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Cauliflower

Brassica oleracea (Botrytis Group)

Last revised August 6, 2004.

Stand Establishment o Fertilizer o Harvesting, Handling, Storage o Curd Defects
Insect Control o Cauliflower Disease Control o Crucifer (Cole Crop) Weed Control


Cauliflower varieties grown in the Pacific Northwest may be categorized into early, or summer types; late, or winter types; and overwinter types. Tropical cauliflowers also exist but are not used in the Pacific Northwest.

Cauliflower plants go through a juvenile stage during which curd initiation does not occur, and cannot be initiated. The end of the juvenile period depends on the variety, and appears to be correlated with the development of a minimum number of leaves (generally 6-8 expanded leaves or 35-50 differentiated leaves, depending on temperature; the range can be much greater under certain conditions).

At the completion of this stage, the plant has reached a mature vegetative phase when curd initiation can occur, or be induced. Varieties differ in the length of time they may remain in a mature vegetative phase before curds are initiated (this is also temperature dependent, with hot temperatures delaying curd initiation). Varieties may also differ in the time required to produce harvestable curds after initiation has occurred. The combination of time required for the juvenile phase, the mature vegetative phase, the time needed to produce a marketable curd after induction, and the response of a variety to temperature at all these stages, determine the suitability and adaptability of a given variety.

The summer cauliflower varieties grown in the Pacific Northwest are intermediate types. They do not need cool weather to initiate curd formation, but will respond to a cool period by initiating curds after they have reached the mature vegetative phase. As Snowball Y types grow through the juvenile stage and reach the mature vegetative phase, curd initiation may be delayed by extended hot weather (above 80 F). After reaching the mature vegetative stage, they may also be prematurely triggered into initiating curd formation by a period of cool temperature (50-60 F). These characteristics can cause harvest scheduling problems. A combination of hot weather early, which may delay the earliest planted fields, and an inopportune cool period later in the season (late July-August), can trigger all vegetatively mature plantings into heading, thus severely compressing the harvest period. This can also result in head initiation before enough leaves have differentiated to provide good head cover, resulting in curd quality problems (depending on variety).

Mean daily temperatures of 58 to 68 F (in September) are ideal for quality head formation of the summer types. Curd formation in most snowball types occurs around 62 F. Temperatures above 68 F during head formation result in poor quality. In recent years, breeders have developed cauliflowers for the tropics that produce good heads under high (68 to 85 F) temperatures.

The curds of the early/summer (snowball) types are not all true flower primordia, but rather a range of undifferentiated shoot apices to flower primordia. The late/winter cauliflowers have curds that are usually true floral primordia. These tend to be mostly lighter weight than the snowball types.

Biennial types are also available for overwinter production. These require a cold induction period prior to curd formation. They remain vegetative, and may reach a very large vegetative size before the cold temperatures of fall and winter end vegetative growth and condition the plant for curd formation the following spring. Breeders have modified some of the winter types so that they will form heads with varying degrees of cold requirement.

There is a green cauliflower (marketed by the name Broccoflower). This is best represented by the varieties Alverde and Macerata. This cauliflower resembles standard white cauliflower in all aspects, except the heads are green, and need not be tied.

Cauliflower and broccoli have also been hybridized to produce a new vegetable hybrid that combines some of the quality traits of both plants. See below, under Novelty varieties.


VARIETIES (maturity ranges from 60 days for early hybrids, 90 days for main season, to over 100 days for late varieties).

Fresh Market

Early: Candid Charm, Rushmore, Snow Crown, Starbrite Y. For trial: Elgon.

Main-season: Andes, Candid Charm, Igloo, Matra, Snowball 123, Snowball Y Improved, Starbrite Y, White Rock. For trial: Icecap, Imperial 10-6, Incline, Ravella, White Magic, White Passion.

Late: Silver Peak, Snowball 123 (more concentrated harvest), Snowball Y Improved, Snowman, Starbright Y. For trial: Blue Diamond, Imperial 10-6, McKinley, Olympus, Silverstar 2320, Snowpak.

Snowman, Profil, Late Man, and Silverstar 2320 have performed well for mid-summer harvest and under high temperatures. Late Man also looked very good in early November.

Winter types, for trial in maritime areas: For very late harvest in Fall and Winter: Snow Prince, Snow Rock, Snow February, Snow March, Snow Supreme (listed in approximate order of maturity). These would be planted in June or July and harvested from November to March in mild winter areas.

Over-wintering, maritime areas: approximately 210-260 days when planted in early September. These varieties are transplanted to the field between August 15 and September 1, and allowed to grow over winter. They are harvested beginning mid-April through May the following spring. The over-wintering varieties are listed in order of their maturity: Armado Quick, Aprilex, Armado May, Armado Tardo, Maystar, Inca, Markanta.

Novelty; cauliflower/broccoli hybrid (approximately 85 days): Green Harmony. Green cauliflower (Broccoflower): Alverde, Macerata, Esmaraldo F1 (see notes above). Cream to orange curds: Marmalade F1 (carotene pigment is stable after cooking).

Processing Varieties

Processors specify varieties. Processors in Oregon require cauliflower that produces dense, heavy heads. Such varieties are represented by Snowball Y types. Varieties used in Oregon are:

Silver Peak, Snowball Y Improved, Snowball 123, Snowman (performed well for mid-summer harvest and high temperatures), Imperial 10-6, Silverstar 2320 (also for harvest during warm weather). For trial: Icecap, Incline, Ravella, White Magic, White Passion.

Overwinter types are not used by Oregon processors.


IMPORTANT

Before planting this Crucifer crop, consider the following important factors:

  1. No crucifer crop, or related weed, has been present in the field for at least 3 years, 5 years preferable. Crucifer crops include cabbage, cauliflower, broccoli, kale, kohlrabi, Brussels sprouts, Chinese cabbage, all mustards, turnips, rutabagas, radishes etc. Cruciferous weeds include wild radish, wild mustards etc. Also, crucifer plant waste should not have been dumped on these fields.

  2. Soil pH should be 6.5 or higher. Soil pH over 6.8 is necessary to manage club root. The application of 1500 lb/acre of hydrated lime, 6 weeks before planting is recommended for soils with pH less than 7.5 for club root control, whenever club root may be suspected.

  3. Arrange to keep transplanted and direct-seeded fields separate to minimize spread of certain diseases that are more prevalent in transplanted fields.


SOIL

Cauliflower may be grown on a variety of soils but it does best on a well-drained, loam soil well supplied with organic matter. Sandy loams are preferred for early crops. Adjust soil pH to 6.0 - 6.8 for maximum yields.


SEED AND SEEDBED TREATMENTS

A seed treatment containing molybdenum is suggested. Dissolve 1/2 ounce of sodium molybdate in 3 tablespoons of water and mix this with the seed to plant 1 acre. Pelletizing is not necessary but primed and coated seed is becoming popular. Consult your seed dealer about the availability of primed seed.

Cauliflower seed numbers approximately 144,000 per pound. Cauliflower is often direct seeded. About 60% of the Oregon acreage is grown from field-grown transplants that are transplanted bare-root. Greenhouse grown "plug plants" are also used, especially for the fresh-market crop where a large head size is not desired, and the added transplant cost is more easily recovered.

Use certified, or hot-water-treated seed and fungicide treat seed to protect against several serious seedborne diseases. Hot water seed treatments are very specific (122 F exactly, for 25 to 30 minutes; the wet seed is then quickly cooled and dried). The seed treatments are best done by the seed company, and can usually be provided upon request.

Seed Beds for Transplants

Locate these in an open, well-drained area, free of club-root. Lime if necessary, and fertilize with 10-30-10 at 625 lb/acre or its equivalent.

When seedlings are to be grown in a seedbed for production of transplants, choose a site where cole crops have not been grown before, or fumigate before seeding with an approved fumigant following label and manufacturer's recommendations.

Always use certified or hot-water-treated seed for transplant production. Seed in a greenhouse for an early crop, in a cold frame for a less early crop, and in outdoor seedbeds when the weather is warm enough for germination and growth (above 50 F). In each case seed 5-6 weeks ahead of when the plants are wanted for transplanting.

Five to 6 ounces of high quality, sized and density graded seed will provide enough transplants to plant 1 acre. In the seedbed use a drill with a scatter shoe to drop 15 to 20 seeds per foot in rows 10 inches apart. This will provide 12-15 plants per foot of row at pulling time. Stands thicker than indicated will produce less desirable, spindly plants.

Properly grown, transplants should be ready in 35-40 days. Use only vigorously growing plants, 4-6 inches tall. Sorting may be necessary if transplant size is variable.

Transplant Bed Fertilization

Broadcast and work into the transplant bed:

  1. 40 to 70 lb N/A.
  2. Apply phosphorus, potassium, sulfur, magnesium, boron, molybdenum, and lime up to the maximum rates suggested below for field applications.
Greenhouse Transplant Production

Precision seed into modular flats, styrofoam trays or blocks of a peat-lite (peat-vermiculite) mix or other suitable growing medium. Crowding should be avoided. Provide 1.5-2.5 square inches per plant in modular trays. Temperatures should be maintained above 45 F at night and below 85 F during the day. Seven days before transplanting start the hardening off process. Protect young transplants nutrient imbalances, from downy mildew and insect pests that may influence the later performance of the transplant.

Follow the same process in a cold frame, or seed directly into the covered soil after it has been limed, fertilized and fumigated as for outdoor seedbeds.


FIELD ESTABLISHMENT

Most cauliflower for both fresh market and processing is transplanted. Fresh market cauliflower is transplanted to the field from about mid-March through July. Cauliflower for processing is transplanted from mid-June through July in order to fit vegetable crop processing schedules.

Although some over-winter production of cauliflower for fresh market and processing has been tried in western Oregon, there have been mixed results and this is not being done at this time.


TRANSPLANTING SOLUTIONS

Dilute solutions of complete fertilizers high in phosphorus promote quick recovery and early growth of transplants. One-half pint of transplanting solution should be injected into the furrow at the roots of each plant at time of transplanting. A transplanting solution may be prepared by dissolving 3 lb 11-48-0 or similar monoammonium phosphate fertilizer in a 55-gallon drum of water.

Transplants should be irrigated immediately after transplanting to establish good root contact with the soil, and subsequently to insure uniform growth (see irrigation section below).


FIELD SEEDING AND THINNING

Successful direct seeding of cauliflower is difficult. Preparation for direct seeding needs considerable attention. A fine-textured soil, free of rocks, clods and trash, firm and very level, is required for precision seeding. Under cloddy or dry surface conditions, a sweep may be necessary to remove clods ahead of the planter shoe, or to allow placement of seed into moisture, without planting too deep. Approximately 40% of processing cauliflower acreage in the Willamette valley is direct seeded.

Use a precision seeder, such as Stanhay, or Gaspardo vacuum planter, to drop 2 seeds 2 inches apart every 15-18 inches. About 5-6 ounces of seed will be needed per acre. Use size and density-graded seed of highest quality. Use vermiculite anticrustant or have solid set irrigation available to keep the soil surface moist and free from crusting until the stand is established.

After the first true leaves have formed, thin the plants so as to leave 1 plant at each location (about 3 weeks after seeding). Avoid delay in thinning since thinning large plants results in too much disruption of the remaining plants, contributing to uneven harvest. Spacing between rows should be 36 or 40 inches.


FERTILIZER

Good management practices are essential if optimum fertilizer responses are to be realized in the production of cauliflower. These practices include use of recommended varieties, selection of adapted soils, weed control, disease and insect control, good seedbed preparation, proper seeding methods, and timely harvest.

Because of the influence of soil type, climatic conditions, and other cultural practices, crop responses from fertilizer may not always be accurately predicted. Soil test results, field experience, and knowledge of specific crop requirements help determine the nutrients needed and the rate of application.

The fertilizer application for cauliflower should insure adequate levels of all nutrients. Optimum fertilization is intended to produce top quality and yields in keeping with maximum returns.

The suggested fertilizer applications are based on a 36-inch row spacing. With decreased row spacings, increased fertilizer rates are suggested.

Recommended soil sampling procedures should be followed in order to estimate fertilizer needs. The Oregon State University Extension Service agent in your county can provide you with soil sampling instructions, soil sample bags, and information sheets.

NITROGEN (N)

A total application of 150-200 lb N/A is suggested. Some growers in the Willamette Valley routinely use applications of 250 lb N/A or more. Cauliflower is very efficient in recovering applied N from the soil, but N rates in excess of 200 lb/A may result in high levels of residual nitrate-N in the soil and nitrate contamination of ground and surface waters.

Broadcast about half of the N just before direct seeding or transplanting or band 60-90 lb N/A with the phosphorus. For both direct-seeded and transplanted crops, sidedress 75 to 100 lb N/acre at time of last cultivation, or 1 to 2 weeks before the first cutting. At the higher rates, two applications should be made 2 to 3 weeks apart.

Recent research at Oregon State University indicates that internal splitting and cavity discoloration of cauliflower increases with increasing rates of nitrogen and water, especially for early season harvested fields. Use nitrogen carefully to minimize these problems.

For the use of N fertilizer solutions for weed control, see the file Nitrogen Fertilizer Solutions Providing Ancillary Weed Control in Cole Crops.

PHOSPHORUS (P)

Phosphorus fertilizer should be banded at the time of seeding or transplanting cole crops. Bands should be located 2-3 inches to the side of the seeds or plants and 3-4 inches deep. Apply P as follows:

           If the soil test*                Apply this amount of
          for P reads (ppm):              phosphate (P2O5, lb/A):

                0 - 30                           150 - 200
               30 - 50                           100 - 150
               Over 50                            80 - 100
*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.

POTASSIUM (K)

Limit band applications of K to 90 lb K2O/A. Broadcast remainder of K and work into seedbed prior to planting. The total of N plus K2O in the band should not exceed 90 lb/A. Apply K as follows:

           If the soil test*                Apply this amount of
          for K reads (ppm):                 potash (K2O, lb/A):

                0 - 150                          150 - 200
              150 - 200                           90 - 150
              200 - 250                           60 -  90
               Over 250                             None
*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.

SULFUR (S)

Include 25-40 lb S/A in the fertilizer program. Sulfur is sometimes contained in fertilizers used to supply other nutrients such as N, P, and K, but may not be present in sufficient quantity.

Plants absorb S in the form of sulfate. Fertilizer materials supply S in the form of sulfate and elemental S. Elemental S must convert to sulfate in the soil before the S becomes available to plants. The conversion of elemental S to sulfate is usually rapid for fine ground (less than 40 mesh) material in warm moist soil.

Sulfur in the sulfate form can be applied at planting time. Some S fertilizer materials such as elemental S and ammonium sulfate have an acidifying effect on soil.

The S requirements of crucifers can be provided by:

  1. The application of 25-40 lb S/A in the form of potassium sulfate or ammonium sulfate at or prior to seeding or planting.
  2. Applying 40-50 lb S/A as fine ground (finer than 40 mesh) elemental S the preceding year.
  3. Applying coarser ground elemental S at higher rates and less frequently.
MAGNESIUM (Mg)

When the soil test value for Mg is below 2 meq/100g soil, band 15- 20 lb Mg/A at transplanting or seeding time. If Mg deficiency symptoms develop, spray with 10 lb Epsom salts in 100 gal water/A.

Magnesium can also be supplied in dolomite, which is a liming material and reduces soil acidity to about the same degree as ground limestone. Dolomite should be mixed into the seedbed at least several weeks in advance of planting and preferably the preceding year. Magnesium can also be supplied by the application of Epsom salts or Sul-Po-Mag fertilizer prior to seeding or transplanting as follows:

* Sul-Po-Mag at 150 to 200 lb/acre.
* OR Epsom salts at 150 to 200 lb/acre.
* OR Dolomitic Limestone at 225 to 275 lb/acre.

BORON (B)

Cauliflower is sensitive to boron deficiency. Apply boron as follows:

                 If the soil test*                 Apply this amount
                for B reads (ppm):                    of B (lb/A):

                      0 - 1                          3 - 4 broadcast
                      1 - 3                          1 - 2 broadcast
                     Over 3                        1/2 - 1 foliar spray
*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.

A satisfactory foliar spray contains 1 lb B/100 gal water. Fertilizers containing B should not be banded.

Fields East of the Cascades or where winter rainfall is low, and to which the higher rates of boron have been applied, should not normally be planted to beans or cucumbers the following year, as both these crops are extremely sensitive to boron.

LIME

If a mineral soil is below pH 6.3 or an organic soil is below 5.5 and/or the calcium (Ca) level is below 8 meq/100g soil, lime should be applied. Compared to other vegetables cauliflower has a fairly high lime requirement.

                  If the SMP Buffer*               Apply this amount
                 test for lime reads:                of lime (T/A):

                     Below 5.6                            5 - 7
                     5.7 - 5.9                            4 - 5
                     5.9 - 6.1                            3 - 4
                     6.1 - 6.3                            2 - 3
                     6.3 - 6.6                            1 - 2
                     Over  6.6                             None
*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.

The liming rate is based on 100-score lime. Lime should be mixed into the seedbed at least several weeks before seeding and preferably the preceding year. A lime application is effective over several years.

Some soils may have a fairly high SMP buffer value (over 6.6) and a low pH (below 6.0). This condition can be caused by the application of acidifying fertilizer. In this case the low pH value is temporary and the pH of the soil will increase as the fertilizer completes its reaction with the soil. This temporary "active" acidity from fertilizer is encountered following recent applications of most nitrogen fertilizer materials. Acidifying fertilizers also have a long term acidifying effect on soil that is cumulative and leads to lower SMP buffer readings.

Sandy soils to which fertilizers have not been recently applied sometimes record low pH and high SMP buffer values. In such cases, a light application of lime (1 to 2 ton/A) should suffice to neutralize soil acidity.

For acid soils low in Mg (less than 0.5 meq Mg/100g soil) one T/A of dolomite lime can be used as a Mg source. Dolomite and ground limestone have about the same ability to neutralize soil acidity.

The P, K, Mg, B, and lime recommendations are based on soil test values from the Soil Testing Laboratory, OSU, Corvallis, Oregon.

These recommendations are largely based on the results of experiments conducted by Oregon State University Agricultural Experiment Station Horticulture and Crop and Soil Science Department research faculty. These recommendations are quoted from OSU Fertilizer Guide FG 27.

MOLYBDENUM (Mo)

A seed treatment containing molybdenum is suggested. Dissolve 1/2 ounce of sodium molybdate in 3 tablespoons of water and mix this with the seed to plant 1 acre.

Molybdenum should be applied to transplant beds at the rate of 2 lbs sodium molybdate/A. If whiptail develops in the field, apply 1/4 to 1/2 lb of sodium molybdate/A as a foliar spray, OR apply 3 ounces of sodium or ammonium molybdate per acre at weekly intervals (3-4 sprays; may be included with insecticide treatment). Molybdenum deficiency is aggravated by pH levels of 5.6 or below. Sodium molybdate contains 40% Mo.

Caution: Forage crops grown on soils previously fertilized with molybdenum may cause molybdenum toxicity when fed to cattle or sheep.


IRRIGATION

After stands have been established provide uniform moisture throughout the growth of the crop. Do not over-water in the first 2-3 weeks after transplanting, or 4-5 weeks after direct-seeding, especially if club root is suspected. However, any moisture stress, especially when cauliflower reaches the 6 to 7-leaf stage may cause cauliflower to button or form heads prematurely. Such heads will be too small for market and are usually yellow due to inadequate leaf cover.

Cauliflower may require 12-15 inches of water depending on planting date, seasonal variation, variety, and number of times the field is harvested.

Soil type does not affect the amount of total water needed, but does dictate frequency of water application. Lighter soils need more frequent water applications, but less water applied per application.

See also the OSU Irrigation Guide for this crop.


TYING

Cauliflower for processing is not normally tied. When this is done to keep heads white, leaves are usually gathered around the head at about the time that they are 1 inch in diameter. Leaves are held together with rubber bands or string. When several tyings are needed, use different colored rubber bands. This facilitates harvest by allowing all plants with the same color band to be harvested at once.


CAULIFLOWER CURD DEFECTS

Ricey: curds acquire a velvety appearance somewhat like a pot of boiled rice. This is caused by the development of small white flower buds. This defect is attributed to high temperatures during curd development and is aggravated by overmaturity and with rapid growth and heavy N side-dressing. Some varieties are more prone to riceyness than others.

Leaves in curd: Small leaves in the curd occur when the plant responds to warm temperature after the curd forms. The cause is due to reversion to vegetative growth.

Yellow and green curds: Yellowing and greening is due to excessive exposure to sunlight and resultant chlorophyll formation. The occurrence of whiptail, a molybdenum deficiency disorder, may contribute to this problem by making it difficult to tie plants, or provide adequate leaf cover, to shield heads from sunlight. Yellowing may also be associated with over-mature heads. (See also item on "purpling" below).

Browning of curds: Brown discoloration and breakdown of curds is associated with boron and calcium deficiency and certain diseases.

Pink curds: Pinking generally occurs in the interior branches of the head. It is reported to be due to excessively cool temperatures at harvest for the variety being grown. Some varieties are more prone to pinking than others. Snowball types are resistant to this defect.

Purple curd discoloration: Purpling occurs on the surface of the head. Varieties differ in their sensitivity to purpling. In sensitive varieties (Snowball types), purpling may be aggravated by overmaturity or poor leaf cover that causes heads, or portions of them, to be exposed to light. Poor plant growth and leaf cover may be caused by compacted soils or nutrient, temperature, water, or other stress conditions that limit growth. In western Oregon, plants in the first fields to be harvested may be stunted due to excessively high temperatures that can occur in late July and early August. Also, premature head initiation may be triggered by cool temperatures (50-60 F). This stops leaf formation and may cause heads to be formed on plants that have inadequate leaf growth for good head protection. When these conditions occur, heads may have to be harvested smaller than desirable, before they become exposed or overmature.

Head shape: Low temperatures promote flat heads while high temperatures promote conical shaped heads.

Internal cavitation and discoloration: Recent research at Oregon State University indicates that these disorders increase with increasing rates of nitrogen and water. Furthermore that boron deficiency may aggravate discoloration, and that high boron applications may not effectively reduce discolored cavities caused by high nitrogen and water rates.

Buttons: Buttoning is the formation of miniature heads of poor quality due to premature shift to generative stage. This is caused by using plants that are quite large (with thick stems) at the time of transplanting to the field. Such plants go quickly into the generative phase producing a smaller than normal head. The condition may also be aggravated by stressful environmental conditions that cause the shift from vegetative to generative growth resulting in buttoning of a percentage of the plants. Severe N deficiency and crowding of plants in the transplant bed have been reported to be contributing factors.

Blindness: A percentage of the plants in the field form no heads at all due to some injury. The injury can be due to cold temperatures slightly above 32 F for spring-planted cauliflower as the cauliflower just passes the seven-leaf stage, or from freezing injury during initial stages of curd formation. For summer-planted, fall harvested cauliflower, other causes for blindness reported are: Growing point damage from insects (larvae of the diamond-back moth, thrips, lygus bug, diabrotica, and certain cutworms), and rodents. Also moisture stress and injury from certain insecticide solvents during periods of high temperature (over 90 F if these occur just at the beginning stages of curd initiation) have also been implicated. Molybdenum deficiency is not believed to be involved, but speculation has centered on calcium and/or boron deficiency during very early stages of seedling growth or transplant production. It is also thought that the latter conditions may be aggravated by factors that limit root growth (herbicide, moisture, compaction etc.)

Frost damage: In general, varieties with good curd protection and dense heads would be less sensitive to early fall radiation frosts (where temperature of plant tissues falls below the temperature of ambient air because of radiant heat loss to the clear night sky) that discolor the curd surface. Leaves tend to protect the curd and greater density would mean greater storage of heat during daylight hours.

Witches brooming: A proliferation of axillary shoots occurs as a result of damage to the growing point. This may, or may not be associated with "blindness" and "buttoning", and may be induced by boron deficiency. Sometimes one or more of these side-shoots will form a small curd.


HARVESTING, HANDLING, AND STORAGE

Cauliflower for processing is scheduled to harvest beginning early September through mid-November. The prime harvest period is from mid September through mid October.

Gross yields of processing cauliflower in the Pacific Northwest range from 12-15 tons/acre, which produces a graded yield of 7-8 tons/acre.

Researchers in the United Kingdom have developed a harvest prediction system that enables growers and processors there to determine time of harvest for a given field or planting. The model has been tested in Oregon without much success.

Begin cauliflower harvest when about 10% of the heads are ready. Harvest is then necessary at about 4 to 8-day intervals, depending on temperature. Harvest cauliflower heads when they are 5-6 inches in diameter. They should be white, not discolored, ricey or blemished. The heads are easily damaged; handle with great care. Fields are usually harvested 5-6 times for processing.

Uniformity of fields of Snowball Y types at harvest depend on a number of factors:

  • Genetic differences among plants and their juvenility period requirement.
  • Differences in the growth rate of the plants in the field, especially when there are sudden changes in temperature during transition from juvenile to mature vegetative phase.
  • Variation in duration of curd growth period requirement.
Cauliflower is hand harvested into large bins for processing. Harvester aids are commonly used to convey cauliflower from the cutting crew to the bins.

In the Willamette Valley, cauliflower harvest for processing begins about September 10 and continues to October 31. The prime harvest period for processing is September 15 to October 15.

STORAGE (Quoted or modified from USDA Ag. Handbook 66 and other sources)

Cauliflower for processing is not normally stored. When storing, store cauliflower at 32 F and a relative humidity of at least 95%. If in good condition, cauliflower can be held satisfactorily for 3 to 4 weeks at 32 F. The storage life is about 2 weeks at 38 F, 7 to 10 days at 40 F, 5 days at 50 F, and 3 days at 60 F. Slightly immature, compact heads keep better than more mature ones. Successful cold storage depends not only on preventing decay, spotting, and water-soaking but also on retarding aging (browning) of the head, or curd, and in preventing the leaves from wilting, yellowing and dropping off. A high relative humidity of at least 95 % is desirable to prevent wilting. Canadian researchers found that a humidity of 98 to 100 % was satisfactory for cauliflower, mainly because it allowed even less weight loss to occur than that at 90 to 95 %.

Containers should be handled carefully to avoid bruising of the heads; they should be stacked with the flower heads down to protect the curds from bruising and from dirt. Slatted crates of bins should be used so that moderate air circulation can remove the heat of respiration. When it is desirable to hold cauliflower temporarily out of cold storage, packing in crushed ice will aid in keeping it fresh. Freezing causes a grayish-brown discoloration and softening of the curd accompanied by a water-soaked condition. After freezing, affected tissues may be rapidly invaded by soft-rot bacteria.

In general, use of various controlled atmospheres has not been promising. The storage life of cauliflower was not extended by either low oxygen or high carbon dioxide at 35, 40 or 45 F, and cauliflower curds were injured by low oxygen (2% or less) or by high carbon dioxide (5 % or more). Injury due to controlled atmospheres is mainly apparent only when the stored product is cooked.

PACKAGING

The University of California-Davis has a file on Minimal Processing of Fresh Vegetables that discusses film wrapping and other topics.

Cauliflower is packaged after being closely trimmed into 1 or 2 layer cartons of 12 to 24 heads, with 12's most common. Much of the cauliflower now marketed is closely trimmed of leaves, prepackaged in perforated film overwraps, and packed in fiberboard containers. The overwraps should provide four to six 1/4-inch holes per head to allow adequate ventilation.


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