Fungus Report - 2001 Crops Day

Evaluation of Fungicides to Control Ascochyta in Chickpea

Hettinger, North Dakota

Eric Eriksmoen - Agronomist

Rick Olson - Technician

Lance Ketterling - Cooperator

Dwelley chickpea was seeded on May 4. Seed was inoculated with rhizobia and treated with LSP and Apron prior to seeding. 50 lbs/acre 11-52-0 plus 10 lbs/acre ‘Roughrider’ (3 lbs/ac copper) fertilizer were applied with the seed. The first treatment application was on July 2 to chickpeas in early bloom. The second treatment application was on July 16 to chickpeas in late bloom. A third treatment application was applied on July 30 to chickpeas that were completely podded and developing peas. Treatments were applied with a tractor mounted CO2 propelled plot sprayer delivering 17 gpa at 40psi through 8001 flat fan nozzles to a 5 foot wide area the length of 10 by 28 foot plots. The experiment was a randomized complete block design with four replications. Visual evaluations for ascochyta infection on crop leaves and pods were on July 13, July 23, July 30, August 6 and on August 13. The trial was harvested on September 6. Harvested seed was cleaned with a clipper mill to remove chaff and weed seeds and then graded according to seed size.

Summary

Weather conditions were ideal for ascochyta development during the month of July with 15 days of measurable precipitation totaling almost 4 ˝ inches of rain. Hot and dry August weather conditions ceased the progression of ascochyta with only 2 days of measurable precipitation totaling 0.13 inches. Evaluations on July 13 showed minor levels of visual ascochyta on all treatments (data not shown). Split applications of BAS 500, BAS 516 and Quadris (trts 4 - 9) provided good season long control of ascochyta, had the highest seed yields, the highest test weights and the highest % of large seed. Split applications of Bravo WeatherStik and Bravo Zn (trts 20 & 21) also provided relatively good seed yields. The single early application of BAS 500 (trts 2 & 3) provided good initial ascochyta control but deteriorated as the season progressed. Seed yield, test weight, seed weight and % large seed from these two treatments were still significantly higher than the untreated check. The second application of BAS 500 (trts 4 & 5) significantly enhanced ascochyta control and seed yields over the single BAS 500 application (trts 2 & 3). Split applications of Bravo Ultrex and Topsin M were not effective in controlling ascochyta. The addition of Scalia to the Bravo Ultrex/Topsin M mixture (trts 12 & 24) did not significantly enhance ascochyta control or seed yield over the single product mixture (trts 10 & 13). Higher fungicide application rates did not significantly enhance ascochyta control or seed yields (trt 3 vs.2, trt 5 vs.4, trt 7 vs.9).

Treatment

Product Rate

7/23

7/30

8/6

8/13

Seed

1000

Seed Size (mm)

Ascochyta Rating

Yield

TWT

KWT

>9

8-9

<8

#

Product

oz/A

0 - 9*

lbs/A

lbs/bu

g

-------- % --------

1

Untreated

0

3.0

5.2

6.8

7.5

462

56.0

256

26

29

45

2

BAS 500

7.2

1.5

1.5

3.5

3.8

1306

59.9

408

70

20

10

3

BAS 500

10.4

1.3

1.7

4.0

4.7

1156

58.6

383

55

26

19

4

BAS 500 / BAS 500

7.2 / 7.2

1.0

1.2

1.8

1.2

1803

60.6

405

80

15

5

5

BAS 500 / BAS 500

10.4 / 10.4

1.2

1.2

1.5

1.8

1725

60.6

411

80

14

6

6

BAS 516 / BAS 516

10.53 / 10.53

1.0

1.0

1.5

1.2

1631

60.9

417

79

15

6

7

Quadris / Quadris

9.2 / 6.2

1.0

1.0

2.2

2.0

1794

60.7

400

78

15

7

8

Quadris / BAS 516

6.2 / 10.53

1.0

1.2

1.8

1.8

1761

60.7

386

77

16

7

9

Quadris / Quadris

6.2 / 6.2

1.0

1.2

2.0

2.2

1643

60.4

425

77

16

7

10

Bravo Ult / Bravo Ult

20 / 20

2.0

3.0

5.5

6.2

806

58.8

346

45

29

26

11

Bravo Ult / Quadris

20 / 6.2

1.2

1.5

2.8

2.5

1543

60.4

430

75

16

9

12

Scalia + Bravo Ult / Scalia + Bravo Ult

10.24 + 14.56 / 10.24 + 14.56

1.5

2.2

4.0

4.8

1134

59.3

378

54

28

18

13

Topsin M / Topsin M

8 / 8

2.0

3.5

5.2

6.2

767

58.8

347

45

29

26

14

Topsin M / Topsin M

16 / 16

2.7

4.3

6.0

7.0

590

58.4

279

31

26

43

15

Topsin M / Topsin M

24 / 24

2.0

4.0

6.0

6.2

562

58.0

271

34

26

40

16

Topsin M / Topsin M

32 / 32

1.6

2.0

4.0

4.3

961

58.1

353

55

25

20

17

Topsin M / Quadris / Topsin M

8 / 6.2 / 8

2.2

1.8

2.8

2.5

1326

60.0

396

65

23

12

18

Topsin M / Bravo Ult / Topsin M

8 / 20 / 8

3.0

3.5

5.0

6.2

694

57.2

318

46

27

27

19

Topsin M / Quadris / Bravo Ult

8 / 6.2 / 20

1.8

2.0

3.5

3.8

1351

60.1

375

67

20

12

20

Bravo WeatherStik / Bravo WeatherStik

32 / 32

1.0

1.8

2.8

3.0

1444

59.8

426

70

19

11

21

Bravo Zn / Bravo Zn

40 / 40

1.3

1.3

2.3

4.0

1495

59.6

341

65

21

14

22

BAS 500 + Topsin M

7.2 + 8

1.2

2.5

3.8

5.2

1119

58.9

374

57

26

17

23

Topsin M / BAS 500

8 / 7.2

2.5

1.8

2.5

3.0

1312

59.8

416

72

18

10

24

Topsin M / Scalia

8 / 10.24

1.3

2.7

4.0

4.7

907

58.5

354

44

31

25

C.V. %

55.2

44.3

30.4

29.2

24.6

1.6

13.4

14.8

16.5

46.8

LSD 5%

1.3

1.4

1.5

1.6

429

1.3

71

13

5

11

*Ascochyta Rating (0-9): 0 = no visual ascochyta on leaves or pods, 9 = dead plants

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