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NDSU Sunflower Information

Sunflower with butterfly

SUNFLOWER GROWTH AND DEVELOPMENT

In a normal year more than 50% of the sunflower acres are planted by May 29^th. Based on the 2011 North Dakota Agricultural Statistics Service, 64% of the sunflower crop in ND was planted by June 12^th. The 2011 crop was planted about two weeks later than the last five year average (Table 1). Growth and development of sunflower is mainly driven by growing degree day (GGD) units. GDD for sunflower is calculated as follows:

Daily Sunflower GDD = ((Daily Max Temp °F + Daily Min Temp °F)/2) - 44 °F. If the daily maximum or minimum temperature is less than 44 °F the number in the formula is set at 44 °F. Table 2 provides an indication of how many GGD’s are needed to reach the different development stages in sunflower. The GGD’s needed are an estimate and may differ between hybrids and growing conditions. In Table 1 GGD’s are given for 2011 from the date of planting to July 25 including the estimated growth stage for Fargo ND. The GGD’s and estimated growth stages can be calculated for any location in ND by using the NDAWN sunflower GGD and growth stages model. Location and planting date can be selected to calculate local GGD’s and estimate of growth stage of the crop

Although the crop was planted later than average, crop development is accelerated due to the hot weather in July. The model is predicting that near Fargo the sunflower has entered its reproductive phase. It is important to scout sunflowers during the reproductive phase for potential insect damage.

In the 2010 sunflower survey conducted in ND, 8.4% of the fields had seed weevil damage and those fields with a problem had 3.5% of the seeds infected.

Banded sunflower moth was found in 27.4% of the samples with 2.7% of the seeds infected in those samples.

Damage due to the sunflower moth was found in 17.9% of the samples with on average 2.4% seeds damaged.

For sunflower insect management see the resources available at: http://www.ag.ndsu.nodak.edu/aginfo/entomology/entupdates/#Sun

Table 1. Percent Sunflower Planted in ND in 2011, GGD from planting to July 25 and estimated growth stage for Fargo, ND.

Date	% Sunflowers Planted 2011	% Sunflowers planted 2006-2010 Average	GGD up to July 25, 2011 Fargo ND.	Estimated growth stage on July 25, 2011, Fargo ND.
May 22	3	29	1550	R4
May 29	8	54	1477	R4
June 5	26	75	1328	R2
June 12	64	90	1185	R1
June 19	78	95	1021	V20
June 26	86	99	874	V19
July 3	91	100	672	V13

Source: USDA NASS ND Crop Report and NDAWN.

Table 2. Selected Growth stages and GGD associated with plant development.

Growth Stage	Description of growth stage	Accumulated GGD
V10	Vegetative sage with 10 true leaves	557
V20	Vegetative sage with 10 true leaves	908
R1	Terminal bud miniature floral head	1048
R5.1	Beginning flowering 10% of head area	1609
R6	Flowering complete ray flowers wilting	1889
R 9	Bracts yellow and brown, physiological mature	2310

For stages of sunflower development see http://www.ag.ndsu.edu/pubs/plantsci/rowcrops/a1145.pdf.

NEW EXTENSION PUBLICATION ON SUNFLOWER RUST
Sunflower rust has re‐emerged a yield limiting disease in the last three years. In June 2011, NDSU published an
Extension publication on sunflower rust (PP‐1557). Included are photos of the pathogen (including the early‐season
stages) and disease assessment diagrams, which will help in determining if a fungicide application is warranted. The
publication is available through the NDSU Extension Service at ND county offices.

SUNFLOWER SURVEY

Hans Kandel

NDSU Extension Agronomist Broadleaf Crops

The National Sunflower Field Survey was conducted in September and early October 2010. In North Dakota 96 fields were inspected. One field was surveyed for every 10,000 sunflower acres in each county, based on estimates by the Farm Service Agency-USDA .

Staff conducting the surveys consisted of an agronomist, pathologists, entomologists and industry staff. The teams were asked to assess each field for which factor was the most yield limiting and which was the second most limiting. Yield-limiting factors to select from included: no problem, birds, disease, drought, drown-outs, hail, herbicide damage, insects, lodging, plant spacing, population, and weeds.

The North Dakota State average yield estimate for the surveyed fields was 1949 lb/a.

2010 Yield-limiting Factors:

In North Dakota plant spacing within the row and disease were the most prominent limiting factors to higher yields (Table 1). Insect damage was considered to be the second most limiting factor in 15.4% of the fields.

In the survey, observers did not find limiting factors in 13.5% of the fields and 35.1% of the fields did not have a second most limiting factor. The average yield of the fields without problems was 2328 lb/a, 1989 lb/a where the surveyors reported plant spacing within the row issues, and 2037 lb/a when diseases caused a yield reduction. Producers are encouraged to plant sunflower carefully to obtain properly distributed plant stands, and manage weeds and diseases appropriately.

Table 1. North Dakota first and second major yield limiting factors 2010 NSA survey in percent of 96 fields.

	Number 1 limiting factor	Number 2 limiting factor
Yield limiting factor	Percent
Plant spacing within row	17.8	12.1
Disease	15.6	11.0
Lodging	12.5	7.7
Birds	10.4	7.7
Weeds	6.3	8.8
Insects	5.2	15.4
Drown out	4.2	1.1
Hail	2.0	1.1
Other (many mentioned population)	12.5	0
No Problem	13.5	35.1

Reference

Kandel, H. 2011. National Sunflower Association Survey 2010 PowerPoint pfd. For full report click here. Maps of the survey can be found by cliking here.

NDSU Sunflower Information

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