| Name | Causal Organism | Part of Plant Affected | Means of Spread | Source of Innoculum | Control |
| Bacterial Brown Rot
(So. Bacterial Wilt) |
Bacterium
(Pseudomonas solanacearum) |
Tubers | Soil and seed | Soil and seed | Avoid infested fields |
| Bacterial Soft Rot | Bacterium
(Erwinia carotovora) |
Tubers | Soil and contact | do-- | Allow tubers to suberize after harvest; dry washed potatoes; minimize wounding. |
| Blackheart | Physiologic | do-- | None | None | Store at temperatures below 70° F
(21° C) with proper ventilation. |
| Blackleg | Bacterium
Erwinia carotovora var. atroseptica |
Tubers & stems | Seed, Soil & mechanical | Seed, (soil) | Use disease-free seed; prevent
wounding; treat and suberize seed pieces; warm seed; sanitize. |
| Calico | Virus
alfalfa mosiac |
Vines & tubers | Aphids & seed | Seed, alfalfa, clover | Eliminate "volunteer" alfalfa plants;
use disease-free seed; control aphids. |
| Corky Ring Spot | Virus
(tobacco rattle) |
Tubers | Nematodes | Soil & seed | Avoid infested fields; use resistant
varieties; control nematodes. |
| Crinkle Mosaic | Virus
(Potato Virus A + X) |
Vines | Aphids, seed & mechanical | Seed | Disease-free seed, resistant varieties, control aphids, sanitation. |
| Dry Rot | Fungus
Fusarium spp. |
Tubers | Soil & tubers | Soil & seed | Prevent wounding at harvest, treat
tubers with fungicide, allow tubers to suberize & then store at low temp. |
| Early blight | Fungus
Alternaria solani |
Vines & tubers | Air & water | Soil; plant debris | Spray with fungicides; practice crop
rotation and sanitation. |
| Enlarged lenticels | Physiologic | Tubers | Not transmitted | None | Promote soil aeration & drainage.
Don't over-irrigate. |
| Fusarium Wilt | Fungus
(Fuarium solani) var eumartii and F.oxysporum) |
Vines & tubers | Soil & seed | Soil & seed | Use disease-free seed; practice crop
rotation. |
| Growth Cracks | Physiologic | Tubers | Not transmitted | None | Use resistant varieties; keep soil
moisture optimum and uniform. |
| Haywire | See purple-top wilt | ||||
| Heat Sprout | Physiologic | Tubers | Not transmitted | None | Use resistant varieties; provide
adequate moisture. |
| Hollow heart | do-- | do-- | do-- | do-- | Space plants closer in rows; use
resitant varieties; provide uniform moisture. |
| Internal Blackspot | do-- | do-- | do-- | do-- | Reduce harvest and grading bruises;
prevent potassium deficiency; keep soil moist prior to harvest; high humidity storage. |
| Internal or heat necrosis | do-- | do-- | do-- | do-- | Use nonsusceptible varieties; provide
adequate soil moisture. |
| Internal sprouting | Physiologic | do-- | do-- | do-- | Do not store at excessively high temperatures. Proper aeration in storage. |
| Jelly-end rot | do-- | tubers (especially long ones) | do-- | do-- | Provide uniform and adaquate soil
moisture. |
| Late Blight | Fungus
Phytophthora infestans |
Vines & tubers | Air, water & seed | Seed; cull piles; volunteers | Use resistant varieties and disease-free seed; spray with fungicides; eliminate cull piles; kill potato foliage 10 days to 2 weeks before digging. |
| Latent Mosaic | Virus (potato virus X) | Vines | Mechanical & seed | Seed | Use resistant varieties or disease-free
seed; sanitation. |
| Leaf roll | Virus (potato roll) | Vines & tubers (net necrosis) | Aphids & seed | Seed (minor weed hosts) | Use disease-free seed; control aphids;
use resistant varieties; rogue diseased plants; isolate from other potatoes. |
| Leak | Fungus (Pythium debaryanum) |
Tubers | Soil | Soil | Prevent harvest injury; suberize in
storage; cool tubers to 40° -45° soon after harvest; avoid poorly drained soils. |
| Mahogany browning | Physiologic | do-- | Not transmitted | None | Store at 40° F or above. |
| Mild mosaic | Virus (potato virus A) |
Vines & tubers | Aphids & seed | Seed | Use disease-free seed or resistant
varieties; control aphids; rogue diseased plants early. |
| Nematode (eelworm) diseases | Nematodes:
Golden (Globodera rostochiensis) |
Roots | Soil & tubers | Soil, seed & equipment | Fumigate or treat soil with nematicides;
rotate crops or fallow fields; prevent movement of material from infested |
| Potato tuber rot (Ditylenchus destructor) |
Tubers | Soil | Soil | fields; use nematode-free seed; use
resistant varieties. For golden |
|
| Root knot (Meloidogyne ssp) |
Tubers & roots | Soil & tubers | Soil & seed | nematodes, observe quarantine
regulations. |
|
| Root lesion or Meadow (Pratylenchus penetrans) |
Tubers & roots | Soil | Soil | ||
| Net necrosis | See leaf roll | ||||
| Psyllid yellows | Insect (Paratrioza cockerelli) |
Vines & tubers | Insect (Psyllids) |
Seed & weed hosts | Control psyllids. |
| Purple-top wilt
(haywire) |
Mycoplasm (aster yellows) |
do-- | Insects (leafhoppers) |
Crop & weed hosts | Control leafhoppers. |
| Rhizoctonia | Fungus (Rhizoctonia solani) |
Stems, tubers & roots | Soil & seed | Soil & seed | Treat seed tubers; avoid planting in cold soils; disease-free seed. |
| Ring rot | Bacterium (Corynebacterium sepedonicum) |
Vines & tubers | Mechanical & seed | Seed, equipment & storage | Plant disease-free seed; use whole seed; disinfect storages and equipment. |
| Rugose mosaic | Virus (potato virus Y + X) |
Vines | Aphids, seed, mechanical | Seed (minor weed hosts) | Plant disease-free seed; control aphids; use resistant
varieties; rogue diseased
plants early, sanitation. |
| Scab, common | Fungus (Streptomyces scabies) |
Tubers | Soil & seed | Soil & seed | Avoid infested fields; use resistant
varieties; rotate crops; treat seed; control pH; maintain uniform moisture. |
| Scab, powdery | Fungus (Spongospora subterranea) |
Tubers roots |
do-- | do-- | Avoid infested fields; use disease-free
seed; rotate crops. |
| Second growth | Physiologic | Tubers | Not transmitted | None | Provide adequate and uniform soil
moisture; use resistant varieties. |
| Silver scurf | Fungus (Helminthosporium solani) |
Tubers | Soil & seed | Soil & seed | Use disease-free seed; practice crop
rotation; resistant varieties. |
| Soft Rot
(see bacterial soft rot) |
|||||
| Southern bacterial wilt (see bacterial brown rot) | |||||
| Spindle tuber | Viroid (potato spindle tuber) | Vines & tubers | Seed & mechanical | Seed | Use disease-free seed; reduce machinery use in fields after plants emerge. |
| Stem-end vascular browning | Wilt fungi & vine killers | Tubers | Dependent on cause | Dependent on cause | Control wilt diseases; apply vine killers properly. |
| Verticillium wilt
(early dying) |
Fungus (Verticillium spp.) |
Vines & tubers | Soil, seed & debris | Soil, seed & other crop debris | Fumigate infested soil; use resistant
varieties; practice long rotations; plant disease-free seed. |
| Wart | Fungus (Synchytrium endobioticum) |
Tubers | Soil | Soil | Do not plant in infested fields;
resistant varieties. |
| Yellow dwarf | Virus (potato yellow dwarf) | Vines 7 tubers | Seed, leaf-hoppers & mechanical | Seed & clovers | Use disease-free seed; control
leaf-hoppers; avoid cloves in rotation. |