2001 Annual Report

Agronomy Management

Dickinson Research Extension Center
1089 State Avenue
Dickinson, ND 58601

Early Season Fungicide Applications May Help

Roger O. Ashley and Dwain Barondeau

Area Extension Specialist, Cropping Systems
Hettinger County Extension Agent

Hard red spring wheat was grown on approximately 1,580,100 acres in 1999 in southwest and south central North Dakota (Beard and Waldhaus 2000).  Foliar diseases such as tan spot and septoria leaf blotch are more prevalent in continuous wheat field than in fields where crop rotation is practiced.  In western North Dakota, of the known previous crops reported in a 1997 study, 75% of the wheat grown had been in fields where wheat or barley was grown the previous year (McMullen, 1998). Rotation to non-host crops provides time for wheat pathogens to degrade.  Some long-lived residual herbicides that producers have used may prevent rotation to non-host crops or producers have limited themselves to continuous wheat or wheat-fallow rotations.

Western North Dakota is often thought to be too dry to support economically damaging levels of foliar diseases.  However rainfall in May and June are sufficient to promote infection of young wheat plants with tan spot and septoria leaf blotch, especially in fields where the previous crop was wheat.  These early infections can reduce both yield and test weight of grain.  Plots in continuous wheat fields in 2000 (Ashley et. al., 2001) responded to an early season Tilt fungicide treatments (2 fluid oz/acre) at Huff and Regent (Table 1 and Table 2).  The fungicide treated plots yielded about 12 percent more grain (6.9 bushel/acre at Huff and 4.5 bushel/acre at Regent) and increased test weight by about two to three pounds per bushel.

Table 1.  Cropping history, wheat variety, crop stage, and disease rating at fungicide application, 2000.

Location

Cropping history

Hard red spring wheat variety – 2000

Fungicide application date

Crop stage fungicide application

Disease rating at application

Haun

%

Beach

1999 sunflower
1998 wheat
1997 mustard

Ernest

5/10/00

4.0 – 5.0

Incidence 10
Severity < 1

Huff

1999 wheat
1998 wheat
1997 barley

Oxen

5/26/00

4.0 – 5.0

Incidence 70
Severity 15

Regent

1999 wheat
1998 wheat
1997 wheat

2398

5/19/00

4.5 – 5.2

Incidence 60
Severity 10

Table 2.  Yield and test weight of hard red spring wheat treated with Tilt in the four to six leaf stage at Beach, Huff, and Regent, ND, 2000.

 -----Beach -----

----- Huff -----

----- Regent -----

Treatment

Yield

Test weight

Yield

Test weight

Yield

Test weight

bu/acre

lb/bu

bu/acre

lb/bu

bu/acre

lb/bu

Tilt

45.3

63.6

61.2

61.5

40.8

62.5

Check

45.2

63.6

54.3

59.5

36.3

59.9

Mean

45.2

63.6

57.8

60.5

38.5

61.2

CV%

3.6

--

3.0

1.2

5.8

1.1

LSD .05

NS

NS

3.9

1.6

NS

1.6

Early season fungicide treatments can be made at the same time as the post-emergence herbicide application.  This is usually in the 4 to 6 leaf stage of wheat plant development.  Tank mixing herbicide and fungicide and applying both at the same time eliminates the cost of a separate application.  Reduced rates of fungicide can be used effectively for these early season applications and producers can expect suppression of tan spot and septoria up to flag leaf emergence with the Tilt product.  The reduced fungicide rates are Mancozeb at 1.0 pound/acre rather than the 2.1 pounds/acre rate or Tilt at 2 fluid ounces/acre rather than the full rate of 4 fluid ounces/acre.  The 1.0-pound/acre rate of Mancozeb costs about $2.00/acre while a Tilt application will add about $4.50 per acre.

Herbicide plus fungicide combinations can provide weed control and maintain crop protection from tan spot and septoria.  Information on pesticide labels usually provides information on all possible registered combinations for each crop.  Table 3 (Zollinger, 2001) provides a summary of mixing instructions for various herbicide and fungicide (Mancozeb and Tilt) combinations.


Table 3
.  Herbicide/fungicide combinations for small grain.

Herbicide

Mancozeb

Adjuvant with Mancozeb

Tilt

Achieve

PROHIBITED

PROHIBITED

PROHIBITED

Aim

Not Prohibited

Yes, if required

Not Prohibited

Ally

Not Prohibited

Yes, if required

Not Prohibited

Amber

Not Prohibited

Yes, if required

Not Prohibited

Assert

Not Prohibited

Yes, see label

Not Prohibited

Avenge

Not Prohibited

Yes, see label

Not Prohibited

Banvel

Not Prohibited

Not recommended

Not Prohibited

Bronate

See Product Bulletin 2EE

Not needed

Not Prohibited

Buctril

See Product

Not needed

Not Prohibited

Canvas

Not Prohibited

Yes, if required

Not Prohibited

Cheyenne

PROHIBITED

PROHIBITED

PROHIBITED

Clarity

Not Prohibited

Yes, if required

Not Prohibited

Curtail/M

Not Prohibited

Yes, if required

Not Prohibited

Dakota

See Dakota Label

PROHIBITED

Not Prohibited

Discover

Not Prohibited

Yes, if required

Not Prohibited

Express

Not Prohibited

Yes, if required

Not Prohibited

Finesse

Not Prohibited

Yes, if required

Not Prohibited

Harmony Extra

Not Prohibited

Yes, if required

Not Prohibited

Hoelon

See Hoelon label Spring Wheat only

Oil Additive

Not Prohibited

MCPA

Not Prohibited

Yes, if required

Not Prohibited

Peak

Not Prohibited

Yes, if required

Not Prohibited

Puma

Not Prohibited

Yes, if required

Not Prohibited

Stampede

See current label

Oil additive only

PROHIBITED

Starane

Not Prohibited

Yes, if required

Not Prohibited

Tiller

See Tiller Label

PROHIBITED

Yes

2,4-D

Not Prohibited

Yes, if required

Not Prohibited

Will early season fungicide applications pay for themselves?  This depends on a number of factors that producers should consider.  The first consideration is was the previous crop wheat?  If the previous crop was wheat chances are good that producers will see a response to early season fungicide applications.  Where good crop rotations are practiced there is little chance that early season fungicide applications will be of any benefit to dryland producers.  Are tan spot and septoria infections present on the leaves at the time of herbicide application?  If tan spot and/or septoria lesions are present on young plants an early season fungicide application may be useful in preventing the disease from moving up the plant as it grows.  Is soil moisture present to promote good yields?  Limited moisture can be more yield limiting than disease.  In terms of bushels/acre increase and dollars returned per acre for a fungicide application, a 10 percent increase in yield for a crop that has a 30-bushel potential is less than a 10 percent increase in yield for a crop with a 40-bushel potential.  And finally are wheat stands sufficient to promote good yields?  Foliar fungicides will not improve stand counts, nor control root disease, nor replace a good fertility program.  Producers need to realistically assess yield potential at the time the fungicide application is to be made.

Fungicide use should be based on crop value (crop yield x expected price) and the potential for yield losses due to foliar leaf diseases.  When tan spot and septoria are present on lower leaves and environmental conditions continue to favor disease development fungicides can provide protection to yield and increase yield levels by 10 percent over unprotected fields.  If disease pressure is very heavy, yield increases may be greater than 10 percent.  Fungicides applied at reduced rates at the time herbicides are applied will reduce costs.  The potential net profit from fungicide use based on a 10% yield increase and a $4.50/acre cost for the fungicide is given in Table 4. 

Table 4. 10% response at $4.50 per acre for fungicide.  The fungicide and the herbicide are tank mixed and applied at the same time. 

Yield (bu/A)

30

40

50

Crop Price

 ----------Return over fungicide cost ----------

$2.60

3.30

5.90

8.50

$2.80

3.90

6.70

9.50

$3.00

4.50

7.50

10.50

$3.20

5.10

8.30

11.50

$3.40

5.70

9.10

12.50

$3.60

6.30

9.90

13.50

Literature Cited

Ashley, R.O., MP. McMullen, H. Peterson, D. Barondeau, and J. Buckley.  2001.  Early foliar application of Tilt fungicide on hard red spring wheat in southwest North Dakota.  In 2001 Dickinson Research Extension Center Annual Report.

Beard L. and E. Waldhaus.  2000.  North Dakota Agricultural Statistics 2000.  North Dakota Agricultural Statistics Service, North Dakota State University, Fargo, ND.

McMullen, M.P. 1998. Effect of previous crop on tan spot and Fusarium head blight in wheat 1997.  In Phytopathology 88:S116.

Zollinger, R.K.  2001.  2001 North Dakota Weed Control Guide.  Cir. W-253.  NDSU Extension Service, North Dakota State University, Fargo, ND.

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