N Deficiency

1
N Deficiency
corn
alfalfa
soybean
Nitrogen deficiency is a nutritional problem that
affects the vegetative part of the plant.
Symptoms include pale, yellowish green leaves
beginning on the older, lower leaves. The
deficiency is favored by cold or wet soils or dry
soil (particularly after midseason).
2
P Deficiency
soybean
sorghum
Phosphorus deficiency is a nutritional problem
that affects the vegetative and fruit parts of
the plant. Symptoms include stunted, spindly
plants with low vigor and dark green leaves.
Older leaves can become brown if the deficiency
continues. In sorghum, low P can lead to
shriveled and poor quality kernels.
3
K Deficiency
wheat
corn
Potassium deficiency is a nutritional problem
that affects the vegetative part of the plant.
Symptoms include a yellowing and dying of the
leaf margins beginning at the tips of the lower
leaves. The older leaves turn color because K is
mobile in the plant and is translocated from old
to young leaves.
4
Fe Chlorosis
wheat
corn
Iron chlorosis is a nutritional problem that
affects the vegetative part of plants. Symptoms
include the upper leaves turning pale green and
almost white between the veins. This deficiency
is favored by high pH, wet compacted soil, and
cool weather.
5
Fe Chlorosis
6
Powdery Mildew
wheat
sugarbeet
Powdery mildew is a fungal disease which affects
the vegetative parts of plants. Shade and high
humidity favor this disease, so close plant
spacing may increase disease development.
Powdery mildews infect a number of different
plant hosts, although each host is infected by a
different species.
7
Smut
Common smut of corn is caused by a fungus and can
affect any part of the plant, but it is most
common on the fruits of the plant. Overwintering
spores of the fungus serve as initial inoculum to
begin infections.
8
Root Rot

• NebGuide G00-1407-A (sugarbeet)
• NebGuide G89-900-A (alfalfa)

Root rots are caused by fungi and affect the
vegetative parts of plants.
9
Ergot

• NebGuide EC97-1874 (wheat)

Ergot disease is caused by fungi and affects the
fruits of plants.
10
Stalk Rots

• NebGuide G99-1385-A (corn)

Stalk rots are caused by fungi and affect the
vegetative parts of plants.
11
Rusts

• NebGuide G95-1250-A (dry bean)
• NebGuide G95-1245-A (wheat)

Rust diseases are caused by fungi and affect the
vegetative parts of plants.
12
Galls
Sugarbeet examples
Gall formation on roots caused by nematodes
Soil fumigation No fumigation
Galls can be caused by fungi or nematodes and
affect the vegetative parts of plants. In this
example, nematodes cause gall formation on the
roots of sugarbeet plants. Wilted, stunted
plants above ground result from the root damage.
Because nematodes survive in the soil, a
difference is visible in plant growth above
ground after soil treatment.
13
Cankers
Cankers are caused by fungi which block vascular
bundles in plants. The example pictured above is
of soybean stem canker. Symptoms include
brownish, slightly sunken lesions on the stem and
browning of the leaves.
14
Blight

• NebGuide G-99-1384-A (corn)
• NebGuide G79-429-A (wheat)

Blight diseases are caused by fungi or bacteria
and affect the vegetative parts of plants. The
two publications listed above for corn and wheat
discuss fungal diseases.
15
Wilts
Potato fusarium
Sunflower verticillium
Wilt diseases are caused by fungi which block
vascular bundles. Symptoms include wilting and
browning of plant tissues and brownish
discoloration in the vascular tissues of the
stem. Fungi which cause wilt diseases are found
in the soil, so control can be difficult.
16
Mosaics

• NebGuide EC89-1871 (WSMV wheat)

Mosaic diseases are caused by viruses and affect
the vegetative parts of plants.
17
Scab

• NebGuide G94-1207-A (wheat)
• NebGuide EC97-1874 (wheat)

Scab diseases are caused by fungi or bacteria and
affect fruits or flowers of plants. Scab of
wheat is caused by a fungus and it affects the
fruits of the plant.
18
Mold

• NebGuide G00-1408-A (corn)

Mold diseases are caused by fungi and affect the
fruits or flowers of plants. Corn grain molds
are caused by fungi and affect the fruits of the
plants.
19
Frost
Frost is a cultural problem that can affect
vegetative or fruit parts of the plant. Plant
tissues are killed by the freezing damage and
bleached or brown areas result. Frost often
occurs when plants are young, and if the growing
point is still below the soil, the plant may
recover.
20
Wind Damage
wheat
Wind damage is a cultural problem that affects
the vegetative parts of the plant. Leaves may
tear and plants may break over from the physical
damage. This damage may lead to plant disease
infection because of the openings that are
available in the plant.
corn
21
Drought
wheat
Drought damage is a cultural problem that affects
the vegetative parts of plants. Damage is often
seen as a drying of the leaves beginning from the
tips and progressing back toward the base of the
leaves. Leaves appear scorched and very dry
because of the lack of water available to the
plants.
22
Hail
corn
wheat
Hail is a cultural problem that affects the
vegetative parts of a plant. The weather event
can cause physical wounding to plants, which may
in turn lead to increased disease due to openings
made in the plant tissue.
23
Herbicide
Herbicide damage is caused by mechanical
practices and affects the vegetative parts of
plants. There are many
different types of herbicides, so the damage they
cause also varies. Growth regulator herbicide
damage is fairly common on soybean and results in
cupping and distortion of the leaves. Herbicide
damage is also usually associated with a pattern
in the field, whereas disease problems are
usually randomly distributed.