Asparagus

Asparagus Evonne Gong Wed, 05/15/2024 - 15:02

Asparagus Disease Control Asparagus Insect Control Asparagus Weed Control

Introduction

Asparagus (Asparagus officinalis) is a perennial crop in the lily family. It originated near the Mediterranean and has been used as an agricultural crop since the time of the ancient Greeks. Asparagus beds usually produce well for 10-15 years, so choose a site with that in mind. Avoid areas where this tall crop could shade other crops. Select soils that are deep and well-drained, such as sandy loams or well-drained loams. However, the water table should not be more than four feet below the surface. The site should not have been planted with asparagus for a long period, preferably never. This is to minimize asparagus crown rot (Fusarium moniliforme) which can survive for a long time in the soil even without a host. Land cropped to corn within three years should also be avoided since some strains of F. moniliforme can also infect corn. Avoid areas subject to late spring frosts as emerging spears are easily injured. Site preparation should begin at least one year prior to planting in order to properly adjust soil pH, fertility, and eliminate serious perennial weed problems.

Types and Varieties

All-male hybrids that are tolerant to crown or root rot caused by Fusarium species should be grown. The varieties listed here are also tolerant to rust. 'Mary Washington' and some other old varieties are still available, but are half male and half female plants, making them highly susceptible to crown rot, and are less productive than all-male hybrids. Male plants do not expend energy producing seed and are thus more vigorous than female plants. Also, the lack of seed precludes the growth of nuisance seedlings which are not productive and act as weeds.

Asparagus Varieties:

Millennium
Purple Passion (purple)

Soil Fertility

The year before planting, adjust the pH and build fertility in the soil based on soil testing results (see Table below). Asparagus does not tolerate acid soils. Apply lime to maintain soil pH at 6.8-7.0. This may require yearly applications of lime. For new beds, deeply incorporate lime to ensure proper pH at crown depth.

Asparagus is planted fairly deeply and the roots are known to penetrate deeper than six feet. Since there is little downward movement of phosphorus in the soil, it is important to get phosphorus into the root zone before planting. Till deeply and mix fertilizer material well into the deep root zone.

Less nitrogen fertilizer will be needed if legume sod was plowed down or if manure was applied (see Table 1 and Table 7 ). The second year after planting, the asparagus should receive fertilizer in the early spring and late summer. In subsequent years the bed should be fertilized after each harvest season. Base fertilizer rates on soil test results.

Asparagus has moderate requirements for boron. For soils low in boron, apply 1-2 lbs per acre of actual boron every three years to asparagus plantings.

Plant nutrition recommendation according to soil test results for asparagus

SOIL TEST RESULTS	NITROGEN (N) - LBS PER ACRE	PHOSPHORUS (P) - LBS P₂O₅ PER ACRE				POTASSIUM (K) - LBS K₂O PER ACRE
SOIL TEST RESULTS	NITROGEN (N) - LBS PER ACRE	VERY LOW	LOW	OPTIMUM	ABOVE OPTIMUM	VERY LOW	LOW	OPTIMUM	ABOVE OPTIMUM
NEW ASPARAGUS BEDS
Broadcast and incorporate	50	150	90	30	0	200	150	75	0
In bottom of furrow at planting	0	30	30	30	30	0	0	0	0
TOTAL RECOMMENDED	50	180	120	60	30	200	150	75	0
ESTABLISHED HYBRID ASPARAGUS BEDS
Broadcast after cutting season	75	150	90	30-60	0	300	150	75	0
TOTAL RECOMMENDED	75	150	90	30-60	0	300	150	75	0
ESTABLISHED NON-HYBRID ASPARABUS BEDS
Broadcast after cutting season	50	150	90	30-60	0	200	100	50	0
TOTAL RECOMMENDED	50	150	90	30-60	0	200	100	50	0

Planting

Crowns. Plant healthy one-year-old crowns in raised beds at the bottom of 8-in. deep furrows. Be sure the bud is facing up and roots are spread out. Space crowns 12" apart in rows 54-60" apart. Closer spacing produces higher yields in early years, but thinner spears in older beds. This will require 8,712-9,680 crowns per acre or 100 crowns per 100 row-feet. This spacing is for hybrids and is somewhat greater than was recommended for less vigorous non-hybrids. Cover with 2" of soil. During the rest of the season the furrow should be filled in bit by bit, without covering the asparagus foliage.

Transplants. Fields can also be planted with 8- to 12-week-old asparagus seedlings after the danger of frost has passed. Plant spacing is the same as for crowns. Care must be taken in order to prevent the small young ferns from being smothered by soil, especially after heavy spring showers. To accommodate the growth pattern of asparagus roots, use trays with straight, non-foam, non-tapering cells measuring 2"x2"x3". Use a sterilized medium consisting of half sand and half peat or use a commercial seed starting mix. Seed germination will take at least three weeks and the soil must be kept uniformly moist during this time. Young seedlings should be fed with quarter- or half-strength soluble fertilizer solution once each week or as needed. The nitrogen in this fertilizer should be in the nitrate form because young seedlings are sensitive to ammonium sources of nitrogen. The seedlings should be grown in the greenhouse for 6-8 weeks followed by two weeks of hardening off, prior to planting after the danger of frost has passed.

Field Culture

It is essential to maintain healthy fern growth during the first two growing seasons. Weed control is easily accomplished by slowly filling in the trenches over the course of the first season. These cultivations can be timed with flushes of weeds. Be sure ferns are not covered. During the second year the beds must be kept weed-free, especially during late summer and fall. Weed competition late in the season will restrict crown growth. Close attention must be given to insects and diseases that attack young ferns. As ferns become vigorous and full, diseases can cause the ferns to die prematurely, especially in late summer and early fall during periods of humid weather. Fungicides should be applied to control this foliage decline.

Mow brush in early spring before spear emergence followed by shallow discing, no deeper than 2-3 in. in order to prevent crown injury. Some growers remove ferns in the late fall or burn the ferns during the winter. This can destroy rust and purple spot inoculum and reduce harboring sites for insects such as asparagus beetles. Beds can also be disced immediately after harvest to control weeds prior to herbicide application.

Harvest and Storage

Spears may be harvested two times at the beginning of the second season. The harvest season is increased one to two weeks in subsequent years and should be six to eight weeks in mature beds, depending on plant health during the previous summer and fall. If spears are predominantly small in diameter, harvest should be stopped. Overcutting causes rapid decline in bed vigor. Spears can be snapped or cut at or below the soil surface. Avoid injury to newly emerging spears.

Once spears have been bunched and trimmed, they should be placed upright in shallow trays of water and kept cool. Ideally, they should be refrigerated at 32-36ºF and 95-99% relative humidity in order to maintain sugar content and tenderness. Storage life under ideal conditions is 14-21 days. Asparagus has a very high respiration rate and benefits from misting when on display.

Mother Stalk Harvest Method (trial only). In Japan and China, harvest throughout the summer is common. In this method, spring harvest is carried out for two weeks, after which three or four strong spears are left to grow into full ferns. From this point, newly emerging spears can be harvested throughout the season into early fall. Spear production is influenced by soil temperature and nutrient availability. Fertigation is usually practiced with this method. Plants have been shown to have similar longevity as those harvested in the spring only.

Asparagus Disease Control

Asparagus Disease Control Evonne Gong Wed, 05/15/2024 - 15:10

Asparagus - General Asparagus Insect Control Asparagus Weed Control

NOTES: For the disease control products listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same active ingredient. Please see Table 26 and Fungicides and Bactericides Alphabetically Listed by Trade Name for more information on products with the same active ingredients.

The symbol ^OGindicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more details.

Crown Rot (Fusarium species)

Vigorously growing plants are less susceptible to crown rot. Buy top quality crowns. Use new land or land where asparagus has not been grown for 10 years. Use tolerant varieties.

Rust (Puccinia asparagi)

Rust disease attacks fern foliage and can spread rapidly, affecting production in subsequent years. Fern residues should be removed and destroyed prior to spear emergence in the spring. Control volunteer asparagus plants that might be infected. Resistant cultivars are not available. Apply fungicides after spear harvest is complete.

Bacillus amyloliquefaciens strain D747 (DoubleNickel 55^OG): 0.25 to 3.0 lb/A; PHI 0d, REI 4h, Group BM02. Disease suppression only. For improved control, mix or rotate with a chemical fungicide.
chlorothalonil (Bravo Weather Stik): 2.0 to 4.0 pt/A; PHI 190d, REI 12h, Group M05. Do not apply within 190 days of the harvest of spears in the following season.
copper (Badge SC): 1.0 to 2.5 pt./A; PHI 0d, REI 48h, Group M01. For suppression. Tank mix with other products registered for rust control. Addition of sticker/spreader recommended.
laminarim (Vacciplant): 14.0 to 22.0 fl oz/A; PHI od, REI 4h, Group P04. See label for application methods and restrictions.
mancozeb (Dithane F45): 2.0 qt/A; PHI 180d, REI 24h, Group M03. Begin applications after spears have been harvested.
mancozeb plus azoxystrobin (Dexter Max): 2.0 to 2.2 lb./A; PHI 180d, REI 24h, Group M03 &11. Begin applications after spears have been harvested. Alternate with fungicides outside of Group 11.
myclobutanil (Rally 40 WSP): 5.0 oz/A; PHI 180d, REI 24h, Group 3. Begin applications after spears have been harvested. Observe a 30-day plant-back interval between the last application and planting new crops at the treatment site.
sulfur (Microthiol Disperss^OG): 10.0 to 30.0 lb/A; PHI 0d, REI 24h, Group M02. Apply to ferns after cutting.
tebuconazole (Monsoon): 4.0 to 6.0 fl oz/A; PHI 180d, REI 12h, Group 3. Begin applications after spears have been harvested. Do not make more than 3 foliar applications per year.
thyme oil (Guarda): See label for rate; PHI 0h, REI 0h, Group NC. See label for application methods and rates. Ensure thorough coverage to the point of runoff ( 15-25 gallons per acre).

Disease Control

Asparagus Insect Control

Asparagus Insect Control Evonne Gong Wed, 05/15/2024 - 15:15

Asparagus - General Asparagus Disease Control Asparagus Weed Control

NOTES: For the insecticides listed below, one product trade name and formulation is provided for each active ingredient (AI) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same AI. Please see Table 27 and Insecticides Alphabetically Listed by Trade Name for more information on these insecticides.

The symbol * indicates a product is a restricted use pesticide. See Pesticide Safety for more details.

The symbol ^OG indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more details.

Asparagus Aphids (Brachycorynella asparagi)

Asparagus aphids are small (1.6-2 mm), oval, green to gray aphids that may be covered in a waxy secretion. They overwinter as eggs on asparagus residue in the field. Eggs hatch in spring and nymphs and adults feed on spears, then on ferns. During the summer, wingless females produce live young (nymphs) which develop into reproductive females in 8-10 days. Populations can build up rapidly especially in hot, dry weather. Aphids feed on new growth and cause shortening of internodes, rosetting, or ‘witches broom’ appearance of the foliage. High aphid populations reduce root growth and plant vigor and may kill seedlings. Younger plantings are most vulnerable, especially 2- or 3-year-old plantings that are not being harvested. Cold winters and aphid infestation have a synergistic effect on plant health, greater than either factor alone. Asparagus aphids can also vector viruses, including asparagus virus I and II (AV-I and AV-II) and tobacco streak virus (TSV). During harvest, monitor any plantings that are not being harvested. After harvest, scout ferns for signs of feeding injury and aphid colonies, especially in the basal regions of the plant. Cultural controls include harvesting spears in spring, because only volunteer plants and young plantings that are not harvested will allow aphids to survive and multiply. Remove dead ferns during the fall or winter, and control between-row volunteers through spring tillage or herbicides. Natural biocontrol is provided by insect predators such as lady beetles, lacewings, predatory midges, and syrphid fly larvae, by the parasitic braconid wasp, Diaeretiella rapea, and by a fungal pathogen that is more active in humid climates. Treat ferns when populations are low, if 5% of ferns show injury. Conserve beneficials by using a selective product. Scout again in 5-7 days to determine if further treatment is needed.

acetamiprid (Assail 30SG): 2.5 to 5.3 oz/A; PHI 1d, REI 12h, Bee: M, Group 4A.
dimethoate (Dimethoate 4EC): 1 pt/A; PHI 180d, REI 48h, Bee: H, Group 1B. Apply after last harvest. Systemic.
insecticidal soap (M-Pede^OG): 1.25 to 2.5 oz/gal water; PHI 0d, REI 12h, Bee: L. Spray to wet all infested plant surfaces. Apply with companion insecticide.
malathion (Malathion 57EC): 1.5 to 2 pt/A; PHI 1d, REI 12h, Bee: H, Group 1B.
petroleum oil (Suffoil X^OG): 1 to 2 gal/100 gal water; PHI 0d, REI 4h, Bee: L. Apply as needed.
pymetrozine (Fulfill): 2.75 oz/A; PHI 170d, REI 12h, Bee: L, Group 9B. Apply to ferns after harvest, and before populations build to damaging levels. Allow a minimum of 30 days between applications.
pyrethrin (PyGanic EC5.0^OG): 4.5 to 17 oz/A; 0.25 to 0.50 oz/gal; PHI 0d, REI 12h, Bee: M, Group 3A.

Asparagus Miner (Opbiomyia simplex)

This fly was introduced to North America from Europe and is present wherever asparagus is grown. It feeds only on asparagus, and is found primarily on older stalks bearing ferns. The adult fly is shiny black, 3-4 mm long, with clear wings. Larvae are whitish, legless, tapered at both ends, with black mouth hooks at one end. Pupation takes place in the larval mine on the stalk. Overwintering puparia are usually in mines near or below ground level. There are 2 generations per year. Adults emerge in May and lay eggs underneath the epidermis of stems, usually near the base of the plant. Larvae feed in June, pupate inside their larval mines, and a second generation of adults emerges and lays eggs in late July or early August. Second generation larvae feed through August and pupate in the fall, overwintering until the following spring. Larvae feed just beneath the surface of the stem, burrowing upwards or downwards and forming mines. While direct feeding damage can girdle stems if there are several mines per stalk, the effect of miners on yield is usually minimal and the injury is largely cosmetic. The most important injury from asparagus miner is due to its association with Fusarium spp. and its ability to vector this pathogen into the plant through feeding wounds. Cultural practices to reduce damage from asparagus miner include removing overwintering stalks and destroying wild asparagus in the vicinity of commercial plantings. Select varieties that are resistant to Fusarium to reduce disease.

acetamiprid (Assail 30SG): 5.3 oz/A; PHI 1d, REI 12h, Bee: M, Group 4A. Suppression only.

Cutworms

Caterpillars hide under the soil surface adjacent to the plant stem during the day and feed after dark. Crooks (misshaped spears) are often caused by cutworms injuring tips at or just below the soil surface or feeding on the sides of young spears. For best results, make pesticide applications between midnight and dawn while cutworms are feeding above ground. Synthetic pyrethroids (group 3A) may work best during cool weather in May. See cutworms in the Pepper and Tomato (Outdoor) sections for more information on the black and variegated cutworms.

carbaryl (Sevin XLR PLUS): 1 qt/A prior to fern growth, 2 qt/A on ferns; PHI 1d, REI 12h, Bee: H, Group 1A.
Chromobacterium subtsugae strain PRAA4-1 (Grandevo^OG): 2 to 3 lb/A; PHI 0d, REI 4h, Bee: M. Group UN.
methomyl (Lannate* LV): 1.5 to 3 pt/A, 1.5 pt/A for variegated cutworm; PHI 1d, REI 48h, Bee: H, Group 1A.
permethrin (Pounce* 25WP): 3.2 to 6.4 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A.
spinosad (Seduce^OG): 20 to 44 lb/A or 0.5 to 1 lb/1000 sq ft; PHI 60d, REI 4h, Bee: M, Group 5. Scatter bait on soil around plants. For postharvest protection of ferns only.

Asparagus Beetles and Japanese Beetle

The common asparagus beetle (Crioceris duodecimpunctata) and spotted asparagus beetle (Crioceris asparagi) overwinter as adults in protected areas along fields, feed and lay eggs in the crop, pupate in the soil, and have 2 or sometimes 3 generations per year. Both species are less than 3/8" long. The common asparagus beetle (CAB) has a bluish-black body with cream-colored, square or rectangular spots, while the spotted asparagus beetle (SAB) is tan to orange with 12 round, black spots. Eggs of CAB are dark brown, laid standing on end in rows along the spears, with 3-10 in each cluster. During harvest, adult feeding by CAB on spears or the presence of CAB eggs can render the crop unmarketable. CAB larvae have 4 instars and are wrinkled, plump, hump-backed, and dull gray or brown with black head and legs. CAB larvae may cause severe defoliation of ferns and decline of the planting. SAB larvae are yellow or orange and feed only on berries. During harvest, scout for adults and eggs on sunny afternoons. Treat spears if >10% of the plants are infested with beetles or 1-2% have eggs or damage. Scout ferns for all life stages of both pests and treat if 50-75% are infested. If possible, spot spray along edges of planting where overwintering adults colonize the field and/or band insecticide over the row to help conserve natural enemies. Use selective insecticides on ferns. During harvest, snap or cut spears close to the soil surface daily and eliminate volunteer plants or treat them with an insecticide to use them as a trap crop. Disk old ferns lightly in the fall and clean areas around planting of debris to reduce overwintering populations. Eliminating female plants, and thus berries, can reduce or eliminate SAB populations. Japanese beetles may feed in ferns in mid-summer.

acetamiprid (Assail 30SG): 2.5 to 5.3 oz/A for asparagus beetle, 5.3 oz/A for Japanese beetle; PHI 1d, REI 12h, Bee: M, Group 4A.
carbaryl (Sevin XLR PLUS): 1 qt/A prior to fern growth, 2 qt/A on ferns; PHI 1d, REI 12h, Bee: H, Group 1A.
dimethoate (Dimethoate 4EC): 1 pt/A; PHI 180d, REI 48h, Bee: H, Group 1B. Asparagus beetle only. Apply after last harvest.
kaolin (Surround WP^OG): 12.5 to 25 lb/A or 25 to 50 lbs/100 gal water; PHI 0d, REI 4h, Bee: L. Suppression and repellence only. Product residue may need to be washed off if applied to spears during harvest. Generally compatible as a tank mix with other insecticides.
malathion (Malathion 57EC): 1.5 to 2 pt/A; PHI 1d, REI 12h, Bee: H, Group 1B.
methomyl (Lannate* LV): 1.5 to 3 pt/A; PHI 1d, REI 48h, Bee: H, Group 1A. Asparagus beetle only.
permethrin (Pounce* 25WP): 3.2 to 6.4 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A. For Japanese beetle control, use high rate.
petroleum oil (Suffoil X^OG): 1 to 2 gal/100 gal water; PHI 0d, REI 4h, Bee: L. For beetle larvae only. Apply as needed.
pyrethrin (PyGanic EC5.0^OG): 4.5 to 17 oz/A, 0.25 to 0.50 oz/gal; PHI 0d, REI 12h, Bee: M, Group 3A.
spinetoram (Radiant SC): 4 to 8 oz/A; PHI 60h, REI 4h, Bee: M, Group 5. Postharvest protection of ferns from asparagus beetle only.
spinosad (Entrust SC^OG): 4 to 6 oz/A; PHI 60d, REI 4h, Bee: M, Group 5. Postharvest protection of ferns from asparagus beetle only.

Insect Control

Asparagus Weed Control

Asparagus Weed Control Evonne Gong Wed, 05/15/2024 - 15:17

Asparagus - General Asparagus Disease Control Asparagus - Insect Control

NOTES: For the herbicides listed below, one product trade name and formulation is provided for each active ingredient as an example of rates, preharvest interval (PHI), restricted entry interval (REI), resistance management group number, and special instructions. In many cases, there are other products available with the same active ingredient. However, not all products with the same active ingredient are registered for use in a crop. Always check the product label to be sure that the crop is listed before using.

Grass Weed Control - New plantings and established beds

clethodim (Select Max): PHI 1d, REI 24h, Group 1. Apply 9-16 oz/A per application, multiple applications are allowed, a minimum of 14 days apart. Do not exceed 64 oz/A per year. Apply to actively growing grasses. Add 1 qt nonionic surfactant per 100 gal of spray (0.25% v:v). Can also be applied as a spot-spray by mixing 1/3-2/3% (0.44-0.85 oz/gal) Select Max and 0.25% v:v nonionic surfactant (0.33 oz/gal). Spray to wet, but do not allow runoff of spray solution.
fluazifop (Fusilade DX): PHI 1yr for high max rate or 1d for low max rate, REI 12h, Group 1. Apply 16-24 oz/A per application, multiple applications are allowed, a minimum of 14 days apart. Do not exceed 48 oz/A per year if harvesting this year or 72 oz/A per year if harvesting next year. Apply to actively growing grasses. Add either crop oil concentrate (0.5-1%, 0.5-1 gal per 100 gal of spray) or nonionic surfactant (0.25-0.5%, 1-2 qts per 100 gal of spray).
sethoxydim (Poast): PHI 1d, REI 12h, Group 1. Apply up to 2.5 pt/A per application, multiple applications are allowed, a minimum of 14 days between applications. Do not exceed 5 pt/A per year. Apply to actively growing grasses. Use with crop oil concentrate (2 pt/A) or methylated seed oil (1.5 pt/A). Note that crop oil can cause injury under hot and humid conditions. Can also be used as a spot-spray by mixing 1-1.5% (1.3-1.9 oz/gal) Poast and 1% v:v crop oil concentrate (1.3 oz/gal). Spray to wet, but do not allow runoff of spray solution.

New Plantings

diquat (Reglone): PHI 1yr, REI 24h, Group 22. Apply 1.5-2 pt/A per application. Only use during site preparation prior to planting. Spray weeds 1-6” tall; retreatment may be necessary to control established weeds. Apply in a minimum of 15 gal/A of spray. Do not allow spray to contact crop stems, foliage, or fruit.
glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9. Apply 10 oz to 3.1 qts/A per application. Do not exceed 5 qts/A per year. Rate depends on target weeds, see label for rate selection. Avoid contact with any part of the asparagus or crop death could occur. May apply during fallow intervals, prior to crop planting, at planting, before crop has emerged, or immediately after cutting before spears have emerged.
linuron (Lorox DF): PHI 1d, REI 24h or 8d, Group 5. For pre- and postemergence control of many annual broadleaf weeds. For preemergence, apply 1-4 lbs/A after applying activated charcoal in a 1” wide band above seeds or crowns. For postemergence weed control, apply 1-2 lbs/A per application, up to 2 applications. Do not exceed 4 lbs/A per year. Spray when ferns are more than 6” tall and weeds are less than 4” tall. Use the lower rate on sandy soils and the higher rate on silt and clay soils.
paraquat (Gramoxone SL 2.0*): PHI 6d, REI 12h or 24h, Group 22. Apply 1.7-2.7 pt/A per application, only 1 application allowed per year. Can be applied before planting or as a stale seedbed application in a minimum of 10 gal/A of spray. May be fatal if swallowed or inhaled. Restricted-use: Applicators must complete an EPA-approved paraquat training every 3 years: https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. Apply a 3-10% solution (3-10 gallons per 100 gallons of spray). Apply in 75-200 gal/A of spray. Can be applied preplant, or as a directed and shielded spray during crop growth. Avoid contact with foliage or crop damage may occur. Spray to wet, but do not allow runoff of spray solution.
pendimethalin (Prowl H2O): PHI 14d, REI 24h, Group 3. Apply 8.2 pt/A, only 1 application allowed per year. Can be applied to newly planted crowns but NOT to a newly seeded crop. When applying to newly planted crown asparagus, ensure crowns are fully covered with 2-4” of soil. Do not apply over the top of emerged spears or injury will occur. On sandy soils do not use more than 2.4 pt/A. Apply uniformly to the soil surface, cultivate or use Gramoxone to control emerged weeds.
terbacil (Sinbar WDG): PHI 5d, REI 12h, Group 5. Apply 1-2 lbs/A per application, multiple applications are allowed. Do not exceed 2.5 lbs/A per year. Direct seed asparagus 1.5-1” deep, then apply activated charcoal in a 1” wide band above seeds or crowns and then apply Sinbar WDG. Use a lower rate on sandy soils.
trifluralin (Treflan HFP): REI 12h, Group 3. Apply 1-4 pts/A per application, multiple applications allowed. Do not exceed 4 pts/A per year. Apply prior to planting or immediately after planting seed and prior to crop germination. Can also apply and incorporated at or before the last cultivation. Rate depends on soil texture and percent organic matter. Incorporate within 24 hours of application and a second time in the opposite direction for best results. Take care not to bring untreated soil to the soil surface during re-incorporation.

Established Beds – Before spear emergence or after harvest season

carfentrazone-ethyl (Aim EC): PHI 5d, REI 12h, Group 14. Apply 0.5-2 oz/A per application, 2 applications allowed per year, a minimum of 20 days apart. Do not exceed 3.8 oz/A per year. Apply as a hooded application, or as a broadcast application after harvest to control broadleaf weeds and existing asparagus tissue.
clomazone (Command 3ME): PHI 14d, REI 12h, Group 13. Apply 42.7 oz/A, only 1 application allowed per year. Apply prior to spear and weed emergence or after a clean harvest in at least 10 gal of spray per acre. All asparagus plant parts must be covered with soil prior to application to prevent injury.
diuron (Diuron 4L): REI 12h, Group 5. Apply 0.8-3.2 qts/A if 1 application is made or apply 0.8-2.4qts/A per application if 2 applications are made. Do not exceed 4.8 qts/A per year. Use the lower rate on sandy soils and the higher rate on silt and clay soils. Can be applied before weeds become established but no earlier than 4 weeks before spear emergence and no later than the early cutting period. A second application can be applied immediately following the final harvest if rainfall is expected.
flumioxazin (Chateau SW): REI 12h, Group 14. Apply 6 oz/A per application, only 1 application allowed per year. Must be applied to dormant asparagus postharvest, at least 2 weeks before spear emergence. If soil has been disturbed within 60 days prior to application or if asparagus is not dormant, crop injury may occur. Must be sprinkler or rainfall incorporated (0.5 to 0.75” of water). Can be tank-mixed with Gramoxone for burndown of emerged weeds.
linuron (Lorox DF): PHI 1d, REI 24h, Group 5. For pre- and postemergence control of many annual broadleaf weeds. Before spears emerge, apply 1-4 lbs/A per application. Do not exceed 4 lbs/A per year, (including applications after spear emergence). Use the lower rate on sandy soils and the higher rate on silt and clay soils.
mesotrione (Callisto): REI 12h, Group 27. Apply 3 to 7.7 oz/A per application, a maximum of 2 applications allowed per year, a minimum of 14 days between applications. Do not exceed 7.7 oz/A per year. Can be applied in the spring prior to spear emergence, or after harvest, or both. When using Callisto after harvest, till the field or tank-mix with Gramoxone to eliminate emerged spears or crop injury may be observed. Callisto provides excellent control of horseweed (also called marestail) and common lambsquarters. Add 1% crop oil concentrate (1 gal per 100 gal of spray solution) or 0.25% nonionic surfactant (1 qt/100 gal of spray solution) if target weeds are emerged at the time of application.
metribuzin (Metribuzin 75): PHI 14d, REI 12h, Group 5. Apply 1.3 to 2.6 lb/A in the spring as a single application or apply 0.6 to 1.3 lbs/A in the spring and 1.3 to 2.0 lbs/A after harvest but before fern emergence as a split application. Do not exceed 2.6 lbs/A per year. Do not apply to established beds after emergence.
napropamide (Devrinol 2-XT): REI 24h, Group 0. Apply up to 2 gal/A, only 1 application allowed per year. Apply to a weed-free soil surface. Incorporate with 2-4” of water through irrigation or rainfall within 24 hours of application.
norflurazon (Solicam DF): PHI 14d, REI 12h, Group 12. Apply 2.5 to 5 lb/A, multiple applications per year are allowed, but maximum rate per year is based on soil texture. Incorporate and activate with water through irrigation or rainfall within 4 weeks of application. Apply as a directed spray to the soil.
paraquat (Gramoxone SL 2.0*): PHI 6d, REI 12h, Group 22. Apply 1.7 to 2.7 pts/A, only 1 application allowed per year. Apply prior to emergence of crop; asparagus plants that have emerged at time of application will be killed. May be fatal if swallowed or inhaled. Restricted-use: Applicators must complete an EPA-approved paraquat training every 3 years: https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training....
pendimethalin (Prowl H2O): PHI 14d, REI 24h, Group 3. Apply 8.2 pt/A, only 1 application allowed per year. On sandy soils do not use more than 2.4 pt/A per year. Apply before spear emergence or after harvest. Do not apply over the top of emerged spears or injury will occur. Apply uniformly to the soil surface, cultivate or use Gramoxone to control emerged weeds.
quinclorac (Quinstar 4L): REI 12h, Group 4. Apply up to 12.6 oz/A per application, only 1 application allowed per year. Apply to the soil after the last harvest, before the first frost. Can add a crop oil concentrate. Apply in a minimum of 10 gal/A of spray. Do not apply when crops are stressed.
sulfentrazone (Aquesta 4F): REI 12h, Group 14. Apply 4.5-12 oz/A per application, only 1 application allowed per year. Rate based on soil texture, organic matter and soil pH. Apply to the soil in the spring, before spears have emerged in 10-40 gal/A of spray. Do not use on soils that have less than 1% organic matter.
terbacil (Sinbar WDG): PHI 5d, REI 12h, Group 5. Apply 1 to 1.5 lbs/A per application, multiple applications are allowed. Do not exceed 2.5 lbs/A per year. Apply after a clean cutting or after the last harvest, prior to spear emergence. Use a lower rate on coarse-textured soils. Do not apply if roots are exposed or if the planting is weak.
trifluralin (Treflan HFP): REI 12h, Group 3. Apply 1 to 4 pts/A per application, multiple applications allowed. Do not exceed 4 pts/A per year. Apply as a single or split application to dormant asparagus in winter or early spring after mature ferns have been removed. Do not apply immediately after harvest in late spring/early summer just before ferns develop. Rate depends on soil texture and percent organic matter. Incorporate within 24 hours of application and a second time in the opposite direction for best results. Take care not to bring untreated soil to the soil surface during re-incorporation.

Established Beds - Postemergence, after weeds germinate

2,4-D sodium salt (Amine 4): PHI 3d, REI 48h, Group 4. Apply 3-4 pt/A per application, up to 2 applications allowed per season, a minimum of 1 month apart. Do not exceed 4.2 pts/A per year. Apply in 50-60 gal/A of spray in the spring. Keep spray off spears and ferns by using drop nozzles. Cut and discard any malformed spears immediately. 2,4-D is hazardous to most horticultural crops. Drift or sprays may seriously injure or reduce yields of these crops. May help to control unwanted seedling asparagus.
clopyralid (Clean Slate): PHI 48h, REI 12h, Group 4. Apply 0.5-0.67 pts/A per application, up to 2 applications allowed per year. Do not exceed 0.67 pts/A per year. Apply before or during the asparagus cutting season or after the final harvest but before fern growth. Following application, wait at least 2 weeks before cultivating. Layby applications should be made as soon as possible after cutting as long as weeds are at the proper stage of growth. Malformed ferns may result from application when spears are more than 3" tall or with open seed heads. When this product is applied during the cutting season, some crooking (twisting) of asparagus spears may occur. Do not apply during the cutting season if crooking cannot be tolerated. Clear-cutting of spears just before applying this product may reduce the occurrence of crooking.
dicamba (Clarity): PHI 24h, REI 24h, Group 4. Apply 8 to 16 fl oz/A per application, multiple applications allowed. Do not exceed 16 fl oz/A per year. Apply to emerged and actively growing weeds immediately after cutting field but at least 24 hrs before next cutting. If spray contacts emerged spears, crooking (twisting) of some spears may result. If crooking occurs, discard affected spears.
glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9. Apply 10 fl oz to 3.1 qts/A per application. Do not exceed 5 qts/A per year. Apply to emerged weeds well before spear emergence in the spring or after cutting season when all spears and ferns have been removed (clean cut). Avoid contact with any part of the asparagus or crop death could occur. Rate depends on target weeds, see label for rate selection.
halosulfuron (Sandea): PHI 1d, REI 12h, Group 2. Apply 0.5 to 1.5 oz/A per application, up to 2 applications allowed per season. Do not exceed 2 oz/A per year. For us in transplanted crowns and established beds only. For transplanted crowns, apply no sooner than 6 weeks after fern emergence. For established beds, apply before, during, or at the end of harvesting season. May cause temporary stunting or twisting of ferns on certain varieties. Crop injury will decrease and weed control will improve when applied with a drop nozzel as a directed spray below the ferns. If targeting nutsedge, split applications during and after harvest are recommended. Use 0.75-1 oz per acre for each application at least 21-30 days apart, when nutsedge is targeted. Weed control may be reduced without the use of a surfactant.
linuron (Lorox DF): PHI 1d, REI 24h, Group 5. For pre- and postemergence control of many annual broadleaf weeds. For postemergence weed control, apply 1-2 lbs/A per application, up to 3 applications, or 1 application of 4 lbs/A at the fern stage as a directed spray. Do not exceed 4 lbs/A per year (including applications before spear emergence). Spray when ferns are more than 6” tall and weeds are less than 4” tall. Use the lower rate on sandy soils low in organic matter, and the higher rate on silt and clay soils.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. PHI 1d, REI 12h, Group 0. Apply a 3-10% solution (3-10 gallons per 100 gallons of spray). Apply in 75-200 gal/A of spray. Can use before planting, or as a directed and shielded spray during crop growth. Avoid contact with foliage or crop damage may occur. Spray to wet, but do not allow runoff of spray solution.
s-metolachlor (Dual Magnum): REI 24h, Group 15. MA, ME, and NH only. Make sure the label for your state is available for download before using this product. This is a restricted label available only to growers who apply through the website www.syngenta-us.com/labels/indemnified-label-login and agree to a waiver of liability. Main target weeds for this registration are galinsoga and yellow nutsedge. All label instructions will be supplied after the application for use is completed.

There is limited local data available for quinclorac (Quinstar), carfentrazone (Aim), sulfentrazone (Aquesta), and diquat (Reglone). There may be potential crop injury concerns with use of these products in our region.

Weed Control