Iv

lontol of WhJeat DHiseases in the Gfulf Coast of \Iabarna
Circular 294 November 1988 Alabama Agricultural Experiment Station Auburn University Lowell T. Frobish, Director Auburn University, Alabama

t1

Information contained herein is available to all without regardto race, color sex, or national origin.

PUBLISHED NOVEMBER

1988-4M

Fungicides for Control of Wheat Diseases in the Gulf Coast of Alabama
ROBERT T. GUDAUSKAS, AUSTIN K. HAGAN, EMMETT L. CARDEN, NORMAN R. McDANIEL, E. DARRELL WILLIAMS, and JOHN A. McGUIRE'

INTRODUCTION

ANY YEAR, the wheat crop throughout Alabama is subject to attack by a number of diseases 2 ,3. Typically, diseases occur more often and cause greater damage in wheat grown in the warmer, humid areas of coastal Alabama. The two most damaging diseases are leaf rust, figure 1, caused by Puccinia reconditaRob. ex Desm. f. sp tritici, and Septoria leaf and glume blotch, figure 2, caused by Leptosphaeria nodorum Miiller (anamorph Septoria nodorum (Berk.) Berk.). While there are wheat cultivars adapted for growing in south Alabama that are resistant to leaf rust, none are available that have good resistance to Septoria leaf and glume blotch (see recent issues of the Small Grain Variety Report, published annually by the Alabama Agricultural Experiment Station, Auburn University). However, even varietal resistance sometimes is ineffective because of the development of new races of causal agents or the occurrence of weather conditions that are so favorable for disease development that damage occurs on cultivars that would otherwise be little affected. Consequently, to insure profitable yields, it often is necessary to use fungicides to reduce disease losses. During the period 1978-82, numerous fungicides were evaluated
'Respectively, Professor of Plant Pathology; Associate Professor and Extension Plant Pathologist and Nematologist; Superintendent and Associate Superintendent, Gulf Coast Substation; former Research Associate; and Head of Research Data Analysis.
2

IN

GUDAUSKAS, R.T, C.G. CURRIER, AND A.K. HAGAN. 1983. Diseases and Their Control.

Pages 11-23 in Wheat Research Report 1983. Research Report Series No. 2. Ala. Agr. Exp. Sta., Auburn University. 3 WIESE, M.V. 1987. Compendium of Wheat Diseases. Second Edition. APS Press. The American Phytopathological Society St. Paul, Minn.

for disease control in wheat plots at the Gulf Coast, Lower Coastal Plain, Sand Mountain, and Tennessee Valley substations2. Although the tests have been continued at most of these locations, lack of consistent disease development has precluded meaningful results from many of them. However, incidence and severity of leaf rust and/or Septoria blotch were sufficiently high at the Gulf Coast Substation, Fairhope, during each of the past 5 years that fungicides could be evaluated for controlling these diseases. Results from these tests are reported here. MATERIALS AND METHODS Plots of Blueboy, Fla. 301, and McNair 1003 wheat were planted in the fall with a standard grain drill at a seeding rate of 90 pounds per acre. Blueboy and McNair 1003 were selected because they were susceptible to Septoria blotch and leaf rust; Fla. 301 was also susceptible to Septoria blotch, but was considered to be resistant to leaf rust 2 . Fla. 301 and McNair 1003 plots were fertilized according to standard soil test recommendations for wheat. Blueboy plots received 60 pounds of additional N in the spring in an attempt to further potentiate yield while controlling diseases. Fungicides were applied in 20 gallons of water per acre to 7- X 20foot plots of wheat using a C0 2-pressurized sprayer. Treatments were made in one or two applications, and were arranged in a randomized block design with five replications. Disease severity in each plot was determined at growth stage 11.2 (Feekes' Scale; soft dough stage) by rating the flag leaves and/or heads of 10-15 plants using a scale of 010, where 0 = no disease and 10 = severe disease. At crop maturity, a 5- X 15-foot swath of each plot was harvested with a plot combine for grain yield determinations. Fungicides tested during the 5-year period included benomyl (Benlate® 50W), capatafol (Difolatan® 4F), CGA-449 50W, chlorothalonil (Bravo® 500), copper-sulfur (Top Cop® with sulfur; 50% S, 4.4% Cu), diniconazole (Spotless® 25W), DS57654, DPX H6573, fenpropimorph, mancozeb (Dithane® M-45, Manzate® 200), myclobutanil (Systhane® 40W), propiconazole (Tilt® 3.6E), RE-36116, terbutrazole (Folicur® 1.2E), triadimefon (Bayleton® 1.8E, 2E, 50W), and triadimenol (KWG-0519). RESULTS Results are summarized by wheat cultivar in tables 1-3. Tests were conducted with Blueboy wheat during 1983-85, but discontinued thereafter. Septoria blotch and leaf rust developed in the tests in all 3 years, and most triadimefon and propiconazole treatments consis[4]

tently reduced the severity of both diseases, table 1. Addition of mancozeb did not increase efficacy or yield response with triadimefon or propiconazole except in 1985. Myclobutanil gave excellent disease control and yield response in 1985, the only year of testing with this material. Yield increases associated with fungicide treatments ranged from 11 to 15 bushels in 1983, 8 to 20 bushels in 1984, and 9 to 27 bushels in 1985. The additional N applied to the Blueboy plots did not appear to effect any appreciable increase in yield. In the Fla. 301 plots, incidence of Septoria leaf and/or glume blotch was low in 1984, 1985, and 1986, table 2, and too insignificant to rate in 1987; leaf rust developed to appreciable levels only in 1986, table 2. In 1984 and 1985, one or two applications of most of the fungicides tested reduced the severity of Septoria blotch as compared to the unsprayed controls. In 1986, only one application of each fungicide was made, and that not until plants were in the initial stages of head emergence. All fungicides gave good to excellent control of both Septoria leaf blotch and leaf rust. Significant yield increases were associated only with the DPX 116573 and propiconazole + chlorothalonil treatments in 1984, and with the terbutrazole, myclobutanil + mancozeb, and propiconazole treatments in 1986. Magnitude of the yield increase was 10 to 12 bushels in each year. In the McNair 1003 plots, Septoria blotch occurred at significant levels only in 1985, and then only on leaves; whereas, the incidence of leaf rust was sufficient to distinguish treatments in each of the 4 years of testing, table 3. Depending on the fungicide, one or two applications gave good to excellent control of leaf rust in 1984, 1985, and 1986, and of Septoria leaf blotch in 1985. Yields from each of the fungicide-treated plots in those years were significantly higher than those from unsprayed plots, ranging in an order of increase of 13 to 33 bushels per acre in 1984, 12 to 25 bushels in 1985, and 21 to 40 bushels in 1986. In 1987, leaf rust appeared relatively late in the season and did not develop to high levels. The first application of fungicide was not made until plants were in the early stage of head emergence, and some plots were inadvertently sprayed again after the crop was in the full head stage. All fungicides tested reduced the severity of leaf rust as compared to unsprayed controls, and yield increases of 5 to 7 bushels per acre were associated with most of the fungicide treatments. DISCUSSION The results of these tests show that yields of the susceptible cultivars Blueboy and McNair 1003 were significantly reduced by dis[5]

eases. Leaf rust occurred more frequently and appeared to cause greater damage than Septoria blotch during the years these tests were conducted. The incidence of both diseases was consistently lower on Fla. 301 wheat, and this cultivar appeared to be less affected by the diseases than the other two cultivars in the tests. As noted earlier, Fla. 301 was regarded as being resistant to leaf rust. However, the increasing occurrence of rust on Fla. 301 in these tests and in variety trials planted at the Gulf Coast Substation and elsewhere in the State 4 indicates that races of the leaf rust fungus that are capable of attacking Fla. 301 are becoming common. These tests also showed that several fungicides gave good to excellent control of Septoria blotch and leaf rust, and that significant yield increases were associated with many of the treatments. Results from these and earlier tests2 generally indicated that maximum control was achieved when the first application of fungicide was made around the time of flag leaf emergence. The comparative efficacy of one application versus two applications was not determined for every fungicide included in these studies. However, the results did show that, in some years, a one-time application of fungicide was sufficient for season-long disease control. This was particularly true for fungicides with systemic activity, e.g. diniconazole, terbutrazole, propiconazole, and triadimefon. For fungicides such as mancozeb that do not have systemic activity, or in years of heavy disease pressure, an additional application(s) might be required for satisfactory control. Fungicides presently labeled for control of leaf rust and Septoria leaf and glume blotch on wheat include mancozeb, benomyl + mancozeb, propiconazole, triadimefon, and triadimefon + mancozeb 5.
4 THURLOW, D. L. AND W.C. JOHNSON. 1987. The 1987 Alabama Performance Comparison of Small Grain Varieties. Agron. and Soils Dept. Series No. 117. Ala. Agr. Exp. Sta., Auburn University. 5 HAGAN, A. K. 1988. Small Grains Disease Control. Pages 80-82 in 1988 Alabama Pesticide Handbook. Circular ANR-500. Ala. Coop. Ext. Ser., Auburn University.

[6]

TABLE 1. DISEASE SEVERITIES AND GRAIN YIELDS FOR PLOTS OF BLUEBOY WHEAT SPRAYED WITH FUNGICIDES, GULF COAST SUBSTATION, FAIRHOPE

Fungicide, a. i.1'Iacre 1983 Mancozeb (25.6 oz.)** ....... Propiconazole
1.8 ....................... 3.6 ....................... 1.8oz. + mancozeb (25.6 oz.)** ...

App.2

Disease severity 3 4 Leaf Septoria blotch 2 rust Glume stg Leaf

Yield/ acre, b.

8, 10.1
8, 10.1 8, 10.1

-5

3.9 c 3.5Scd 3.0 de 2.7 e 2.7 e
-

6.3 ab

23.7 bcd 29.6 ab 27.5 abc 33.7 a 34.3 ab 17.9d 27.3 abc 27.3 abc 27.4 abc 30.Oab 18.6 cd 32.8c 27.7cd 50.8 a
53.6 a

oz.** oz.**

2.0Of
1.7 f 2.2eof 1.6f 7.1a 4.3 c 3.S cd 5.5 b 2.9 de 6.8 a 2.Ua 2.4a 1.4 b

3.6 oz. + mancozeb (25.6 oz.)** Sulfur
46.4 oz. + copper (4

...

8, 10.1 8, 10.1
8, 10.1

oz.)**........

5.3 a

Triadimefon 50W 1loz.** ........................

2 oz.** ........................ l oz. + mancozeb (25.6 2 oz. + mancozeb (25.6 oz.)** .

8,10.1 oz.)**..8, 10.1
8, 10.1 8, 10.1 8, 10.1 8, 8, 8, 8, 10.1 10.1 10.1 10.1 2.1c 3.1b

8,10.1

-

4.0Obc
3.7 cd 3.7 cd 3.4 cde 4.7 ab 2.3b 3.8a 1.5 c 1.3 c 1.6 bc 1.4 c
3.5 a

-

None (check) ................... 1984 Chlorothalonil (16.6 oz.)** .......... Mancozeb (25.6 oz.)** ............. Propiconazole 1.8 oz.**...................... 3.6 oz.**...................... 1.8 oz. + mancozeb (25.6 oz.)** . 3.6 oz. + mancozeb (25.6 oz.)** .. Sulfur
46.4 oz. + copper (4

.

0.5Sfg 0.2 g 0.9 ef 0.3 ab 3.7 ab 1.8 cd 1.5 c 1.2 de 1.3 c

1.i1b
2.5 a 2.1la 1.2 b 1.2 b 1.3 b 2.6a

1.3 b

1.ib

47.6 ab
52.5 a

oz.)**........ oz.)** .

8, 10.1

29. lcd 43.2 b 49.O ab 47.3 ab 49.S ab 24.3d (Continued)

Triadimefon 5OW 1loz.** ........................ 2 oz.** ........................ l oz. + mancozeb (25.6 oz.)**..8,
2 oz. + mancozeb (25.6

8,10.1 8,10.1 10.1
8, 10.1

None (check)....................

4.0Oa

1.8 bc 1.5 c 1.4 c 1.2 de 3.8 a

[7]

TABLE 1 (CONTINUED). DISEASE SEVERITIES AND GRAIN YIELDS FOR PLOTS OF BLUEBOY WHEAT SPRAYED WITH FUNGICIDES, GULF COAST SUBSTATION, FAIRHOPE

Fungicide, a.i.1/acre 1985 Mancozeb (25.6 oz.)* ............... Myclobutanil 3 oz.* ......................... 3 oz. + mancozeb (25.6 oz.)* ...... Propiconazole 1.8oz ........................ 3.6oz......................... 1.8 oz. + mancozeb (25.6 oz.)* .... 3.6 oz. + mancozeb (25.6 oz.)* .... Triadimefon 50W 1 oz.* .......................... 2oz.*.......................... i oz. + mancozeb (25.6 oz.)* ...... 2 oz. + mancozeb (25.6 oz.)* ...... None (check)......................
2

sApp.
9,10.1 9, 10.1 9, 10.1 9, 9, 9, 9, 9, 9, 9, 9, 10.1 10.1 10.1 10.1 10.1 10.1 10.1 10.1 .-

Disease severity Septoria blotch Leaf rust Glume Leaf 2.0b 0.7cd 0.4 de 0.3e 0.2e 0.2 e 0.1 e 1.5b 1.0c 1.0 c 0.5 cde 4.6 a 2.9b 2.0cd 0.8 fg 1.4de 0.6g 0.7 fg 0.3 g 2.8b 2.2c 1.8 cd 1.2 ef 3.9 a

4 3,

Yield/ acre,

-

23.0 e 29.7cd 33.9 bc 30.9cd 34.8b 35.4 b 41.0 a 27.3de 28.5d 32.3 bcd 35.8 b 14.4 f

-

'Active ingredient. Crop stage at time of application, based on Feekes' scale: 8 = flag leaf just visible, 9 = flag leaf emerged, 10.1 = head beginning to emerge.

30- scale; 10

0 = disease free, 10 = severely diseased.

4In a given year, values in the same column and followed by the same letter are not significantly different, according to Duncan's Multiple Range Test (p = .05). SDisease did not develop. *Plus Triton CS-7 at 1 pint per 100 gallons. **Plus Penetrator II at /2 pint per acre.

[8]

FIG. 1. Wheat leaves with pustules, or spore masses, of leaf rust.

FIG. 2. Symptoms of Septoria leaf (right) and glume (left) blotch.

i .-1" 1

t

i

iP4' %

TABLE 2. DISEASE SEVERITIES AND GRAIN YIELDS FOR PLOTS OF FLA. 301 WHEAT SPRAYED WITH FUNGICIDES, GULF COAST SUBSTATION, FAIRHOPE

Fungicide,

1 a. i. /acre
.

sapp2

stg Leaf

Disease severity' 4 Septoria blotch Leaf 2

Yield!
acre, 4

Glume

rust

bu.

1984 Chlorothalonil (16.6 oz.) .......... Diniconazole 0.8 oz. + captafol (16 oz.) ........ DPX H6573 1 oz.* ....................... 1.5 oz.*....................... 2 oz.* ....................... l oz. + mancozeb (25.6 DS 57654 (16 oz.)................

8, 10.1 8, 10.1 8, 8, 8, 8, 8, 8, 8, 9 8, 9, 8, 8 8 8 8 10.1 10.1 10.1 10.1 10.1 10.1 10.0 10.0 10.3 10.1

0.9 cd 0.4 de 0.2 e 0.2 e 0.2 e 0.3 e 1.3 c

0.9 cd 0.4 ef 0.7 cdef 0.9 bc 0.6 cdef 0.8 cde 1.0 bc 1.3 b 1.1 bc 1.1 bc 0.9 bc 0.3 f 0.4 def 1.1 bc 0.8 bcd 0.9 bcd 0.9 bcd 1.8 a

-5
-

52.5 abc 52.5 abc 53.4 abc 55. lab 50.1labc 47. lhc 47.S abc 49.9 abc 48.9 abc 46.5Sbc 51.6 abc 58.0Oa 52.5 abc 48.0 abc 51.9 abc 48.8 abc 52.3 abc 43.3 c

-

oz.)*..

Mancozeb (25.6

oz.)*

..............

2.0Ob
1.1 e 0.4 de 0.2 e 0.1 e 0.1 e 0.7 cde 0.2 e 0.4 de 1.1 c 3.8 a

Propiconazole 0.9 oz.**...................... 1.8 oz ....................... 1.8 oz.**...................... 1.8 oz. + chiorothalonil (17.6 oz.). . RE 36116 (8 oz.)................. Terbutrazole 2 oz.......................... 4 oz .......................... 2 oz. + triadimenol (0.5 oz.).. 2 oz. + triadimenol (1 oz.)... None (check).................... 1985 CGA 449 4 oz .......................... 8Soz .......................... Diniconazole 0.8 oz....................... 0.8 oz. *** .................... 1.6 oz ....................... 1.6 o.***................... Fenpropimorph 8Soz .......................... 12 oz ......................... 16 oz .........................

-

-

9, 10.2 9, 10.2

1.3 def 1.6 cdef 2.2 abcd 2.3 abcd 2.8 ab 2.5 abc

-

53.5 a 50.3 abcd 51.9 abc 473cd
47.7

-

bcd

49.3 abcd 48.1 bcd 49.7 abcd
45.5Sd

3.0Oa
2.9 a
-

-

-

2.9 a

(Continued)

[10]

TABLE 2 (CONTINUED). DISEASE SEVERITIES AND GRAIN YIELDS FOR PLOTS OF FLA. 301 WHEAT SPRAYED WITH FUNGICIDES, GULF COAST SUBSTATION, FAIRHOPE

Fungicide, a.i.'/acre 1985 Mancozeb (25.6 oz.)* .............. Propiconazole 1.8 oz. ........................ 1.80oz ......................... 1.8 oz. / CGA 449 (8 oz.) .......... Terbutrazole (3.6 oz.) .............. Triadimefon 2E (4 oz.).............. Triadimefon 50W (4 oz.) ............ Triadimenol (4 oz.).................. None (check) ...................... 1986 Diniconazole 0.8 oz.*** ................. ..... 1.6 oz.*** ...................... 0.8 oz. + mancozeb (25.6 oz.)*** .. Mancozeb (25.6 oz.)* ............... Myclobutanil 1.9 oz.* ............ .......... 1.9 oz. + mancozeb (25.6 oz.)* .... Propiconazole 1.8 oz.......................... 3.6 oz ......................... Terbutrazole (3.6 oz.) .............. Triadimefon 1.8E (4 oz.)............ Triadimefon 50W 4 oz............................ 1 oz. + mancozeb (25.6 oz.)* ...... None (check) ......................

stage

Disease severity34 Septoria blotch Leaf rust Glume Leaf 1.0 ef 1.0 ef 1.0 ef 0.9 ef 0.9 ef 1.3 def 1.8 bcde 0.7 f 3.0 a -

Yield/ acre, 4 bu.

9, 10.2 9 9, 10.2 9/10.2 9, 10.2 9, 10.2 9, 10.2 9, 10.2

-

49.9 abcd 48.3bed 50.3abcd 50.7abc 53.9 a 52.3ab 47.9 bcd 50.3 abcd 50.9 abc

-

-

-

-

10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2

0.9 cde 1.1c 1.c 1.6b 0.5fg 0.6 ef 0.3gh 0.1h 0.1 h 0.7 def 1.0cd 1.0 ecde 3.4 a

-

-

-

0.1ef 0.1ef 0 f 2.3b 1.3c 0.7 d 0.4e 0 f 0 f 0.4 e 0.3ef 0.7 d 4.4 a

51.4ab 53.5ab 44.6 b 49.5ab 48.6ab 55.0 a 52.4ab 57.2a 57.0 a 54.0 ab 53.0ab 53.9 ab 45.1 b

-

-

-

-

'Active ingredient. 2 Crop stage at time of application, based on Feekes' scale: 8 = flag leaf just visible, 9 = flag leaf emerging, 10 = late boot, 10.1-10.2 = head beginning to emerge. In a given year, values in the same column and followed by the same letter are not significantly different, according to Duncan's Multiple Range Test (p = .05). SDisease did not develop. *Plus Triton CS-7 at 1 pint per 100 gallons. **Plus Penetrator II at V2pint per acre. ***Plus Crop Oil Concentrate at 1 percent (v/v). ****Plus WK Surfactant at 1 percent (v/v).

304

10 scale; 0 = disease free, 10 -= severely diseased.

[11]

TABLE 3. DISEASE SEVERITIES AND GBAIN YIELDS FOR PLOTS OF MCNALR 1003 WHEAT SPRAYED WITH FUNGICIDES, GULF COAST SUBSTATION, FAIRHOPE

Fungicide, a.i.1'/aere

sapp.

Disease severity 3 4 , stg Leaf
2 Septoria blotch Glume

Yield!
acre,

Leaf

rust

bu.4

1984 Chiorothalonil (16.6 oz.) ............ Diniconazole 0.8 oz... . . . . .. . . ... 0.8 oz. + captafol (16 oz.) .... DPX H6573 1.5 oz.*........................ 2oz.*.........................

8, 10.1 8, 10.1 8, 10.1 8,10.1 8,10.1
8, 10.1

-5
-~ -~

-

1.4 c
d d d d d
-

54.0Of 64.8 bed 70.6 ab 68.1 66.3 66.4 58.8 abc abc abc def

-~ -~ -~

-

oz.)* ... Mancozeb (25.6 oz.)*...............

DS 57654 (16oz.)..................
Myclobutanil 3 oz ........................... 4 oz ........................... Propiconazole 1.Soz .........................
1.8

1 oz. + mancozeb (25.6

8,10.1
8, 10.1

.lc 1.5 c 0 0 d d

55.7eof

8,10.1 8,10.1 9
8, 10.1

-

-

64.3 bcd 63.9 bcd 68.9 ab 72.7 a 71.8Sa 52.9f 58.8 def 61.8 def 55.5 ef 40.2 g

1.8 oz. + chlorothalonil (17.6 oz.).. 9, 10.3 RE 36116 (8 oz.)................... 8, 10.1 Terbutrazole 2 oz.......................... 8 2 oz. ± triadimenol (0.5 oz.) ... 8
Triadimefon 50W (2 oz.)

oz.**.........................

-

-

0.2 d 0 d 0 d 2.9b 1.2ec 1.1 c 1.5 c 4.8 a

............

8

None (check).................... 1985 CGA 449 4 oz.......................... 9,10.2 8Soz.......................... 9,10.2 Diniconazole 0.Soz ......................... 9
0.8

6.4 b 6.0 b 2.3 cd 2.4cd 1.9 de 2.1 d

-

7.l1b

7.0Ob
15f 1.3 ef

39.2 f 39.4 f

1.6 oz ......................... 1.6 oz.****..................... Fenpropimorph S oz.......................... 12 oz.......................... 16 oz..........................

OZ.****

.....................

9

9 9 9 9 9

1.of

1.1 ef

50.9 cde 55.8 be 54.8 bed 53.7 bede

4.1lb
3.7bc 4.5 b

4.2 be 50.3 de 3.Scd e 3.9 cd 148.7 e
149.1

(Continued)

[12]

TABLE 3 (CONTINUED). DISEASE SEVERITIES AND GRAIN YIELDS FOR PLOTS OF MCNAIR 1003 WHEAT SPRAYED WITH FUNGICIDES, GULF COAST SUBSTATION, FAIRHOPE

Fungicide, a. i. '/acre

sapp.

Disease severity3 4 ' stg Leaf
2 Septoria blotch

Yield! rust
acre, 4

Glume

Leaf

bu.

1985
Mancozeb (25.6

oz.)* ..............

9, 10.2

4.0Ob
1.2 def 0.3 f 1.0 def 0.2 f 1.2 def 1.1 def 0.5 f 6.9 a

-5

2.6 de
1.le f

48.9e
51.9 cde

Myclobutanil (3 oz.)*............... 9, 10.2 Propiconazole 9, 10.2 1.8 oz .........................
1.8Soz.I/CGA (8oz.) .............

9/10.2
10.2 10.2 10.2 10.2

0.l1f
0.9 f 0.1lf 1.1 ef 1.3 ef 0.3 f 7.3 a

Terbutrazole (3.6 oz.) .............. Triadimefon 2E (4 oz.).............. Triadimefon 50W (4 oz.) ............ Triadimenol (4 oz.)................. None (check).................... 1986 Diniconazole
0.8 1.6

9, 9, 9, 9,

55.0 bcd 53.1 bcde 62.0 a 52.3 cde 50.9 cde 57.4 b 36S8f

0.8 oz. + mianicozeb (25.6 oz.)**** 9, 10.2 Mancozeb (25.6 oz.)................ 9, 10.2 Myclobutanil
1.9

oz.*** ..................... oz.***...................... oz.)*

9, 10.2 9, 10.2

-~ -~ -

-

f f .lf 2.6 b 0.6 de 0.2 f 0.8Sd

76.6 bcd 76.7 bcd 82.8Sab 70.4 de 69.7 de 75.4 bcde 73.7 cde 78.2 abcd 81.1 abc 86.6 a 79.9 abc 76.2 bcd 67.2 e 46.0Of
i

oz.*........................
....

9, 10.2

-

-

1.9 oz. + mancozeb (25.6

9, 10.2

Propiconazole 1.8Soz ......................... 1.8Soz ......................... Terbutrazole 3.6 oz ......................... 3.6 oz ......................... Triadimefon 1.8E (4 oz.) ............ Triadimefon 5OW 4 oz..........................
1loz.

9 9, 10.2 9 9, 10.2 9, 10.2 9,10.2

-

-

0.3ef
-

-~ -~ -

f f

0.1lf

/mancozeb (25.6

oz.)* ........

9/10.2

0.1lf
-

1.6 c 4.9 a

None (check)....................

(Continued)

[13]

TABLE 3 (CONTINUED). DISEASE SEVERITIES AND GRAIN YIELDS FOR PLOTS OF MCNAIR 1003 WHEAT SPRAYED WITH FUNGICIDES, GULF COAST SUBSTATION, FAIRHOPE

Fungicide, a.i./acre

stage

Disease severity 3,4 Septoria blotch Leaf

Yield/ acre,

Leaf 1987 Benomyl
4 oz. + mancozeb (25.6 oz.)*...... 10.2, 10.5 -5
-

Glume

rust

bu.

4

-

1.5 b

27.0 bed

Diniconazole 0.8 oz.*** ...................... 10.2 0.8 oz.*** ...................... 10.2, 1.6 oz.*** ...................... 10.2 1.6 oz.*** ...................... 10.2, 0.8 oz. + mancozeb (25.6 oz.)*** .. 10.2, Mancozeb 25.6 oz.* ....................... 10.2 25.6 oz.* ...................... 10.2, 25.6 oz. + triadimefon (1 oz.)* .... 10.2, Propiconazole 0.9oz .......................... 10.2, 1.8 oz ......................... 10.2 1.8oz. ......................... 10.2, 3.6oz. ......................... 10.2 Terbutrazole (3.6 oz.) .............. 10.2 Triadimefon 50W 2 oz...........................10.2, 4 oz...........................10.2 None (check)............ ........... 'Active ingredient. 2

10.5 10.5 10.5 10.5 10.5 10.5 10.5

-

-

-

-

0.1c 0.1c 0.1c 0 c 0.1 c 1.5b 1.5b 0.2 c 0.1c 0.1c 0 c 0.2c 0 c 0.2c 0.4c 3.4 a

28.9abc 30.4ab 29.8ab 28.2abc 32.2 a 28.2abc 29.3ab 30.2 ab 30.9ab 31.5a 30.0ab 28.2abc 31.3a 29.1abc 29.3ab 24.5 cd

-

-

-

-

-

-

10.5

Crop stage at time of application, based on Feekes' scale: 8 = flag leaf just visible, 9 =

flag leaf emerging, 10 = late boot, 10.1-10.2 = head beginning to emerge, 10.5 = head fully emerged. 10 scale; 0 = disease free, 10 = severely diseased. In a given year, values in the same column and followed by the same letter are not significantly different, according to Duncan's Multiple Range Test (p = .05). 5Disease did not develop. *Plus Triton CS-7 at 1 pint per 100 gallons. **Plus Penetrator II at V/2 pint per acre. ***Plus Crop Oil Concentrate at 1 percent (v/v). ****Plus WK Surfactant at 1 percent (v/v).

30-

[14]

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rxpertmeiit stauon System

AUBURN UNIVERSITY

WT\ith an agricultural resetrch unit in everx- major soil area, Auburn JInivejrsitx serves the needs of field crop, livestock, forestry, and horticultural producers in each region in Alabama. Evern citi zen of the State has a stake in this research program, since atny advantage fr(m ne", and more econlomicl wxax s of producing and handling farm products directly benefits the consuming public.

I,..
12

to0 11? 13

Research !'nr t TdentjW

® Main Agricultural Experiment Station, Auburn.
w E. V. Smith Research Center, Shorter.
1. Tennessee Valley Substation, Belle Mina. 2. Sand Mountain Substation, Crossville 3 North Alabama Horticulture Substation, Cullman 4. Upper Coastal Plain Substation, Winfield 5 Forestry Unit, Fayette County. 6. Chilton Area Horticulture Substation, Clanton. 7. Forestry Unit, Coosa County 8 Piedmont Substation, Camp Hill. 9. Plant Breeding Unit, Tallassee. 10 Forestry Unit, Autauga County. 11. Prattville Experiment Field, Prattville 12 Black Belt Substation, Marion Junction. 13 The Turnipseed-Ikenberry Place, Union Springs. 14. Lower Coastal Plain Substation, Camden. 15. Forestry Unit, Barbour County. 16. Monroeville Experiment Field, Monroeville. 17. Wiregrass Substation, Headland. 18 Brewton Experiment Field, Brewton 19 Solon Dixon Forestry Education Center, Covington and Escambia counties. 20. Ornamental Horticulture Substation, Spring Hill. 21. Gulf Coast Substation, Fairhope.