Can Headline® Fungicide Improve Sunflower Health?
Sunday, April 15, 2007
filed under: Disease
Just as a boost in plant vigor has been demonstrated with the use of a seed treatment, might a foliar fungicide boost plant health, with benefits that go beyond disease control? BASF, maker of the fungicide Headline® (Pyraclostrobin), believes so – in fact, the company has gone so far as to trademark the phrase “Plant Health” in Headline product literature.
Here’s what BASF product literature has to say about the effect of Headline on soybean plant health: “During bloom, R1 to R3 stage, requirements for carbon and nitrogen are significantly higher causing reproductive stress. Should these elements not be in adequate supply, the plant’s reproductive cycle can be limited, ultimately compromising quality and yield. The active ingredient in Headline fungicide (F500) actually improves the metabolic efficiency of the plant, increasing the available reserves of carbon and nitrogen needed to counter stress, while sustaining reproductive energy for maximum quality and yield.”
Headline is labeled on sunflower for preventative control of a number of diseases, including alternaria leaf spot, powdery mildew, cercospora leaf spot, septoria leaf spot, downy mildew, and rust. The use rate per application is 6 to 12 oz/ac, with a limit of two applications per season. Adjuvant: NIS at 0.125-0.25% v/v. There is a minimum 21 day preharvest interval from the time of application. Product cost is about $10-$12/ac for a 6 oz treatment.
Application timing is R1-R4, or prior to disease development. R1 is the stage of sunflower when the terminal bud forms a miniature floral head rather than a cluster of leaves. When viewed directly from above, the immature bracts form a many pointed star appearance. At R4, the inflorescence begins to open. When viewed from directly above, immature ray flowers may be visible. Thus, application timing is close to early flowering, when a first insecticide treatment is recommended on confection sunflower for some insect pests, including the banded moth, seed weevil, and lygus. Headline can be tankmixed with an insecticide.
Representatives with the company say several years of BASF research has resulted in data which indicates that Headline has a positive effect on plant health and yield in a number of crops on which the product is labeled, including sunflower.
Jeremy Frie, technical service representative with BASF, says the product is believed to increase plant growth efficiency and tolerance to stress, as well as prevent even low levels of disease from interfering with optimum plant growth and reproductive potential.
Varied yield responses
BASF has worked with growers to conduct 11 on farm side-by-side trials of Headline on sunflower, two conducted in 2005 and nine last year, with interesting results. Headline was applied at 6 oz/a to R1-R2 sunflower. All of the sunflower trials treated with Headline yielded better than the untreated checks, from a low of 18 lbs to a high of 405 lbs. In one of the two trials in 2005, there was a 300 lb difference on a downy mildew resistant hybrid (3,310 lb/a) treated with Headline compared to the untreated (3,010 lb/a). The average yield response across the 11 side-by-side trials was 156 lb/ac.
“We’ve been evaluating the effect of Headline in different crops, and some respond more than others, including sunflower,” says Frie.
However, other public-conducted trials have shown no significant yield response, in the absence of disease conditions. An on-farm soybean trial conducted by the University of Minnesota last year near Thief River Falls, Minn., concluded that “under very low disease pressure none of the treatments showed significant differences when compared with the control/no treatment applied” (www.nwroc.umn.edu – click on ‘cropping issues of NW MN’ then ‘2006 on-farm trials book.’)
No differences in plant health, disease, or yield were observed in trials with Headline on corn last year at the U of M Southwest Regional Outreach Center, Lamberton. The SWROC has also conducted fungicide studies the past few years on soybeans. One study last year at Lamberton evaluated foliar fungicide and insecticide effects on soybean disease suppression, senescence and yield. The conclusion: “These data hint at possible synergy between products but not in a strong way. This trial is similar to many others that show reduced disease and likely related delayed senescence with fungicide applications, in particular strobilurins and strobilurin + triazole mixes. However, like many other trials disease and insects populations are not necessarily yield limiting.” (see complete details of the corn and soybean fungicide research online at http://swroc.coafes.umn.edu).
Crop response was investigated with Headline fungicide on a direct-seeded, Clearfield™ sunflower hybrid in 2005 at the NDSU Research Extension Center in Carrington. Rates of 3, 6, and 9 oz were applied at R1. Crop maturity, seed yield, test weight, and oil content were similar among treatments (www.ag.ndsu.nodak.edu/carringt/ - click on ‘agronomy’ then ‘research projects,’ ‘plant pathology,’ then ‘sunflower.’)
Still, there are observations to suggest, as Frie of BASF put it, that “something is going on here.” Former NDSU plant pathologist Carl Bradley, now at the University of Illinois, agrees that there seems to be some sort of positive plant physiological effect, although more needs to be known about this link – does it occur in the absence of disease pressure? Is it affected by other variables, such as weather and moisture conditions? Do certain crops or varieties respond more than others? Do other Strobilurin fungicides (such as Quadris®, by Syngenta, also labeled for sunflower) have a similar affect?
The best advice for a grower might be to evaluate the effect of Headline or Quadris yourself, in side-by-side, treated versus non-treated comparisons, at the labeled rate and recommended treatment timing. Use a weigh wagon or yield monitor to measure any difference in yield. Then contact the National Sunflower Association, because we’d welcome the grower observations to this plant health debate. The Sunflower will feature grower observations and an update on more research planned in public locations in a future issue. – Tracy Sayler