Vegetable trials are among the best education-al tools available to Extension personnel—they should be an integral part of every agricultural county agent’s program. Field trials and demon-strations introduce new varieties, methods (Fig. 1), or concepts to local farmers. They also offer the county agent new opportunities to work closely with cooperating farmers, who are usually leaders in the community, as well as agricultural industry representatives.

For the best chances of success, county agents need to carefully choose the varieties to evaluate; select appropriate cooperating farmers to work with; establish the responsibilities of the agent and farmers; obtain seed, supplies, and equipment; establish the trial; make observations, take mea-surements, and take photos throughout the trial; and analyze and disseminate the results.

Choosing varietiesLimit the number of varieties or treatments in

your demonstration. The number may depend on: ◆ The number of new varieties available in a

particular crop ◆ The resources available, including land and

harvest labor ◆ The frequency of harvest; for example, you

may need to plant fewer varieties of a crop such as cucumbers or peppers (Fig. 2), which must be harvested several times a week, than once-harvested vegetables such as potatoes or carrots

In all variety evaluations, include the standard, recommended local variety as a basis for compari-son with the newer varieties or breeding lines. The same holds true for concept demonstrations that compare local practices with the new techniques.

Guidelines for Conducting Extension Vegetable Trials

Joseph G. Masabni and Frank J. DainelloExtension Vegetable Specialist, and Former Extension Horticulturist

The Texas A&M University System

EHT-0319/13

Figure 1. Pumpkins being evaluated to determine whether raised beds will help control root nematodes. (photo by Robert Burns).

Figure 2. Plant fewer varieties of crops such as pepper because they must be harvested three to five times in a season.

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To allow enough time to acquire seed, choose the varieties to evaluate at least 2 months before the planting date. Request seeds of varieties that are known to produce well in your area. For help with variety selection, contact Extension vegetable specialists and seed company representatives. Ask them to prioritize the varieties in case you don’t have room or resources to try them all.

Get as much information as possible from the company about its seed, including germination percentage, seed treatments, and expected days to maturity. This data may influence your seeding rates or plot design. It may also explain any later problems in stand establishment or seedling vigor.

Selecting cooperatorsFarmers who participate in on-farm research

are called cooperators. The success or failure of any field demonstration is closely related to the people selected to be cooperators.

A cooperator should be: ◆ Interested in the project ◆ Willing to contribute to the demonstration’s

success ◆ An experienced grower, preferably of the

vegetable to be evaluatedWork with as many cooperators as possible. They

will enable you to evaluate varieties or concepts under different field and management conditions.

Assigning responsibilitiesIt is vital to clarify the responsibilities of both

the agent and the cooperators before starting the trial. Draw up an agreement (next page) and have it checked by the county Extension director and/or regional program director. Print the agreement on your letterhead, sign it, and have it signed by the cooperator. Deliver the agreement both orally and in writing.

Responsibilities of the Extension agent and the cooperator vary from one demonstration to anoth-er. In general, the Extension agent is responsible for:

◆ Obtaining seed or transplants ◆ Establishing the plots and giving the cooper-

ator a field map and treatment codes

◆ Keeping yield and other records and obser-vations

◆ Summarizing the data, preparing a report, and disseminating the information, making sure that the cooperators receive a copy of the report

◆ Coordinating field days and other activities related to the trial (Fig. 3)

Figure 3. A field day in Amarillo on the results of a study on drought-tolerant corn hybrids. (photo by Kay Ledbetter).

The cooperator is generally responsible for providing land as well as management and mainte-nance inputs such as fertilizer, fumigation, mulch, weed management, and pest control.

The cultural methods for the demonstration plot should be the same as for the cooperator’s crop and in accordance with Extension recommendations.

Obtaining seedCollect all seed and other supplies needed to

conduct the trial at least 1 month before the antici-pated planting date. Most seed companies are eager to cooperate in Extension trials by supplying seeds in exchange for receiving a written report of the results.

Hybrid seed is generally available from the developing company and associated dealers; open-pollinated varieties may be available from several sources. The major sources of vegetable seed are listed in the Vegetable Grower’s Handbook, which is available from the Texas A&M AgriLife Book-store at https://agrilifebookstore.org/. Extension vegetable crops specialists can supply the names of specific people to contact at many seed companies.

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Vegetable Variety Demonstration Agreement

Vegetable _______________________________ Study ____________________________________

This agreement establishes responsibilities of the County Extension Agent and the Cooperator to ensure the demonstration’s success insofar as possible.

Responsibilities of the Cooperator include:

Responsibilities of the Agent include:

Joint responsibilities include:

As part of this demonstration, an Extension field day £ will £ will not be held at the site.

Signed:

__________________________________________ _________________________________________Cooperator Extension Agent

Date: ______________________ Date: ___________________

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TABLE 1: General supplies needed for most field demonstration projects

Item Description/use

Bags, paper Heavy weight; in various sizes for harvesting small plots; for larger commodities, plastic buckets and/or bushel baskets may be needed

Buckets, picking Plastic nesting buckets of about ½ bu; may be supplied by cooperator

Calipers Available in sizes to measure produce from cherry tomatoes to watermelons

Camera For photographing the plots and harvested crops

Data sheets Designed specifically for each crop

Flagging tape or tags For labeling picking buckets, plots, etc.

Flags 2–3 ft long, can be color coded to mark plots for easy identification

Fruit-sizing rings May be purchased or created to conform to USDA grade specifications, such as for cantaloupe or honeydew

Hand seeder Adapted precision-type seeder from a company such as Cole, Earthway, or Esmay

Knives In assorted sizes for harvesting

Labels Wooden, 10–12 in. long, for identifying treatment in the field

Marking pens and pencils Weatherproof

Marking wheels or sticks Convenient distances for in-row plant spacing

Mulch punch Plastic, 2–3 in. in diameter, for making plant holes in mulched beds

Planter flats or other transplant trays

1–2½ in. cells will accommodate most vegetables

Publication USDA Grade Standards for the various commodities: http://www.ams.usda.gov

Refractometer Hand-held type for determining soluble solids, such as for muskmelon or watermelon

Rulers and yardsticks Heavy duty, accurate measurement

Scales Preferably hanging, milk type with 20–60 lb capacity, or household or platform scales with 12–60 lb capacity

Seed envelopes Clasp type for easy resealing

Stakes, cages, and string For crops requiring support; usually supplied by the cooperator

String To align field stakes

Tape Steel or fiberglass, 100 ft or more, for laying out plots

Tripod Folding or rigid, for supporting hanging scales

For the trial to be a success, the seeds or trans-plants must be available in time to fit into the grower’s planting schedule. In many parts of the state, trials of transplants such as tomato and pep-per entail more logistical problems than those of direct-seeded crops. A solution is to supply the seed for producing the transplants to the grower or to a producer of bedding plants.

Gathering supplies and equipmentGenerally, demonstrations should not require

expensive or elaborate equipment. Some items are

necessary for most demonstrations (Table 1); oth-ers are specific to the vegetables being studied.

Most of these materials are available from sever-al sources, including laboratory, forestry, or horti-cultural supply companies as well as local hardware, discount, garden, and farm supply stores. Occasion-ally, some pieces of equipment may need to be built to meet the requirements of the demonstration.

Establishing the trialDemonstration trials should be conducted in

season—that is, planted at the normal time for your

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area and the crop being evaluated. Finalize your plans well before the anticipated planting date. You’ll need to coordinate with the farmer in advance and continue communication throughout the planting.

The most accurate method for conducting trials is randomization and replication. Replications are repeated, independent plantings or treatment applications. Other than plantings for demonstra-tion purposes, conduct all vegetable trials using this method. If the trial is set up properly, the statistical analysis of the data is more likely to be valid.

Replications: Determine the number of replications (reps) for your project according to the variability of the site conditions (such as differences in drainage or soil fertility), the type of treatment (such as a pesticide application), and the type of plants to be evaluated. More replications would be needed for crops that are planted far apart or that grow large, such as vining plants; fewer replica-tions would be needed for crops planted closely or smaller plants, such as herbs. Generally, four reps are enough.

The unit of land where the varieties are planted is known as a plot. In a replicated trial, each rep-licate should contain a plot of the suggested size (Table 2) for each treatment. For crops not listed in Table 2, use the guidelines of similar crops; for example, the format for cowpeas would be like that for beans. Contact an Extension vegetable special-ist for suggestions on crops that do not seem to fit these guidelines.

The procedures for trial establishment depend on the size of the cooperator’s operation and/or treatment limitations such as the amount of seed samples.

For small projects, mark out a representative plot of the required size that the cooperator will leave for you to seed or transplant by hand or with small equipment. It usually works best for the coop-erator to plant the field and the demonstration area immediately afterward under your supervision.

For larger projects, where seed supplies are plentiful and the crop is planted mechanically, the plots can be seeded in rows with the cooperator’s

TABLE 2: Guidelines for conducting trials of selected crops grown in Texas

Vegetable Plot size # Harvests Data to record Observations

Bean, snap 10–20 ft row, 2 in. in-row plant spacing on 38–40 in. beds; 1 plant row/bed

1–3 Days to first harvest; yield, expressed as 30 lb bushels (for multiple-harvest plots, early yield is desirable); plant height; pod color, length, shape (round, oval, or flat), straightness (qualitative); qualitative pod removal force requirement (for machine harvest)

Insect problems; suscepti-bility to disease; in areas of high pH, susceptibility to iron chlorosis

Broccoli and cauliflower

20–40 plants spaced 6–12 in. apart; 1–2 plant rows/38–40 in. bed

1–3 Days to first harvest, early and total yield expressed as 23 lb cartons, head or curd diameter, head or curd weight, number of harvests, percent marketable

Susceptibility to disease and disorders such as hol-low stem; uniformity; head tightness, cover, shape (domed), leafiness, color; broccoli bead character-istics

Cabbage 20–40 plants spaced 6–12 in. apart, 2 plant rows/38–40 in. bed

1–3 Days to first harvest, yield expressed as 50 lb cartons or crates; average head weight, core length; head, shape, tightness; plant color; percent marketable

Susceptibility to disease; incidence of tip burn

continued on next page

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TABLE 2 continued

Vegetable Plot size # Harvests Data to record Observations

Carrot 2-row bed, 20 ft long; the center 8–10 ft; try for 1 in. in-row plant spacing

1 for each variety at ¾–1 in. shoulder diameter, processing types at ≥2 in. shoulder diameter

Days to harvest, yield expressed as 50 lb units or tons/A for processing; percent marketable; root length, diameter, shape, color (external and internal)

Susceptibility to disease; top vigor, height; predominance of core

Corn (sweet) 25 ft long rows; 12 in. in-row plant spacing: 1 row if varieties maturing at about the same time, 3 rows for pollination if not; separate endosperm types at least 500 ft if possible

1 Days to mid-silk to estimate harvest date, yield expressed as 42 lb crates containing 4½–5 dozen ears, number of marketable ears, days to harvest, plant height, ear length and diameter, husked ear length, number of kernel rows, tip fill, husk cover

Susceptibility to disease; lodging; ease of snapping; flag leaves; kernel color, sweetness, tenderness; tendency for double ears

Cucumber (slicers)

12–25 plants/entry, 1 ft in-row spacing on 38–40 in. beds

5–10, ideally every other day

Days to first harvest, early and total yield expressed as 55 lb bushels

Fruit deformity, average fruit weight and length, susceptibility to disease

Cucumber (pickling)

20–40 plants, 6 in. in-row spacing on 38–40 in. bed, 1–2 plant rows/bed

1 Fruit weight expressed in tons/A; fruit color, length, diameter; Pickling Cucumber Improvement Committee (PCIC) values for pickles in four grades: #1s: 1 in. diameter, #2s: 1–1.5 in. diameter, #3s: 1.5–2 in. diameter, #4s: more than 2 in. diameter

Fruit deformity, average fruit weight and length, susceptibility to disease

Lettuce 1 bed: 20 ft long x 38–40 in. wide; 2 plant rows/bed with 6 in. in-row plant spacing

1 Yield expressed as 50 lb cartons containing 24 heads; days to harvest; head weight, firmness; percent harvested or marketable

Susceptibility to disease; incidence of defects such as cracked rib, tip burn, and bolting; ability to hold in the field

Muskmelon 15–25 plants spaced 1 ft apart, 6 ft beds with 1 plant row, train vines on beds to make harvest easier and prevent variety mixture during harvest

3–5 Days to first harvest; early and total yield expressed as cwt (hundredweight or 100 lb); fruit weight, shape, size (small, medium, large); cavity dimensions; flesh width; soluble solids

Susceptibility to disease, fruit flesh color, presence of sutures, netting characteristics

continued on next page

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TABLE 2 continued

Vegetable Plot size # Harvests Data to record Observations

Onion 2 rows, 10–20 ft long with 3 in. in-row plant spacing

1 Yields expressed as 50 lb bags; days to harvest; percent marketable; bulb diameter, weight; neck diameter (10 bulbs of the predominant size)

Susceptibility to disease; incidence of defects such as bolting, rots; curing characteristics

Pepper 20–30 plants with 12 in. in-row plant spacing, 1–2 plant rows/ 38–40 in. bed

3–5 at full green maturity

Early and total yields expressed as 25 lb bushels, days to harvest, fruit weight, number of fruit per bushel, number of lobes, wall thickness, length/diameter ratio

Susceptibility to disease

Potato 1 row, 20 ft long with 12 in. in-row plant spacing

1 Yield expressed as cwt; days to harvest; tuber shape; skin color, type (smooth, russet); specific gravity

Susceptibility to disease, occurrence of tuber defects

Radish 3–4 ft row, 36–48 plants

1, varieties may require different harvest days

Days to harvest; average root weight; proportion of roots in size classes; marketable yield expressed as 12 lb cartons; proportion of roots that are marketable; incidence of defects, splits, cracks, misshapen roots, pithiness, black root rot

Susceptibility to disease, leaf characteristics

Squash and pumpkin

12–25 plants Squash: every other day for 3–5 weeks; pumpkin: 1

Yield expressed as 42 lb bushels for summer squash and cwt1 for winter squash and pumpkin; early yield for summer squash; days to first harvest; fruit color, number, shape; fruit weight and marketable percent for pumpkin and winter squash

Susceptibility to disease, plant habit

Tomato 10 plants with 2–3 ft in-row plant spacing; 6 ft plant beds with 1 plant row; should be trellised, caged, or staked

3–5 Yield expressed as 25 lb cartons; days to first harvest; fruit weight, shape; proportion of extra-large, large, medium, and small fruit

Susceptibility to disease, occurrence of fruit defects (cracking, blossom end rot)

Watermelon 10–12 plants spaced 2–3 ft apart on 6–10 ft beds, train vines on beds to make harvest easier and to prevent variety mixture during harvest

1 Early and total yield expressed as cwt, days to first harvest, average fruit weight, percent soluble solids (sugars)

Susceptibility to disease, rind characteristics, internal characteristics

1: cwt or hundred weight is equal to 100 pounds. For example, a winter squash harvest of 1,000 lb would equal 10 cwt.

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equipment. After emergence, you can select uni-form areas in the field for observation, yield, and other measurements.

It is harder to determine the number of plants to grow in each plot. For tomatoes and peppers, 8 to 12 plants per plot might be satisfactory; a bean plot might require a minimum of 60 to 100 plants.

It may be unrealistic to plan a replicated trial for vegetables that must be harvested often, such as okra and summer squash. For these vegetables, you may use single plots of each variety, with each plot being two or three times larger than the size suggested in Table 2.

TABLE 3: An example of a code assignment for five varieties of tomatoes: ‘Big Girl’, ‘Desirable’, ‘Gold Nugget’, ‘Star’, and ‘Sweet Wonder’

Code Variety

1 ‘Sweet Wonder’

2 ‘Big Girl’

3 ‘Star’

4 ‘Gold Nugget’

5 ‘Desirable’

Figure 4. Harvest in a study on short-day onions.

Place each variety or treatment randomly within each replicate by using a computer-generated program, dealing playing cards, or dropping plot markers.

Computer-generated programs: Enter the code numbers into a form at Random.org (http://www.random.org/), Research Randomizer (http://www.randomizer.org/), or a similar site.

Playing cards: Each suit can represent a dif-ferent replicate. Shuffle the cards well. As you deal them, place each number in a blank space on your field map (Table 5). Remember, always begin left and proceed to right.

Plot markers: 1. Identify all plots with plot markers. 2. Label each marker with the replicate number

and treatment number.3. Sort all like rep numbers into a bundle.4. Drop each bundle separately and pick up

each marker randomly.5. Assign a spot on the map in the appropriate

rep in the order that the marker was picked up.

For a field design to be valid statistically, each replicate must be adjacent to or touch another rep at some point, as must all treatments (plots) within each replicate. Always select uniform spots in a field large enough to accommodate all replicates of the test (Fig. 4).

To reduce variability and increase precision, in-clude guard rows around the test plot area. A guard row is an extra row planted on both sides of the trial with plants like those in the test area. Plants on the borders of a plot may have access to more light,

The design used most often for trials is the randomized complete block. A block is a collection of plots, each with homogeneous plants and/or microenvironments. A block can have groupings of similar plants, treatments, or site conditions. The conditions within a block should be as homo-geneous as possible; between blocks, there may be large differences.

Randomly assign the varieties or treatments within each block. Randomization ensures that each plant has the same chance of receiving any of the treatments. Begin the randomization process by arbitrarily assigning a code number to each variety or treatment (Table 3).

To simplify the procedure, draw up a blank field map depicting all replicates, with a slot for each treatment or variety entry. Table 4 is an example of a blank field map with four replicates.

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nutrients, or space for roots than the plants in the center of the plot. They also may be subject to more damage from insects, diseases, or wind. Guard rows reduce these border effects.

Consider allotting space at the beginning of the trial to be left unharvested to show to field day participants. These observation rows are especially useful for the plants of leaf and root crops that are destroyed during harvest.

Clearly mark all plots with large field stakes and flags. Smaller stakes and flags can disappear over the 3-month period of most trials. Create a field map showing the plots and surrounding areas, and give a copy to the cooperator.

During the trial, keep careful records of data on yield, plant height, days to first harvest, and other

parameters specific to the crop being studied (Fig. 5).

For help in analyzing the data and advice on ap-propriate statistical analysis, contact an Extension vegetable specialist.

Shooting photographsTake photos of plot establishment, plant emer-

gence, transplanting, harvest, harvested plant products, and striking differences among varieties in performance or disease susceptibility. These photos will be extremely useful for future Exten-sion meetings and publications.

Label the treatment or variety legibly. Prepare the labels in the office beforehand to ensure that they are available for photographing plots at the appropriate times.

Reporting yieldsOften the predetermined in-row spacing will

not produce a perfect stand. If the varieties’ stands deviate greatly, your results and interpretations could be faulty. Therefore, always count stands and subject the results to statistical analysis. It is more meaningful to report the plant stands and actual yields rather than calculated yields based on a per-fect stand. Calculated yields may be exaggerated because of reduced in-row plant competition.

Yields can be reported by plot, by acre, or by 1,000 linear bed feet (lbf). Plot yields provide a

TABLE 4: Example of a blank field map on which to enter treatments or varieties

Bed 1 2 3 4 5 6 7

Replicate 1

Guard row Guard rowReplicate 2

Replicate 3

Replicate 4

TABLE 5: Example of a field map with the varieties placed in random order

Bed 1 2 3 4 5 6 7

Replicate 1

Guard row

5 3 1 2 4

Guard rowReplicate 2 3 4 2 1 5

Replicate 3 4 1 5 2 3

Replicate 4 1 2 3 4 5

Figure 5. For cabbage, keep records on such data as plant color, average head weight, the number of days to first harvest, and yield expressed as 50-pound cartons or crates.

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good comparison among the varieties or treatments being evaluated. However, there is some advantage in reporting acre yields instead, because they can be compared with grower yields or state average yields, which are expressed by acre.

Where wide-row cultural systems are used, it may be more useful to express yields per 1,000 lbf.

Disseminating the resultsA trial is not complete until the report is written

and the results are sent to the cooperator(s), the Extension vegetable specialist, and the seed compa-nies that supplied the materials.

To disseminate the results further and maxi-mize the educational and personal benefits of your demonstration trial, consider the following sugges-tions.

Conduct a field day to allow growers to study the varieties and/or concepts (Fig. 6). A success-ful field day will require good publicity, personal reminders to key growers, signs directing visitors to the field, well-marked plots, and field maps with treatment codes to distribute.

This type of meeting usually works best with only a brief introduction of what is being done and why, followed by self-guided tours through the plots. Be available to respond to questions, but allow the growers to evaluate the varieties for themselves.

Some light refreshments will help keep the growers around to discuss what they have learned and give you a chance for more interaction. The re-freshments could be sponsored by a seed company or another agribusiness.

Contact the local farm newspaper editor, who may publish an article and/or photo-

graphs on the demonstration to inform growers who could not attend.

Include demonstration results in your county newsletter to give access to the results to those not at the meeting. It will also give all growers a record of the final results for their files.

AcknowledgmentThe information in this publication was initially

developed by Don Maynard, an Extension Vege-table Specialist at the University of Florida, and modified to meet the needs of Texas county agents.

Figure 6. A field day allowing growers to evaluated varieties being studied.

Texas A&M AgriLife Extension ServiceAgriLifeExtension.tamu.edu

More Extension publications can be found at AgriLifeBookstore.org

Educational programs of the Texas A&M AgriLife Extension Service are open to all people without regard to race, color, sex, religion, national origin, age, disability, genetic information, or veteran status.

The Texas A&M University System, U.S. Department of Agriculture, and the County Commissioners Courts of Texas Cooperating.

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