TEXAS AGRICULTURAL EXPERIMENT STATION R. D. LEWIS, Director College Station, Texas BULLETIN NO. 689 JUNE, 1947 SWEET CORN TESTS IN THE LOWER RIO GRANDE VALLEY B. S. PICKETT Formerly Horticulturist, Substation No. 15 Weslaco, Texas AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS GIBB GILCHRIST, President VB81-847-3M-L180 0. 74>» [Blank Page in Original Bulletin] Maximum total yields in this test were obtained with Ioana when about 27,000 plants per acre we-re grown. Size of ear was, however, too small under such crowding for good commercial production. It is recommended that planting rate and spacing be ad- justed so that there are between 11,000 and 13,000 plants per acre. This will allow good-sized ears to develop and will not seriously cut total production. Five degrees of resistance to ear worm could be determined. The most outstanding resistant va- rieties were Bantam Hybrid 57, Golden Hybrid 54, Magnagold, and Silvercross Evergreen. Ioana and Erie were somewhat inferior to these varieties but are still good resistant varieties. The most sus- ceptible varieties were Gold Rush Hybrid, Golden Cross Bantam, and North Star. Ifitroduction . . . . CONTENTS IOIIIIOI Spacing and Its Effect on Yield . . . . . . . . . . . . . . . . . . . . . Method..._......_... Results....v.................. . . . . . . . Varieties of Sweet Corn ..I . . . . . . . . . . . . . . . . . . . . . . . . Studies on Earworm Resistence . . . . . . . . . . . . . . . . . . . . Sunimary .- . . . .. -----. u not o \ 0000 n unis a g BULLETIN NO. 689 JUNE 1947 SWEET CORN TESTS IN THE LOWER RIO GRANDE VALLEY B. S. Pickett, Formerly Horticulturist Substation No. 15, Weslaco, Texas g Sweet corn as a commercial croplin the Lower Rio Grande Valley of Texas dates from 1938 when F. H. Vahlsing Company planted 400 acres of the hybrid variety Ioana. Since that time the acreage of sweet corn planted has increased until it is probably the second most important spring vegetable crop. g Because of the increasing importance of sweet corn to the vegetable fgrowers, thegfindings of the Lower Rio Grande Valley Experiment Sta- Ition (Substation No. 15) are here presented. a SPACING AND ITS EFFECT ON YIELD Spacing is very important in the production of sweet corn, both from the standpoint of yield and the size of ear. A study of sweet corn spacing, begun in 1943 and completed in 1944, gave satisfactory answers to this question (1). Methods The experiment was laid out with four replications. Spacings were l arted at 12 inches and increased at 8-inch intervals up to 36 inches. eds were planted at the rate of of one, two, three and four seed per hill. lats were 3 rows, 3 feet apart by 30 feet long, and only the middle row as harvested as a test row. The variety of corn used was Ioana produced the Associated Seed Growers of New Haven, Connecticut. This is bentioned because there appears to be some slight difference in the per- vormance of Ioana from different sources. Results The effect of planting rate on yield is not directly concerned with final n‘ nd. For this reason, stand is not considered in this part of the report. A able 1 gives the results as obtained from the field notes. vvAnalysis indicated very little effect of number of seeds planted per fll on yield. The maximum yield for Ioana sweet corn was calculated result from a stand of 27,000 plants per acre. However, it is not always irable to produce a maximum yield because there may be too many zérs- that are too small for market purposes. ' ' L 1. Pickett, B. S. The effect of spacing and numberHof kernels per hill on sweet corn 1.. ‘elds. Proc. Amer. Soc. Hort. Sci. 45:421-424. 1944. 6 BULLETIN NO. 689, TEXAS AGRICULTURAL EXPERIMENT STATION Table 1. Yield per plat of green corn (pounds) Number of kernels per hill 1 2 3 4 12-inch spacing 19.12 14.88 15.25 11.50 14.25 10.18 15.51 17.50 5.44 8.62 11.00 10.88 11.00 18.00 15.25 10.75 Total....... 49.81 51.68 57.01 50.63 20-inch spacing 8.00 14.50 11.31 9.88 11.25 12.50 19.31 12.50 5.50 10.25 15.00 15.75 10.50 9.31 12.50 8.75 Total . . . . . . . 35.25 46.56 58.12 46.88 28-inch spacing 9.8a 13150 15.75 10.50 2.12 5.44 13.06 12.75 4.00 7.69 5.75 5.25 5.69 8.06 _ 9.25 " 5.25 Total . . . . . .. 21.69 34.69 43.81 33.75 36-inch spacing 7 31 9 06 7.00 4 62 5 00 4.62 16.62 10 25 4 50 7.12 11 25 7 7 00 9 25 13.75 6 94 Total . . . . . .. 23.81 30.05 48.62 29.06 Table 2. Average yield at diflerent spacings and seeding rates Spacingbetween hills Pounds per plat No. kernels per hill Pounds per plat (inches) 12 13.07 1 8.16 20 11 .68 2 10. 19 28 8.37 3 12.98 36 8.22 4 10.01 Table 3. Number of mature stalks per plat expressed as percent of the number of seeds Q planted Kernels per hill Spacing (inches) 1 2 3 4 Average 12 71 56 55 57 60 20 89 67 59 47 66 28 100 72 62 51 71 . ‘36 100 78 66 45 72 ; Average . . . . . . . . . . . . . . . . . 9o es so 50 67 Ealihanmcamuhem. . 1 SWEET CORN TESTS IN THE LOWER RIO GRANDE VALLEY 7 Highest calculated yieldslare obtained when seed are planted at the rate of three kernels per hill, and when the 1x3-foot spacing is used. i Maximum ear size was obtained with a stand of some 13,200 plants per acre. - . An experiment to check the data obtained in the first study was set up i the following year. This experiment was also used as a study of machine a planting. A 16-hole plate seeder operated at tractor speed (1-1) calculated to result in a spacing of 5 inches was used for one set of three plats. Another set was planted with a 12-hole plate seeder at the same speed i to give a spacing of 6.5 inches and, at two-thirds tractor speed, to give a spacing 9.5 inches. Actually these stands were not attained. The closest spacing was approximately 10 inches; the next was 16 inches, and the greatest spacing was 26.5 inches. Table 4. Results obtained by machine spacing Average spacing Hills per acre Ear weight Yield er acre (inc es) (lbs.) l s.) l0 17,750 ' .31 5572 l6 ll .083 .60 6488 26.5 6.685 .82 5342 Greater ear size was obtained in this experiment than in the previous one, and ear size was more directly affected by stand density. As a result i the conclusion must be drawn that, in general, a spacing of less than 12 to 15 inches should be used only on fertile land provided with adequate and timely irrigation. ' VARIETIES OF SWEET CORN During the past three years more than 100 varieties of sweet corn j have been tested in a limited way to determine their adaptability to this Earea. Of these, 42 can be obtained from commercial sources. Only the 5i, best of these will be described and discussed. H Ioana: At present this is the, major variety grown in the Lower Rio iGrande Valley. It is the first of the hybrid sweet corn varieties carrying ‘gtrue earworm resistance; for this reason it was the first to make com- ymercial production possible in this area. As compared with a number of j newer varieties Ioanv is only fairly resistant to the insect. Ioana was gjloriginated by Dr. E. S. Haber of the Iowa Agricultural Experiment Sta- fltion. The ear is 7% to 8 inches in length, almost cylindrical and well filled to the tip. Husk cover is heavy enough to prevent serious damage by d birds up to harvest time. Color of kernels is a rather light golden yellow. L The variety is very attractive when cooked. It ships and handles well ‘through the retail markets. J Golden Hybrid 2439: This variety was first tried at the Weslaco station in 1944. It proved to be somewhat heavier in yield than Ioana that year and S . BULLETIN NO. 689, TEXAS AGRICULTURAL EXPERIMENT STATION also the year following. It is not as resistant to earworm as Ioana, and is little if any better from the standpoint of quality. It is a 12- to l4-rowed variety under Lower Rio Grande Valley conditions, and is from 7 é to 8%» inches in ear length. The plants sucker strongly and the ear size tends to be somewhat reduced by this habit at normal plant spacings. It is apparent- ly more attractive to birds than Ioana, but on the whole the variety is well adapted to commercial production in this area. Erie (Bantam Hybrid 51): This variety, and Bantam Hybrid 5'7, ap- pear to be the finest of the new va- rieties for this region. Erie has more earworm resistance than either Ioana or Golden Hybrid 2439. It is less sub- ject to bird damage than 2439, and suckers less. The» plant is taller and more vigorous than most of the sweet corn varieties studied. It is slightly later than Ioana but not later than 2439. The ear is clear, light golden yellow, 12- to 14-roWed, and an inch longer than Ioana. Quality is good, rather better than 2439. Bantam Hybrid 57: This variety’ is in many respects similar to Erie. However, the shuck cover is very short. As a result, birds and insect predators are apparently able to de- stroy many young earworms before they have done much damage. The ears appear remarkably clean and free from injury at harvest time. Figure 1. Typical ears of variety Erie. Yields of both Erie and Bantam Hybrid 57 are considerably above yields for Ioana or Golden Hybrid 2439. Other Varieties: There are a number of other excellent varieties of corn that do not meet market requirements for one reason or another. Tristate, Goldengrain and Goldenlast are all very high-yielding varieties. They have good ear length, but they are 16- to 18~rowed varieties. Such thick ears do not produce the pack-out count required by shippers. Golden Hybrid No. 10, produced by W. A. Huelson of the University of Illinois, is an excellent variety with only the fault of folding the husk leaves in. between the kernel rows. It sometimes does not fill well at the tip but this is not a serious fault. SWEET CORN TESTS IN THE LOWER RIO GRANDE VALLEY 9 Table 5. Variety results with yellow sweet corn Average yield Pounds per acre corrected Variety Average accordin to Rank 1944 1945 1946 stan Allegheny . . . . . . . . . . . . . . 2,744 2,880 . . . . . . . . Burpee Cross . . . . . . . . . . . 32 33 . . . . . . . . Early Bancross . . . . . . . . . . 606 . . . . . . . . . . . . . . . . . . . . . . Golden Cross Bantam . . . . 1 ,238 1 ,280 . . . . . . . . *Golden Hybrid 2439. . . . . 3,766 3,880 9 Ioana . . . . . . . . . . . . . . . . . . 2,768 2,860 . . . . . . . , Lincoln . . . . . . . . . . . . . . . . 1 ,264 1 ,302 . . . . . . . . North Star . . . . . . . . . . . . . 78 82 . . . . . . . . Northern Crozs . . . . . . . . . 84 88 . . . . . .-. . Ohiogold 1 . . . . . . . . . . . . . . 3,506 3,680 10 Top Flight Bantam . . . . . . 1 ,089 1 ,089 . . . . . . . . Carmel Cross . . . . . . . . . . . 4 48 . . . . . . . . *Golden Hybrid No. 10. . . 4,356 4,500 3 Gold Rush Hybrid . . . . . . . 113 118 . . . . . . . . Aristogold 1 . . . . . . . . . . . . 3,308 3,410 . . . . . . . . Aristogold 2 . . . . . . . . . . . . 2,991 ,991 . . . . . . . . Dependogold . . . . . . . . . . . 3,450 3,450 . . . . . . . . Evergold . . . . . . . . . . . . . . . 2,375 2,490 . . . , . . . . Goldenlast . . . . . . . . . . . . . . 4,538 4,675 4 June Gold . . . . . . . . . . . . .. 3,060 3,210 _ . . . . . . ., Tristate . . . . . . . . . . . . . . . . 5,462 5,462 2 T endermost . . . . . . . . . . . . . ,00 ,05 . . . . . . , . Magnagold . . . . . . . . . . . . . 3,505 3,620 . . . . . . . . Kiawak . . . . . . . . . . . . . . . . 746 ' 720 . . . . . . . . Wappoo . . . . . . . . . . . . . . . . . . . 482 466 . . . . . . . . Alameda . . . . . . . . . . . . . . . . . . 1,700 1 ,7OO . . . . . . . . Tenderdee . . . . . . . . . . . . . . . . 3,356 3,240 . . . . . . . . Goldengram. ._ . . . . . . . . ,950 6,720 1 *Bantam Hybrid 51 (Erie) . . . . . . . . 2,140 6,295 4,218 4,075 6 *Bantam Hybrid 56 . . . . . . . . . . . . . . 2,960 4,715 3,838 3,700 8 *Bantam Hybrid 57. . . .‘ . . . . . . . . . . 4,080 4,990 4,535 4,370 5 Golden Hybrid 50 . . . . . . . . . . . . . . . 1,740 . . . . . . . . 1 ,740 1 ,740 . . . . . . . . *Golden Hybrid 54 . . . . . . . . . . . . . . . 4,000 . . . . . . . . ,000 4,000 7 Carowa. . . ._ . . . . . . . . . . . . . . . . . . . . . . . . . . .. 197 197 186 . . . . . . . . Drouth Resistant Golden Cross Bantam . . . . . . . . . . . . . . . . . . . . . . .. 1,291 1 ,291 1 ,2l8 . . . . . . . . Suncross . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,558 3,558 3,378 . . . . . . . . Tenderbest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,016 2,016 2,020 . . . . . . . . *Excellent types, worth field trial. Up to this time there has been no interest in varieties of white sweet corn for shipping. Nevertheless, the Lower Rio Grande Valley station has carried on a number of tests with white sweet corn. Of the 1'7 commercial white hybrids tried, only Stowell’s Evergreen Hybrid No. 14 x 15 and Silver- cross Evergreen have given good enough performance and general charac- teristics to make them especially desirable for either canning or fresh market varieties. 0 Silvercross Evergreen: This variety is a 14- to 16-rowed variety about 7 1o 8 inches in ear length. The variety has a heavy husk cover, is quite resistant to earworm, and of good quality. The ‘plants are extremely vigorous and moderately resistant to corn rust. Stowell’s Evergreen Hybrid 11, 9015: This is a variety introduced by the University of Illinois. It is quite similar in habit and character to Silvercross Evergreen. - 10 BULLETIN NO. 689, TEXAS AGRICULTURAL EXPERIMENT STATION Table 6. Variety test results with white sweet corn Average yield _ Pounds per acre corrected Variety Average accordin to 1944 1945 1946 stan Keystone Evergreen . . . . . . . . . . . . . . 3,880 624 . . . . . . . . 2,252 2,300 Sachem . . . . . . . . . . . . . . . . . . . . . . . . . 4,890 . . . . . . . . . . . . . . . . 4,890 5,870 Winnebago . . . . . . . . . . . . . . . . . . . . . . 2,620 . . . . . . . . . . . . . . . . 2 ,620 3,150 Country Gentlemen 5 x 10. . . .. . . .. 1 ,560 . . . . . . . . . . . . . . .. 1,560 1,875 Country Gentlemen 8 x 6. . ._ . . . . . . 3,500 2,654 . . . . . . . . 3,077 2,420 Narrow Grain 17x11 . . . . . . . . . . . . . . 2,880 . . . . . . . . . . . . . . . . 2,880 3,460 Narrow Grain 14x13 . . . . . . . . . . . . . . 3,100 911 . . . . . . . . 2,006 , . Narrow Grain 26x15 . . . . . . . . . . . . . . 4,550 . . . . . . . . . . . . . . . . 4,550 5,460 Shoeped Hybrid . . . . . . . . ._ . . . . . . . . . 2,500 . . . . . . . . . . . . . . . . 2 ,500 3,000 Stowell’s Evergreen Hybrid 14x15. . 3,760 5,755 3,314 4,276 4.276 Stowell’s Evergreen Hybrid (Burpee) 1 ,790 243 . . . . . . . . 1 ,0l6 926 Aristogreen . . . . . . . . . . . . . . . . . . . . . . 250 . . . . . . . . . . . . . . . . 250 300 Silvercross Bantam . . . . . . . . . . . . . . . 2,500 . . . . . . . . . . . . . . . . 2,500 3,000 Silvercross Evergreen ._ . . . . . . . . . . . . 4,375 7,482 4,556 5,471 5,471 Silvercross Narrowgram . . . . . . . . . . . . . . . . . . . 7,408 4,218 5,813 5.400 Oregon Evergreen . . . . . . . . . . . . . . . . . . . . . . . . 3,020 . . . . . . . . 3 ,020 2,240 Narrowgrain 5x22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,943 5,943 7 .350 Other varieties of white sweet corn of merit are the Narrowgrain Hybrids 5x22’ and 26x15. Neither of these two varieties seems to have adequate earworm resistance to make it a satisfactory canning corn variety. Each could be properly trimmed for shipment as fresh ears, however. STUDIES ON EARWORM RESISTANCE It has been generally stated that husk extension and tightness are important factors in earworm resistance. Barber (2) reports that when the varieties Golden Cross Bantam and Marcross 6-13 have short husks due to drouth they are more severely attacked than when they have normal husk cover. Dicke and Jenkins (3) state that earworm resistance in field corn is increased by good husk cover folding tightly about the tip of the ear. Richey (4), however, was unable to state that any observable characteristics were concerned in earworm resistance in a study of some susceptible varieties of field corn. The corn earworm (Heliothis armigera (Hbn.)) is the most serious‘ insect pest of corn in the Lower Rio Grande Valley. A careful record of earworm infestation of the various varieties on trial has been maintained. To determine the earworm index, two grades of infestation were re- corded. Ears not invaded by the insect were scored 0; ears invaded but not commercially damaged were given a rating of 1; ears commercially damaged were given a rating of 10. For example, Ioana in one test 2. Barber, G. W. Husk development of sweet corn as affected by moisture supply, ° an important factor in corn earworm control. Jour. of Agr. Res. 68:73-77. 1944. 3. Dicke, F. F., and M. T. Jenkins: Susceptibility of certain strains of field corn in hybrid combinations to damage by corn ear worms. U.S.D.A. Tech. Bul. 898. 1945. 4. Richey, F. D. Maize hybrids susceptible to earworm: Heritable difierences in sus- ceptibility of corn hybrids to early attack. Jour. of Hered. 35:327-328. 1944. Y‘°'”""'F "W'"V1T""Wwrm"mwmw,vv-w 09' - -v - SWEET CORN TESTS IN THE LOWER RIO GRANDE VALLEY l} showed 5 percent of the ears commercially damaged, giving a score of 50. An additional '75 percent were invaded but not damaged seriously, which adds '75, the total score in this case being 125. Five varieties that have been in- cluded in the trials each of the years discussed and which were fairly rep- resentative of the whole, were used as a standard of comparison. These varieties-Ioana, Golden Hybrid No. 10, Golden Hybrid 2439, Tristate and Goldengrain —- have been considered fairly earworm resistant, but actually they vary considerably among them- selves in this respect. Golden Hybrid No. 10 is the most resistant of the group, Golden Hybrid 2439 the least resistant, and Ioana, Tristate and Goldengrain, which have almost the same degree of resistance, are inter- mediate. Judging from these studies there seem to be about five groups each carrying more or less resistance. Gold Rush Hybrid, Golden Cross Bantam and North Star seem to be most sus- ceptible. Northern Cross, Evergold and June Gold may carry some resist- ance; Golden Hybrid 2439, Aristogold Bantam, Goldenlast and Silvercross Bantam seem to have slightly more resistance. The first group carrying really marked resistance includes Ioana, Tristate, Goldengrain, Erie, Bantam Hybrid 56, Dependogold and Topflight Bantam. The most resistant varieties so far tested are Aristogold Bantam Ever- green, Bantam Hybrid 5'7, Golden Hybrid 50, Golden Hybrid 54, lVIagna- gold and Silvercross Evergreen. What the genetic factors may be in resistance are not to be obtained from the data collected up to this time. It is apparent, however, that husk and silk characteristics are not the sole causes of resistance. In the group carrying the most resistance are to be found varieties with relatively tight and relatively loose husks. The extension of the husk beyond the tip is not itself an important characteristic in these varieties since Figure 2. Typical ears of Bantam Hybrid 57. Bantam Hybrid 57 has so little husk cover that ears are frequently exposed at the tip. Golden Hybrid 54, however, is well covered with a husk extension of from two to three inches. In 1945 two plantings of Ioana were made. The first planting matured with normal husk cover and 12 BULLETIN NO. 689, TEXAS AGRICULTURAL EXPERIMENT STATION showed an earworm index of 195. The second planting, because of climatic and water conditions, had almost no husk extension ‘beyond the ear, and had an earworm index of only 67. Additional varieties which appeared in both tests were somewhat more free of worms in the latter planting than they were in the earlier test, but not to the same extent, the average reduction being almost 30 points. It is suggested in these particular cases that the young earworm larvae were exposed longer to attacks by predacious insects and possibly by birds. Many of the ears of both varieties showed evidence of the presence of young ear worms at one time. Table 7. Comparative ear worm resistance* " _ Index of infestation Variety Average 1944 1945 1946 Ioana . . . . . . ._ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 195 388 259 Golden Hybrid 1O . . . . . . . . . . . . . . . . . . . . . . . . . 81 97 300 159 2439 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450 356 320 375 Tristate. ._ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 206 350 239 Goldengrain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 197 390 247 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 208 350 256 Aristogold Bantam . . . . . . . . . . . . . . . . . . . . . . . . 371 238 . . . . . . . . . . 304 Aristogold Bantam Evergreen . . . . . . . . . . . . . . . 69 70 430 190 Bantam Hybrid 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 260 249 Bantam Hybrid 56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 310 275 Bantam Hybrid 57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 290 194 Dependogold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407 98 250 252 Evergold. . _. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 410 . . . . . . . . . . . . . . . . . . .. 410 Golden Grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 197 390 280 Golden Hybrid 50 . . . . . . . . . . . . . . . . ._ . . . . . . . . . . . . . . . . . . 107 . . . . . . . . . . 107 Golden Hybrid 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 . . . . . . . . . . 100 Goldenlast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540 250 . . . . . . . . . . 395 Junegold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 590 . . . . . . . . . . . . . . . . . . . . 590 Magnagold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 101 . . . . . . . . . . 107 Silvercross Bantam . . . . . . . . . . . . . . . . .1 . . . . . . . 314 . . . . . . . . . . 400 357 Silvercross Evergreen . . . . . . . . . . . . . . . . . . . . . . 61 141 . . . . . . . . . . 101 To Flight. . . . ._ . . . . . . . . . . . . . . . . . . . . . . . . . . 150 . . . . . . . . . . 400 275 Go d Rush Hybrid . . . . . . . . . . . . . . . . . . . . . . . . 500 1000 . . . . . . . . . . 750 Golden Cross Bantam . . . . . . . . . . . . . . . . . . . . . . 600 960 . . . . . . . . . . 780 North Qtar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 920 . . . . . . . . . . . . . . . . . . . . 920 Northern Cross . . . . . . . . . . . . . . . . . . . . . . . . . . . 640 . . . . . . . . . . . . . . . . . . . . 640 *No infestation is 0._ ; _ Complete commercial infestation 1000. None of the most severely infested varieties has especially tight husks; yet many of the least susceptible varieties have husks no tighter. Another interesting observation is that many of the varieties having high earworm resistance were frequently least affected by bud worm early in the growing season. From the data, it- is suggested that there may be as many as 5 degrees of earworm resistance in sweet corn varieties. Within the 5 groups there appears to be enough variation to suggest that hereditary characteristics alone may not account for all apparent resistance. For example, as many ears of Bantam Hybrid 57 showed the presence of earworms as in the case of Bantam Hybrid 51. The important difference was not number of ears infested, butthe damage done by the earworms. Extremely long a.i..»a‘i_nmlaw\.... SWEET CORN TESTS IN THE LOWER RIO GRANDE VALLEY 13 i husk extension, which with the accompanying length of silk, provides l‘ food for the earworm until the corn is ready for harvest, may also reduce damage from the pest. I SUMMARY 1. Spacing for ‘sweet corn is as important from the standpoint of éar i size as from the standpoint of yield. A spacing of 11,000 to 13,000 plants f per acre appears best. This allows a possible yield of from 125 to 170 _. half-bushel bag-s of corn per acre, including cull-out. 2. New varieties of yellow sweet corn well adapted to the Valley are I Erie and Bantam Hybrids 56 and 57. Other “varieties that may have value 3A as shipping. varieties are Golden Hybrid 10 and Golden- Hybrid 54. Some excellent varieties needing trial in large acreages for both shipment and possible canning are the 16- to 18-rowed varieties Tristate, Goldenlast 1 and Goldengrain. 3. White sweet corn varieties worthy of trial as canning varieties are i Narrowgrain 26x15 and 5x22; and the Evergreen hybrids Silvercross ‘i and 14x 15. 4. Resistance to ear worm apparently varies in about five steps, from 7 susceptible to highly resistant. Within these groups there is some varia- ' tion which may be ascribed to exposure of the insect to attack by eippredators, or as in the case of extremely long husk extensions simply j; supplying food to the insect in sufficient quantity that damage to the ‘ear does not occur. -