field
shot - winter injury followed by drought
Pictures of drought injury:
field
shot - winter injury followed by drought
dry
planting conditions - poor wheat stand
Hosts: Plant species and varieties differ in their ability to tolerate drought conditions.
1) Emerged leaves show wilting, followed by yellowing and leaf burn
2) Reduced coleoptile length and leafing out underground occurs if dessication/drought occurs at germination.
3) Seedlings may die after germination
4) Reduced plant stand
5) Tillers aborted prior to flowering
6) Reduction of tiller roots, tillers, spikelets, florets, plant growth, and yield
7) Empty and bleached white heads or parts of heads (1).
Look-alike symptoms:
2) Low pH
3) Salt damage
4) Frost injury
6) Winterkill
8) Russian wheat aphids
9) Herbicide injury due to:
a) Acetanilides (Stampede)
b) Amino acids (Roundup)
c) Bepyridyliums (Avenge, Cyclone, Gramoxone, Gramoxone Extra, Reglone, Sweep)
d) Dinitroanilines (Edge, Prowl, Sonalan, Treflan)
e) Phenoxy-carboxylic acides (2,4 D, Compitox, MCPA, Mecoprop)
f) Thiocarbamates ( Far-Go, Avadex BW)(1)
Favorable conditions:
1) Dry soils at planting
2) Drying winds, hot temperatures, and lack of moisture after planting
Pattern in field: Injury is more common in areas with lighter
soil or topography (1).
Infestation levels: Several days of hot weather during emergence can decrease the coleoptile length which causes the seedling to leaf out underground. Dry seedbed results in reduced germination rate. Germination and shoot elongation will cease altogether when soil temperature is above 90 F. all growth in developed plants will stop at 85 to 90 F (1).
History in MT and US: The Northern Great Plains are well-known for wide fluctuations in moisture and temperature. Drought is common in Montana especially in the eastern part of the state.
Crop losses: If soil moisture conditions improve and the growing point remains viable, the plant may recover, but with varying degrees of yield loss (1).
Controls:
Cultural controls:
Resistant varieties: Small grain varieties differ in their tolerance to high temperatures and drought (1).
Biological controls:
Chemical controls:
References: 1) Guide to Herbicide Injury Symptoms in Small
Grains. Second Edition. 1992. Agri-Growth Research, Inc., Hollandale,
MN, p.45-46.
Pictures of frost injury:
barley
heads - affected by frost injury
frosted
winter wheat - Phillips Co. Jack Lang farm - frosts May 27, June 12,
June 27, 7 frosts during 1969 season
frost
injury - Phillips Co. Jack Lang farm, 1969
Hosts: All plants are prone to frost injury, but some are more resistant than others.
Symptoms of frost injury:
1) Just after exposure to frost or cold, leaf tips or entire leaves appear water soaked and dark green. Sometimes the entire field turns a purplish color. One or two days lates the leaves dry out and turn brown.
2) Horizontal bands of alternating yellow and green leaf tissue often occurs when cold nights are followed by warm days. This is called the "Rugby Stocking" effect (1,2).
3) Stem contriction beneath nodes
4) Empty and bleached white heads (2).
Look-alike symptoms:
light
frost - while heads are in the boot, could resemble banvel injury
- Hessian fly damage as a seedling
- Russian wheat aphids (2)
- Herbicide injury symptoms due to
a) Amino acids (Roundup)
b) Bipyridyliums (Avenge, Cyclone, Gramoxone, Gramoxone Extra, Reglone, Sweep)
c) Isoxazolidinones (Command)
d) as-Triazines (Sencor, Lexone)
e) s-Triazines (Aatrex, Atrazine, Bladex)(2).
Favorable conditions:
LEAVES:
- Frost tolerance varies with variety and plant age. Old leaves are more sensitive to freezing than young leaves.
- As a general rule, wheat leaves can tolerate 15 to 20 F temperatures when they are not hardened off and 0 to 10 F when they are hardened. Cold hardening occurs at temperatures below 48 F.
ROOTS:
- Roots are rarely injured since the soil acts as an insulator. However, roots can be killed at temperatures below 23 to 26 F.
STEM ELONGATION:
- Injury that occurs while internodes are elongating often can be recognized by peelng bck the leaf sheaths from the top to bottom. This exposes the internode sections. Injury will show up as a thin, often collapsed, and brownish section of the stem about 1 to 3 inches long. The injury can occur at the top, middle, or base of the internode. Empty heads will result.
- If the growing point of the main stem or tiller is killed before heading, the main stem or tiller will die. When this hapens, new shoots can arise from the crown.
HEADS:
- Injury to heads can occur anytime after stem elongation has begun. However, frost damage to developing heads often is not visible until heading is complete.
- Frosts after head initiation has already begun may cause trapped heads, twisted awns, and sterile florets at the tip of the heads.
- Frost damage during boot to eary heading may affect the entire head, the tip, the base, both tip and base, or the middle section of the head.
- Heads that were pollinating when cold temperatures occurred likely will have sterile grain (3).
- Exposed heads damaged by frost are empty and bleached white (2). Sudden frosts when plants are actively growing favors injury.
Pattern in field:
- Low areas and coulees where heavier, cold air settles
- Areas with high organic matter soils are most likely to show damage (2).
Infestation levels:
- Plants may recover if the growing point is not damaged. To determine viability of affected plants, examine the growing pint of the plant two days following the frost. If the growing pint has turned brown and is decaying, the frost has damaged that main stem or tiller and it will not recover.
- Injury to the developing heads can occur at or beyond the fourth-leaf stage. The head or spike is initiated on each tiller during the four-leaf stage and before stem elongation occurs (2).
History in MT and US: Frost injury is fairly common in Montana due to sporadic cold spells occurring into late spring and early summer when wheat is actively growing. Higher altitude areas of the state are most susceptible.
Crop losses: Yield losses will depend on the symptom severity and stage of the wheat during the frost or cold occurred (3).
Cultural controls:
Resistant varieties:
Biological controls:
Chemical controls:
References: 1) MPHR 5/15/80 2) Guide to Herbicide Injury Symptoms
in Small Grains. Second Edition. 1992. Agri-Growth Research, Inc.,
Hollandale, MN, p.57-59. 2) Cook, R.J. Veseth, R.J. 1991. Wheat Health
Management. APS Press, St. Paul, MN, p. 23 - 23. 3) Riesselman, J.
Frost-injured cereals. Montana Crop Health Report, July 15, 1988.
Picture of hail injury:
Hosts: Any crop can be affected.
Symptoms of hail injury:
Trapped heads and curled leaves. To distinguish from herbicide injury,
examine stems for hail bruised areas which first appear white and later
turn brown and
necrotic (1).
Look-alike symptoms: These symptoms can also be caused by phenoxy herbicides. See "symptoms" above.
Favorable conditions:
Pattern in field:
Infestation levels:
History in MT and US: Hail storms are quite prevalent in Montana especially in the eastern and central parts of the state (2).
Crop losses: If hail occurs when wheat is still in the vegetative state, yield loss will be less than if it occurs after heading has been initiated (2). The greatest damage is incurred if plants are injured during the period of their greatest metabolic activity. Researchers found that destruction of the leaves of winter wheat plants early in the spring had little effect on the yield of the crop. However, when leaves were removed in the boot stage, a 30% yield reduction occurred (2). Wheat plants with hail injured peduncles often lose their heads, especially if the injury occurred above the flag leaf. The higher the break occurs on the plant, the greater the chance of losing the head. This probably is due to the effect of wind on the wheat heas which are more exposed than those which hang at lower levels (2). A curled head condition often results from hail injury to the top of the sheath above the enclosed head. Yield losses in curled heads relative to normal ones ranged from 1 to 10% (2).
Controls:
References: 1) MPHR 7/2/80 2) Afanasiev, M.M. 1967. "The effect
of simulated hail injuries on wheat" Montana Agricultural Experiment Station,
Bulletin 613.
Hosts:
Symptoms of heat canker:
1) Plant appear pinched wher the stem contacts the soil surface.
2) Leaf blade has a brown to black band (burn line) at the soil surface.
3) Leaves will topple over depending on degree of burn.
4) Sudden, rapid browning of the flag leaf (3).
Look-alike symptoms:
2) Hessian fly damage in 3- to 4- leaf stage
3) Herbicide injury due to:
a) as-Triazines (Lexone, Sencor)
b) s-Triazines (Astrex, Atrazine, Bladex)
Favorable conditions: Where a marginal root system development combines with lush foliage production, a sudden change from wet and cool to hot, dry, and windy weather and heating of the soil causes firing of wheat. The plants can't replace moisture lost to transpiration (1, 3). When temperatures go above 90 - 95 F, wheat stops growing and can even lose weight. This is because photosynthesis slows down dramatically and respiration increases with increasing temperatures up to 100 F. Wheat is especially sensitive to high temperatures when first planted and during seedling emergence and tillering. It also can be injured or stressed by high temperatures during the conversion to reproductive development, stem extension, heading, and flowering. Also, during especially hot days, the photosynthate produced does not exceed that lost to respiration. As a result, the leaves are smaller and heads much reduced in size. A hot spell during stem elongation can result in fewer florets per spikelet. A hot spell during flowering can result in sterility (2).
Pattern in field: Heat canker can occur anywhere in the field.
Infestation levels: Heat canker is most likely to occur to plants at an early stage and affected plants may lose some leaves. However,the growing pint is protected in the soil an dis agle to produce more leaves.
History in MT and US:
Crop losses: Generally, heat canker will not result in yield losses.
Controls:
References: 1) Guide to Herbicide Injury Symptoms in Small
Grains. Second Edition. 1992. Agri-Growth Research, Inc., Hollandale,
MN, p.61-62. 2) Cook, R.J. Veseth, R.J. 1991. Wheat Health Management.
APS Press, St. Paul, MN, p. 58. 3) Riesselman, J. Potential for heat injury.
Montana Crop Health Report, June 15, 1990, No. 5.
Hosts: Small grains and most other crops. Barley can grow at slightly higher saline levels than wheat (2).
Symptoms of salt damage:
1) Seeds swell but fail to germinate
2) Slow germination and emergence
3) Reduced stand
4) Tip burn in young leaves due to salt concentration in this area (1).
Look-alike symptoms:
3) Winterkill
4) Herbicide injury due to dinitroanilines (Edge, Prowl, Sonalan, Treflan)
5) Herbicide injury due to thiocarbamates (Far-Go, Avadex BW)
6) Herbicide injury due to acetanilides (Stampede) (1).
Favorable conditions:
1) Salty soils, saline seeps
2) Starter fertilizer with a high salt index
3) Dry seed bed and compacted soils (1).
Pattern in field: Symptoms may be most severe in areas with poor drainage (1).
Infestation levels: Injury will occur in areas of the soil with salt concentration that are high enough to produce necrosis in small plants (1). The upper level of salinity for growth of cereals is from 10 - 15 mmhos/cm (2).
Life cycle: Most salinity problems develop in a field when dissolved salts that are transported from other areas of a field concentrate in areas of poor drainage. Salt accumulation increases when water is removed through transpiration or evaporation. This leaves salts in the soil (1).
History in MT and US: Saline seep and salt injury problems are common in certain areas of Montana such as the Choteau Co.- Geraldine area.
Crop losses: Losses increase as salt concentrations increase in the soil.
Controls:
Cultural controls: Plant deep rooted perennial crops such as alfalfa in saline seep recharge areas.
Resistant varieties:
Biological controls:
Chemical controls:
References: 1) Guide to Herbicide Injury Symptoms in Small
Grains. Second Edition. 1992. Agri-Growth Research, Inc., Hollandale,
MN, p.45-46. 2) Duczek, L.J. 1993. The effect of soil salinity on common
root rot of spring wheat and barley. Canadian Journal of Plant Science,
v. 73 (1), pp. 323 - 330.
Hosts: Any plant can be susceptible, especially those with tender leaves and stems.
Symptoms:
1) Small abrasions on leaves caused by blowing sand
2) Abrasions are often copper-tone in color
3) Severe injury may result in complete desiccation of the plant
4) Shredding of leaf tissue (1).
Look-alike symptoms:
Herbicide injury due to:
a) Benzonitriles (Buctril, Pardner)
b) Bepyridyliums (Avenge, Cyclone, Gramoxone, Gramoxone Extra, Reglone, Sweep)(1).
Favorable conditions: Injury is caused by impact of soil particles blown by high winds against the leaves (1).
Pattern in field: Light, sandy soil areas or areas where soil is powdery and loose on top are the most common areas of sandblasting in a field (1).
Infestation levels: Mild injury will be cosmetic and new leaves will show no injury. Plants may be cut off at the soil surface in severe cases and affected pants may not recover if addtional stresses affect the plants (i.e., drought, herbicide injury, etc.)(1).
History in MT and US: High winds during the early season when there is little plant material covering the soil can cause sandblasting in Montana.
Crop losses: Repeated occurrence of sandblasting may affect plant vigor, stand establishment, and yield potential (1).
Controls: Grass, tree, or shrub barriers around fields and/or long narrow stripes alternating with stubble fields can decrease wind speed and sandblasting. Tillage to produce larger soil clumps can decrease damage.
References: 1) Guide to Herbicide Injury Symptoms in Small
Grains. Second Edition. 1992. Agri-Growth Research, Inc., Hollandale,
MN, pp. 63-64.
Hosts: Most crops can be affected.
Symptoms of soil crusting:
BELOW GROUND SYMPTOMS:
1) Emerging shoot may bend over
2) Shoot may emerge through the side of the coleoptile
3) Seedlings are yellow in appearance, twist and begin to leaf out below ground.
4) Roots develop normally.
ABOVE GROUND SYMPTOMS:
1) After emerging, leaves are often twisted and kinked, and do not unroll properly from the coleoptile.
2) Uneven stand (1).
Look-alike symptoms:
2) Wet soil and weather stress
3) Herbicide injury due to benzoic acid in the soil (Banvel, Banvel SGF)
4) Herbicide injury due to dinitroanilines (Edge, Prowl, Sonalan, Treflan)
5) Herbicide injury due to thiocarbamates (Far-Go, Avadex BW)(1)
Favorable conditions:
1) Working wet soils
2) Soils high in clay content (1) and low in organic matter (2).
3) Heavy rains shortly after seeding
4) Deep planting (1).
Pattern in field: Areas of the field that are prone to standing
water or areas with low organic matter are most likely to have crusting
problems (1).
Infestation levels: Small grains can tolerate a crust up to 0.25 inches thick. However, if seeds are planted too deeply, the seedlings will leaf out underground and even a light crust can prevent the plants from emerging. The plants will recover if they can break through the ground and favorable environmental conditions exist (1).
Life cycle: When cereal grain seedlings are trapped under a crust, they will continue to grow and elongate as long as there is stored energy in the seed. When that runs out and the new seedling is not photosynthetically active, it dies. In cool weather, a seedling may be alive under a crust for many days. As soil temperatures increase, survival time is reduced (2).
History in MT and US: Soil crusting is common in Montana especially in spring crops when hot, dry conditions occur soon after seeding and seal off the soil surface.
Crop losses: If rain or cultural breakup of the crust do not occur in time or are not effective, replant decisions must be made. It is important to evaluate the existing stand and determine its yield potential. Expense of replanting and the possibility of having another crusting problem in June are important considerations (2).
Controls:
1) If plants have not yet emerged, the soil can be broken with spring coil harrows, drag, rotary hoe, or a double disc grain drill. The object is to gently break the crust into small chunks and slightly move it in the process (1,2).
2) The equipment used and its adjustment will vary from field to field. It is probably best to set the equipment, do a small patch, evaluate the soil manipulation, and then let the hired man finish the job (2).
3) If plants have emerged, a harrow may break the coleoptile tips.
4) A double disk opener drill set at 0.5 inch deep, rotary hoes, or leaving more residue on the surface by less tilling may help also (1).
Resistant varieties: Healthy seed of varieties with rapid emergence capabilities can minimize damage due to soil crusting.
References: 1) Guide to Herbicide Injury Symptoms in Small
Grains. Second Edition. 1992. Agri-Growth Research, Inc., Hollandale,
MN, p.45-46. 2) Helm, J.L. 1994. "Is soil crusting your problem?" North
Dakota Crop and Pest Report. 5/19/94 No. 3.
Picture of wet soil damage:
rain
devastated winter wheat - north of Glendive, MT
Hosts:
Symptoms of wet soil or weather stress:
- Uneven emergence
- Yellowing of underground leaf foliage
- Yellow, dark green or reddish-purplish foliage
- Slow crop development
- Loss of plant vigor and growth during growing season
- Root diseases often develop in response to wet weather stress. These include common root rot, Fusarium foot rot, and Take-all (1).
Look-alike symptoms:
- Herbicide injury due to:
a) Aryloxphenoxy-propionic acids/cyclohexandediones
(Achieve, Assure, Assure II, Excel Super, Fusilade 2000, Fusilade II, Hoe-Grass, Hoelon, Option II, Poast, Select)
b)Benzoic acids in the soil (Banvel, Banvel SGF)
c) Dinitroanilines (Edge, Prowl, Sonalan, Treflan)
d) Thiocarbamates (Avadex BW, Far-Go) (1).
Favorable conditions:
- Below normal temperatures (less than 40 F) during seedling emergence favors injury.
- If the soil is water-logged at the time of cold weather and crop emergence, the risk of seedling blight and crown rot greatly increases.
- Low temperatures coupled with other interacting factors such as wet soil, soil surface crusting, planting depth, and seedling diseases determine the extent of seedling stress or injury (1).
Pattern in field: Temperature effects on seeling emergence and development often are present in the entire field. Hoever, the cold soil temperature effects will be greater in low areas of the field, areas with heavy surface residues, or on north-facing slopes (1).
Infestation levels: Low temperatures coupled with other interacting
factors such as wet soil, soil surface crusting, planting depth, and seedling
diseases determine the extent of seedling stress or injury.
History in MT and US:
Crop losses:
Controls:
Cultural controls:
Resistant varieties:
Biological controls:
Chemical controls:
References: 1) Guide to Herbicide Injury Symptoms in Small
Grains. Second Edition. 1992. Agri-Growth Research, Inc., Hollandale,
MN, pp. 65-66.
Picture of wind injury:
wheat
- Banner Co. (also, high temperatures)
Hosts:
Symptoms of wind injury:
Look-alike symptoms:
Favorable conditions:
Pattern in field:
Infestation levels:
Life cycle:
History in MT and US:
Crop losses:
Controls:
Cultural controls:
Resistant varieties:
Biological controls:
Chemical controls:
References:
.
Pictures of winterkill:
field
shot - wheat affected by winter injury followed by drought
Hosts:
Symptoms of Winterkill (winter injury):
- Plants with one or more leaves killed
- Patches of dead plants in the field
- Tiller development without accompanying root system growth
- Wilting, yellowing and some leaves dying after good spring green-up
(1).
Look-alike symptoms:
- Herbicide injury due to:
a) Amino acids (Roundup)
b) Bipyridyliums (Avenge, Cyclone, Gramoxone, Gramoxone Extra, Reglone, Sweep)
c) as-Triazines (Lexone, Sencor,)
d) s-Triazines (Astrex, Atrazine, Bladex)
Favorable conditions: Winterkill can be caused by:
- Inadequate varietal winter hardiness,
- Incomplete hardening in the fall before to extreme cold occurs,
- Development of several tillers because of early seeding leaves plants in a more vulnerable state (2).
- Lack of snow cover during extreme cold (1), and
- Warm early spring temperatures followed by extreme cold.
Pattern in field:
- Injury can occur across entire fields if pants have not hardened sufficiently to cold temperatures.
- Injury can occur in any area where the soil is suddenly exposed and cold temperatures occur shortly thereafter (1).
Infestation levels:
- Low temperatures may kill the leaves, but recovery will occur as long as the crown is not killed.
- Less affected plants may green-up in the spring with lush foliage. Due to inhibited root growth and under-developed tiller roots, plant growth may be reduced and symptoms similar to drought stress may result.
- Winter wheat plants with several tillers harden less and are more vulnerable to winterkill than younger plants.
- Plants that are in the three- to four-leaf stage and have a good root system are at the ideal stage of development for winter survival and rapid recovery in the spring (1).
History in MT and US: Winterkill occurs quite commonly in Montana, especially in areas of the state that have low temperatures and little or no snow cover.
Crop losses:
Controls:
Cultural controls:
Resistant varieties:
Biological controls:
Chemical controls:
References: 1) Guide to Herbicide Injury Symptoms in Small Grains. Second Edition. 1992. Agri-Growth Research, Inc., Hollandale, MN, pp. 67-68. 2) Watkins, J.E. et al. "Root and crown rot- Winterkill complex of winter wheat" NebGuide, Cooperative Extension, University of Nebraska-Lincoln, G92-1097-A.
