Gadenin日本語Get the appThe tree defends itself, which is why the list is short
Pawpaw leaves, twigs and bark carry natural compounds that most chewing insects and browsing mammals find repellent. In practice that means deer, which will strip almost any other young fruit tree in a rural garden, leave pawpaw alone, and it means the tree needs no routine spray program at all. Growers coming from apples or plums are usually surprised at how little there is to do.
Because there is so little insect pressure, most pawpaw problems are cultural rather than biological: too much sun on a young tree, too much water at the root, not enough water in midsummer, or lime in the soil. Diagnose in that order before you go looking for a pest.
The one specialist feeder that is welcome is the zebra swallowtail caterpillar, which can only develop on pawpaw. It eats a few leaves on an established tree and does no meaningful damage. Leave it.
| Symptom | Most likely cause | What to do |
|---|---|---|
| Leaf edges bleached then brown, young tree | Sun scorch, no shade in years 1-2 | Put up 50 percent shade cloth immediately, water deeply |
| Whole tree wilts, soil is wet | Root rot from saturated soil | Stop watering, improve drainage or replant on a mound |
| Whole tree wilts, soil is dry | Drought stress | Deep soak, then mulch to 3 in (7.5 cm) |
| Yellow between green veins | Soil too limy for pawpaw | Acidify with sulfur, use acidic mulch |
| Purple-black spots on leaves in wet weather | Fungal leaf spot | Rake and remove fallen leaves; no spray needed |
| Flower stems chewed, buds drop before opening | Peduncle borer larvae | Pick off and destroy affected buds |
| Shoot tips webbed together with leaves | Pawpaw webworm | Cut out and destroy the webbed tip |
| Small fruit all drop in early summer | Incomplete pollination or water stress | Hand pollinate more thoroughly, water through fruit set |
| Bark split on the trunk after winter | Winter sun scald on thin young bark | Wrap or shade the sunny side of the trunk in winter |
Sun scorch, the commonest killer of young trees
More pawpaws are lost to full sun in their first two summers than to every insect combined. The seedling leaf is adapted to understory light and burns in the open: the margins pale, then go papery brown, then the whole leaf drops. A young tree that defoliates in midsummer has no way to rebuild its reserves before winter and often does not leaf out the following spring.
The fix is preventative, not curative. Shade from planting onward, at roughly 50 percent, on a frame or as burlap on the south and west sides, removed at the start of the third season. If a tree has already scorched, put shade over it at once, water deeply and expect a lost season rather than a lost tree.
Confusingly, the same brown-edged leaf appears from drought and from salt or fertilizer burn at the root. Check the soil moisture under the mulch first: dry means water, wet means look at drainage, and correct moisture with full exposure means it is the light.
The two insects worth knowing
Only two insects cause real crop loss, and both are handled by hand rather than by spray. Neither justifies a broad insecticide, which in a pawpaw would kill the flies and beetles that are the tree's only pollinators.
- Peduncle borer A small larva bores into the flower stalk in spring. The bud yellows, the stalk shrivels and the flower drops before it opens. Losses are usually a fraction of the bloom on a healthy tree. Walk the tree during flowering, pick off any bud with a shriveled or blackened stalk and destroy it rather than dropping it under the tree.
- Pawpaw webworm Caterpillars web the leaves and shoot tips together into an untidy bundle and feed inside it, occasionally boring into a young stem. Cut the webbed tip out with pruners the day you see it and burn or bin it. Left alone it can kill a shoot on a young tree but rarely troubles a mature one.
- Fungal leaf spot In a wet summer, purple-black blotches appear on the leaves and sometimes on the fruit skin. It is cosmetic and the fruit inside is fine. Rake up and remove the fallen leaves in autumn to break the cycle, and thin the canopy in dormancy so air moves through it.
- Fruit-eating wildlife Deer avoid the tree but raccoons, opossums, squirrels and foxes go straight for ripe fruit and will take a crop overnight. There is no repellent that works reliably. The practical defense is to pick at the firm-but-yielding stage and finish ripening indoors.
Never apply a broad-spectrum insecticide to a pawpaw in flower. The flies and beetles it kills are the only insects that pollinate the tree, and there is no crop without them.
Keeping notes that make next year easier
Pawpaw problems repeat in the same places and at the same points in the season. Write down the date you first see webbed shoot tips, the date buds start dropping, and which trees show it. Note the position of each tree and which side of it scorches. Two seasons of that is enough to tell you which week to start walking the trees and which tree needs the shade screen left up an extra year.
Record the failures honestly too, including the trees you lost and what the soil was like where they stood. Pawpaw sites fail for consistent reasons, and the wet corner that killed one tree will kill its replacement.