While high-oil corn plantings are growing at a rapid pace, farmers may want to proceed with more caution in light of recent pollination problems in west central Ohio and a few other isolated areas.

In 1997, 20 farmers in Ohio's Champaign and Logan counties suffered substantial yield losses when they planted high-oil corn into corn-on-corn fields. Interestingly, these same farmers reported normal yields from the high-oil corn they planted in rotation with soybeans or wheat. Seventeen of the 20 farmers who experienced problems have met with an attorney to seek restitution from the companies involved.

After two successful years of growing Pfister TopCross high-oil corn, Burley Hall, his son Chad and his half-brother Joe Smith, who farm together, planted 1,250 acres of Pfister TC Blend high-oil corn in 1997 (their total corn acreage). Where the high-oil corn was planted in rotation with soybeans, they harvested 155 to 160 bu./acre. However, the 600 acres of high-oil corn they planted in continuous corn fields yielded only 6 to 35 bu./acre. Poor pollination and reduced kernel set were evident. Conventional corn in a neighbor's nearby field yielded normally (150 to 170 bu./acre), according to Hall.

He figures their farm operation lost $240,000 of potential high-oil corn income. They will recover $50,000 of that loss through crop insurance. "This is a devastating loss. The companies say this is an isolated problem, but I wonder if it would have come to light if we hadn't planted such a large acreage to high-oil corn," Hall says.

Although his loss was not as severe, Sheffield, IL, grower Ken Brummel says he also experienced pollination problems on three different high-oil TC Blends in 1997. Heat and drought stress during May and June affected yields of both conventional and high-oil corn in the area. "My high-oil corn yielded 86 bu./acre; about 30 percent less than conventional corn in the immediate area. Kernels were aborted on both the conventional corn and the high-oil corn, but the conventional corn was completely pollinated. The ears on my high-oil corn were only partially pollinated," reports the Sheffield grower. "In ideal conditions high-oil corn works. Two years ago I produced high-oil corn that yielded 135 bu./acre. But, in my opinion, the high-oil production system does not work when you have stress conditions. As we move into an era of more specialty crops we need the assurance that these products work. Farmers' can't stand the risk."

Unfilled ears. About 2,000 out of 10,000 acres of high-oil corn near West Liberty and Urbana, OH, were affected by pollination and kernel set problems, according to Peter Thomison, agronomist, Ohio State University. Poor kernel set of less than 50% was observed in a number of TC Blends with different pollinators and from different seed companies.

Adverse weather and severe Western corn rootworm beetle pressure in continuous corn fields contributed to the problem. Delayed planting the previous year may have resulted in an unusually high beetle population. The farmers used soil-applied insecticides, but their effectiveness was reduced by adverse spring weather conditions that delayed crop emergence.

"In fields following corn, there was usually extensive silk clipping, root lodging or goosenecking of the plants, Thomison says. "Rootworm beetles can cause significant yield losses during pollination if silks are severely clipped before pollination is 50 percent completed. Potential for such injury could be considerably greater with a TC Blend compared to a normal hybrid since less than 10 percent of the plants in a blend would be producing pollen."

Uneven plant development also was evident in most fields. Most of the fields were planted in early to mid April, but emergence was delayed by cold, wet soil conditions throughout much of May. "Uneven plant emergence and development probably resulted in a wider range of silking dates. There may have been inadequate pollen available for late silking plants," Thomison surmises.

Fewer pollinators. The TopCross high-oil grain production system involves planting a blend of two types of seed corn. About 90 to 92% of seed in the blend is the "grain parent," an elite male-sterile hybrid that doesn't produce pollen. The remaining 8 to 10% is a special "pollinator" licensed through a DuPont seed development collaboration. Pollen shed from these pollinator plants contain special genes that cause higher oil production in the kernel.

Steve Butzen, agronomy information specialist with Pioneer Hi-Bred International, notes that TC Blends may be more vulnerable to severe stress than normal hybrids. "There's two different genetic sources of seed in the field and each may react differently to adverse conditions. If development of the 'grain parent' and the 'pollinator' get out-of-sync it could adversely affect pollination," he says.

Agronomists for Dupont and Pfister agree that rootworm beetles and adverse weather contributed to this isolated problem. They note that these 2,000 acres represent less than one percent of the 700,000 acres of high-oil corn planted in 1997. They do not attribute the poor yields to the grain parent or the pollinator seed. DuPont agronomist Stuart Kaplan disagrees with claims that TC Blends are more vulnerable to stress and poor pollination. "TopCross pollinators shed more pollen per plant and shed it for a longer time. Pollen will shed for up to two weeks compared to 6 to 8 days in a field of normal corn," he says. "More pollen is produced than in conventional fields where half the plants have fertile tassels."

However, in its "limitation of warranty and liability statement," Dupont Quality Grains acknowledges that insects and disease injury, hail damage and drought stress during the period between planting and immediately after pollination may result in an insufficient quantity of pollen or missed timing of pollen shed in relation to silking. It notes these conditions can also affect conventional corn.

Must watch closely. High-yield management practices recommended for use in normal corn production become especially important in TopCross high-oil corn production.

Farmers should not plant high-oil corn following corn without implementing a proper insect scouting program. Planting in rotation with another crop is recommended because it reduces disease and insect pressure which when severe may affect TC Blends more than normal corn, according to Thomison. It also reduces volunteer corn which could fertilize the grain parent and reduce overall oil content.

Linda Wyss, Pioneer's product manager for corn feed traits, says Pioneer will focus on customer education as it launches its first two TC Blend products this year. "To reduce risk and maximize yields of TC Blends, growers should increase plant populations by 2,000 ppa, plant on their best soils, plant in rotation with another crop, follow isolation requirements, conduct an active scouting program, consider irrigation and take out multi-peril crop insurance," she advises.

Scouting throughout the growing season is imperative, agrees Thomison. "Early season insect problems which reduce stand or injure young plants could be particularly serious in TC Blends if the number of functioning pollinator plants is reduced below the level needed for successful pollination," he says.

Similarly, excessive pollen feeding and silk clipping by insects such as aphids, rootworm beetles and Japanese beetles could pose a greater threat to TC Blends than to normal corn because of the limited number of pollinators," he adds. Some companies suggest growers consider the higher value of TopCross grain when determining economic thresholds for pest control.

Thomison notes crop rotation may no longer be an effective deterrent against Western corn rootworm in areas of Illinois and Indiana where Western corn rootworm has been reported to damage corn following soybeans.

Some companies suggest using conventional tillage to help ensure even emergence and thereby enhance uniform development of the TC Blend pollinators and grain parents. If planting early or using reduced tillage, seeding rates should be adjusted 10 to 15% higher to compensate for increased seedling mortality.