| AFFECTING GENERAL PLANT, ROOT PROBLEMS: |
|
CONDITION
|
CAUSE
|
 |
Yellow,
stunted plants that wilt during bright, hot days and recover at night. |
Usually a sign of
root injury. Pull up plant and check for root-knot nematodes or cabbage
root maggots (below)
|
|
Irregularly
shaped galls |
Root-knot nematode
(Meloidogyne spp.)
|
|
Roots
are riddled with slimy, winding tunnels |
Cabbage root maggots
|
|
| AFFECTING LEAVES: |
|
CONDITION
|
CAUSE
|
|
Yellow
v-shaped spots on leaf margins with blackened veins; stems show
internal black streaks |
Black rot (Xanthomonas
campestris)
|
|
Yellowish
leaves, lower leaves drop; stunted plants may have twisted stems,
usually occurs soon after transplanting |
Fusarium yellows ()Fusarium
oxysporum)
|
|
Yellow
leaves, older leaves first, slow growth |
Nitrogen deficiency
|
|
Older
leaves whitish and drooping |
Cold injury, wind
injury
|
|
Yellow,
curled leaves; stunted plants |
Aphids
|
|
White to
bronze spots, wilted leaves |
Thrips
|
|
White
spotting, then brown, often distorted leaves that wilt and die |
Harlequin bug (Margantia
histrionica)
|
|
Light-colored
spots on leaves turn papery; white mildew on leaf undersides |
Downy mildew (Peronospora
effusa)
|
|
Small
pitted holes, shot-hole injury |
Flea beetles (Phyllotreta
spp.)
|
|
Large
irregular holes |
Imported cabbage worm
(Pieris rapae), Cabbage
looper, Diamondback
moth (Plutella xylostella), or Grasshoppers (Melanoplus
spp.)
|
|
Leaves
with meandering tunnels |
Leafminer
|
|
| AFFECTING HEADS: |
|
CONDITION
|
CAUSE
|
|
Hollow
stem, smaller, uneven head formation |
Excess nitrogen, or
potassium deficiency
|
|
Black
areas in center of head |
Rot due to water
collecting inside head
|
|
Small
heads that form prematurely (bolt) |
High temperature
stress, poorly adapted variety, or exposure of plants to fluctuating
warm/cool temperatures
|
