.

Persistent morning hand-picking into soapy water is the most effective home control there is, and on a vigorous established plant the damage is usually cosmetic and needs nothing else. Neem deters feeding rather than killing, and has to be reapplied. For heavy pressure, spinosad or a targeted insecticide labeled for the plant will work - but time any spray away from bloom and apply it at dusk to protect bees, and observe the pre-harvest interval on anything you eat. On flowering plants, some gardeners simply shear the blooms off for a couple of weeks and let the plant rebloom once the wave has passed, which removes the lure as well as the damage. Young plants and young trees are the ones worth defending: a mature tree or an established vine tolerates several weeks of leaf loss without lasting harm.

Hand-picking is genuinely the main defense in a home garden. Go out in the cool of the morning while the beetles are sluggish, hold a tub of soapy water underneath, and knock them in - they drop when disturbed, so most fall straight into it. Do it daily through the flight: because the beetles call each other in, taking them off early stops a plant becoming a beacon. Do not put pheromone or lure traps anywhere near the garden - they demonstrably pull in far more beetles than they catch. And do not count on lawn grub control: milky spore has performed poorly and inconsistently in field trials across most of the US, and treating your own turf does not reduce the adults feeding on your plants, because they fly in from surrounding properties. Where it is practical, row cover or netting through the peak flight excludes them outright. Otherwise riding out the six-to-eight-week wave is a legitimate strategy, since most established plants absorb the damage.

Japanese beetles are metallic green-and-copper beetles about half an inch long that emerge in early summer and feed for six to eight weeks. They feed in aggregating masses - one beetle's feeding releases a scent that draws in more - so a plant goes from untouched to covered in a couple of days. They chew the soft tissue between the leaf veins and leave the veins standing, so the leaf ends up as a brown lace skeleton, and they shred open flowers and sometimes ripening fruit as well. They work the sunniest upper parts of a plant on warm afternoons. The white C-shaped grubs spend the rest of the year in turf and pasture soil eating grass roots, and the adults then fly in from wherever they hatched, which can be some distance away.

Attacks the trunk, not the fruit - gum-and-frass at the soil line is the diagnostic sign.

Gummy sap mixed with sawdust-like frass oozing from the lower trunk and crown, and wilting or dieback on a young tree.

Dig out and destroy larvae from the trunk with a wire in spring/fall; targeted trunk sprays or beneficial nematodes drenched at the base help. Protect young trees especially.

Keep trees vigorous and avoid trunk wounds; keep mulch and weeds off the trunk base so borers can't hide; monitor the crown area. Pheromone traps help time management.

A clearwing moth whose larvae bore into the trunk at and just below the soil line, girdling and killing branches or whole young trees - one of the most serious pests of peaches and nectarines, especially on young trees.