2006 Sunflower Survey Observations
Monday, January 15, 2007
filed under: Optimizing Plant Development/Yields
A sampling of sunflower fields across the Plains was evaluated in 2006 to determine production issues and opportunities. The annual sunflower field survey covered counties with at least 20,000 acres of sunflower. There was one field stop per 10,000 acres, with 162 fields surveyed – 84 in North Dakota, 34 in South Dakota, 10 in Minnesota, 15 in Kansas, 13 in Colorado, and 6 in Texas.
Larry Kleingartner, executive director of the National Sunflower Association, says that the U.S. sunflower survey data allows researchers to asses if there are emerging production and pest issues to address, and provides data for gaining EPA registrations for sunflower pest products. Results are also used to develop sunflower research priorities, and help the NSA assess pest treatments and the need for new pest products.
“We appreciate the cooperation of sunflower producers whose fields were included in the survey, and the nearly three dozen extension, university, and industry folks who invested their time to make the 2006 Sunflower Survey possible,” he says.
The survey confirmed that overall, producers are doing a good job at managing the crop, says Kleingartner, with yields and quality higher than anticipated due to good stewardship. “The hybrid seed companies are providing improved products each year, and the new pesticide tools are getting the job done for the majority of farmers,” he says.
North Dakota State University extension agronomist Duane Berglund coordinated the survey project. Complete survey results are available on the NSA’s web site, www.sunflowernsa.com – click on the ‘Growers’ link, then ‘USA Sunflower Survey.’ There, see the link to a PDF of the entire 2006 survey results, or click on ‘USA Sunflower Survey Maps,’ a link to an NDSU site with graphics of survey specifics by state.
Following are a number of observations from the 2006 Sunflower Survey.
Row Spacing, Tillage
Sunflower in most states was planted at row spacings greater than 20 inches, with N.D. the one exception, where narrow row planting is common. “Still more wheat in a lot of areas in N.D., and not as much corn as in other areas, so they’re using air seeders for wheat and sunflower, not planters.”
Most of the states are a mix of tillage systems, except Minnesota and South Dakota. Clearly, says Berglund, the influence of no-till guru Dwayne Beck, who manages the Dakota Lakes Research Farm near Pierre, S.D., is behind the high no-till adoption in South Dakota, which shows up in this survey. That stands in contrast to western Minnesota, where more confection sunflower in the survey and better moisture conditions (in fact, often excessive) combine for more reliance on conventional till. In North Dakota, more fields surveyed in the northern half of the state were conventional till, and more fields in the southern half minimum till or no-till
Top Yield Limiting Factors
Drought was the leading yield robber of sunflower in the Dakotas and Colorado, and in Minnesota, it was weeds and disease. Weeds were a leading problem for sunflower in Kansas as well, and in fields surveyed in north Texas, plant spacing.
Texas A&M extension agronomist Calvin Trostle notes that seeding rates for Texas - particularly at the level of irrigation that producers use - are lower than often used in the High Plains. This may exacerbate skips at planting that can be 4-5' of row, an area larger than what sunflower can fully compensate for. Planting depth might be a related issue.
"Best results are consistently obtained with planting into moisture at a depth sufficient to ensure time, particularly for larger confectionary seed, to imbibe the necessary water to germinate before hot, windy conditions may dry soils to the seed zone. If this happens, combined with individual planter units perhaps not being set properly, then there is a sizable blank in the row where no plants were ever established. This in turn reduces yield," says Trostle.
There were many fields where quality and yield was not impacted by any production issue. “We have been seeing this more consistently in the last several years, as farmers have more tools to deal with pests like wire worm and weeds,” says Kleingartner.
Sclerotinia was negligible to nonexistent in all states surveyed, mostly because of the dry conditions, and in part to hybrid tolerance that has been improving the past few years.
Other minor diseases showed up, however: incidence of phomopsis stem canker was over 10% in Minnesota, verticillium over 7% in Kansas, and rhizopus about 6% in the fields surveyed in Colorado and Texas. “It is possible that hail or insect damage in already drought-weakened plants made them more susceptible in cases to some of these minor diseases,” Berglund speculates. Keep in mind too that incidence measures whether a disease symptom was observed, he adds, and not necessarily that it was severe enough to result in yield losses.
Rust could also be detected, although at low levels. Rust was down from levels detected in the High Plains last year, under 1.5% severity in affected areas of the states surveyed, with the exception of Minnesota, where severity was estimated at about 3.5%, which would still be considered minor. “Late summer rains and above normal temperatures may have encouraged rust development there, and there were also more confection fields surveyed in Minnesota, which might not have the same level of rust tolerance compared to oils,” says Berglund.
The incidence of rust in the survey, albeit at low levels, indicates that it may be an emerging issue, and one that plant breeders will take into consideration.
Lodging was generally minor, although 8% ground lodging was observed in the fields surveyed in Minnesota, related perhaps to the higher incidence of phomopsis, which can result in weakened stems, exacerbated perhaps by larger, heavier confection heads. Root upheaval showed up in some of the sunflower fields surveyed in South Dakota, which may be related to storm damage.
Stem weevil activity increased compared to the 2005 survey in Texas, South Dakota, and most noticeably in Colorado. The biggest issue with stem weevil is potential lodging, although lodging was not a significant issue when the survey was taken in late September and early October.
Fields with high stem weevil infestations can be trouble spots for weevil activity the following season. Weevil larvae overwinter in chambers constructed in the lower stalk or crown roots of the sunflower plant. In the spring, larvae pupate in these chambers of infested stalks, from which adults emerge by chewing through the stalk mid/late June.
Producers should keep in mind as they shop for next year’s seed that some sunflower hybrids have better stalk strength than others. Plant population can also influence stalk diameter. Research at North Dakota State University indicated that in sunflower with a weevil population averaging 12 larvae per stalk, lodging was low at both 9,000 and 18,000 plants per acre, while almost 25% of plants lodged when stalk density increased to 36,000 plants per acre.
Long Horned Beetle
Long-horned beetle (also called stem borer - Dectes texanus) activity was also above levels detected in 2005, particularly in Colorado, Kansas, and South Dakota, primarily in the same central area of the state where stem weevils were a problem.
This insect has been researched by Kansas State University entomologist J.P. Michaud. His findings indicate that yield damage is minimal unless harvest is delayed. He reports that early or timely harvest will eliminate most instances of lodging due to this insect – it is interesting to note that lodging was not reported to be a problem in Kansas or Colorado (see lodging graphic). Avoid rotating soybeans after sunflower where this insect has been a problem. See fact sheet online: http://www.planthealth.info/borer_basics.htm
The following graphics summarize the incidence of broadleaf and grassy weeds at survey sites. Note that with incidence, the presence of weeds is identified, although they may or may not have been at densities to result in economic damage.
Weed pressure appeared to be more of a problem in the High Plains compared to the 2005 survey observations. That may be due in part to the dry conditions. For example, Berglund speculates that some of the pre-emerge herbicides might not have received sufficient rainfall to fully activate.
More detailed county-by-county observations of weed findings in the 2006 Sunflower Survey – including reports by specific weed and estimated infestation pressure – can be found online at the links provided at the beginning of this article.
– Tracy Sayler