From: Brian Lo <dragon@csulb.edu>
Newsgroups: rec.gardens
Subject: FAQ: Spinach
Date: Wed, 1 Mar 1995 09:10:09 -0800
SPINACH
Spinacia oleracea
GENERAL
The use of proper varieties is especially important. Slow growing, slow
bolting (slow premature seed-stalk development) varieties are used for late
spring and summer harvest, while fast growing (those also tend to be fast
bolting) vigorous varieties should be used for fall, winter and early spring
harvest. Lengthening days and increasing temperatures predispose spinach to
bolting . The bolting response to long days and increasing temperatures is
increased by exposure of young plants to low (40-60 F.) temperatures. Disease
resistance in spinach varieties is developed for the season to which the
variety is adapted. With proper selection of varieties, spinach production
for the fresh market is possible almost year-round in western Oregon.
Traditionally, prickly seeded varieties were known as fall harvest, and
winter types, while round seeded varieties were referred to as summer spinach.
However, new varieties of round seeded spinach, make these designations less
important.
Flat, semisavoy and savoy leaf varieties are used for different markets.
Generally the flat and some of the semisavoy varieties are used for process-
ing. All three types are used for fresh market with semisavoy and savoy types
predominating. When the savoy types are used for processing plant growth
regulators may sometimes be applied prior to harvest to cause a more upright
leaf growth and reduce the risk of soil contamination. This is important due
to the difficulty in removing soil from savoy leaves during washing and
processing.
SPINACH VARIETIES (approximately 40-50 days).
Where downy mildew (Peronospora effusa) may be a problem, select resis-
tant varieties listed in the disease control section. The varieties Baker,
Cascade, Olympia, Rainier, Shasta, St. Helens, Polka, and Wolter, among others
have resistance to races 1, 2 and 3 of downy mildew . A new race 4 has been
identified in California in 1989 to which these and most commercial varieties
are susceptible. Research in California indicates that the varieties Bossa-
nova, Bolero and RS1250 have resistance to strain 4. The variety Coho has
resistance to White Rust.
Beet Western Yellows tolerance for trial: Ambassador, Rainier, Rhythm9
NIZ 46-17, and Hyb#7
Savoy types used where Cucumber Mosaic Virus may be a problem are
Bloomsdale Long Standing and Winter Bloomsdale. These may be planted in fall,
winter or early spring.
Exceptional bolting tolerance: Martine, Bejo 1369, Splendor
PLANTING DATES
Planting dates for certain varieties are chosen so as to grow the most
vigorous variety possible and yet avoid the risk of bolting. Bolting risk
increases as day length, temperature and plant density increases and as soil
moisture or plant nutrients decrease. Suggested varieties are:
Planting Dates Leaf Type and Variety
------------------ -----------------------------------------------------
Flat Semi-Savoy Savoy
Early (winter or Baker, Polka, Avon, Baker, Savoy Supreme
before May 1) Symphony, Wolter Melody, Skookum,
Tyee, Indian
Summer
Exceptional bolting tolerance: Martine, Bejo 1369, Splendor
Asian leaf type for trial: Imperial Sun.
Resistance to Downy Mildew strains 1,2,3 and 4: Bolero, Bossanova (both
smooth)
Mid-season (May 1 Baker, Olympia, Melody, Skookum Bloomsdale L.S.
to July 31) Polka, Symphony Tyee, Indian
Summer, Mazurka
Exceptional bolting tolerance: Martine, Bejo 1369, Splendor
Beet Western Yellows tolerance for trial: Ambassador, Rainier, Rhythm9
NIZ 46-17, and Hyb#7
Late (August 1 to Baker, Olympia, Avon, Chinook II Iron Prince,
mid-September) Polka, Wolter Hyb.#7, No.7R, Vienna
St. Helens, Skookum
Hybrid 424,
Estivato
Overwinter (mid to Baker, Cascade, Chinook II, Iron Prince
late September) St. Helens, No. 7
Hybrid 424,
Wolter
Asian leaf types for trial: Imperial Express and Imperial Star
Other leaf types:
New Zealand spinach (Tetragonia tetragonioides) is a tender annual with
fleshy stems and leaves, resembling spinach. It has very limited commercial
demand, but because of its adaptability to hot summer temperatures and
drought, it is popular among some home gardeners.
Spinach beet and Swiss chard (Beta vulgaris Cicla group), a form of
common table beet or leaf beet, grown for their succulent leaves which can be
harvested over an extended period. Swiss chard has large, well developed
petioles that may be red, white or green. These are grown for limited
markets, and primarily in home gardens. Sugar beet leaves may also be used as
a substitute for spinach, and are considered superior to table beet leaves.
Malabar spinach is in a different family altogether. The genus is
Basella, and three species are common: B. rubra, B. alba and B. cordifolia,
red stem, green stem and heart-shaped leaf forms respectively. This is a
warm-season crop which produces aggressive vines that may reach 10-15 feet in
length. The succulent leaves and tender shoots are marketed at specialty
markets and are used the same as spinach.
SEED COMPANIES
Abbott & Cobb Inc. POB F307, Feasterville, PA 19047
Alf Christianson Seed Co. POB 98 Mount Vernon WA 98273
Asgrow Seed Company, POB 5038, Salinas CA 93915
Bejo Seeds, 1323 E. Fir St. Mount Vernon, WA 98273
Ferry-Morse Seed Co. POB 4938, 555 Codoni Ave. Modesto, CA 95352
*Harris Moran Seed Co. 4511 Willow Road, Suite 3. Pleasanton, CA 94588-2709.
510/416-8400. FAX 510/416-8499
Nickerson-Zwaan Seed Co. POB 1787, Gilroy, CA 95021
Rogers NK. POB 4727, Boise, ID 83711
Nunhems Zaden, Canners Seed Corp. 221 E. Main St. Lewisville, ID 83431
Rijk Zwaan, Inc. 35 Harmony Rd. Warren, NJ 07060
Royal Sluis Inc. 1293 Harkins Rd. Salinas, CA 93901
Stokes Seeds Inc. POB 548, Buffalo, NY 14240
Sunseeds, 2320 Technology Pkwy. Hollister, CA 95023
W. Osborne Seed Co. Int'l. 1679 Highway 99 South, Mount Vernon, WA 98273
Zenner Bros. Seed Co., Inc. 1311 S.E. Gideon St. Portland, OR 97202
SOILS
Muck soils provide needed organic matter and high, uniform, moisture
content. Sandy loams may be used. A pH. of 6.2 to 6.9 is optimum with a pH.
between 6.5 and 7.0 being ideal for good growth. Spinach grows very poorly at
pH. below 6.0.
SEED AND SEED TREATMENT
Summer spinach variety seed numbers approximately 2,800 per ounce, while
New Zealand spinach seed numbers about 350 per ounce. Use only seed that has
been treated. Spinach is susceptible to damping off.
TEMPERATURE
Recent research indicates that a temperature of 50-63 is ideal for
optimal growth.
SEEDING
Use a precision seeder to plant about 10 seeds per lineal foot of row.
This will provide about 6-8 plants per foot, the desired stand. Space rows in
sets 10-12 inches apart or singly 18-36 inches apart. This method will
require 2-4 lb./acre of seed. If a precision seeder is not used, approximate-
ly 10-15 lbs. of seed are needed per acre. Generally a lower seeding rate is
used when spinach is planted for processing, and a higher rate when spinach is
to be bunched or bagged. Seeding rates should be reduced when spinach is to
be grown during high temperatures.
FERTILIZER
A soil test is the most accurate guide to fertilizer requirements. As a
general guideline broadcast and disc in the following:
Muck Soils Mineral Soils
Nitrogen (N) 30-50 lb./acre 60-100 lb./acre
Phosphate (P2 05) 100-150 lb./acre 100-150 lb./acre
Potash (K2 0) 0-150 lb./acre 0-150 lb./acre
Micronutrients should be applied only on the basis of soil test.
IRRITGATION
Spinach is a quick-growing, shallow-rooted crop that is not tolerant of
water stress. Maintain adequate moisture by frequent irrigation when neces-
sary but avoid irrigation practices that splash soil onto the leaves or damage
them.
HARVESTING, HANDLING AND STORAGE
Spinach for processing yields are approximately 8 to 10 tons per acre.
Fresh market yields are 80 to 150 cwt./acre.
For processing - harvest before plants are too large or begin to bolt
(usually when 16" to 17" tall). Sometimes a second cut is made for a chopped
pack after suitable regrowth has developed.
At harvest, the first cut is made 6-7 inches above the ground in order
to eliminate as much stem and petiole as possible for the whole leaf pack.
This also is done to avoid as many of the yellow or old leaves as possible.
At the second cutting, small disks are used to cut away these yellow or old
leaves and to remove some soil away from the crown to facilitate harvest.
Depending on temperature, and plant density, 3-4 weeks are needed between the
first and second cutting to obtain adequate regrowth.
For fresh market - plants should be dry and slightly wilted to prevent
petiole breakage. Harvest by hand, cut above the crown or soil line and
bunch. Care should be taken to exclude leaves that are dirty with soil or are
yellow. Bunched spinach must be handled extra carefully to reduce breakage of
plants or bunches during bunching, washing and packaging.
Freshly cut spinach is highly perishable. Care is needed in keeping
loads from overheating. Loads must be cooled if they are to be transported
long distances to the processing or packing plant.
STORAGE (quoted form USDA Ag. Handbook # 66):
Hold spinach at 32 F and 95 to 100% relative humidity. Spinach is very
perishable; hence, it can be stored for only 10 to 14 days. The temperature
should be as close to 32 F as possible because spinach deteriorates rapidly at
higher temperatures. Crushed ice should be placed in each package for rapid
cooling and for removing the heat of respiration. Top ice is also beneficial.
Hydro-cooling and vacuum cooling are other satisfactory cooling methods for
spinach.
Most spinach for fresh market is prepackaged in perforated plastic bags
to reduce moisture loss and physical injury. Controlled atmospheres with 10
to 40 percent carbon dioxide and 10% oxygen have been found to be beneficial
in retarding yellowing and maintaining quality.
PACKAGING
Spinach is commonly packaged in 20-22 lb. cartons and wire-bound crates,
packed 2 dozen each; or 7 l/2-8 lb. 12 film bags, each 10 oz, in master
cartons; or 20-25 lb. bushel baskets and bushel crates.
PEST CONTROL FOR SPINACH
THE PESTICIDES LISTED BELOW, TAKEN FROM THE PACIFIC NORTHWEST PEST
CONTROL HANDBOOKS, ARE FOR INFORMATION ONLY, AND ARE REVISED ONLY ANNUALLY.
BECAUSE OF CONSTANTLY CHANGING LABELS, LAWS, AND REGULATIONS, OREGON STATE
UNIVERSITY CAN ASSUME NO LIABILITY FOR THE CONSEQUENCES OF USE OF CHEMICALS
SUGGESTED HERE. IN ALL CASES, READ AND FOLLOW THE DIRECTIONS AND PRECAUTION-
ARY STATEMENTS ON THE SPECIFIC PESTICIDE PRODUCT LABEL.
USE PESTICIDES SAFELY!
Wear protective clothing and safety devices as recommended on the label.
Bathe or shower after each use.
Read the pesticide label--even if you've used the pesticide before. Follow
closely the instructions on the label (and any other directions you have).
Be cautious when you apply pesticides. Know your legal responsibility as a
pesticide applicator. You may be liable for injury or damage resulting from
pesticide use.
WEED CONTROL
Cultivate as often as necessary when weeds are small. Proper cultiva-
tion, field selection and rotations can reduce or eliminate the need for
chemical weed control.
THE WEED TREATMENTS LISTED BELOW ARE TAKEN FROM THE PACIFIC NORTHWEST
WEED CONTROL HANDBOOK, AND ARE FOR INFORMATION ONLY. CONSULT PRODUCT LABELS
FOR CURRENTLY LEGAL REGISTRATIONS, RATES, AND COMPLETE INSTRUCTIONS.
STALE SEEDBEDS FOR VEGETABLE PRODUCTION
Stale seedbeds are sometimes used for vegetable production when other selec-
tive weed control practices are limited or unavailable. The concept depends
on controlling the first flush of emerged weeds before planting or emergence
of the crop followed by minimal soil disturbance which reduces subsequent weed
flushes during establishment of the crop. Following establishment, other weed
control practices including cultivation or use of other herbicides can be
used.
1. Prepare a seedbed, preferably 2 to 3 weeks before planting to achieve
maximum weed seed germination near the soil surface. Soil temperatures
and moisture must be reasonable or results will be erratic.
2. Plant the crop with minimum soil disturbance. Otherwise, new weed seed
will be exposed to favorable germinating conditions.
3. Just before or after planting but before crop emergence, treat the
field by flaming or with herbicide to kill all germinated or exposed
weeds.
Weed Treatment Active Ingredient Per Acre and Application Comments
------------------------------------------------------------------------------
Flaming
Use liquid propane or similar fuel-burning equipment to quickly sear the
weeds, but not consume them with flame.
------------------------------------------------------------------------
glyphosate Consult Labels
Roundup
Roundup RT
(E. Washington and
Idaho only)
or Honcho +
nonionic surfactant
Apply to actively growing weeds either preplant in conjunction with site
preparation or preemergence crops listed on the label. Consult label
for specific rates, times of application, and perennial species control-
led. Generally 1 to 1.5 lbs ai/A should be used for annual weeds, while
perennial weeds require higher rates. Addition of a surfactant or
ammonium sulfate improves activity when weeds are stressed. Do not
apply more than 8 lbs. ai/A per year, nor plant non-labeled crops within
12 months following application. (Inhibits production of 3 amino acids
and protein synthesis.)
______________________________________________________________________________
PREPLANT, PREEMERGENCE, AND POSTEMERGENCE
Weed Treatment Active Ingredient Per Acre and Application Comments
------------------------------------------------------------------------------
diethatyl ethyl 2 to 4 lb ai/A
Antor
Select rates according to soil types listed on the label and apply at
planting or shortly after, but before weeds emerge. Use higher rate for
each soil type when shepherdspurse is a problem. Activate with rainfall
or overhead irrigation within 7 to 10 days. (Inhibits roots and
shoots).
------------------------------------------------------------------------
cycloate 2 to 3 lb ai/A
Ro-Neet
In Washington, a special local needs (SLN WA-930019) is available.
Apply preplant to soil dry enough for thorough mixing and incorporate 2
to 3 inches deep immediately by cross-disking or using a rotary tiller.
Use on mineral soils only. Seed may be planted immediately. (Inhibits
shoot growth).
------------------------------------------------------------------------
phenmedipham 0.5 to 1.0 lb ai/A
Spin-Aid
Apply any time when spinach are past 4-6 leaf stage and before weeds are
at the 2-leaf stage. Avoid applications when weather conditions may
change rapidly from cool and cloudy to warm and sunny days, or when
spinach are stressed from insect, disease, disease, or cultivation in-
jury. Tip burn or temporary growth retardation and chlorosis may occur,
although plants usually recover within 10 days. Do not apply within 60
days of harvest. Avoid diluting herbicide more than one quart/7 g water
in spray tank as this can cause precipitation of the chemical. (Inhib-
its photosynthesis).
------------------------------------------------------------------------
sethoxydim 0.28 lb ai/A
Poast
Identify susceptible grasses and apply at optimum growth stage listed on
the label. Add 2 pints/a nonphytotoxic crop oil concentrate to im-
prove leaf absorption. Erratic control often occurs when grasses are
stunted or stressed from drought, high temperature, or low fertility.
Resistant grasses include annual bluegrass and all fine fescues, whereas
quackgrass can be suppressed. Do not apply within 15 days of spinach
and leaf lettuce harvest or 30 days for head lettuce, nor exceed 3
pints/A per season. Avoid applications when temperatures exceed 90 F or
when relative humidity exceeds 60%. (Inhibits fatty acid production,
cell membranes, and new growth.)
______________________________________________________________________________
______________________________________________________________________________
INSECT CONTROL
Proper rotations and field selection can minimize problems with insects.
THE PESTICIDES LISTED BELOW ARE TAKEN FROM THE PACIFIC NORTHWEST INSECT
CONTROL HANDBOOK, AND ARE FOR INFORMATION ONLY. CONSULT PRODUCT LABELS ARE
CURRENTLY LEGAL REGISTRATIONS, RATES AND COMPLETE INSTRUCTIONS.
Insect and Description Control, Active Ingredient Per Acre
---------------------------------------------------------------------------
Loopers, including Phosdrin - 0.5 to 1.0 lb
Alfalfa looper
Autographa californica methoxychlor - 2.25 lb
Mottled gray moth, 1 1/2 inches, Dibrom - 1.0 to 1.5 lb
with silver markings on fore-
wings. Worms are slender, (1 Lannate - 0.45 to 0.9 lb
inch) dark olive-green with paler
head. Marked with three light permethrin - 0.1 to 0.2 lb
stripes. Move in a looping manner. Do not graze or feed treated
crop refuse to livestock.
Bacillus thuringiensis
1 to 2 qt. Use an appropri-
ate spreader-sticker.
Through underleaf coverage
essential.
Pyrellin - 1 to 2 pt
Larvin - 0.4 to 0.75 lb
diatect - 1 to 3 lb formulation
---------------------------------------------------------------------------
Aphids, including malathion - 1.25 lb
Bean aphid
Aphis fabae Phosdrin - 0.25 to 1 lb
Black plant louse that colonizes diazinon - 0.5 lb
foliage.
Dibrom - 1 to 1.5 lb
Green peach aphid
Myzus persicae dimethoate - 0.25 lb
Yellowish pink to pale green azinphosmethyul - 0.375 to 0.5 lb
plant louse with a large distinct
blotch on top of abdomen. Pyrellin - 1 to 2 qt
Melon aphid diatect - 1 to 3 lb formulation
Aphis gossypii
Small plant louse, yellowish to dull
green. Pale forms have dark mottlings.
---------------------------------------------------------------------------
Cutworms and Armyworms permethrin - 0.1 to 0.2 lb
Dark, shiny larvae of moths. In- diazinon - 3 to 4 lb
habit top 1 to 3 inches of soil. Cutworms only.
Phosdrin - 0.25 to 0.5 lb
Cutworms only.
Lannate - 0.45 to 0.9 lb
Armyworms only.
carbaryl - 0.5 to 2 lb
carbaryl bait - 1 to 2 lb
Bacillus thuringiensis -
1 - 2 qt. Use an appropriate
spreader-sticker.
Larvin - 0.4 to 0.75 lb
---------------------------------------------------------------------------
Garden Symphylan Telone II - preplant
Scutigerella immaculata
Telone C-l7 - preplant
Small, white, centipede-like
animals in the soil.
---------------------------------------------------------------------------
Lygus bugs malathion 1 lb
Lygus spp.
Adults, about 3/16 inch long,
have a light yellow ;"V" on
back. Damage young seedlings
by sucking plant juices.
---------------------------------------------------------------------------
Leafminers including dimethoate - 0.25 lb
Spinach leaf miner
Pegomya hyoscyami diazinon - 0.5 lb
Larvae of slender, gray fly. Phosdrin - 0.5 to 1.0 lb
Maggots are small, pale green
to whitish. Enter leaf tissues Dibrom - 1 to 1.5 lb
and feed between leaf sur-
faces causing colorless permethrin - 0.1 to 0.2 lb
blotches on leaves. Do not graze or feed treated
crop refuse to livestock.
Pyrellin - 1 to 2 pt
azinphosmethyl - 0.375 to 0.5 lb
---------------------------------------------------------------------------
Cucumber beetles including methoxychlor - 1 to 2.25 lb
Western spotted cucumber beetle
Diabrotica undecimpunctata carbaryl - 1 to 2 lb
Yellowish-green, black-spotted beetle. Pyrellin - 1 to 2 pt
Common to western Oregon. Damage usually
limited to young plants. diatect - 1 to 3 lb formulation
---------------------------------------------------------------------------
Wireworms diazinon - 3 to 4 lb
Limonius spp.
Telone II - preplant
Brown, jointed larvae of click
beetles. Kill young seedling Telone C-17 - preplant
plants.
______________________________________________________________________________
______________________________________________________________________________
DISEASE CONTROL
Proper rotations, field selection, sanitation, spacings, fertilizer and
irrigation practices can reduce the risk of many diseases. Fields can be
tested for presence of harmful nematodes. Using seed from reputable seed
sources reduces risk from seed born diseases.
THE PESTICIDES LISTED BELOW ARE TAKEN FROM THE PACIFIC NORTHWEST DISEASE
CONTROL HANDBOOK, AND ARE FOR INFORMATION ONLY. CONSULT PRODUCT LABELS FOR
CURRENTLY LEGAL REGISTRATIONS, RATES AND COMPLETE INSTRUCTIONS.
----------------------------------------------------------------------------
SPINACH -- (Beet) WESTERN YELLOWS
Cause: Beet western yellows virus, an increasingly significant pathogen in
western Oregon. The principal vector is the green peach aphid, Myrus
persicae, although other aphid vectors are likely. After acquiring the virus
from infected plants, aphids may retain for life the ability to transmit the
virus. An enormous number of crop and weed species are susceptible to this
virus; thus the natural inoculum reservoir is hardly avoidable. Crop plants
commonly infected in western Oregon include beets (table and sugar), broccoli,
most clover species, mustard, lettuce, pea, radish, spinach, Swiss chard, and
turnip. Weed species commonly infected in western Oregon include burdock,
Canada Thistle, cutleaf geranium, dog fennel, groundsel, pigweed, redstem
filaree, weedy clovers, and wild mustard.
Symptoms: Leaves turn yellow prematurely, typically beginning at the margins
and progressing inward, with veins and midribs tending to remain green. The
oldest leaves tend to become yellow first, with upward progression of yellows
symptoms, resulting in reduced and abnormal growth (i.e., unmarketable).
~Control: Attempts are underway in 1991-92 to identify lettuce and spinach
cultivars and breeding lines that are both suitable to the Pacific Northwest
and resistant to this virus. No other control measures are considered
practicable.
------------------------------------------------------------------------------
SPINACH -- (Cucumber) MOSAIC
Cuase: Cucumber mosaic virus (CMV), a pathogen spread by aphids. CMV overwin-
ters in the seeds of wild cucumber and in wild perennial milkweed, ground
cherry, and matrimonial vine.
Symptoms: The virus causes a yellow and green mottle of the leaves and some
mild leaf distortion.
~Control:
1. Remove wild cucumber vines, milkweed, and other susceptible weed hosts
to within 1,000 feet of the field if possible.
2. Control aphids by spraying and dusting.
3. The cultivar `Early Hybrid' is resistant.
-----------------------------------------------------------------------------
SPINACH -- DAMPING-OFF
Cause: Pythium sp. and Rhizoctonia solani. Under moist conditions these
soil-infesting fungi can build up rapidly and attack young germinating
seedlings.
Symptoms: As young spinach plants appear at the surface of the soil, their
stems are attacked and they wilt, fall over, and die. Germinating seed is also
attacked.
~Control: Use seed treatment with Thiram. See Spinach--Seed Treatment, or
where Pythium sp. are a problem, Ridomil 2E may be added, broadcast, or
broadcast and incorporated at the broadcast rate of 4 to 8 pt/A in 20 to 50
gal of water/A. Banded rates are determined by band width, row spacing, etc.,
and can be calculated by means of a table provided on the label. Incorporation
should be to a depth of 2 inches when used. If beds are formed, Ridomil should
be applied and incorporated before beds are formed. Ridomil 5G also may be
applied to spinach. See product label.
Or, Anchor flowable at 1.5 fl oz/cwt seed.
---------------------------------------------------------------------------
SPINACH -- DOWNY MILDEW
Cause: Peronospora effusa, a fungus. This organism overwinters on dead spinach
and refuse.
Symptoms: Pale yellowish spots develop on the leaves which have a gray to
purple downy growth on their undersurfaces, particularly in wet weather. The
infections may be scanty or numerous, often growing together. Where severe,
plants are stunted or die.
~Control:
1. Where possible rotate crops to land not having grown spinach for several
years.
2. Resistant varieties and the race they resist are: `Nores', `Duet', `Early
Hybrid 7' (1,2); `Dixie Market', `Hybrid 424' (1,2); `Polka' (1,2,3); `St.
Helens' (1,2,3); `Resistoflay' (1,2); `Baker' (1,2,3); `Jade' (1,2,3);
`Olympia' (1,2,3); `Rainier' (1,2,3); `Shasta' (1,2,3); `Woster' (1,2,3);
`Melody' (1,2); `Debut' (1,2,3); and `Meridian' (1,3).
3. Commercial spinach should be grown in areas where downy mildew is not a
serious problem.
4. Apply fosetyl-Al at 1.6 to 4 lb ai/A. Do not apply in less than 15 gal
water/A or more than 7 times/season or within 3 days of harvest.
5. Ridomil 2E applied at planting and repeated at 40-day intervals gives
control where resistance is not a problem. To minimize development of
resistance, do not use as a foliar spray once the disease has developed. See
product label.
6. Apply fosetyl-Al (Aliette) at 1.6 to 4.0 lb ai/A. Do not apply in less
than 15 gal water/A. Do not apply within 3 days of harvest. See label for
crop damage warnings.
---------------------------------------------------------------------------
SPINACH -- FUSARIUM WILT
Cause: Fusarium oxysporum f. spinaciae, a fungal disease that can survive in
the soil for several years in the absence of a spinach crop. This fungus can
also survive on infested seed and cause disease in fields previously free of
spinach wilt.
Symptoms: Two types of symptoms are commonly observed in seed crops: (1) a
seedling disease which can be confused with damping-off and (2) premature
dying of older plants. In the seedling stage the plants will appear normal
until the first true leaves form. At this time the cotyledon leaves will wilt
and in 7 to 10 days the plant dies. The roots may have a black lesion at the
base, and the vascular tissue will be darkened or discolored and few feeder
roots develop. Plants may be killed at any time from the seedling stage to
seed crop maturity. Symptoms on older plants are: General yellowing of the
lower leaves early maturity of the plant premature death and very little seed
production and, in some instances, death of the plant prior to seed develop-
ment. When older plants are pulled and examined, they may have darkened
vascular tissue and extensive secondary root order. The base of the stem,
when cut longitudinally, will be discolored and mycelium of the fungus may be
seen. In general, older diseased plants appear to be suffering from extreme
drought and/or severe root rot.
~Control:
1. Use resistant varieties such as `St. Helens', `Jade', `Chinook II', and
`Skookum'.
2. Avoid planting on soil known to be infested with Fusarium wilt of spinach.
3. Practice crop rotation and do not plant spinach in consecutive years (4 to
6 year rotation may aid in the control of wilt).
4. Plant early. This may reduce seedling disease because of lower soil
temperature during initial development of the plant.
______________________________________________________________________________
______________________________________________________________________________
---------------------------------------------------
---------------------------------------------------
This information was adapted by the Oregon State
University Extension Service from Oregon and
Pacific NW publications as well as other vegetable
production guidelines from public institutions
in the U.S. and Canada. These guidelines are
intended as a general guide for Oregon commercial
vegetable producers. Address comments or questions
to your County Extension Agent or Dr. N. S.
Mansour, Department of Horticulture, Oregon State
University, Corvallis, OR 97331.
---------------------------------------------------