’08 Crop Survey Summary
The National Sunflower Association has been conducting in-depth field surveys for the last seven years, with the exception of 2004. Qualified volunteers randomly stop at approximately one field for every 10,000-15,000 acres on a county basis. Each volunteer uses the same format to determine yield-limiting factors, assess incidence and type of weeds, insect damage/presence, disease and agronomic issues such as plant spacing. The survey is conducted during the latter half of September prior to the first hard freeze so the presence of disease can still be identified. The survey summary has become a key factor for directing research and keeping ahead of approaching problems.
Determining a yield-limiting factor is a judgment call. Surveyors do an objective yield estimate and then consider what two factors might have limited yield. The top factors tend to vary from region to region; but disease, plant spacing and weeds continue to rate very high.
Of real interest is the fact that the “no problem” category is gaining each year. That is when the surveyors feel that the field has reached its peak potential and there are no management issues that can be identified.
Coordinator of the national survey, North Dakota State University professor emeritus Dr. Duane Berglund, says producers are doing a better job with the tools they have. “Although weeds continue to rank as a problem, we are seeing less and less fields with a serious weed problem,” Berglund remarks. “That obviously relates to better and more herbicide tools and farmers simply doing a better job with those herbicides. We have seen a considerable decline in insect damage as well, and that is again a factor of farmers doing a better job of scouting and timely treating.”
The equal distribution of plants in the field reflects good plant spacing. Plant skips may be the biggest problem. There could be various reasons for the skip, including no seed drop, dormant seed, poor seed-to-soil contact, lack of soil moisture, insect damage to the seedling, seedling disease or some type of animal damage.
“By the time we get to the field in late September, these early possible reasons for skips are impossible to identify,” Berglund notes. “We know the insect and fungicide seed treatments have eliminated some of the culprits. My guess is that planter calibration is the first place to look. We definitely see more skips in a solid-seeded field that is planted with an airseeder. We know it is a calibration issue when we see two or three plants in the same spot.” Berglund assumes that a field with poor plant spacing can have a 25% and higher yield penalty. “If other conditions in the field — such as disease and weed control — are good, then a field with good plant distribution usually measures out to over a ton and sometimes well over a ton.”
Kochia continues to be the most consistent weed throughout the production region. “It is such a prolific and competitive weed,” Berglund observes. But, he adds, we don’t see the heavy infestations that were more common a few years ago. “It usually is a light infestation.”
Other common weeds identified by the surveyors include Canada thistle and marshelder in North Dakota; common ragweed, biennial wormwood and redroot pigweed in Minnesota; redroot pigweed and green foxtail in South Dakota; Canada thistle and redroot pigweed in Manitoba; palmer amaranth and puncturevine in Kansas; and Russian thistle, redroot pigweed and puncturevine in Colorado.
Phil Stahlman, weed scientist at Kansas State University’s Agricultural Research Center at Hays, is concerned about the increasing pressure from palmer amaranth. “The weed grows very rapidly and commonly grows as tall as six feet; sometimes even taller. [So] palmer amaranth is a serious competitor in Kansas sunflower,” Stahlman says.
“We have a number of tools — such as soil-applied Spartan®, Beyond® and Express® —that can do a good job on palmer amaranth under good conditions; but the weed has to be small and actively growing to get a good kill with postemergent herbicides. It is especially tricky when conditions are dry at the time of application, which is so often the case in western Kansas.”
Diseases continue to rate high in the surveyed fields. Rust was the big story in the northern states. Rust was evident very early in north central North Dakota. NDSU extension plant pathologist Sam Markell says early rust has the capacity to spread very quickly and impact yield; it all depends on the weather. “There was considerable fungicide sprayed for rust control in North Dakota this summer,” Markell relates. “It is interesting to note that the incidence of rust in South Dakota and the High Plains states was lower than last year.” Markell adds that he has had a several harvest reports of rust-damaged fields with poor yields that had not been treated.
Phomopsis was quite common this year, especially in northern Minnesota, northeastern North Dakota, Kansas and Manitoba. USDA-ARS research plant pathologist Tom Gulya identified the disease in northern Minnesota while conducting the survey. “Some fields had a high percentage of infection while others were disease free. However, it is more than I have seen in the past, so it is one of those issues [on which] we are going to have to get aggressive,” Gulya states.
Phomopsis is a stalk disease that can result in reduced yield and lodging. It has been an issue in Europe for many years, and good progress on hybrid resistance has been made. Most of the Phomopsis-infected fields that Gulya viewed were infected late in the season and typically did not have an impact on yield or lodging. Reports of Verticillium are slowly increasing as well. This is a disease in which USDA has already invested time and resources.
Because of excellent new-crop prices, there was a lot of scouting and spraying for insects in 2008.
One of the visual field signs of either the banded moth or sunflower moth is webbing on the heads. All states reported a significant reduction in webbing, with the exception of Kansas. Seeds were collected from each field and will be analyzed for all head insects. Those results will be available in early January.
The long-horned beetle (Dectes) has been an insect of concern. A stalk-tunneling insect, it is found primarily in the High Plains but has been moving further north. Surveyors cut open five stalks per field looking for the beetle or stem weevils. In 2008 the number of plants infested with long-horned beetle larva was up in Kansas but down sharply in South Dakota and nearly unchanged in North Dakota. This insect continues to be on the radar screen since no commercial insecticide control is available at present.
Berglund says the value of this annual sunflower field survey is to keep track of these kinds of emerging issues and put plans into action before a pest becomes endemic. The National Sunflower Association, USDA and various state universities have been doing a good job in investing in the future and avoiding unanticipated problems, he observes.
— Larry Kleingartner
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