VI. Tests of Inbred Strains for Disease Resistance

Last spring seed of five inbreds furnished by Wiggans, one by Hayes, one by Kvakan, three by Bryan, and five by Singleton were sent to eight cooperators in various parts of the United States. The severe drouth and heat in some areas made possible a good comparison of the inbred lines in regard to resistance to firing.

The following tables and supplementary notes on the inbreds were received by the Co-op:

Arlington Experiment Farm, Rosslyn, Virginia -

• Line		Date Silked	Total No. Plants	No. Erect Plants	No. Smutted Plants	Remarks
  Co 206		7/30	27	3	0	Very little pollen
  Co 208		7/26	34	13	0	Good line
  Co 210		7/30	36	1	2
  Co 211		7/26	33	21	0	Pollen 5 or 6 days later than silks
  Co 214		7/26	29	17	0
  S283		7/30	14	12	0
  I 234		8/10	29	17	0
  Dr 276 A		8/10	30	9	0
  WD 456 A2		8/2	23	22	1	Very good line
  Kvakan 6991		7/30	9	2	0	Light green & spotted No good here
  Singleton	C2		25		0	Too early. Entirely unsuited to Arlington conditions
  "	C6		36		2
  "	C13		39		2
  "	C85		33		0
  "	C78		34		1

M. T. Jenkins

Ames, Iowa -

The season in Iowa was so unfavorable that observations must not be taken too seriously. Early lines were more affected by these conditions than the later lines. No attempt was made to hand-pollinate any ears. Under open-pollination the set of seed was fair on some lines and poor on others.

The season was good for testing smut resistance, the smut infection being about as heavy as in 1935. The following notes were made on the inbred lines:

• C 206: Free from smut; no firing of leaves, tassels good, ear shoots good but poorly filled; roots weak; plants about 5' high; ears about l-1/2 to 2' high; not very promising.
• C 208: Smutted ears on about 30% of the plants; tassels good; one or two top leaves fired; plants erect; ear shoots good but not very well filled; tendency toward 2-eared condition and some multiple earing; rather promising stock except for the smutting of the ears.
• C 210: One smutted plant in a total of 36; roots weak, badly lodged; not at all promising.
• C 211: No smutted plants; extremely early, very short plants; produced considerable seed; a useful stock.
• C 214: No smut; roots very weak; unproductive; not promising.
• S 283: No smut; early; lodging-resistant, at least until late in the season when a tendency toward stalk-breaking became apparent; produced a fair amount of seed for the season; probably a useful line.
• Kvakan 6991: About one-third of the plants had bud smut; stalks weak, broke badly; not promising.
• I 234: Rather late compared to others in this group but also relatively good; only two smutted plants in a total of 33 (bud smut); good set of seed; promising but possibly rather late for general use.
• Dr 2764: Two suckers with ear smut and one plant with stalk smut just below the ear; short, thick, well-filled ears; very weak roots; not especially promising.
• WD 456A2: Four plants with small bud smut galls near the base of the plant; no lodging; ears fairly well-filled with seed of excellent quality; poor pollen producer; relatively late; an excellent line for Iowa conditions but probably too late for general use.
• Sweet Corn Lines: All of these lines were so extremely early and made such poor growth under the prevailing conditions that fair judgment can hardly be passed upon them. They were nearly or quite smut-free. Numbers C6, C13, C78, and C85 had a fair set of seed. They are not promising for our conditions.

A. A. Bryan

Columbia, Missouri -

• Line	Firing Notes
  Co 214	yellow green in color; no ear shoots
  S 283	tassels were blasted on 7/6; first silk appeared 7/9
  Co 206	wilted badly followed by firing and tassel blasting; tassels blasted 7/15
  Co 208	little firing but tassels blasted 7/15
  Co 210	little firing but tassels blasted 7/16
  Co 211	upper leaves fired; tassels blasted 7/9
  Kvakan 6991	very slender stalk; yellow green color; tassels blasted 7/9; first silks 7/11
  Dr 276 A	lower leaves fired 7/17; pollen shed 7/17
  WD 456 2A	silked 7/13; all tassels blasted by 7/17
  Bryan 234	upper leaves fired 7/15; first silks 7/20

No rust, bacterial blight or smut was noticed in these cultures. None of the strains produced ears.

G. F. Sprague

Durham, North Carolina -

• Approximate order of adaptability	Number of diseased plants observed		Maturity	Miscellaneous observations
  	Smut	Rust
  Group I (good)
  1.*Dr 276-A	0	0	late	general appearance sturdy
  2.*Co 208	0	13(50%)	med.	Rust injury negligible
  3.*S 283	0	0	med.
  4.*WD 456-A2	0	0	med.	two plants runty
  Group 2 (fair)
  5. Co 210	0	0	med.	seg. small plants
  6. Kvakan 6991	0	0	med.
  7. I 234	1(5%)	0	late
  8.*C 78	1(3%)	0	med.
  Group 3 (poor) (not in order)
  C 85	1(5%)	0	med.-late	Two "F1 hybrids" ruled out.
  #Co 211	0	0	med.	General appearance satisfactory
  Co 214	0	0	med.	Very few seeds on open-pol. ears
  Co 206	0	0	med.	Not much pollen; probably protandrous
  C 13	0	0	early
  C 2	0	0	med.
  C 6	0	0	med.-early

* eight to 20 hand-pollinations in each of these inbreds.
# all pollination failures were of same date. This inbred may deserve better rating.

Conditions prevailing here last summer were in general too favorable to afford a rigorous test. The weather was consistently hot but rainfall was adequate (for late plantings which included these inbreds). No firing, no lodging, and no bacterial blight was observed. The infrequency of smut and rust infection in the inbred lines may not mean much, since my cultures generally suffered little from smut rust.

I had occasion to use some of these inbreds in crosses and also made a few self and sib pollinations in each line. The rating as to adaptability is based largely on the results of these pollinations. The proportion of successful pollinations and the yield of grain resulting provided a basis for rating.

H. S. Perry

Morgantown, West Virginia -

• Line	Height (inches)	% lodging		Rooting system	% Smut	No. Plants	Remarks
  		bent	lodged
  Bryan 276 A	44	24	12	fair	0	39	Very short ears
  " 234 *	70	0	0	v. good	0	25	#1 of Iowa lines, late
  " 456 A2	65	0	0	v. good neck	10.3	29	#2 of Iowa lines,
  Co 206	53	72	9	fair neck	7.7	13
  Co 208	50	0	0	v. good neck	7.7	13
  Smut check					gen'l 26.3	19
  Co 210	60	0	33	fair	0	11
  Co 211	42	0	0	poor	0	15
  Co 214	33	0	0	poor	0	11
  S 283	50	0	0	good	0	18
  Wiggans 206-32⊗*	65	90	0	poor	0	52
  " 211-10⊗	45	0	0	good	ear 3.8	52
  " 212-18⊗	5	20	15	fair	below ear 1.5	66
  " 210-11⊗*	64	15	10	fair+	ear, neck 3.4	59
  " 209-13⊗	46	70	0	----	0	10	stalks break down early
  Smut check					gen'l 54.9	51
  Wiggans 208-9⊗	58	5	5	good	0	47	stalks break down early
  Hayes S-42	58	0	10	fair	0	51
  Singleton C78, C 13, C 85, C 2, C 6	Planted late and on different plot, no smut. May be able to run this 1938

* These are considered the best lines.

C. R. Burnham

Ithaca, New York -

• Inbred line	Smut	Rust	Ears	Maturity	Plant Type
  Co 206	Some ear smut	1	fair	med.	weak stalk
  Co 208	Badly smutted	2	poor	med.	very desirable
  Co 210	Moderate amt.	2	poor	med.	slender stalk
  Co 211	Trace	1	good	med.	sturdy plants
  Co 214	0	2	good	early	sturdy plants
  S 283	0	3	fair	med.	very weak
  WD 456-A2	Trace	1	good	late	rel. sturdy
  Dr. 276A	0	1	good	late	short, sturdy
  I 234	Trace	1	good	late	rel. sturdy
  Kvakan 6991	Moderate amt.	4	v. poor	med.	lodged badly

(Rust notes taken latter part of Sept., rating is 1-5)

No bacterial blight and very little firing.

Inbred Co 211 is the most desirable one of this group for Ithaca. It excells in the favorable combination of suitable maturity, resistance to smut, good plant type, good ears, and vigor. It did show some top firing, however.

Co 208 has excellent plant type and proper maturity but it has much tassel and ear smut. Bryan's inbreds Dr 276A, I 234, and W.D. 456A2 are eliminated only because of maturity. They are too late for Ithaca.

D. G. Langham

Summary

A general summary of the above tables approaches impossibility, and may not be desirable, anyway, because certain inbreds are best adapted to certain localities. We note, however, that inbreds WD 456-A2, Co 208, Co 211, and S 283 met with the greatest approval and should be included in the test another year. Perhaps inbreds Dr 276A, I234, Co 210, and Co 206 should also be tested further.

Several of the cooperators in this test of inbred lines for disease resistance have suggested that a uniform system of taking notes on the different inbreds be established. What is your opinion in the matter? If those of you who are interested will send to the Co-op. the type of form that you prefer for this purpose, we will attempt to combine the best suggestions into one blank to be used in 1937.

Any of you who would like to conduct this test on disease resistance in 1937 will please notify us soon. If you have some inbreds that are quite resistant to disease and have desirable plant type, we should like to include them in the test this year. There is, of course, a limit to the number of inbreds we can handle properly.

(D. G. Langham)
Secretary