Biology Reference
In-Depth Information
P OSTHARVEST
D ISEASE .
Sphaeropsis
on fruit; G. fuseum, CA; G. globosum (0, I),
on leaves and fruit, eastern states to IA, MN;
G. hyalinum (0, I), FL; G. kernianum (0, I),
on leaves and fruit, AZ, CO; G. nootkatense
(0, I), on Asiatic pear, AK; G. sabinae, MI.
S CAB . Venturia pyrina, general.
S POT A NTHRACNOSE , Scab. Elsino¨ pini, OR, WA.
V IROID . Pear Blister. Argentina.
V IRUS . Apple Chlorotic Leaf Spot, Spy Epi-
nasty Decline, Virginia Crab Stem Pitting
and Brownline, Apple Mosaic, Flat Limb,
Pear Vein Yellows/Red Mottle, Pear Ring-
Pattern Mosaic, Pear Latent on Bradford
Pear ( Pyrus calleryana ), MD; Pear Stony
Pit, Pacific Coast states, NY; Pear Decline,
CA, OR, WA; Pear Leaf Curl, CA; Pear
Bark Measles, CO; Apple Stem Pitting,
Argentina.
Fire blight is the limiting factor in pear produc-
tion, many orchards having been abandoned
because of this devastating bacterial disease.
Kieffer pears and some Asiatic varieties are resis-
tant and are being used in breeding; some resistant
forms are now available. Sprays during
blossoming, usually an antibiotic, sometimes com-
bined with weak copper, are used in conjunction
with sanitary measures for fire-blight control. Pear
decline, a virus disease transmitted by the pear
psylla, is serious on the Pacific Coast.
pyriputrescens, MI.
P OWDERY M ILDEW . Podosphaera leucotricha,
CO, MD, OR, WA; P. oxyacanthae, NJ.
R OT , Bitter; Twig, Branch Canker. Glomerella
cingulata, widespread but not destructive.
R OT , Black; Canker; Leaf Spot. Physalospora
obtusa, widespread.
R OT , Brown. Monilinia fructicola, eastern states,
TX, WA.
R OT , Brown; Blossom Blight. Monilinia laxa.
Pacific states.
R OT ; Blossom and Twig Blight.
Botrytis
cinerea, widespread.
R OT , Collar, Root. Phytophthora cactorum,
widespread; P. citrophthora, CA.
R OT ,Fruit.Alternaria sp., black mold; Aspergil-
lus sp., cosmopolitan; Botryosphaeria ribis,
black rot, VA; Cephalosporium carpogenum,
storage; Trichothecium roseum,occasional
pink mold; Cladosporium sp., occasional;
Coprinus urticicola,OR;Gloeosporium sp.,
widespread Neurospora sitophila,ripero ,
NC; Penicillium spp., blue mold, widespread;
Phialophora malorum, ;Phoma
exigua; P. mali; Rhizopus nigricans,black
mold, cosmopolitan; Pleospora fructicola;
Sclerotinia sclerotiorum, CA, WA;
Sporotrichum malorum, storage rot, OR,
WA; Phacidiopycnis washingtonensis (also
Canker and Blight), WA; Sphaeropsis
pyriputrescens,WA;Potebniamyces pyri,
WA.
R OT , Heart. Fomes
Pea-Tree (Caragana)
igniarius; F. pinicola;
Polyporus spp.
R OT , Root. Armillaria mellea, widespread;
Phymatotrichum omnivorum, AZ, OK,
TX; Xylaria sp., ID, IN; Xylaria mali, VA;
Phytophthora cinnamomi.
R OT , Silver Leaf. Stereum purpureum, NY, OR;
S. hirsutum, trunk rot.
R OT , Stem, Calyx. Phacidiopycnis piri (also can-
ker and postharvst fruit rot), OR.
R OT ,
B ACTERIAL
Hairy
Root.
Agrobacterium
rhizogenes, KY to NE, OK.
B LIGHT , Leaf. Ascochyta sp., OH; Septoria sp.,
MN.
B LIGHT , Pod. Botrytis cinerea,MA.
D AMPING -O FF . Rhizoctonia solani,ND.
L EAF S POT . Phyllosticta gallarum, AK, WI.
P OWDERY M ILDEW . Microspora (Erysiphe)
palczewskii, AK, ID, MN, ND, WA;
Erysiphe arborescens, WI, Quebec, Canada.
R OT , Root. Pellicularia filamentosa, ND;
Phymatotrichum omnivorum, TX;
Phytophthora cactorum, wilt, of seedlings.
Trunk.
Schizophyllum commune,
cosmopolitan.
R UST . Gymnosporangium clavariiforme (0, I),
leaves and fruit, SC: G. clavipes (0, I), chiefly
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