Asparagus_Production_Manual_for_Kosovo_Asparagus.docx

Kosovo Asparagus Production Manual, Sept. 2011

Kosovo Green Asparagus Production Manual September 2011

John L. Casazza JLC Consulting

Introduction & History

Asparagus is an ancient Mediterranean grass and is a member of the Liliaceae family of plants (lily family), now subdivided into the Asparagaceae family. It has separate male and female plants with edible shoots that later grow into a much branched, feathery, fern like frond with small leaf like needles called cladodes. Asparagus officinalis, as the commercial variety of asparagus is classified is a perennial crop which is productive for ten to fifteen years after establishment. It originated along the seacoasts of Europe and Asia and has been cultivated for over 2000 years. It was first domesticated and cultivated by Macedonians in 200 BC. Asparagus has also been depicted in ancient Egyptian writings and was grown in Syria and Spain in ancient times. There is a recipe for cooking asparagus in the oldest surviving book of recipes, Apicius’s 3rd century “CE DE re coquinaria, Book III”.

The prolifically cultivated vegetable is popularly consumed in many parts of the developed world and developing world. According to Brian Benson in his 2009 Update of the World’s Asparagus Production Areas, Spear Utilization and Production Periods, there are at least sixty-two countries producing asparagus in the world with an estimated total area of 195,819 hectares. Major asparagus production can be found in China, the United States, Spain, the Philippines and Australia while Mexico and Peru have increased production to meet the continued demand from their importing countries. Green asparagus production in 2009 is up at 62% of the total volume with 78% marketed as fresh asparagus versus 57% green and 65% marketed as fresh in 2005. Domestic consumption of asparagus increased 4% from 53% in 2005 to 57% in 2009, and conversely worldwide export percentages decreased by 4%, from 47% in 2005 to 43% in 2009.

The popularity of the vegetable is generally attributed to the unique taste and to the symbolism of it arising first in early spring over other popular vegetables. There is also a growing realization of the health and nutritional aspect of asparagus as it is found to contain twenty-five (25) calories per serving of five spears and zero (0) fat, with no cholesterol or sodium, 1% of total carbohydrate and 8% of dietary fiber. It contains two (2) grams each of sugar and protein and of the daily recommended intake of essential vitamins and nutrients it has 10% of vitamin A, 15% of vitamin C, and 2% of calcium and iron. It also contains beneficial quantities of vitamin K and folic acid.

Producing asparagus in Kosovo will be a pioneering effort that will project the country favorably as one of the next agricultural exporters of asparagus to the European market while improving the availability and marketability of locally produced and imported asparagus.

Production Requirements

Climate – Asparagus is adaptable to temperate regions where low temperature, below 10˚ C, or drought induce a dormant stage in the crop. The minimum soil temperature for germination is 10˚ C while the optimum soil temperature for germinations ranges from 16˚ to 30˚ C with 24˚C as the ideal temperature. The crop does well under cold season conditions; however, the rate of growth is temperature sensitive. The length of time required for the asparagus shoot to grow from ten (10) centimeters to twenty-five (25) centimeters varies from 5.3 days at a mean daily temperature of 11˚ C, to 1.9 days at a mean temperature of 25˚ C. Rhizome buds form at temperatures between 16˚ and 32˚ C, while root and fern development are reduced at temperatures below 13˚ C and above 29˚ C. High temperatures cause the spear tips to open prematurely (“feather”) reducing overall spear quality. Asparagus does well where winters are cool and the soil occasionally freezes at least a few inches deep.

Kosovo’s annual climate ranges from an average maximum of 3˚ C and an average minimum of -4.6˚ C in January to an average maximum of 28.1˚ C and an average minimum of 13.7˚ C in August. Cold seasonal climates from January to March and from October to November would prohibit asparagus bud formation and induce dormancy in the colder months. The higher temperatures of late August through September would cause premature spear opening. This puts the productive months for asparagus in Kosovo from late April or early May through July and early August. This period catches the late European market with the best opportunity for exporting asparagus to Italy and Greece and in the later part of the season to Germany.

Soils & Site Selection – Asparagus should be planted in light textured soils, preferably sandy loams but can be planted in either sandy or loamy soil. Medium light texture allows adequate spear growth while maintaining the beds intact during the rainy or harvest season. Sandy soils may cause undue erosion and heavier soils will interfere with the proper spear production and emission of the spears from the soil. Avoid soils heavier than sandy loam soils even though sandy clay loam soils may be planted to asparagus with the crowns planted at shallower depths, maximum six inches. Expect lower productivity and lesser longevity of the field with heavier soils. Soils should be deep, free of stones and gravel that could interfere with bed formation and spear development. Asparagus requires a rooting depth of one & one-half (1.5) meters. Organic material content in the soils above two (2) percent is favorable. Also, asparagus should not be planted in areas planted to asparagus in the past.

Good drainage is important to long term asparagus production. Any situation where water is ponded or soil is saturated for any extended period is detrimental to crown growth and spear initiation. Leveling the field with a mechanical grader with a final slope of one-half to one percent is recommended for gravity irrigation systems. This will also help get water off the field while avoiding erosion and not interfere with gravity fed irrigation systems. Drip irrigation can work well for asparagus on slopes greater than one percent as long design criterion takes this into account. Asparagus will not tolerate standing water for more than eight hours after a heavy rain.

Variety Selection – The most common and universally used variety around the world for commercial asparagus production is UC 157, F1 hybrid. It’s adapted for warm climates and moist soils and shows tolerance to Fusarium and Rust. Spear quality is good and the green spears tight tipped, smooth and medium in spear diameter.

UC 115 F1 hybrid or the renamed DePaoli variety is a hybrid variety well suited for early production in warm climates. The spear heads remain tightly closed until the spear is tall, resulting in a high level of spear quality. DePaoli has moderate levels of tolerance to Phytophthora spear rot.

Jersey Giant is an all-male hybrid developed at Rutgers University. It is adapted to temperate and cool climates. Spear size is medium to small and yield potential is high. The color is green with slightly purple bract. The variety shows resistance to rust.

Selecting the UC developed varieties and the Jersey/Rutgers varieties will provide a thorough evaluation for yield and quality, disease resistance and longevity under the environmental conditions of Kosovo. Over time, some European varieties should be explored as alternatives as those adapted to the local markets within the region.

Land Preparation - Soil should be worked properly with appropriate tractors and implements so that it is loose enough to form into troughs and beds for planting of asparagus. Reaching the desired soil condition with the least amount of mechanical work is preferred. Subsoiling, plowing and discing should be conducted as necessary and can be carried out by the evaluation of the grower.

Planting – Asparagus can be established by three methods: transplanting ten (10) – twelve (12) week old greenhouse seedlings, planting of one year old field grown crowns, or direct seeding. Crowns or seedlings should be planted to the asparagus beds after the threat of first frost in the spring. Late summer and fall plantings of spring planted seedlings into a seed bed is permitted as long as sufficient irrigation is available to keep the seedlings viable and hydrated during the hot dry summer months. Planting one year old crowns in spring will produce yields of seven hundred fifty (750) kilograms to one thousand (1,000) kilograms per hectare of asparagus the following year. Direct seeding of asparagus in Kosovo is not recommended because of sufficient greenhouse resources to germinate seedlings capable of being planted to a seed bed in the late summer or fall.

Row Cultivator – Bed Former

Seedling transplants or one-year old crowns are normally placed at the bottom of a furrow and soil is mounded over the plants as they develop to fill in and form a raised bed. Bed width varies from one hundred (100) to one hundred eighty (180) centimeters, depending on the grower’s preference. I recommend a center-to-center spacing of one hundred and fifty (150) centimeters which allows ample access by tractors and mechanical and labor operations.

In-row plant-to-plant spacing for seedling transplants and crowns is fifteen (15) to thirty (30) centimeters for densities of forty-four thousand (44,000) to twenty-two thousand (22,000) pants per hectare. I recommend a plant-to-plant spacing of twenty two (22) centimeters that will give a final planting density of thirty thousand planted per hectare.

Plant asparagus crowns or rhizomes (roots plus buds) so the tops of the crowns are fifteen (15) to twenty (20) centimeters below the top of the bed. Make a planting furrow of twenty (20) to twenty-five (25) centimeters with a moldboard plow and tractor with tires spaced at one and one-half (1.5) meters. Make a small mound at the bottom of the furrow as a seating for the planted crown. Be sure to segregate the crowns by size so that similar sized crowns are planted together in the same rows.

Place the crowns at the proper spacing spreading the roots over the mound and making sure the buds of the crowns are facing up. Cover the crowns and but with no more than five (5) centimeters of soil. As the ferns begin to grow, cover it gradually with soil removed in cultivation operations mechanically or by hand. Use the crown covering as part of a mechanical or hand weeding operation. The crown should be fully covered shifting the adjacent soil over the crown before the winter dormancy and in time for the fern removal the following spring. A round bed with the apex at one & one half meters and the crown buried fifteen (15) to twenty (20) centimeters should be the final outcome.

Crown Depth, 15 to 20 centimeters

Bed Spacing, 150 centimeters

1. Crown placed at 15 – 20 cm

2. Buried with 5 cm soil at planting

3. Cover in a few months as ferns grow

4. Final crown position at 15 – 20 cm below the surface.

Weed Control & Cultivation- Elimination of the noxious weeds prior to planting is critical. Start working the soil a year before crown planting by disking the soil, allowing small weeds to surface, repeat disking using a stale technique, or planting cover crops and use of herbicides if necessary as a last resort. Always check the labels and use according to the prescribed volumes and timing of application. Check for approval to use the herbicide in Kosovo per local laws and regulations and according to USAID policy on the use of non EPA approved agricultural chemicals. Always observe pre-harvest interval and re-entry periods for the specific herbicide.

Cultivation of the bed can serve many purposes. To control winter annual weeds that have emerged in the field, cultivate at a shallow depth after the winter ferns (i.e., trash or ferns from previous season) have been mowed or burned off. Avoid damage to crowns by straddling the beds. At no time should tractor tires be driven on or across the rows. Following harvest, the field should be disked or tilled again to eliminate weeds that have emerged since the last cultivation and to prepare the field for summer fern production. Cultivation between the rows with a high-clearance tractor and 3-point hitch-mounted row cultivators will control the bulk of inter-row weeds during the growing season. One of the most common row cultivators for asparagus beds is a Lilliston Rolling cultivator. A row crop cultivator can also be used to reform the troughs and throw dirt up and onto the beds to reshape them and cover weeds. During harvest of spears and during fern production, in-row cultivation opportunities are limited. Yet, these in-row weeds pose the greatest threat because weed competition with ferns interferes with crown storage and reduces yield the following growing season.

Lilliston Rolling Cultivator

Recommended herbicides for use on asparagus are:

Table 1

1.2 to 2.5 – Postemergence

Fluazifop, MOA 1 Sethoxidim, MOA 1

0.2 to .3 Postemergence

Napropamide, MOA 15

1.2 to 2.5 Preemergence &

9.88 Preemergence

Asparagus (established) Preemergence

Fluazifop, MOA 1 Sethoxidim, MOA 1

0.2 to .3 Postemergence not be used within 1 day of harvest

Pre-Plant Fertilizer & Fertilizer Maintenance –

Ideal soil pH for asparagus is between 6.5 and 7.5. Acidic conditions (less than 6.5) can lead to reduced growth and yield. Corrective annual applications of lime may be necessary to elevate pH levels. Asparagus has a high tolerance for salt; a saturated soil extract can have an electrical conductivity (EC) as high as 6 dS/m with no impact on yield.

Pre-plant applications of cattle or chicken manure are very valuable and will reduce the chemical fertilizer requirement during establishment and during maintenance of the crop. Applications depend on availability of manure with amounts up to forty (40) MT per hectare incorporated into the topsoil at least six months but preferably a year prior to crown transplanting. Manure will add significant amounts of nitrogen, phosphorous, potassium and essential micronutrients. Annual maintenance applications of chicken manure at rates between seven to twelve tons per hectare and applications of cattle manure at rates between fifteen and twenty-five metric tons per hectare tons acre incorporated into the tops and sides of the beds will maintain the nutrient level and contribute to the annual requirement of nitrogen for the next year’s fern growth.

Phosphorous is important for root growth and especially during crown establishment. Phosphorous fertilizer is needed only at planting. Soil test will indicate how much phosphorous is needed. Fields with Olsen (bicarbonate extractable) soil phosphorous greater than fifteen (15) ppm have modest pre-plant phosphorous requirements of less than one hundred fifteen (115) kg/ha of P2O5 fields with less than ten (10) ppm soil phosphorous may require up to two hundred twenty five (225) kg/ha of P2O5.

Soils with exchangeable potassium of one hundred (150) ppm require no pre-plant potassium applications while fields with less than one hundred (100) ppm may benefit with an application of up to one hundred thirty-five (135) kg/ha of K2O. If needed, a maintenance application in the third and subsequent years of one hundred twelve kg/ha of K2O may be used.

Pre-plant applications of nitrogen will depend on the soil test and the amount of pre-plant manure applied. As insurance for the first year’s growth and for building up of nitrogen in the crowns, an application one hundred twelve (112) to two hundred twenty-five (225) kg/ha of nitrogen (N) may be used. An established asparagus field might require one hundred twelve (112) to four hundred forty eight (448) kg/ha of nitrogen (higher rates applicable to the sandy soils with low cation exchange capacity and low organic material. Any decision to apply fertilizer should be based on complete soil analysis and leaf nutrient analysis.

Programs should be set up to systematically analyze soil and asparagus leaf tissue and work with Technicians from the Institute to determine optimum soil and leaf nutrient levels and what materials could be used when nutrient levels fall below the optimal levels. An indication of the proper nutrient levels in both soils and leaves are indicated in tables from; Nutrient Status of Asparagus (Asparagus officinalis L.) Leaf and Soils in Western Thailand. YAMPRACHA, S.*, N. BOONPLANG and N. PHANCHINDAWAN, Department of Plant Production Technology, Faculty of Agricultural Technology, King Mongkut’s Institute of Technology, Ladkrabang, Bangkok, 10520, Thailand.

Fertigation using a drip irrigation application has significant benefits in being able to put fertilizer within the root zone and by putting specific soluble nutrients when needed. Fertilizer guides and manuals are available for consultation and field technicians with experience in fertilizers and fertigation should be consulted regularly.

Irrigation – Adequate moisture should be maintained for good germination and early seedling growth. Do not let asparagus dry while they are establishing a root system during the first two months. Water stress during this stage can reduce yields over the life of the plant. After the root system is established, irrigation cycles can be reduced to maintain the roots healthy and hydrated.

Flood, sprinkler or drip irrigation can be used for the asparagus planting in Kosovo. Flood irrigation needs to be managed especially during the harvest as alternate beds can be watered as required to allow the harvest labor to pass on dry and firm ground. Alternate rows can be flooded as the earlier rows dry to complete the cycle. Heavier cycles of flood irrigation are carried out after the end of harvest in tandem with the fertilization and before the first rains to push the spear and fern growth for the final summer accumulation of carbohydrates in the growing crown.

Sprinkler irrigation is a viable option but tends to cause more bed erosion and weed proliferation over the field. It is difficult to manage during the harvest as labor walkways are wetted causing a messy environment and possible compaction of the inter-rows by the passing tractors or harvest labor.

Drip irrigation is becoming a more common application for asparagus irrigation. There are two thoughts for considering drip tape location in asparagus plantings. Place the drip tape at twenty-five (25) centimeters, in the bottom of the planting trench and cover with soil. Use this as the base for placing the asparagus crown or seedling in the bottom of the trench during planting. Cover the crown as normal in the planting section described above. The advantage of placing the drip tape below the crown is that the wetting profile will remain below the surface, thus reducing weed germination and weed pressure along the bed. The disadvantage of placing the drip tape below the crown is that roots may tend to clog the orifice of the drip emitter thus shutting off the water supply along sections of the tape.

Another line of thinking is to cover the crown and place the drip tape above the crown instead of below the crown. Once the crown is laid down in the twenty-five (25) to twenty-two (22) centimeter trough, cover the crown with five (5) centimeters of soil. Place the drip tape on top of the soil and above the crown and cover over time as the crow develops and cover per the planting instruction listed above. The advantage of this method is the water saturates the soil above the crown thus fully bathing the roots with each watering and avoids roots clogging the drip tube orifice. The disadvantage is that depending on the texture of the soil, water may get to the surface and germinate weeds. A shallower drip line may result in greater rodent damage.

Size the drip tape as required meeting the water holding capacity requirements of the soil. The distance between emitters is usually forty-five (45) centimeters. This may be adjusted to achieve the appropriate application rate. Emitter flow rates of 0.6 to 3.8 liters per hour may be employed depending on the soil infiltration rate and the application rate desired. Typically 1.0 liter per hour emitters is used. Dripper line thickness generally runs between thirteen (13) to thirty-five (35) mil, with sixteen (16) mil the most common.

Timing of first application after the winter dormancy depends on the winter’s rainfall and could be as early as pre-harvest, during the harvest or after the final harvest. Some measure of soil moisture should be practiced to understand the water stress levels and under what conditions asparagus irrigation should be initiated. The plants will use two & one-half (2.5) to five (5) millimeters of water per day during active fern growth. As a rule of thumb, soil water levels should not be allowed to deplete more than fifty (50) to sixty (60) percent of field moisture capacity in the active root zone between fifteen (15) to sixty (60) centimeters of soil or go beyond a soil tension of seventy (70) centibars before initiating irrigation.

Theoretically, within the root zone between fifteen (15) to sixty (60) centimeters of sandy soil, the asparagus plant will use fifty percent of the available moisture in four days; in a loamy sand soil fifty percent of the water is depleted in eight (8) days; eleven (11) days in a sandy loam and seventeen days in a clay loam. However, evapotranspiration and rainfall influence irrigation requirements so technical formulas for irrigation need to be followed.

Under Kosovo conditions irrigation may be initiated as early as the harvest season but more than likely there will be adequate rainfall in the spring with water stress occurring later in the summer or fall during or after the harvest season. The systems should be in place to irrigate whenever required and in the amounts required.

The maintenance of your drip system centers on identification of the factors which can lead to reduction of the performance of your drip system and procedures to mitigate these negative impacts. Factors that can slow or stop flow through the drip system include suspended material, chemical precipitation, biological growth, root intrusion, soil ingestion and crimping of the dripperline. To ensure maximum system life requires that you reduce or eliminate the impact of the negative factors. This may require water treatment and a systematic program for regular maintenance. Consult with irrigations specialists and refer to the manuals for irrigation line maintenance before performing the procedures.

One of the best guides on asparagus irrigation is the NETAFIM USA, Asparagus Production Manual Using Sub Surface Irrigation.

Insect Pest Control – Various insect pests found in asparagus in limited or economically damaging populations should be first controlled using tested Integrated Pest management techniques and by the use of approved pesticides for use on asparagus.

Recommended treatments for asparagus insect pests are the following:

Disease Control – Fusarium wilt (Fusarium oxysporum, f.sp. asparagi and Fusarium moniliforme) is the most serious disease affecting asparagus production worldwide. It causes a slow decay of the crown and reduction in spear size and number, ultimately leading to lower yields. The problem increases with the age of the crop stand. Severity of the disease can be reduced with the selection of vigorous growing varieties (hybrids), use of clean seed and one-year-old crowns grown in non-infested soil, and good irrigation management. Replanting asparagus in the same area should be avoided for at least a ten (10) year period.

Asparagus crown and spear rot (Phytopthora magasperma var. sojae) is a soilborne fungal disease that is a problem particularly in soils that are saturated due to poor drainage. Crown rot and spear rot can occur if corrective and preventative measures are not employed resulting in stand loss and reduced production. Chemical and cultivation controls can be employed against this disease. Also, good drainage by sub-soiling, high bed construction and leveling the soil with one-half percent slope to facilitate water runoff prior to planting helps to avoid the environment suitable for fungus development.

Asparagus rust (Puccinia asparagi) and Cersopora stem and leaf spot (Cersopora asparagi) are tow fungal disease affecting the asparagus fern. They may require chemical control during some years. Good irrigation management, wide row spacing, highand orientation of planted rows with the prevailing wind may help reduce the incidence of asparagus rust. As with crown and spear rot, good drainage and soil leveling reduce the possibility of a wet environment.

These are the major fungal diseases affecting worldwide asparagus production. Asparagus purple spot and asparagus viruses I and II are also diseases encountered in asparagus but with less frequency and severity.

There are few organic control methods for asparagus diseases. Most controls are associated with use of sensible cultural practices, use of clean seeds and transplants, and incorporation of measure to ensure good drainage prior to planting.

Chemical controls for asparagus diseases are listed below. Always refer to the label for harvest interval and reentry period.

Fosetyl-AL

0.60 kgs/has

4.5 kgs/has

Sulfur Tebuconazole 354 gms/has Read Label 125 to 193 gms/has

Cholrothalonil Myclobutanil

1.8 kgs/has

3.75 to 7.5 kgs/has 142 gms/has

Fusarium wilt (Fusarium oxysporum, f.sp. asparagi and Fusarium moniliforme)

Asparagus rust (Puccinia asparagi)

Harvesting & Handling – Mature ferns are either chopped, often as part of the green trash hauled from the field, or windrowed with a swather or windrower. The ferns can also be mowed with a tractor mounted or pulled mower. After drying, chopped ferns may be burned and/or incorporated into the bed with a rotary power tiller. Fern chopping occurs generally in the late winter or early spring after the ferns have died-back from the winter dormancy. Following chopping, the planted beds are reworked to loosen the surface soil, reshaped with a Lilliston Rolling cultivator or row crop cultivator to consolidate the bed and trim off weeds that sprouted during the winter and spring, and fertilized if necessary. No irrigation is probably necessary since winter rains will be enough to get soil to field capacity.

Forage Cutter – Can be used for cutting asparagus ferns

Once the soil temperature gets to 10˚ C the spears begin to emerge. Emerging spears should be cut by hand. Early in the season fields are harvested every two to three days. Spears are cut at an angle just below the soil surface with an asparagus knife. Spindly and otherwise deformed spears are cut and discarded to allow for growth of the marketable spears. Cut spears must be approximately twenty-five (25) centimeters to allow for trim to twenty-three (23) to twenty (20) centimeters of all green asparagus during packing. Harvested spears are collected and placed on the beds in bunches or carried to collection centers around the field. The spears are placed in field boxes on a cart or trailer pulling tractor. Then they are taken out of the field and hauled to sheds for grading, packing, trimming and cooling.

Defects and loss of production can occur for various reasons. Prolonged wind or pelting by hailstones can cause the spears to bend. Asparagus roots and ferns or emerging spears grow best between temperatures 18˚ C and 29˚C with reduced development at temperatures lower than 13˚C and higher than 29˚C. Higher temperatures cause the spear tips to open prematurely, making the spear unmarketable in a condition commonly called “feathering”. Low temperatures reduce the emission of new buds on the crown. Freezing temperatures during spear emergence can cause “frosting”, discoloration of green spears. Frosted spears may still be marketable but will deteriorate quickly and lose quality and should be discarded to prevent market rejections.

Excess harvesting leads to a decline in production and a proliferation of small spears. A full cutting season of five to eight weeks may begin the third or even the fourth year after planting. Fields in the second year of production after transplanting crowns or seedlings may be harvested yielding seven hundred fifty (750) kilograms to one thousand (1,000) kilograms per hectare. They should only be harvested during the optimum periods and for three to four weeks at the most. Any excess harvest will debilitate the crown and reduce production over the life of the crop.

Asparagus can be harvested fully in the third to fourth year. Yields of three thousand (3,000) kilograms to six thousand (6,000) kilograms per hectare per year are typical production volumes for a continuous cropped field.

Spear quality in relation to the duration of harvest needs to be monitored closely starting in the fifth to six week of harvest. When the diameter of spears harvested declines, the spear tips open early and the crown begins to dehydrate and shrivel, it is time to stop harvesting. These are indications that the crown carbohydrate content is low and to continue harvesting will debilitate the crown and affect harvest volumes for the upcoming year.

Asparagus fields should produce good yields for eight (8) to ten (10) years. Asparagus is capable of a much longer production life, but it is usually limited in later years by weed infestations, disease infections, and overcutting of the beds.

Harvesting asparagus with gloves and asparagus knife

Post-harvest Handling – Asparagus is segregated, sized, checked for uniformity and quality characteristics, packed in either wood or fiberboard containers fitted with a moistened pad at the boase, hydro-cooled and kept in refrigerated storage generally at a packing shed as close to the production area as possible. For the European market, bundles are packed in one (1) kilogram bunches with six (6) bunches per box or in a loose pack of seven (7) kilograms.

Asparagus bundled and packed with cold storage indicator

Shoots are packed according to “Extra Class” or Class I.

“Extra Class” – Superior Quality. Very well formed and practically straight. Very compact tips. A few slight traces of rust (removable by normal peeling). No traces of woodiness. Green asparagus must be totally green. The cut at the base must be square. When packed in bundles, outside shoots can be beveled less than or equal to 1 centimeter. Tolerance: 5% by number or weight out of standards, but conforming to Class I standards, or exceptionally coming within Class I tolerances, or having slight unscarred, after-harvesting cracks.

Class I – Good quality. Well-formed and may be slightly curved. Compact tips. Slight traces of rust (removable by normal peeling). A trace of woodiness on the lower part is permissible, provided it disappears with normal peeling. Green asparagus must be green for 80% of the length. The cut at the base must be as square as possible. Tolerance: 10% by number or weight out of standards, but conforming to Class II standards, or exceptionally coming within Class I tolerances, or having slight unscarred cracks appearing after harvest.

Class II – Not considered because of poor commercial quality. May be sold locally but poor quality does not even merit commercial consideration.

Sizing Extra & Class I – Length is not less than seventeen (17) centimeters with a maximum length of twenty-seven (27) centimeters. Maximum difference in length of shoots packed in firmly bound bundles is less than or equal to five (5) centimeters.

Sizing Extra & Class I – Minimum diameter is three (3) millimeters with the variation between the thinnest and the thickest shoot in the same package or the same bundle is eight (8) millimeters maximum. Size tolerance: 10% by number or weight of shoots out of specification with a deviation of plus or minus one (1) centimeter in length and plus or minus tow (2) millimeters in diameter.

Uniformity: in origin, quality, color group, and size (where sizing is compulsory). Visible part representative of the entire content. Color: shoots of different color groups may be allowed within the following limits. 10% by number or weight of another color group.

Packaging – The produce must be packed in a way to ensure its protection. Materials must be new, clean and of a proper quality. Non-toxic ink or glue. Packages must be free of all foreign matter. Material is generally water resistant since it is subject to hydro-cooling and high moisture environments.

Presentation – (a) in bundles, firmly bound and protected by paper. Outside shoots must correspond in appearance and diameter with the average of the whole bundle. “Extra” Class shoots in a bundle must be of the same length. In any one package: bundles of the same weight and length and evenly arranged. (b) in unit packages, or arranged but not bundled in the package. This could be defined as loose pack.

Cold Chain – Asparagus has a high moisture requirement so it’s necessary to minimize the time left out in the field under sun, or left on the field trailer waiting for transport to the packing shed. Taking the “field heat” out of the product is the key. Some field trays or bins include a lining of wet burlap sack or other water absorbent material to keep the asparagus temperature from rising cool and keep it hydrated. In some cases the trays or bins are hydro-cooled as soon as they arrive at the packing shed, especially if they are going to be stored for a long time prior to packing. Some of the field trays are stored in refrigerated containers or in a cold storage shed to prevent further rises in temperature. In other cases hydro-cooling occurs after packing and before storage in the refrigerated warehouse. To hydro-cool the asparagus, chlorinated water at approximately 1˚ C to 3˚ C is drenched over the shoots for approximately fifteen (15) minutes to remove the field heat from the spears. To maximize shelf life, asparagus needs to be stored at 2˚ C to 4˚ C with ninety (90%) percent to ninety-five (95%) percent relative humidity.

Preparing the asparagus for transportation requires arranging the cartons of asparagus on pallets and using corner posts and straps to consolidate and unitize the load. Pallets are arranged inside the containers with considerations for adequate cold air movement around the outsides of the boxes. Asparagus can continue to respire, even in the container. Poor air circulation can lead to quality issues and loss of shelf life.

At high temperatures, asparagus spears lose natural sugar, flavor, and vitamin C and they become tough and start to decay. If rapidly cooled and held at 2˚ C asparagus may be kept for about three (3) weeks. Desiccation can occur rapidly if the butt ends of the asparagus spears are not placed on wet pads. Spear will continue to elongate if not properly cooled and hydrated.

Bibliography

1. Asparagus, Vegetable Production Crop Guide for the Atlantic Provinces. 2005. Prepared by the Advisory Committee on Vegetable Crops, Published by authority of the Atlantic Provinces Agriculture Services Coordinating Committee

2. The Origin of Asparagus, from www.docstoc.com, September 2011

3. The World’s Healthiest Foods, www.whfoods.com, September 2011

4. Asparagus Production in California, 2011, UC Agriculture and Natural Resource, UC Vegetable Research Information Center, UC Davis.

5. The 2010 North Carolina Agriculture Chemical Manual, North Carolina Cooperative Extension Service, College of Agriculture and Life Sciences, N.C. State, Raleigh, N.C.

6. Commercial Asparagus Production, 2001, Douglas C. Sander, Extension Horticultural Specialist, Department of Horticultural Sciences, College of Agriculture and Life Sciences, North Carolina State University.

7. NETAFIM USA, Asparagus Production Manual Using Subsurface Irrigation.

8. University of Minnesota Extension, Vegetable Crop Management. Growing Asparagus in Minnesota. A Production Guide: Vincent A. Fritz, Carl J. Rosen, William D. Hutchison, Roger L. Becker, Janna Beckerman, Jerry A. Wright, Cindy B.S. Tong, and Terry Nennich.

9. ADC Commercialization Bulletins #10, published by the Agribusiness Development Centre of the USAID funded Uganda’s Investment in Developing Export Agriculture (IDEA) Project.

10. EU Marketing Standard, Asparagus – File number 4, version 2, Source EU, by Freshfel Europe. Reference – Regulation 2399/1999 of 9 of November, 1999. Amended by Regulation 46/2033 of 10 January 2003.

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