Compendium of Potato Diseases - (PDF, 101 mb) - USAID
Compendium of Potato Diseases - (PDF, 101 mb) - USAID
Compendium of Potato Diseases - (PDF, 101 mb) - USAID
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Surface and or interior<br />
Shades <strong>of</strong> green tuber greening<br />
Underlying tissue collapsed sunscald<br />
Subsurface tissue<br />
Blue to black blackspot<br />
Dried. s<strong>of</strong>t or sunken wind injury<br />
Brown at stolen attachment stem-end browning<br />
Necrotic arcs to flecks TRV, PMTV<br />
Center. hollo or cracked hollow heart<br />
Interior firm<br />
Necrotic trust colored) spots or flecks principally in medullary<br />
tissue internal heat necrosis, phosphorus deficiency, calcium<br />
deficiency. AMV. PAMV. PYDV. TRV<br />
Necrotic to tan discolored areas PVY'<br />
Rust colored arcs or rings I'RVPMTV<br />
Net (phloem) scattered necrosis PI.RV. low temperature injury.<br />
stem-end browning, PAMV<br />
At stolon attachment stem-end browning, chemical injury, low<br />
temperature injury, calcium deficiency, Fusarium wilt, Verticillium<br />
wilt<br />
Mahogany colored interior low temperature injury<br />
With glassy texture, starch depletion second growth<br />
Interior firm to solt<br />
Smoky gray discoloration low temperature injury, leak<br />
Black medulla blackheart<br />
Vascular discoloration<br />
S<strong>of</strong>t texture, ooze \;hen squeezed ring rot, brown rot<br />
Firm to s<strong>of</strong>t. dark low temperature injury<br />
F-irin. confined to vascular area, brown to black possibly with watersoaked<br />
border FtUsariuni wilts<br />
Firm near stolon attachment calcium deficiency, stem-end<br />
browning, Fusarium ssiIs<br />
Netlike. more severe near stolon end Verticillium wilt, chemical<br />
iniury, stei-end brow.ning<br />
Discoloration evident through skin<br />
Indistinct lines, arcs, or blotchy areas TRV. PMTV, TSWV.<br />
PAMV<br />
As raised rings PMIV<br />
(iras-brown discoloration brown rot, pink rot, pink eye<br />
Chalky<br />
Normal Tuber<br />
white<br />
Shape,<br />
spots<br />
Surface<br />
belosw skiti.<br />
Blemished<br />
later<br />
Without<br />
dry' granular.<br />
Active Rot<br />
becoming<br />
darker rot newiatode<br />
rlisters I NYV<br />
Bros n rings to necroic areas PVY'. PMI Y. TRY<br />
Skin cracked tither cracks, Rhioctoni, PYI)Y, PSTY PMTY<br />
INV, boron deficiency<br />
Or feathered surface abrasions<br />
lenticels affected enlarged lenticels, bacterial s<strong>of</strong>t rot, powdery scab,<br />
sten rot, charcoal rot, gangrene, PSTV<br />
( t nderyling tissue brown to black pink rot<br />
Stolon attachment discolored chemical injury.jelly end rot, stem-end<br />
browning, brown rot, ring rot, stein rot, Verticillium wilt,<br />
Fusarium wilts, horon deficiency, charcoal rot, pink rot<br />
Also <strong>of</strong> nedullarv areas s<strong>of</strong>t rot, blackleg<br />
Eves discolored<br />
Principally at tuber tip pink eve. Verticillium wilt<br />
Anywhere charcoal rot, Fusarium wilts<br />
)ark colored gangrene<br />
With soiladhering browuri rot<br />
Purplish black raised spots skin spot<br />
With watery exudate frozen tubers<br />
Wounds infected bacterial s<strong>of</strong>t rot,powdery scab, leak. Fusarium<br />
tuber rots, gatngrene<br />
tubrlowsnganyre<br />
Shalhiss- lesiorvs anywshereBrwlein<br />
Necrotic skin, dark gangrene, sunscald. high temperature field<br />
injury. low temperature injury, wind injury. TNV<br />
Silvery sheen to light brownish surface silver scurf<br />
Silvery to brown with very small black scerotia--- black dot<br />
Irregular purplish brown lesion nematodes<br />
Raised lesions<br />
Purplish corky to necrotic spots. sometimes around eyes --skin<br />
spot<br />
Circular lesions Ihecaphora smut<br />
Reddish purple mycelium and sclerotia on surface, sunken areas<br />
below violet root rot<br />
Brown sunken blotches PAMV<br />
Brown to dark sunken pits, russet or raised lesions or russet<br />
discoloration<br />
Underlying tissue firm. corky, at stolen end - potassium deficiency<br />
Tan brown to black--common scab, TNV<br />
Raised pustules white, later depressed, dark brown-powdery scab<br />
Pitted Rhizoctonia<br />
Necrotic <strong>of</strong>ten in bands. scablike---chemical injury<br />
Firm lesions, slightly sunken, relatively shallow<br />
Reddish brown--late blight<br />
Black--early blight<br />
Purplish mycelial mat- -violet root rot<br />
Circular---Fusarium wilts, Fusarium tuber rot<br />
Active Rot<br />
Skin cracks, discolored- -ring rot<br />
Cavities spongy, shrunken--Fusarium tuber rots<br />
With white mycelium and black sclerotia-white mold<br />
Cortex less severely rotted than medulla--ring rot leak<br />
Possible holes through the tuber--lightning injury<br />
Gray smoky discoloration<br />
Of cortex, vascular ring. or medulla--low temperature injury<br />
Black medulla -- blackheart<br />
Anywhere bordering rotted tissue- leak<br />
Water%<br />
At stolon end - -jelly end rot<br />
On exposure to air shades <strong>of</strong> pink. brown to black-frost injury<br />
Charcoal rot. later spongy -leak, pink rot<br />
Later chocolate brown dries as zonate lesions--- Rhizopus<br />
Semiwatery<br />
Brown flabby decay--gray mold<br />
Light gray, cavities with mycelium, and black sclerotia-charcoal rot<br />
Advancing margin clearly delimited--.-white mold. Fusarium tuber rot<br />
Dark line -leak. pink rot<br />
Tissue firm to dry, punky with cavities<br />
Pustules <strong>of</strong> spores on surface--- Fusarium tuber rot<br />
Dry granular, shrunken - rot nematode<br />
Vascular tissue discolored reddish brown to black-brown rot, ring rot<br />
Lesions thu<strong>mb</strong>nail to deep. dark cavities --gangrene<br />
Loose gray white mycelium on surface and in soil, rot black,<br />
carbonaceous-- Rosellinia<br />
Fanlike mycelium on tuber and on soil surface, semifirm decay, cheesy<br />
rot- stem rot<br />
Tuber shell remains -- leak<br />
Secondary Rots<br />
Slimy, cream to tan. <strong>of</strong>ten foul odor-bacterial s<strong>of</strong>t rot. Fusarium<br />
tuber rots. These and others follow primary pathogens such as brown<br />
rot, ring rot, low or high temperature injury, blackheart, late blight,<br />
stem rot, charcoal rot. Rhimopus rot, and rot nematode.<br />
Seed Tubers<br />
Decay-oxygen relations, blackheart, ader e temperature (low or<br />
high), Fusarium tuber rots, leak, bacterial s<strong>of</strong>t rot, stem rot<br />
Dormant, or delayed in germinating- PYDV.APMV, mycoplasmas<br />
Dormancy lacking-- psyllid yellows, witches' broom, second growth<br />
Abnormally thin--genetic abnormalities, hair sprout, mycoplasma<br />
Many- witches' broom<br />
Growing into the tuber--- internal sprouting<br />
Forming tuber directly--second growth, secondary tubers, hair<br />
sprouts, calcium deficiency<br />
Swollen, curved--coiled sprout<br />
Necrotic<br />
.Just below tipi--calcium deficiency<br />
S<strong>of</strong>t, progressing from seed piece -blackleg<br />
Brown lesions<br />
In storage, transverse cracks-- skin spot with girdling<br />
In field-- Rhizoctonia<br />
Stolons<br />
Short---potassium deficiency<br />
Numerous. long---genetic abnormalities<br />
Dark, covered by gray-white mycelium--Rosellinia<br />
Necrosis -pink rot<br />
Brown lesions skin spot<br />
And girdling Rhizoctonia<br />
With dotlike sclerotia- black dot<br />
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