Biology Reference
In-Depth Information
R
OT
, Gray Mold. Botrytis cinerea, chiefly in
greenhouses, sometimes outdoors.
R
OT
, Root. Fusarium sp., KY, OH;
Phymatotrichum omnivorum, AZ, TX;
Phytophthora cryptogea, CA; P. drechsleri,
Mexico; Pythium myriotylum, VI.
R
OT
,Watery Soft; Drop. Sclerotinia sclerotiorum,
widespread; S. minor, in transit and market.
R
UST
. Puccinia dioicae (0, I), IN, MN, ND, WI;
II, III on
Carex
; P. hieracii (II), CA.
S
LIME
M
OLD
. Physarum cinereum, occasional
under glass.
V
IRUS
. Cucumber Mosaic,NY;Sonchus Yellow
Net,FL;Tobacco Rattle,CA;Lettuce Mosaic,
general; Radish Yellows; Lettuce Big Vein,
associated with
Olpidium brassicae
in roots,
FL; Tomato Spotted Wilt, CA, HI, TX;
Tobacco Necrosis; Lettuce Infectious Yel-
lows,AZ,CA;Lettuce Speckles Mottle,CA;
Tomato Bushy Stunt,CA;Tobacco Streak,
FL; Potato Leafroll. Pacific Northwest, Cucur-
bit Yellow Stunting Disorder,CA;Impatiens
Necrotic Spot,CA.
W
HITE
R
UST
. Albugo sp., TX.
W
ILT
, Leaf Blight. Pythium tracheiphilum, WI;
Fusarium oxysporum f. sp.
Lettuce (Lactuca)
A
NTHRACNOSE
. Marssonina panattoniana,NYto
FL, CA, MI, OR, TX, WA.
B
ACTERIAL
Leaf Spot. Xanthomonas campestris
pv. vitians, OH.
B
ACTERIAL
Marginal Leaf Blight. Pseudomonas
fluorescens pv. marginalis, KS, MO, NJ, NY;
P. cichorii, NY.
B
ACTERIAL
,MLO.Aster Yellows (white heart,
Rio Grande Disease) and California Aster
Yellows, widespread.
B
ACTERIAL
Rot. Pseudomonas viridilivida, DE,
LA, MI, NH, NY, VA, WA.
B
ACTERIAL
Soft Rot. Erwinia carotovora, cos-
mopolitan in market.
B
ACTERIAL
Wilt. Xanthomonas vitians, NJ, NM,
NY, PA, SC, VA.
B
LIGHT
, Southern. Sclerotium rolfsii, CA, FL,
NC, SC, TX, VA.
C
ORKY
R
OOT
. Rhizomonas suberifaciens, FL.
D
AMPING
-O
FF
; Stump Wilt; Stunt. Pythium spp.,
cosmopolitan.
D
OWNY
M
ILDEW
. Bremia lactucae, general.
L
EAF
S
POT
.
Alternaria
sp.,
secondary;
lactucum, AZ,
Cercospora longissima, FL,
IL,
IN, TX,
CA.
Nonparasitic tipburn is the most general of let-
tuce diseases, prevalent at high temperatures when
soil is deficient in moisture. Some hot weather
varieties are rather resistant. Spacing plants well
apart in a well-drained soil will reduce bottom rot
and drop. Eliminate wild weed hosts and spray for
leafhopper vectors to reduce aster yellows.
VA, WI;
Septoria lactucae, occasional
in
East and central states, to CO, FL, MN.
L
EAF
Y
ELLOWING
;S
TUNT
. Pythium uncinulatum,
CA.
N
ECROSIS OF
R
OOTS
,S
YSTEMIC
. Plasmopara
lactucaeradicis, hydroponically grown, VA.
M
OLD
, Leaf; Seed. Pleospora herbarum, FL,
KY, NY.
N
EMATODE
. Naccobus batatiformis.
N
EMATODE
, Lesion. Pratylenchus sp.
N
EMATODE
, Root Knot. Meloidogyne hapla.
N
EMATODE
, Sting. Belonolaimus gracilis.
N
ONPARASITIC
. Tipburn. High temperature and
excessive transpiration.
Brown Blight. Cause unknown, AZ, CA.
P
OWDERY
Leucojum (Snowflake)
L
EAF
S
CORCH
, Red Blotch.
Stagonospora
curtisii, CA.
N
EMATODE
, Meadow. Pratylenchus sp.
R
OT
; Scale Speck, of Bulbs. Botrytis sp., CA.
M
ILDEW
.
Golovinomyces
cichoracearum, CA, MI.
R
OT
, Basal. Phoma exigua, CA.
R
OT
, Black Root. Thielaviopsis basicola, CA.
R
OT
, Bottom; Damping-off. Rhizoctonia solani,
general.
Leucospermum
B
LIGHT
. Calonectria colhounii,HI.
W
ILT
. Verticillium dahliae, CA.
