Crop Profile for Grass Seed in Idaho
Production Information

Idaho ranks first nationally and accounts for 50 percent of U.S. Kentucky bluegrass (Poa
pratensis L.) seed production. In 1999, Idaho harvested 36 million lbs of Kentucky bluegrass
seed valued at $45 million from about 60,000 acres

In 1999, Idaho also grew about 25,000 acres of other important grass seed crops including
10,000 acres of bromegrasses (Bromus sp.), about 5,000 acres of fine-leaf fescues (Festuca
sp.), about 6,000 acres of timothy (Phloem pretensis), and about 4,000 acres of wheatgrasses
(Agropyron sp.)

Kentucky bluegrass seed yields average 600 lb per acre and an average price of $0.75 per lb.
Fescues, timothy, and wheatgrass typically produced 300-400 lb per acre with a price of
$0.5-$10.00 per lb.

Production cost for first year establishments of irrigated bluegrass averages $330 per acre,
whereas $230 per acre is invested to establish non-irrigated bluegrass seed. After the first
year, annual production costs average $500 per acre for irrigated bluegrass seed, and $307
per acre for non-irrigated. Annual production costs for established brome, timothy, and
fescue average $200 per acre.
Production Regions
Kentucky bluegrass production is concentrated in Benewah, Kootenai, Latah, Lewis, Idaho, Nez
Perce, and Clearwater Counties. About 1,000 acres of irrigated bluegrass also is grown in
southwestern, southcentral, and southeastern Idaho. Most all timothy is grown in Boundary
County. Fine-leaf fescues and wheatgrasses are grown in Nez Perce, Idaho, and Clearwater
Counties, and on about 1,000 irrigated acres in southern Idaho.
General Cropping Practices
Kentucky bluegrass and other grass seed crops contribute significantly to Idaho’s agricultural
economy. More than 20 bluegrass seed varieties and several species of fescues and wheatgrasses
are produced to meet the demand of landscape businesses, sod farms, pastures, export hay crop,
erosion control practices, CRP plantings, lawns, sports fields, and golf courses. In any given
year, about 20 percent of the Idaho grass seed crop is exported. In addition to a cash crop,
Kentucky bluegrass reduces soil erosion and water loss from the hilly, steep-sloped growing
regions of northern Idaho.
Kentucky bluegrass and other grass seed crops are well adapted to northern Idaho where cool
wet winter and spring promote both vegetative growth and seed production. The dry summers
are excellent for crop maturation and drying. These climatic factors are the main reason for
Idaho’s excellent bluegrass seed yield and quality.
Annual precipitation of the production region ranges from 17-33 inches with more than twothirds occurring in the six-month period, October through March. Elevation ranges from 1,800
to 3,800 feet. Topography of the region is characterized by steep rolling hills with up to 80
percent of the cropland having slopes from 8-30 percent. The Rathdrum prairie (Kootenai
County) is the northern most bluegrass production region on a flat glacial outwash plain. The
soils of this region contain a high percentage of gravel, and irrigation is essential for grass seed
production. The grass seed receive 24 inches of water during the growing season from natural
rainfall and approximately 12 irrigations. Six inches of water is applied in each of September,
May, June, and July.
Kentucky bluegrass and other grass seed crops can be spring planted or fall planted to allow
seedlings to take advantage of early spring moisture. Where grass is seeded following a grain
crop, the grain stubble is burned, plowed or harrowed several times to break chaff rows. Grass
seed is planted to a depth of ¼ inch. Conventional drills typically produce better bluegrass
stands than broadcast seeding or no-till drill. Kentucky bluegrass does not produce seed the first
year. A bluegrass field typically will produce seed two to seven years. A typical 12-year
rotation is grass seed seven years, wheat two years, lentils one year, barley one year, and fallow
one year.
Mature grass crops are swathed in early July and dried in the field two-three weeks before
harvest by specially adapted grain combines. Harvest time is critical to obtain the highest yield
of quality seed. Harvesting high moisture seed can reduce seed quality and require supplemental
drying. Delay in harvest will cause seed shatter. After harvest, crop residues are removed by
burning or in some instances by mechanical collection. Removal of residue permits higher seed
yields the subsequent year. Some value-added industries have developed techniques to utilize
the residue into manufacturing building materials, erosion control blankets, etc.
Integrated Pest Management
Post-harvest destruction of grass residue by burning has been practiced for the past 20-30 years
to increase grass seed yield and to suppress pests (disease, weeds, and insects), and to reduce
pesticide input. Burning suppresses or eliminates major diseases such as ergot, rust, powdery
mildew, and leaf spot. Effectiveness of soil-active herbicides for weed control also is improved
with field burning. Public concern for air quality, however, could promote legislation against
open-field burning. Harvested grass fields typically yield one-six tons of post-harvest residue
per acre. Without removal by burning or mechanical methods, this residue limits the health of
the grass stand and can reduce seed yields by 80 percent. Under dry conditions, a 100-acre field
typically can be burned in two-three hours. Without economical alternatives to burning, pest
problems and pesticide use is expected to increase.
Insects
Troublesome pests of grass seed crops include the sod webworm, plant bugs, winter grain mites,
cutworms, armyworms, and thrips. In a given year, up to 30 percent of the grass seed acreage is
treated with an insecticide. Because few insecticides are registered on grass seed crops, the loss
of one or more of these insecticides would significantly affect Idaho grass seed production.
Insect damage to grass seed crops varies among grass cultivars and species, from year to year,
and within the production region. Grass species and grass cultivars vary in phonological
development, and their susceptible growth stages may or may not coincide with damaging levels
of insects. In addition, differences in climate conditions within the region affect grass and insect
maturity. These factors result in unique insect problems and require careful assessment in each
production site.
Sod webworm (Chrysoteuchia topiaria)
Sod webworms, commonly called “lawn moths,” are a serious pest of several grass seed crops.
Larvae feed on many grass species, but particularly damage bluegrass and fine-leafed fescues
grown in the northern most part of the production region. Uncontrolled larvae can destroy an
entire bluegrass field and spread to adjacent grass fields, especially in dry years. They feed at
night on grass crowns and reside in burrows lined with silk webbing during the day. Adults are
typically inactive during the day and fly at night, scattering their eggs into the grass crop. Eggs
hatch in about one week; the first generation larvae feed until mid summer. A second generation
occurs during the remainder of the season. Generations may overlap with all stages present by
late summer. Damage to susceptible grass crops is most obvious in spring and fall.
Chemical control
Chlorpyrifos (Lorsban 4E) – Chlorpyrifos is applied to about 10 percent of bluegrass and fineleaf fescue acres at a rate of 1 lb ai/acre, once per year. Chlorpyrifos controls sod webworm,
cutworms, and armyworms.
Biological control
B.T. subspecies kurstaki (Javelin WG) – Javelin is applied to about 5 percent of the grass seed
acres at a rate of 1 lb/acre, once per year. Javelin is only effective on 1st and 2nd instar larvae.
Control is variable where 4th and 5th instar is present.
Meadow Plant Bug (Leptoperna dolabrata)
Meadow plant bugs feed on many species of grass seed crops. The economic loss caused by
plant bug feeding would average 50 percent if not controlled. Most damage by plant bugs is
done to the older, common varieties of bluegrass. Many newer varieties such as South Dakota,
Palouse, and Newport have an effective level of resistance, and currently do not require
treatment. Adult plant bugs damage the seed crop by feeding on florets and preventing seed
development. The bug also limits the survival of newly planted grass seedlings. Continued plant
bug feeding can eventually destroy the grass field. Some research has reported that the meadow
plant bug causes silvertop, a serious problem in grass fields not burned. The grass panicles of
Kentucky bluegrass turn white prematurely and seed never develops in these panicles, thus
reducing seed yield.
Chemical control
Dimethoate (Dimethoate 400) – Dimethoate is applied to about 20 percent of the grass seed
acres at a rate of 0.3 lb ai/acre once per year. Dimethoate applied for meadow plant bug control
also controls thrips.
Cutworm and Armyworms (many species)
Cutworms and armyworms frequently damage grass seed crops below and aboveground.
Cutworms tend to feed on crowns and leaves of developing plants during fall, winter and spring
months. Armyworms generally feed on foliage in mid to late summer. Cutworms and
armyworms are more effectively controlled when they are small and immature. Control of
cutworms and armyworms is typically achieved by insecticides applied for sod webworm
control.
Chemical control
Chlorpyrifos (Lorsban 4E) – Chlorpyrifos is applied to 5- 10 percent of the grass seed acres at
a rate of 1 lb ai/acre, once per year.
Winter Grain Mite (Penthaleus major)
Winter grain mites do not reach economically damaging levels each year. In years when severe
infestations occur, the economic value of the grass crop can be reduced by 20-40 percent.
Winter grain mites are active throughout the year but are particularly numerous during warm
winter months.
Chemical control
Dimethoate (Dimethoate 400) – Dimethoate is applied to about 20 percent of grass seed acres at
a rate of 0.3 lb ai/acre once per year. In most instances, this application provides control of plant
bugs and thrips.
Weeds
Perennial, annual, grassy, and broadleaf weeds cause major problems in grass seed production.
Left uncontrolled, weeds would cause an economic loss of 50-80 percent to grass producers. In a
given year, about 30-50 percent of all grass seed acres is treated with a herbicide. Many of the
herbicides are used minimally, but are important to control specific weeds on specific grass
cultivars and grass species.
Weeds are best controlled post-harvest in the fall when fall moisture has stimulated weed
germination and growth. If fall moisture is sufficient, weeds can be controlled in the spring.
Crop residue removal by burning increases the effectiveness of fall-applied herbicides. Some of
the most serious weeds affecting grass seed production include bedstraw, wild oats, cheatgrass,
volunteer bluegrass, speedwell, quackgrass, windgrass, Canadian thistle, and escaped timothy.
Weeds, especially noxious weeds, compete with the grass crop and contaminate the harvested
grass seed. Only a few bedstraw seeds can lead to rejection of the entire seed lot since there is
zero tolerance for bedstraw seed in grass seed. Weeds require higher processing costs to reduce
the contamination to acceptable contract levels. Annual weeds such as wild oat, cheatgrass,
volunteer bluegrass, and windgrass, compete in newly established grass seed crops and limit
uniform grass establishment. At harvest, weeds interfere with threshing, reduce harvest
efficiency, and increase mechanical damage to the grass seed.
Chemical control
Dicamba (Banvel, Banvel SGF, Clarity) – Dicamba is applied to about 50-80 percent of all
grass seed acreage at a rate of 1.0 lb ai/acre, once per year. Dicamba is important in controlling
many broadleaf weeds not controlled by herbicides such as 2,4-D. Dicamba can be applied in
the fall to control broadleaf weeds and in the spring to control broadleaf and grassy weeds such
as cheatgrass.
Metribuzin (Sencor DF, Sencor 4F) – Metribuzin is applied to no less than 50 percent of the
grass seed acres for volunteer grass control at a rate of 0.3 lb ai/acre, once per year.
MSMA (Bueno 6) – MSMA is the only chemical that provides grassy weed control in new
bluegrass seedlings whenapplied at a rate of 0.75 lb ai/acre once per year.
Primisulfuron methyl (Beacon) – Primisulfuron is applied to about 20 percent of the bluegrass
seed crop at a rate of 0.5 oz ai/acre, once per year. Primisulfuron use has declined in the past
few years and is currently used to control quackgrass in newly established bluegrass crops.
2,4-D (several trade names) – 2,4-D is applied to 5-10 percent of the grass seed acres at a rate
of 0.4 lb ai/acre, once per year. 2,4-D provides cost effective control of many broadleaf weeds
and provides the option of spring or fall weed control.
MCPA (MCPA) – MCPA is applied to about 5 percent of the grass seed acres at a rate of 0.5 lb
ai/acre once per year. MCPA is especially useful for controlling broadleaf weeds in newly
established grass seed crops.
Difenzoquat (Avenge) – Difenzoquat is applied to about 5-10 percent of the grass seed acres at a
rate of 0.25 lb ai/acre, once per year. Difenzoquat is effective against wild oats and other grassy
weeds.
Bromoxynil (Buctril 4E) – Bromoxynil is applied to about 10 percent of the grass seed acres at
a rate of 0.4 lb ai/acre, once per year. Boromxynil is important because it can be applied anytime
after grass seed emergence to control small broadleaf weeds.
Fluazifop (Fusilade 2000) – Fluazifop is applied to about 10 percent of the fine-leaf fescue
grass crop once per year at a rate of 0.2 lb ai/acre. Fluazifop is the only herbicide available to
control grassy weeds such as quackgrass in fine-leaf fescue seed crops.
Imazamethabenz (Assert) – Imazamethabenz is applied to about 5-10 percent of the grass seed
acres at a rate of 0.45 lb ai/acre, once per year. Imazamethabenz is important in localized areas
where wild oat and grassy weeds are a problem.
Chlorpyralid + 2,4-D (Curtail) – Curtail is applied to about 5 percent of all grass seed acres at a
rate of 1 lb ai/acre, once per year. Metolachlor is a recent use and has replaced some dicamba
use for broadleaf weed control.
S-metolachlor (Dual Magnum) – Metolachlor is applied to 10-30 percent of the grass seed
acres at a rate of 1 lb ai/acre, once per year. Metolachlor is a recent use and has replaced some
dicamba use for broadleaf weed control.
Diuron (Karmex) – Diuron is applied to about 10 percent of the grass seed acres once per year.
Diuron is applied at a rate of 1 lb ai/acre in bluegrass and 2 lb ai/acre in fescue seed crops.
Diuron is important against annual grasses and broadleaf weeds in new and established grass
stands.
Glyphosate (Roundup) – Glyphosate is applied to about 5 percent of the grass seed acres as a
spot or wicking treatment to control various weeds. Glyphosate is applied at a rate of 4 lb ai in 5
gallons of water.
Fluroxypyr (Starane) – Fluroxypyr is a new product granted a section 24c in Idaho for
bedstraw control. Fluroxypyr is applied at a rate of 0.12 lb ai/acre, once per year. Growers are
currently evaluating the effectiveness of Fluoxypyr, and its use is expected to increase over the
next several years.
Diseases
Uncontrolled grass diseases can reduce the quality and yield of the crop by 20-100 percent and
cause problems in seed certification. In any given year, about 40-70 percent of grass seed
acreage receives a foliar fungicide treatment for disease control. Nearly all bluegrass seed grown
under irrigated conditions in southern Idaho require a fungicide application for disease control.
The cool, humid, and cloudy conditions in spring and later fall of northern Idaho, and irrigated
conditions in southern Idaho, favor development of leaf, stem and crown rust, powdery mildew,
ergot, silvertop, and leaf spot.
Silvertop (Fusarium poae)
This fungus is associated with silvertop but only after physical damage to the plant has been
done. Several insects including thrips, stem borers, and plant bugs cause physical damage and/or
inject plant toxins during feeding. Affected seed heads die and bleach white, appearing to
mature early, but do not set seed. Control of meadow plant bug and other insects with
insecticides may reduce the incidence of the disease. Burning fields after harvest has reduced the
incidence of this disease when caused by plant bugs. The elimination of postharvest residue by
open-field burning may increase the incidence of silvertop.
Stem rust (Puccinia graminis subsp. Graminicola)
Rust fungi infect susceptible grass cultivars and cause moderate to severe damage if left
uncontrolled. Fungi survive from season to season in infected foliage of most grasses and other
host plants. Stem rust attacks fine-leaf fescues, bluegrass, and several other grass species.
Moderately warm, moist weather conditions favor rust development. Dew for 10-12 hours also
is sufficient for the spores to infect grass plants.
Powdery mildew (Peronspora parasitica)
All grass species are susceptible to powdery mildew, but is more severe on Kentucky bluegrass,
wheatgrasses, and fescues. The casual fungus over-winters on infected plants and plant debris.
Spore are dislodged easily and spread by wind. Severely infected grass stands can be destroyed
by powdery mildew if left uncontrolled.
Leaf spot (Drechslera spp. and Bipolaris spp.)
Leaf spots of grass seed crops are caused by Drechslera spp. and Bipolaris spp. These two
species are the most common and serious cool season grass fungi in North America. Kentucky
bluegrass and fescues are most susceptible to leaf spot, which is favored by warm temperatures
(70 degrees F) and high humidity. Leaf spot typically develops from windborne spores. Signs of
infection are dark brown rot on grass crown and roots. Plants with crown infection are
weakened, and may die during hot, windy weather.
Ergot (Claviceps purpurea)
Ergot is particularly a problem in north Idaho bluegrass seed production. About 200 grass
species are hosts for ergot including bluegrass and fescue seed crops. Wild bluegrass plants are
highly susceptible and their presence near seed fields is an important source of inoculum. This
fungus over-winters on or near the soil surface and germinates in spring. The grass flower is the
only susceptible part to infection. The degree of infection and damage caused by ergot depends
on grass species and amount of inoculum present. Infected florets also secret plant sap called
honeydew, which is high in sugar content and attract insects that are efficient sources of spread.
Economic loss caused by ergot typically averages about 9 percent in bluegrass and fescue seed
crops. Most losses are related to additional costs to reclean infected seed, with some losses
relating to reduced seed set, increased sterility of neighboring spicklets, and reduced grass seed
weight. Additional costs of ergot contamination can occur through cost of disposal of infected
seed screenings. Standards for pure seed allow up to 1 percent by weight inert matter. Since
ergot is included as a component of inert, ergot levels greater than 1 percent do not meet purity
standards.
Chemical Control of Grass Diseases
Propiconazole (Tilt) – Tilt is applied to 50-60 percent of the grass seed crop once or twice per
year at an average rate of 4 oz/acre. Tilt offers protection against rusts, powdery mildew, and
other incidental diseases. Tilt is especially useful for early season rust control on north Idaho
bluegrass seed and irrigated bluegrass seed in southern Idaho.
Triadimefon (Bayleton) – Bayleton is applied to 20-30 percent of the grass seed acres at a rate
of 6 oz/acre once per year. Bayleton controls a spectrum of diseases including powdery mildew
and rusts. Bayleton is absorbed and works systemically within the grass plant.
Tebuconazole (Folicur) – Folicur is applied to about 10 percent of the grass seed crop at a rate
of 0.19 lb ai/acre once per year. Folicur controls rusts, powdery mildew, ergot, and other
incidental diseases.
Azoxystrobin (Quadris) – Azoxystrobin is an experimental fungicide that may be more
effective in rust control than the above fungicides.
Prepared by:
Samuel Fuchs, Extension Support Scientist I.
University of Idaho, Moscow, Idaho.
References
Bateman, S., and J. Henderson. 2000. Personal communication. Jacklin Seed Co. Nez Perce,
Idaho.
Johnston, W. J., Golob, O. T., and J. W. Sitton. 1997. Control of ergot in Kentucky bluegrass
seed field using Tilt 3.6 E and Sylgard 309. Fungicide and Nematicide Tests 52:385.
Johnston, W. J., and J. Sitton. 1997. Diseases in dryland and irrigated cropping systems without
grass burning. GSCSSA Prog. Rep. WSU, OSU, U of I, USDA.
Pacific Northwest Insect Management Handbook. 2000.
Pacific Northwest Weed Management Handbook. 2000.
Pacific Northwest Disease Management Handbook. 2000.
Pfender, W., and R. R. Burr. 1998. Comparison of fungicides and initial spray dates in control of
stem rust on perennial ryegrass grown for seed. A.P.A. Fungicide and Nematicide Tests 53:471.
Sitton, L. W., Bragg, J., and C. T. Golob. 2000. Investigations into insect vectoring of Fusarium
Poae in Bluegrass seed crops. 59th Annual Pacific Northwest Insect Management Conference.
Imperial Hotel, Portland, Oregon.
Smathers, R. 1997. Bluegrass seed establishment: irrigated. Crop Budget Enterprise. EBBI-BEI97. Coll. of Ag., University of Idaho, Moscow, Idaho.
Smathers, R. 1997. Bluegrass Seed Production. Crop Budget Enterprise. EBBI-BS-97. Coll. of
Ag., University of Idaho, Moscow, Idaho.
Smathers, R. 1997. Bluegrass Seed Production. Irrigated. Crop Budget Enterprise. EBBI-BSI-97.
Coll. of Ag., University of Idaho, Moscow, Idaho.
Wiese, M. 2000. Personal Communication. Professor Plant Pathology. University of Idaho,
Moscow, Idaho.