Biology Reference
In-Depth Information
Growth Cracks. Fluctuating moisture.
Hollow Heart. Excessive soil moisture and
fertility.
Hopperburn. Marginal necrosis from leafhop-
pers. General.
Internal Brown Spot. Various physiological
factors.
Knobbiness, “second growth”. Extreme fluctua-
tions of soil moisture.
Lenticel Enlargement. Wet soil or oxygen
deficiency.
Mahogany Browning. Low temperature, ME.
Marginal Browning,
R
OT
, Dry. Fusarium graminearum, ND;
F.
torulosum,
F.
oxysporum
and
F. sambucinum, MI.
R
OT
, Gray Mold; Shoot Blight. Botrytis cinerea,
AK, CT, ID, ME, OH.
R
OT
, Pink, Watery. Phytophthora
erythroseptica, DE, ID, LA, ME, MA, OK,
PA; P. parasitica, TX; P. cryptogea, TX.
R
OT
, Root. Armillaria mellea, CA, FL, MI, OR,
WA, WI, WY; Phymatotrichum
omnivorum, TX; Helicobasidium
purpureum, MA, MT, NE, NY, ND, OK,
OR, TX, WA;
bronzing.
Potassium
Fusarium solani
f.
sp.
deficiency.
Ozone. Purple-black specks from air pollution.
Pitting, Spot necrosis of tubers. Oxygen defi-
ciency in storage.
Pointed Ends. Irregular growth conditions.
Psyllid Yellows. Insect injury, western states.
Ring Spot. Zonate, depressed lesions. Cause
unknown.
Scald of tubers. Overheating, sunburn, frequent
in South.
Spraying. Internal concentric necrosis. TRV or
PMTV Virus.
Sprout Tubers; “Little Potato”. Overheating in
storage; planting in dry, cold soil.
Stem-End Browning. Vascular necrosis. Virus.
Stem Necrosis; Defoliation. Manganese toxicity
in acid soil.
Tipburn. Abrupt transition from cool, moist to
hot, dry weather, general.
P
HYTOPLASMA
, Aster Yellows. Candidatus Phy-
toplasma asteris, NE, TX.
P
HYTOPLASMA
. Potato Purple Top, MT, Canada,
Mexico, Russia, U.S.
P
HYTOPLASMA
, Zebra Chip Disease. Candidatus
Liberibacter psyllaurous, CA, Honduras,
Mexico; C. L. solanacearum, AZ, CA, CO,
KS, NE, NV, NM, TX. Central America, Gua-
temala, Mexico.
P
OWDERY
M
ILDEW
. Golovinomyces
cichoracearum, CA, KY, NJ; Oidium sp.;
MD, NJ, OH, PA, UT, western U.S;
Leveillula taurica, WA.
R
OT
, Charcoal. Macrophomina phaseoli, CA,
GA, IL, OK, TX.
R
OT
,Collar.Fusarium solani f. sp. eumartii,CA.
eumartii, CA.
R
OT
, Silver Scurf. Spondylocladium atrovirens,
general but less frequent in the South;
Helminthosporium solani, NY.
R
OT
, Stem. Sclerotinia sp., FL, ME, SC;
S. minor, CA; S. sclerotiorum, FL, MA,
MT, NY, OR, TX, WA, general.
R
OT
, Tuber. Aspergillus niger; Fusarium spp.;
F. solani, jelly end-rot; Gliocladium sp., sec-
ondary; Oospora pustulans, skin spot; Peni-
cillium spp., blue mold; Phoma tuberosa;
Phomopsis tuberivora; Phytophthora
drechsleri, P. nicotianae, FL, MO, NE, TX;
Rhizopus spp.; Trichothecium roseum, pink
mold; Xylaria apiculata.
R
OT
, Tuber Sprout. Fusarium sambucinum, MI.
R
OT
, Watery Leak. Chiefly Pythium
debaryanum, common in West; Pythium
spp.
S
CAB
. Streptomyces scabies, general; Powdery
Scab, Spongospora subterranea, AK, ND;
Russet Scab, Streptomyces sp.
V
IRUS
. Apical Leaf Roll, unidentified; Potato
Aucuba Mosaic, NY; Potato Calico strain
of Alfalfa Mosaic; Potato Crinkle; Mild
Mosaic (Virus X plus A); Green Dwarf;
Beet Curly Top; Potato Leaf Roll, general;
Potato Leaf Rolling Mosaic; Mottle (Potato
Virus X); Potato Rugose Mosaic (Potato
Virus Y), general; Potato Virus Y, Mexico;
Potato Spindle Tuber (viroid), general;
Potato Vein Banding; Potato Witches'
Broom; Potato Yellow Dwarf; Potato Yel-
low Spot; Tobacco Ring Spot; Potato Corky
Ring Spot
(Tobacco Rattle), MI, MN, ND,
