Diseases of apples (Malus domestica) include:
| Bacterial diseases | |
|---|---|
| Blister spot | Pseudomonas syringae pv. papulans |
| Crown gall | Agrobacterium tumefaciens |
| Fire blight | Erwinia amylovora |
| Hairy root | Agrobacterium rhizogenes |
| Nematodes, parasitic | |
|---|---|
| Dagger nematode | Xiphinema americanum Xiphinema rivesi Xiphinema vuittenezi |
| Lesion nematode | Pratylenchus spp. Pratylenchus penetrans |
| Pin nematode | Paratylenchus spp. |
| Ring nematode | Criconemella spp. |
| Root-knot nematode | Meloidogyne spp. |
| Viral diseases | |
|---|---|
| Apple chlorotic leafspot | genus Trichovirus, Apple chlorotic leafspot virus (ACLSV) |
| Apple dwarf (Malus platycarpa) | Apple stem pitting virus (ASPV) (? not US/CAN) |
| Apple flat apple | genus Nepovirus, Cherry rasp leaf virus (CRLV) |
| Apple mosaic | genus Ilarvirus, Apple mosaic virus (ApMV) genus Ilarvirus, Tulare apple mosaic virus (TAMV) |
| Apple stem grooving = Apple decline of Virginia crab | genus Capillovirus, Apple stem grooving virus (ASGV) |
| Apple stem pitting = apple Spy 227 epinasty and decline | Apple stem pitting virus (ASPV) |
| Apple union necrosis and decline | genus Nepovirus, Tomato ringspot virus (ToRSV) |
| Viroid diseases | |
|---|---|
| Swollen apple | Apple fruit crinkle viroid (AFCVd) |
| Apple dimple fruit | Apple scar skin viroid (ASSVd) |
| Apple fruit crinkle | Apple fruit crinkle viroid (AFCVd) (Japan) |
| Apple scar skin = apple dapple, apple sabi-ka, apple bumpy fruit | Apple scar skin viroid (ASSVd) |
| Suspected viral- and viroid-like diseases | |
|---|---|
| Dead spur | GTP, unidentified |
| False sting | GTP, virus suspected |
| Green crinkle | GTP, virus suspected |
| Rough skin | GTP, virus suspected |
| Star crack | GTP, virus suspected |
| Phytoplasmal diseases | |
|---|---|
| Apple chat fruit | Phytoplasma suspected |
| Apple decline | Phytoplasma suspected |
| Apple proliferation | Phytoplasma |
| Rubbery wood | Phytoplasma suspected |
| Miscellaneous diseases and disorders | |
|---|---|
| Bitter pit | Localized calcium deficiency |
| Blossom blast | Boron deficiency |
| Burrknot | Genetically predisposed rootstock |
| Fruit cracking | Genetic |
| Fruit russet | Frost, sprays, etc. |
| Green mottle | Unidentified |
| Hollow apple | High temperature |
| Internal bark necrosis = measles | Low pH and mineral nutrient imbalance |
| Internal browning | Boron and calcium deficiencies, etc. |
| Jonathan spot | Reduced by controlled atmosphere storage |
| Narrow leaf | Genetic |
| Necrotic leaf blotch of ‘Golden Delicious’ | Rapid synthesis of gibberellins triggered by environmental factors |
| Spray injury | Spray |
| Storage scald | Injury to fruit surfaces by naturally occurring gases produced by the fruit |
| Sunburn | Sun injury to fruit |
| Sunscald | Freezing of bark following high temperatures in winter |
| Water core | Sorbitol accumulation |