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Laying the Foundation

Tuesday, February 1, 2000
filed under: Planting Systems

Two out of every six rows of sunflower that Euvene Gilbert and his grandson, Warren, produce are never harvested. Furthermore, their

remaining rows - all of which are irrigated - probably will not, even in

a good year, average much more than 500 pounds of seed per acre.

A Great Plains commercial sunflower producer would shudder at the

thought of losing one-third of his acreage and ending up with that sort

of yield level. For Gilbert, however, it's just business as usual; the

same outcome occurs every year.

The Gilberts, who farm near Chico, Calif., are foundation seed

producers, serving as the crucial "intermediary" step between seed

company breeding nurseries and the hybrid seed production fields. It's

their job to increase the volume of female seed available for planting

in hybrid seed fields the following year.

The Gilberts' 1999 30-acre confection foundation seed field was

planted in a "4:2" pattern: four rows of females for every two rows of

males. That's a common configuration in California foundation sunflower

fields - and different from hybrid seed production fields, where

configurations such as 14:4, 10:2, 8:2 or 6:2 are more likely to be


Why is the ratio of male-to-female rows higher in foundation seed

fields? There are several reasons, according to Bill Vaccaro of Vaccaro


First, the foundation male line often is a single-headed plant, whereas

the males in hybrid seed production fields are multi-headed. So these

males do not produce as much pollen on a per-plant basis.

Second, when producing the female inbreds, "it's very important to

have as high a genetic purity as possible," Vaccaro says. Increasing

the percentage of male plants helps bees "flood" the females with pollen

to maintain the necessary genetic purity.

Finally, a 4:2 pattern ensures a closer proximity of each male row

to the female rows. "Often, the amount of pollen isn't as critical as

the distance away from the female," Vaccaro explains. "Because these

females are all pollinated by bees, we need to keep the male close to

the female. So pollination efficiency becomes a matter of how many

times the bee crosses over from the male to the female."

Euvene Gilbert, who has been growing sunflower for more than 20

years, used to be a hybrid seed producer. Now, however, he and Warren

raise foundation seed exclusively. The per-acre sunflower income

doesn't match that from their almond orchards, he says - but it compares

quite favorably with other crops in their rotation.

Because it is sourced directly from breeders' nurseries, the volume

of planting seed for foundation seed fields is limited. Field sizes

("blocks") are usually quite small. Today, block sizes of 10 to 15

acres are fairly common; years ago, sizes of two, three or four acres

were routine. At 30 acres, the Gilberts' 1999 field was abnormally

large, making life easier for both the grower and the seed contractor.

Like hybrid seed producers, the Gilberts try to do as much ground

preparation as possible in the fall. In March, following a preplant

burndown with Roundup, they make a pass with their Lilliston cultivator,

simultaneously applying and incorporating starter fertilizer into the

bed centers.

Their herbicide (Treflan) goes on during the planting pass and is

immediately incorporated. "We run a knife ahead of our row gangs to cut

off the tops of our beds; then we throw moist soil from the side of the

bed up on top," Gilbert says. "We plant through that to place the seed

into moist, firm soil with the loose mulch on top."

The Gilberts' six-row sunflower planter carries female seeds in its

four center units and male seed in the outer two, so each pass leaves a

1:4:1 pattern. (Some growers use a separate two-row planter for the

males. Also, it's not uncommon for half the males to be planted several

days ahead of the other half to ensure the availability of sufficient

male pollen in the field across the entire female bloom period.)

Every row is irrigated in the Gilbert foundation seed fields.

Soils within their fields range from a light loam to heavy clay,

providing a real irrigation efficiency challenge. They'll typically

irrigate four times a season. Since the ground is still fairly loose at

the time of the initial watering and readily soaks up moisture, "we put

on a tremendous amount of water - sometimes more than an acre-foot,"

Euvene reports. Later applications are not as heavy, but he estimates

they'll still use a total of 3.0 to 3.5 feet per acre of water per

season, "plus our [normal] 20 inches of winter rain."

Because they don't have a drainage network on their ranch, the

Gilberts must manage their irrigation very proficiently to avoid having

standing water at field ends. Not only is that wasteful; but

temperatures often are around 100 degrees during irrigation periods, so

sunflower plants surrounded by standing water would essentially be


The man who sets irrigation tubes for Gilbert has been with him for

12 years and understands how each field handles water. That's a huge

benefit, Euvene affirms. During the initial irrigation, for example,

pushing that acre-foot of water through the field's first 70 rows might

take 17 to 18 hours; but because of differing soil types within the

field, "the next 70 rows might take only nine hours." The volume of

water is managed via the number and diameter of siphon tubes feeding

each row from the main ditch at the head of the field.

Vaccaro pays foundation seed growers like the Gilberts an attractive

flat rate per acre for their services. Yields are lower than those of

most hybrid seed fields. That's partly due to the higher percentage of

male rows in foundation fields; also, because foundation seed often

tends to be more difficult, culturally, to produce.

Seed is provided at no cost to the grower. The contractor also is

responsible for in-season roguing and for the harvesting of the

foundation fields. (In hybrid production fields, the grower typically

carries out the harvest under supervision of a company fieldman.) The

foundation seed grower is responsible for weed control, fertilization,

irrigation, bees, removing male rows, defoliation and any insecticide

applications. The company monitors each foundation field very closely

and, under terms of the contract, has the right to require such


"Because the foundation fields are so important for our hybrid seed

production the next year, we ask these growers to do a lot of things,"

Vaccaro relates. "Fields have to be perfect. If hand weeding needs to

be done, we expect them to do it. If we ask them to bring in extra

bees, they'll do so."

Assurance of genetic purity actually begins with field location.

The California Crop Improvement Association (CCIA) mandates that

foundation seed sunflower fields cannot be within 2.5 miles of each

other. CCIA personnel inspect each foundation field at least twice per

season, normally at the onset of bloom and again at full bloom. To

ensure genetic purity, very restrictive requirements govern the number

of allowable "off-types," and such plants must be promptly removed if

the number exceeds the limit. - Don Lilleboe

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