Subject: FAQ: Onions Greens

From: Brian Lo <[email-masked]>
Date: Wed, 1 Mar 1995 14:56:42 -0800

GREEN BUNCHING ONIONS

      Bunching onions are produced from thickly planted white onion varieties
of Allium cepa and more recently also from the non-bulbing Allium fistulosum
species.  Interspecific varieties are represented by the variety Beltsville
Bunching.  

VARIETIES

      Allium cepa types - for early crop:  White Lisbon, White Knight, South-
port White Globe, White Spanish Bunching.

      A. cepa x A. fistulosum types:  Beltsville Bunching.  

      A. fistulosum types - non-bulbing; resistant to pink root and botrytis
leaf blight; cold hardy; for later crops and for overwintering:  Ishikura,
Tokyo Long White, Hishiko, Japanese Bunching, Tokyo Bunching.  For trial: 
Kincho (reported tolerant to high temperatures).
      Red bunching onion:  Santa Clause, "Ishikuro" type, but with rose-red
stem that can add color to salads.  Red color intensifies with colder weather.

SEEDING AND GERMINATION

      Green onion seed numbers approximately 9,500 per ounce.  Use high
quality fungicide treated seed.  Since onion seed has poor useful longevity
(less than 2 years), unless stored under ideal conditions.  Germination will
occur at temperatures from 46 to 86 F. with the optimum at over 60 F.

      Seeding rates for bunching onions depends on the spacing between rows. 
Approximately 10 to 15 lbs of seed are used at about 15 inch spacing, but at
the closest spacings up to 25 lbs of seed per acre may be needed.  

SEED COMPANIES

Abbott & Cobb Inc. POB F307, Feasterville, PA 19047
Asgrow Seed Company, POB 5038, Salinas CA 93915
American Takii Inc., 301 Natividad Rd. Salinas, CA 93906
Champion Seed Co. 529 Mercury Lane, Brea, CA 92621-4894  714/529-0702
Crookham Co. Caldwell, ID 83606
Dakota Seed International Inc. POB 5467, Saginaw, MI 48603
Elsoms Seeds Ltd. Spalding, Lincolnshire, England PE11 1QG
Ferry-Morse Seed Co. POB 4938, 555 Codoni Ave. Modesto, CA 95352
Harris Moran Seed Co. 3670 Buffalo Rd. Rochester, NY 14624
Nickerson-Zwaan Seed Co. POB 1787, Gilroy, CA 95021
Petoseed Co. Inc. POB 4206, Saticoy, CA 93303
Rio Colorado Seeds, Inc. 4701 Gila Ridge Road, Yuma AZ 85365
Sakata Seed America Inc. Morgan Hill, CA
Scottseed.  4876 N. Road H. Vale OR 97918  503/473-3246 
Shamrock Seed Co., Inc. POB 4443 Salinas, CA 93912
Sluis & Groot of America Inc. 124 Griffin Street, Salinas, CA 93901
Stokes Seeds Inc. POB 548, Buffalo, NY 14240
Sunseeds, 2320 Technology Pkwy. Hollister, CA 95023
Thompson & Morgan Inc.  POB 1308, Jackson, NJ 08527
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

      A pH of 5.3 to 6.0 is suitable for organic soils but a pH of 6.5 to 7.0
is preferred for mineral soils.

      When the pH is below the range considered suitable, lime should be
applied and incorporated thoroughly to a depth of 6 in. or more.  Lime should
be applied in the fall or as early in spring as possible.

      A late summer green-manure crop of oats, plowed down or worked in,
before the ground becomes too wet to work is beneficial.  An application of
ammonium nitrate when the green-manure crop is being turned in will help break
down the material.

FERTILIZER

      A soil test is the most accurate guide to fertilizer requirements.  The
following recommendations are general guidelines.

      Prior to transplanting or seeding broadcast and incorporate the follow-
ing:

      Nitrogen: 50-70 (N) lb/acre.  Add other nitrogen as needed to keep tops
green and vigorous under different temperature and rainfall conditions. It may
be necessary to side-dress the crop with an additional 75-100 lb/acre of
nitrogen.

Nitrogen liquid fertilizer formulations having herbicidal effects:

      AN-20, Ammonium Thiosulfate and mixtures of these two materials can be
used in a number of crops.  Monocarbamide Dihydrogensulfate (Monourea sulfuric
acid) is used in Alliums such as onion, shallots, leeks and garlic.  The
amount of nitrogen per gallon of material, the rate at which it is applied,
and the phyto-toxicity of the material determines what crops these can be used
on.

      Monocarbamide Dihydrogensulfate (Monourea sulfuric acid) is also sold as
an herbicide under different trade names (see below).  ALWAYS FOLLOW THE LABEL
WHEN USING THIS MATERIAL AS AN HERBICIDE.

      All of these materials, when applied at the proper time and manner have
the added benefit of ancillary control of many small (less than 3 inches)
broad-leaf weeds such as groundsell, pineapple weed, shepherdspurse, mallow,
pigweed, hairy nightshade chickweed and many others.  Poor, or no control is
obtained on lambs quarters, purslane, henbit, black nightshade, knotweed, sow
thistle, malva goosefoot and grasses.

      When using these nitrogen sources in foliar applications, follow cau-
tions listed.  Severe crop injury may occur if cautions are not observed.  

General cautions that apply to nitrogen liquid fertilizer formulations are:

      *  Apply to onions only after the first true leaf is as tall as the flag
leaf and before onions are 8 inches tall.  
      *  Do not apply within 4 days of a period of cool, cloudy or rainy
weather, or if free water is present on the leaves.
      *  Discontinue application if spray droplets do not roll off or "bead-
up" on the leaves.  This indicates a deficiency of adequate waxy cuticle, and
may be a temporary condition due to rapid growth, cloudy or rainy weather, or
more seriously, the lack of adaptability of the variety.
      *  Do not apply within 4 days after a foliar pesticide has been applied,
or with any wetting agent. 
      *  Use large nozzles to minimize misting
      *  Direct the spray to the base of the crop with wide, low nozzles, or
use crop shields whenever this can be done while still obtaining complete
coverage of the weeds.

AN-20 fertilizer formulation:

      This is a manufactured 20-0-0 formulation (containing 20% N) that may be
applied at 50 to 70 gallons of product per acre as a foliar spray.  This
formulation weighs 10.55 lbs per gallon and contains 2.11 lbs N/gallon of
product and would provide approximately 100 to 140 lbs N/acre (but some N is
lost through volatilization).  Do not irrigate for 48 hours after application,
but irrigate then to move the fertilizer into the root zone.

      When this treatment is used, subsequent nitrogen side dressings may be
reduced by a portion of the amount of N applied in the treatment.

      Note: Mixtures of An-20 and Ammonium thiosulfate (usually 1:1) can be
made which will reduce the amount of nitrogen applied, provide some sulfur (if
AN-20 only would have been applied, and reducing the sulfur if only Ammonium
thiosulfate were to be used), and be as effective as either material alone. 
Application rates are still held at 50 to 70 gallons of the mixture per acre. 

      Note:  This formulation is different from a solution that could be
prepared by dissolving ammonium nitrate in water.  Such a solution would not
have the same concentration or herbicidal effect.

      Also, To prevent crop injury, follow the cautions listed above.

                                     *****
Ammonium thiosulfate:

      This is a manufactured 12-0-0-26 formulation (containing 12% N and 26%
sulfur) and weighs 9.33 lbs per gallon.  It may be applied at 50 to 70 gallons
of product per acre as a foliar spray.  This solution contains 1.12 lbs nitro-
gen and 2.4 lbs sulfur per gallon of product and would provide approximately
55 to 75 lbs N/acre (some N may be lost through volatilization).  At the
application gallonage mentioned, about 150 to 168 lbs of S are also applied. 
Do not irrigate for 48 hours after application, but irrigate then to move the
fertilizer into the root zone.

      When this treatment is used, subsequent nitrogen side dressings may be
reduced by a portion of the amount of N applied in the treatment.

      Note: Mixtures of An-20 and Ammonium thiosulfate (usually 1:1) can be
made which will reduce the amount of nitrogen applied, provide some sulfur (if
AN-20 only would have been applied, and reducing the sulfur if only Ammonium
thiosulfate were to be used), and be as effective as either material alone. 
Application rates are still held at 50 to 70 gallons of the mixture per acre. 

      Also, To prevent crop injury, follow the cautions listed above.

                                     *****

Monocarbamide Dihydrogensulfate (Monourea sulfuric acid) 15-0-0-16 (ENQUIK or
n-pHuric):

      This product is also registered as an herbicide to be applied at 10 to
30 gallons of product per acre as a foliar spray.  FOLLOW THE LABEL INST-
RUCTIONS WHEN USING IT AS A NITROGEN SOURCE OR AS AN HERBICIDE.  It weighs
12.65 lb/gallon and contains 1.9 lbs of nitrogen and 2.0 lbs sulfur per gallon
of product.  It is most generally used at about 15 to 20 gallons per acre pro-
viding approximately 28 to 38 lbs of N per acre (but some N is lost through
volatilization).  Apply in sufficient water to get good foliar coverage
(approximately 1:1 dilution).  Do not irrigate for 48 hours after application,
but irrigate then to move the fertilizer into the root zone.  

      When this treatment is used, subsequent nitrogen side dressings may be
reduced by a portion of the amount of N applied in the treatment.

      CAUTION:  This solution is corrosive, and can injure skin and damage
spray equipment.  Use proper safety precautions and suitable spray equipment
(stainless steel).

      Also, To prevent crop injury, follow the cautions listed above, and
FOLLOW ALL LABEL INSTRUCTIONS. 
                                     *****

      Phosphate: 145-155 (P2 O5) lb/acre. 

      Potash: 150-170 (K2 O) lb/acre. 

THE EARLY CROP

      The early crop may be clump-seeded, 5-6 seeds per cell, in flats and
grown to transplant size in plant-houses, green-houses, or cold frames.  When
ready the seedlings are planted in clumps in rows which are 12 to 15 inches
apart.

LATER CROPS

      Seed as soon as the soil can be worked.  Four to 7 rows, 12-15 inches
apart, are seeded to each set, or bed.  Use a scatter shoe to plant a band 2-4
inches wide and seed 35-50 plants per foot of row.  Approximately 6-8 lbs. of
seed may be needed per acre for direct-seeding.

IRRIGATION

      Onions are shallow-rooted.  Maintain the top foot of soil at 65-70% of
field capacity or more.  In western Oregon 12-15 inches of water may be
necessary for a 60 to 70 day crop.

HARVESTING, HANDLING AND STORAGE

      Harvest should begin when onions are 1/4 to 1/2 inch in diameter at the
base.  There should be at least 2 inches of white shank.  Onions are hand
pulled and bunched with 6-9 onions held together with rubber bands.  Pulling
is usually done without undercutting.  Bunching is usually done in the field. 

      Field boxes are moved to the processing sheds within two to three hours
of being harvested.  The onions are run through a washer/cooler machine which
automatically washes them in a 33 to 35 F water bath.  Green tops are usually
trimmed to 12 inches.  In some cases harvested onions are bunched in the
packing shed.  

      Chilling the wash water removes field and ambient heat from the onions. 
They are then immediately packed, 4 dozen bunches to a paraffin coated box,
containing about 11-12 pounds of onions. 

      STORAGE (Quoted from USDA Ag. Handbook #66):

      Hold green onions at 32 F and 95 to 100 % relative humidity.  Green
onions (scallions) and green shallots are quite perishable and are normally
marketed promptly.  They can be stored 3 to 4 weeks at 32 F if moisture loss
is prevented.  Crushed ice spread over the onions aids in supplying moisture. 
Packaging green onions in perforated polyethylene film also will aid in
preventing moisture loss.  Storage life at 50 F for green onions is only about
1 week.  Higher temperatures favor more rapid yellowing and decay of the
leaves.

      Vacuum cooling is effective for removing field heat, but the onions
should be wetted first and packed in polyethylene-lined cartons to minimize
moisture loss.

      For maximum storage, a controlled atmosphere of 1 % oxygen with 5%
carbon dioxide at 32 F should allow 6 to 8 weeks storage.  However, the green
onions must be properly packed in waxed cartons or poly-lined containers.  The
freezing point of green onions is about 30 F.       
PACKAGING

      Green bunching onions are commonly packaged in cartons holding 4 dozen
bunches weighing 11-12 lbs. and iced to weigh 25-29 lbs, or in larger wire-
bound crates weighing a total of 47-54 lbs. 

                     PEST CONTROL FOR GREEN BUNCHING ONIONS

     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.

WEED MANAGEMENT GENERAL STRATEGY

Onions are a noncompetitive crop with short, vertical leaves that fail to      
form a canopy that suppresses weeds.  Weeds are managed with selective         
herbicides combined with frequent cultivation.  Winter cover crops or        
crop rotations enhance both soil and weed management.
______________________________________________________________________________

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. 
      ------------------------------------------------------------------------
paraquat                0.625 to 0.94 lb ai/A
  Gramoxone Extra    
  (see remarks)                                

      Restricted-use pesticide.  Do not ingest or inhale spray mist.  Wearing
      protective face shields, respirators, and clothing is advised.  Apply
      during or after planting, but before crop emergence.  Add a nonionic
      surfactant or crop oil concentrate according to label specifications,
      taking care to avoid anionic formulations that react in the tank to form
      insoluble precipitates.  Exposed crop plants will be killed.  Do not
      apply preplant or preemergence to soils lacking clay minerals, such as
      peat, muck, pure sand, or artificial planting media.  (Acts as contact;
      absorbs energy produced by photosynthesis forming peroxides that disrupt
      living cells.) 
      ------------------------------------------------------------------------
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 nonlabeled crops within
      12 months following application. (Inhibits production of 3 amino acids
      and protein synthesis.)
______________________________________________________________________________

ONIONS--MINERAL SOILS

Weed Treatment              Active Ingredient Per Acre and Time of Application
------------------------------------------------------------------------------
DCPA                              6 to 9 lb ai/A 
  Dacthal         

      Apply after planting to moist soil surface before weeds and onions
      emerge.  In eastern Oregon and Washington when rainfall is sparse,
      shallow incorporation using a nailboard has improved weed control. 
      Results are improved with overhead irrigation immediately following
      application.  Consult label for planting sensitive crops within 8
      months.  (Inhibits mitosis).                    
      ------------------------------------------------------------------------
monocarbamide           10 to 30 gal product/A     
  dihydrogensulfate 
  Enquik                                        

      Apply in sufficient water volume for full coverage when first true leaf
      is as tall as flag leaf.  Repeat applications may be necessary.  Do not
      apply in presence of free moisture or within 5 days after a foliar
      pesticide application.  Repeat as required until crop is 8 inches tall;
      then direct sprays between rows.  
      ------------------------------------------------------------------------
bromoxynil              0.25 to 0.38 lb ai/A 
  Buctril                                       

      Do not ingest or inhale spray mist and prevent contact with skin. 
      Wearing protective face shields, respirators, and clothing is advised. 
      For use in Idaho and east of the Cascades in Oregon and Washington only. 
      Apply in 50 to 70 gal water for thorough coverage when onions have 2 to
      5 true leaves.  Apply on sunny days when plants are dry and humidity  
      is low.  Do not apply west of the Cascades or when the protective waxy
      cuticle on onion leaves may be thin or damaged.  Application can be 
      preemergence, but irrigation or rainfall within 2 days of application
      may result in crop injury.  Do not add adjuvants.  Injury can sometimes
      occur even under ideal conditions (Precise action unknown; acts as a
      selective contact that disrupts cell membranes). 
      ------------------------------------------------------------------------
paraquat                          0.625 to 0.94 lb ai/A  
  Gramoxone Extra     

      A restricted-use pesticide.  Do not ingest or inhale spray mist. 
      Wearing protective face shields, respirators, and clothing is advised.   
      Apply before, during, or after planting, but preemergence to crop to
      control emerged weed seedlings only.  Add a nonionic surfactant or crop
      oil concentrate according to label specifications, taking care to avoid
      anionic formulations that react in the tank to form insoluble pre-  
      cipitates.  Preharvest interval is 60 days.  (Acts as contact; absorbs
      energy produced by photosynthesis forming peroxides that disrupt living
      cells.) 
      ------------------------------------------------------------------------
sethoxydim                          0.19 to 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 improve
      leaf absorption. Erratic control often occurs when grasses are stunted
      or stressed from drought, high temperatures, or low fertility.  Resis-
      tant grasses include annual bluegrass and all fine fescues, whereas
      quackgrass can be suppressed.  Do not apply within 30 days of harvest,
      nor exceed 4.5 pints/A per season.  (Inhibits fatty acid production,
      cell membranes, and new growth.)
______________________________________________________________________________

ONIONS - MUCK OR PEAT SOILS 

Weed Treatment              Active Ingredient Per Acre and Application Comments
------------------------------------------------------------------------------
monocarbamide           10 to 30 gal product/A
  dihydrogensulfate   
  Enquik                                        

      Oregon special local needs (SNL-OR850029) label.  Apply in sufficient
      water volume for full coverage when first true leaf is as tall as flag 
      leaf.  Repeat applications may be necessary.  Do not apply in presence
      of free moisture, or within 3 days after a foliar pesticide application. 
      Do not apply to green onions after they reach 8 inches to avoid scaring. 
      Adjust fertilizer rates for nitrogen and sulfur. (Acts as contact).      
      -----------------------------------------------------------------------
sethoxydim              0.19 to 0.28 lb ai/A
  Poast               

      Identify susceptible grasses and apply at optimum growt 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 temperatures, or low fertil- 
      ity.  Resistant grasses include annual bluegrass and all fine fescues,
      whereas quackgrass can be suppressed.  Do not apply within 30 days of
      harvest, nor exceed 4.5 pints/A  per season.  (Inhibits fatty acid
      production, cell membranes, and new growth.)
------------------------------------------------------------------------
paraquat                0.625 to 0.94 lb ai/A  
  Gramoxone Extra     

      A restricted-use pesticide.  Do not ingest or inhale spray mist. Wear-
      ing protective face shields, respirators, and clothing is advised. 
      Apply before, during, or after planting, but preemergence to crop to
      control emerged weed seedlings only.  Add a nonionic surfactant or crop
      oil concentrate according to label specifications, taking care to avoid
      anionic formulations that react in the tank to form insoluble precipi-
      tates.  Preharvest interval is 60 days.  (Acts as contact; absorbs
      energy produced by photosynthesis forming peroxides that disrupt   
      living cells.)
______________________________________________________________________________
______________________________________________________________________________

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 FOR
CURRENTLY LEGAL REGISTRATIONS, RATES AND COMPLETE INSTRUCTIONS.

Insect and Description        Control, Active Ingredient Per Acre
---------------------------------------------------------------------------
Cutworms and Armyworms                      Lannate - 0.45 to 0.9 lb
Different species         
                                            Bacillus thuringiensis - 1 to 2
Small to large larvae that chew             qt.  Use a spreader-sticker to 
holes in bulbs and leaves.                  enhance control.  
                                            
                                            Phosdrin - 0.25 to 0.5 lb       
                                            Climbing cutworms only.

                                            permethrin - 0.1 to 0.3 lb
---------------------------------------------------------------------------
Brown wheat mite                            
Petrobia latens

Small, light tan to brown active 
mite.  Damages leaves.
---------------------------------------------------------------------------
Bulb mites                                  soil fumigation
Rhyzoglyphus sp

Small white mites capable of causing
damage to developing bulbs and intro-
ducing pathogenic fungi.  Damage can
continue in storage.
--------------------------------------------------------------------------
Onion thrips                                azinphosmethyl -
Thrips tabaci                               0.5 to 0.75 lb                
                                                                          
Adults are small, pale yellow to light      malathion - 1 to 2 lb       
brown in color with feathery wings.                                       
Young are plae yellowish-green and          Phosdrin - 0.5 lb
wingless.  They feed on onion foliage                                         
and cause it to become white, killing       diazinon - 0.5 lb
the tops and reducing yields.                                             
                                           methyl paration - 0.5 to      
WARNING: Microencapsulated methyl             0.83 lb                          
parathion (Penncap-M) should never be       
sprayed on blooming weeds in onion          Lannate - 0.45 lb
fields or adjacent fields. If misused,                                    
this formulation is especially hazard-      permethrin - 0.15 to 0.3 lb        
ous to honey bees and other pollinating
insects because of its strong tendency      Pyrellin - 1 to 2 pt
to contaminate pollen.                      
---------------------------------------------------------------------------
Onion maggot                                ethion 5G - 0.4 to 2 lb 
Delia antiqua                               
                                            Dyfonate - 1 lb   Use Dyfonate     
Adult is a fly, pale to dark gray           only where organic matter        
in color, less than inch in                 exceeds 10 percent.              
size. Larvae are legless, blunt             
white maggots that kill seed-               diazinon - 1 lb                
lings and damage bulbs of                   Furrow applications only.      
older plants.                                                               
                                            malathion - 1.5 to 2 lb            
                                            Use for adult control.         
                                                                           
                                            diazinon - 2 to 4 lb           
                                            preplant broadcast             
---------------------------------------------------------------------------
Pea leafminer                               diazinon - 0.5 lb
Liriomyza huidobrensis                                         
                                            
Larvae of tiny fly. Mine in
leaves. When abundant, cause
leaves to wither from tip downward.
---------------------------------------------------------------------------
Wireworms                                   diazinon - 3 to 4 lb  
Limonius spp.                                                     
                                            Telone II - preplant 
Brown, jointed larvae of click
beetles. Kill young plants,                 Telone C-17 - preplant 
weaken older ones.
___________________________________________________________________________
___________________________________________________________________________

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.

ONION -- BASAL ROT

Cause: Fusarium sp., soilborne fungi. 

Symptoms: Yellowing, wilting, and lack of vigorous growth. Red-brown rot where
roots are attached to the base. The rot and discoloration usually affect all
of the base and upwards into the scales.  Sometimes a weft of mycelium
develops over the surface of the base or between the affected scales. Rot may
progress in storage under situations where elevated moisture levels exist.
Infection is often associated with pink root, maggots, or other insect injury.

Control:

1.  Protect plants from insect, fertilizer, or other injury.

2.  Rotate crops use well-drained soil.

3.  Some soil chemicals have been tried but at present none are being recom-
mended.

In a test in Malheur County, the following varieties had less basal rot when
compared to a number of other varities: `Golden Cascade', `Cima', `Oro
Grande', and `Cashe'.   Other onion varieties described as tolerant but not 

tested in Oregon are `Bronze Reserve', `North Star', `Sassy Brassy', and
`Sentinel'.
---------------------------------------------------------------------------
ONION -- DOWNY  MILDEW

Cause: Peronospora destructor, a fungus. This organism survives the winter on
infected plants or on old onion plant material in the field.

Symptoms: Bluish, downy spots appear on the leaves. Plants may be dwarfed,
distorted, and pale green. Spots develop first with a water-soaked appearance,
later taking on a purplish shade. In dry climates, the leaf spots may be white
in appearance. As the spots enlarge, often girdling the leaves, a whitish mold
develops on the surface of the spot, later turning black. Secondary leaves may
develop on infected plants, retarding normal bulb development. Plants are not
often killed, but bulb quality is poor and often spongy.

Control:

1.  Avoid poorly-drained soils.  

2.  Practice a 3-year crop rotation where possible.

3.  Destroy onion plant refuse and cull piles.

4.  Eradicate perennial onions or wild onions.  

5.  Use Allium fistulosum varieties that are resistant. 

6.  Spray with one of the following:

      a.  Mancozeb (dry onions only) at 1.6 to 2.4 lb ai/100 gal/A.
      b.  Maneb at 1.6 to 2.4 lb ai/A.
      c.  Ridomil MZ58 at 1.5 to 2 lb product/A.
      d.  Ridomil/Bravo 8l W at 1.5 to 2 lb product/A. 
      e.  Fosetyl-Al (Aliette) at 1.6 to 2.4 lb ai/A.
      f.  Fixed copper.

Residues:

      Mancozeb - Tolerance 0.5 ppm.  Do not apply within 7 days of harvest. 
                  Do not apply to exposed bulbs.
      Maneb - Do not apply more than 16.8 lb ai/A/season.  Do not apply within
                  7 days of harvest.
      Fosetyl-Al -- Do not apply within 7 days of harvest.
      Ridomil/Bravo 81W - Do not apply to dry bulb onions within 7 days of 
            harvest or to green onions within 21 days of harvest or more than
            4 times on green onions.  See product label for rotation restric-
            tions.
---------------------------------------------------------------------------
ONION -- NEMATODE (Stubby Root)

Cause: Paratrichodorus allius. An ectoparasitic nematode that overwinters in
the soil. The largest populations of nematodes and conspicuous plant symptoms
occur during cool, damp springs. 

Symptoms: Roots are extremely short with yellow to brownish cast plants are
stunted usually in spots in the field.

Control:

1.  Telone II at 4.5 to 36 gal/A (follow label recommendations).  Fumigate in
the fall.

OR

2.  An in-furrow spray of 1.5 to 2 gal Vydate L (broadcast basis) in 20 to 50
gal of water or .75 to 1 gal Vydate L (broadcast basis) as an in-furrow drench
in 100 to 150 gal of water are usually adequate to control the problem. In
situations with extremely high nematode presence, two or three postemergence
applications may be made.  See label--Oregon only (SLN OR-810033).

Residues: Telone II. Preplant soil treatment. Seal soil for 7 to 14 days then
aerate 1 week for each 10 gal/A applied--longer in case of heavy rains or
temperatures below 60 F--until the odor of the fumigant is gone. Do not treat
extremely heavy soils. Do not apply near living plants. Considered to be a
nonfood use.

Soil fumigants. If fall fumigation is done, beds will be free of fumigant by
spring planting.

Vydate. Limit 14 days before harvest. Such late applications will not be
effective in any case.

Sampling: Stubby-root nematodes are migratory ectoparasites (see "Nematodes-
Life Histroy), and are found only in the soil.  Before planting crops suscep-
tible to stubby-root nematodes, soil samples should be taken with sufficient
lead time to implement management procedures if necessary.  If this is soil
fumigation, it may be several weeks before crops can be planted.  Fall
sampling for crops to be planted the following spring is an excellent strate-
gy.  For diagnosis, submit both soil and onions containing roots.
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ONION -- PINK ROOT

Cause: Pyrenochaeta terrestris, a fungus. This fungus may live in the soil
saprophytically for several years.

Symptoms: The disease may appear either in young seedlings or later throughout
the growth of the onion. There is a yellowing of roots followed by a
pinkish-colored root development. These take on a bright-pink shade and die.
New roots produced thereafter become diseased and also die. As this process
continues through the growing season, the bulbs lack normal development and
are reduced in size and vigor with stunted tops.

Control:

1.  A crop rotation in which onions are planted only every 5 years will reduce
the severity of infection however, some plants will be invaded by the fungus.

2.  Use adequate fertilizer, irrigation, cultivation, etc., to stimulate rapid
bulb growth.

3.  Some partially resistant varieties of the sweet spanish type are avail-
able.

4.  Preplant soil fumigation with Telone C-17 is effective in control of the
disease on mineral soils at the rate of 5.1 to 41 gal/A. Not effective on peat
soils. Note: Fall fumigation is more effective than spring.

5.  The varieties `El Capitan', `Avalanche', `Bullseye', `Bravado', `Merit',
`Durango', `Yula', `Armada', `Valdez', and `Fiesta' were bred for resistance. 
`Yellow Globe Danvers' types are resistant.

Caution: Since the fumigation must be done prior to planting, it is important
that the planting row be directly over the fumigated soil when only the
planting row is treated. Variations of a few inches can cause complete loss of
control. Not effective on peat soils.
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ONION -- PURPLE BLOTCH

Cause: Alternaria porri, a fungus. The organism overwinters on dead, diseased
onion trash in the field and on infected bulbs. Infection often follows injury
caused by other fungi, e.g., Botrytis, or by sand or dust during windstorms.
The spores require rain or persistent dew to cause infection. The optimum
temperatures are 77o to 81o F.  Almost no infection occurs below 55 F. The
disease is sometimes severe in irrigated onion-growing areas of eastern
Oregon.

Symptoms: On the leaves a small, water-soaked area develops, which soon turns
brown. As the spot enlarges, zones may appear, and it turns purplish. White
margins often encircle the purplish centers.  When the weather is moist, the
surface of the spot usually becomes covered with a brownish-black, powdery
fungus growth. Leaves with large spots turn yellow and are blown over by the
wind. Infection of the leaves may be noticed by the presence of leaf spots
very soon after infection has occurred, sometimes within 2 days.

Bulb decay may occur during and after harvest. It shows first as a watery rot
starting around the neck and is particularly noticeable because of the
yellowish to wine-red discoloration in the neck region.  As the fungus moves
through the onion tissues, they dry and take on a papery texture toward the
outside. `Sweet Spanish' onions are very susceptible to purple blotch.

Control: The disease does not occur in Oregon with sufficient frequency to
warrant an annual spray program. Spraying as soon as the disease occurs will
prevent further spread of the disease. The variety `Fiesta' has tolerance.
Other control practices which will reduce losses are:

1.  Destroy old onion pulp piles.

2.  Handle and harvest with care, destroying any diseased onions.

3.  Proper curing of bulbs in field--lift and allow to dry several days
before topping.

Spray: Mancozeb (dry bulb onions only) (Dithane M-45, Manzate 200)--1.6 to 2.4
lb ai/100 gal/A.

Bravo 720 at 1.5 to 3 pt/a (2 pt maximum) on dry bulb onions in sufficient
water to cover.

Maneb at 1.6 to 2.4 lb ai/A.  Do not apply more than 16.8 lb ai/A/season.  Do
not apply within 7 days of harvest.

Ridomil/Bravo 8l W 1.5 to 2 ai/A.

Rovral WP--1.5 lb/A in 50 to 100 gal of water.

Spray fixed copper.  Several formulations and products are available.  See
product labels for rates.

Tolerance: Mancozeb (dry bulb onions only)--Tolerance 0.5 ppm.  Do not apply
within seven days of harvest. Do not apply to exposed bulbs.

Maneb--Tolerance 7 ppm. No time limitation.

Bravo 720--Tolerance 5 ppm on green onions, 0.5 ppm on dry bulb onions. Do not
apply within 14 days of harvest (green onions) or 7 days of harvest (dry
onions). Do not apply more than three times per season on green onions. 

Ridomil/Bravo - See cautions under downey mildew.

Rovral WP--Tolerance 0.5 ppm. Do not apply within 4 days of harvest.

Copper:  Exempt.
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ONION -- SEED TREATMENT

Aids in control of smut, seed decay, and damping-off.

Thiram-- or 2 t/lb or 1 lb product for 10 lb seed for smut.
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ONION -- SMUT

Cause: Urocystis cepulae, a fungus. This fungus survives saprophytically in
the infested soil for several years. It attacks only members of the onion
family including onion, leek, and Welsh onion.

Symptoms: The disease appears first in the stems of the young plant as it
emerges. Infected areas have a raised blisterlike appearance near the ground
level. These rupture to expose black powder masses of spores. Numerous
seedlings are killed during the emergence period, and those which live produce
distorted bulbs having darkish streaks and numerous smutty lesions.

Control:

1.  Pelleted onion seed using Thiram with a methocel sticker has been used in
some areas. Such pelleted seed is applied at the rate of 5 lb/A.

2.  Small onion sets and young onion plants may be set out in infested soil
without apparent danger of infection.

3.  Control smut by an in-furrow drench at seeding of mancozeb or Maneb at 2.4
lb actual/A (29,000 linear feet of furrow).
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ONION -- STINKING ROT

Cause: Unknown species of Pseudomonas and Erwinia.

Symptoms: First symptoms appear in late June. Either the inner or outer whorl
of leaves, but usually not both, become flaccid and rapidly change from green
to white to brown and collapse to the ground. Soon the disease progresses to
the apparently unaffected parts, with water-soaking and collapse following.
After collapse of the foliage a watery, foul-smelling liquid exudes from the
bulbs.

Further spread of the disease is reduced by warm, dry summer weather. Slightly
affected plants may recover, but usually are distorted and chlorotic. Bulbs
infected late in the season may appear, but decay during storage. The disease
does not spread from bulb to bulb in storage.

This disease has been widely distributed in western Oregon onion-growing
areas, and occurs in Oregon and Southwestern Idaho onion-growing areas.
There is a lower incidence of this disease in furrow or rill-irrigated fields.

Control:

1.  Some control can be obtained by using water from deep wells, rather than
from ditches.

2.  Reduce mechanical injuries during cultivation and weeding.

3.  Thoroughly cure onions before storing.
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ONION -- WHITE ROT

Cause: Sclerotium cepivorum, a fungus. The fungus can remain viable in the
soil for many years without the presence of the host--probably as long as 8 to
10 years. Other hosts include garlic, leek, shallot, and other allium sp. 

Symptoms: The leaves of a diseased plant decay at the base, turn yellow, wilt,
and topple over. The older leaves collapse first. Roots are rotted and the
plant can be easily pulled up. Fluffy mycelium may be present on the remaining
roots and bulb. Affected bulbs may become watery and the outer scales cracked
as they dry and shrink.  Small (1/50 inch) sclerotia are formed in affected
parts of the bulb and on the surface, often around the neck. The sclerotia are
smaller and rounder than those of Botrytis (the cause of the neck rot dis-
ease).

Control: Idaho law forbids the import of sets, bulbs, or other material
infected with white rot.  Avoid the movement of contaminated soil or machinery
into clean fields.  

Treatment of heavily infected areas of organic soils with 400 lb of methyl
bromide/A tarped has been useful in reducing inoculum in infested fields.

Spray 2 lb of Ronilan 50 WP in a 4- to 6- inch band in 400 gal of water/A or
in a 2- to 4- inch band in 100 gal of water/A over the seed row.  Apply at
least 2 more applications of 2 lb of Ronilan 50 WP in 100 gal of water/A at
4-6 week intervals.

Residues:

Ronilan--Do not apply more than 10 lbs. Ronilan/A in one crop season.  Do not
apply within 18 days of harvest.  Do not apply through any type of irrigation
system.
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         ---------------------------------------------------
         --------------------------------------------------- 
         This  information was prepared 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 9733l.             
         --------------------------------------------------- 
         ---------------------------------------------------

---

From: [email-masked] ()
Date: 3 Mar 1995 19:08:04 GMT

Recently a kind soul from Oregon has been posting some very informative
FAQs related to specific veggies.  Is there some place where these are 
archived?  Is this an obvious answer that I should have know already?  :-)  

I've located the FAQs for rec.gardens.roses, and one for plants-by-mail 
out on the WWW, but nothing as extensive as the recent veggie ones from 
Oregon.

thanks,

- Tom

ps - I already checked the group news.answers, and I didn't see anything
on gardening in there.

---

From: [email-masked] ()
Date: 3 Mar 1995 19:08:04 GMT

thanks,

- Tom