29.12.2012 Views

Compendium of Potato Diseases - (PDF, 101 mb) - USAID

Compendium of Potato Diseases - (PDF, 101 mb) - USAID

Compendium of Potato Diseases - (PDF, 101 mb) - USAID

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

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 />

109

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!