Baxter, A. J.

Dollinger, E. J.

Findley, W. R.

Saboe, L. C.

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RESEARCH CIRCULAR 175 APRIL 1969 Maize Dwarf Mosaic Virus in Corn Hybrids W. R. FINDLEY, E. J. DOLLINGER, L. C. SABOE, and A . J. BAXTER OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER Wooster, Ohio CONTENTS * Introduction __________________ - - - - - - - - - - - - - - - - ____ - - - - - - - - - _ 3 Experimenta I Procedure ___________ - - - - - __ - - - - - _______ - ___ - _ _ _ 3 Findings ____________________ - ____ - - - - - - __ - - ____ - _ _ _ _ _ _ _ _ _ _ _ 4 ON THE COVER Relative yields of maize dwarf mosaic virus susceptible corn at left and resistant corn at right. AGDEX 111/632 4-69-SM Maize Dwarf Mosaic Virus in Corn Hybrids W. R. FINDLEY, E. J. DOLLINGER, L. C. SABOE, and A. J. BAXTER1 INTRODUCTION In 1968, corn hybrids were grown on the Vaughters' farm along the Ohio River near Portsmouth, Ohio, for yield and other performance data. This was a cooperative test conducted by the U. S. Department of Agriculture, Ohio Agricultural Research and Development Center, and Ohio Cooperative Extension Service. The test included 39 hybrids from commercial interests and 5 open-pedigree experimental combinations from the Ohio Agricultural Research and Development Center. An attempt was made to include all hybrids sold in the area as resistant to maize dwarf mosaic virus (MDMV). EXPERIMENTAL PROCEDURE On May 22, the test area was fertilized by broadcasting and disking in sufficient fertilizer for a calculated 150-bushel yield goal. Planting was attempted May 23 but was delayed because of heavy rains. A few days later, approximately 10 feet of water flooded the area and an un-known quantity of the fertilizer was lost. Hybrids were planted June 10 in four replications of two-row plots, with 3-foot isles between tiers of plots. Rows were spaced 40 inches apart and plots, including the isle, were 22 feet long ( 1/297-acre). Two seeds were planted at spacings approximating 10 inches. Each row of the two-row plots was thinned to 27 plants ( 16,038 plants per acre). Emergence and distribution of plants in the plots were uneven due to soil crusting from heavy rains which followed planting. It was not possible to obtain a uniformly distributed plant stand in many plots. In general, however, stands were considered satisfactory. The planting was kept weed-free by a 4-pound per acre pre-emer-gence application of atrazine and some hoeing. Ear height means were determined by measuring all plants in each plot from ground level to the top ear node. Lodging data were recorded October l 7. Plants broken below the lowest ear node were counted as stalk-lodged. Root-lodged plants were leaning 45 degrees or more from upright. 1 Research Agronomist, Crops Research Division, Agricultural Research Service, U. S. De-partment of Agriculture; Professor of Agronomy, Ohio Agricultural Research and Development Center; Extension Agronomist, The Ohio State University, Columbus; and Area Extension Agent, Agronomy, Washington Court House, Ohio. 3 Each hybrid row was harvested and sampled for moisture. The first two replications and eight entries of the third replication were har-vested October 17 and 18. Harvesting was delayed by rain and was completed November 2. All ears in each row were harvested and their weight to the nearest 1/10 pound was recorded. A few entry harvest weights were adjusted for poor stand. Counts of ears harvested ex-cluded ears with less than 4 inches of grain. Grain for moisture determinations was obtained by shelling two kernel rows from ten randomly selected cars. Hybrid plot MDMV ratings were made by using a 1-9 scale; 1.0 indicated no visible virus symptoms and 9.0 complete susceptibility. Plant stunting was not associated with virus ratings of 3.0 or less. Rat-ings of 4-9 indicated increasing degrees of stunting and ratings of 6-9 increasing effects of the virus on ear shoot development. Plants which rated 9.0 were severely stunted and had little or no ear shoot develop-ment. FINDINGS Incidence of MDMV was high. Average performance of all hy-brids tested is given in Table 1. By July 8, MDMV symptoms were evident in plants of the more susceptible hybrids. Many hybrids appeared free of MDMV symp-toms as late as August 20. On August 28 and September 11 when the plots were rated, a high incidence of MDMV was found in surrounding, susceptible corn. Agreement between hybrid row data was good. Therefore, thr statistical analysis was computed by using the two-row plot smns. Favorable weather conditions prevailed throughout the growing season and test uniformity was satisfactory. The yield per acre coeffi-cient of variation value was 8.72 percent. Least significant differences ( L.S.D.) at the 5 percent probability level were computed for yields and MDMV ratings. This value is use-ful in interpreting the results because it indicates the magnitude of the difference calculated to be real and not due to chance alone 19 times in 20. Comparisons using the least significant difference are most mean-ingful when made with a common standard. Correlation coefficients between yields and the August 28 and Sept-ember 11 MDMV ratings were -0.52 and -0.77, respectively. These values are significant at the 1 percent probability level, indicating that hybrid susceptibility to MDMV is highly correlated to high yield loss where the disease occurs. Perfect correlations of 1.00 rarely occur; however, failure to obtain a better relationship between yield and MDMV rating may be due in part to imperfections in the rating scheme. Most of the discrepancy reflects tolerance of certain hybrids to virus infection. It should be emphasized that the data are for 1 year. Discounting MDMV effects, soil fertility and other growing conditions make some parts of a test plot more productive than others. A hybrid may rank high for yield only because it happened to be planted on a favored spot in the field. Planting each hybrid in four different places in the field partially equalizes such differences. However, chance still plays a part in determining yields and causes some differences not inherent in the hybrids themselves. It is possible that location effects caused small dif-ferences in the MDMV reactions of certain hybrids. For these reasons, data for 2 or more years are considered more reliable. Obviously, low yielding hybrids which rated susceptible to MD:MV should not be grown where the disease occurs. It is not possible to pre-dict accurately the performance under different growing conditions of those hybrids which had better than average yields, standability and MDMV ratings. 5 TABLE 1.-Average Performance of Corn Hybrids Grown in Four Replications Near Portsmouth, Ohio, in 1968. Ears Yield Moisture Lodging Days per per al lo Halt Ear 100 MDMV MDMV Hybrid No. or Pedigree Acre Harvest Stand Stalk Root Silk Ht. Plan ls Rating Rating Bu. % % % % No. In. No. 8-28 9-11 Funk Bros. 21821 102.9 31.3 97 7 1 61 46 99 3.5 2.8 funk Bros. G-4660 92.0 34.9 96 18 1 65 52 118 2.3 2.5 Funk Bros. G-47 61 93.7 40.7 98 0 0 65 46 108 l.5 2.5 Funk Bros. 18472 81.6 29.l 96 6 l 61 39 101 l.8 3.3 Mortin 400M 67.8 25.2 95 19 2 62 41 102 4.0 5.3 Pioneer 3182 (X4482A) 96.0 34.8 95 13 0 66 49 l 01 3.3 2.5 Pioneer 31 88 IX521 B) 101.1 34.4 100 5 0 65 46 98 3.0 2.3 Pioneer X5475 125.9 36.5 98 8 0 63 50 107 l.8 l.3 °' Ruff ERXl 258 74.4 33.7 94 11 2 64 46 99 3.8 3.8 Ruff RXl 260 84.2 32.5 96 15 l 64 47 94 4.0 3.8 Ruff RW22 80.9 40.5 96 11 4 66 49 100 2.3 3.5 Ruff RW24 83.2 39.1 96 9 0 66 46 104 3.3 3.8 DeKalb XL72 83.3 33.4 94 11 0 63 41 105 l.O 2.5 DeKalb XL372 70.9 33.0 99 25 1 63 38 100 2.3 4.3 DeKalb XT872 86.1 33.8 96 23 0 64 43 99 l.8 4.0 DeKalb XL342 73.5 30.4 95 34 0 62 41 111 3.8 5.3 DeKalb 88511 96.8 32.7 93 6 1 61 44 103 3.5 4.3 DeKalb 88147 115.4 33.2 100 13 0 63 48 108 l.O l.5 Hiser VR850 91.3 31.6 97 17 1 64 46 109 3.0 4.0 Hiser H832 70.7 31.4 90 15 1 63 43 99 4.3 5.3 Moews SM738 56.4 32.0 93 32 2 66 41 89 5.0 7.0 Moews SM77ST 97.7 34.4 95 9 2 65 46 97 3.0 3.0 Moews SM77STA 96.1 31.9 97 17 4 63 46 95 2.8 2.8 Moews Exp. 838 61.0 32.7 93 16 2 66 43 89 4.8 6.3 TABLE 1 (Continued).-Average Performance of Corn Hybrids Grown in Four Replications Near Portsmouth, Ohio, in 1968. Ears Yield Moisture Lodging Days per per at to Halt Ear 100 MDMV MDMV Hybrid No. or Pedigree Acre Harvest Stand Stalk Root Silk Ht. Plants Rating Rating Bu. % % % % No. In. No. 8-28 9-11 PAG SX17 106.1 36.8 97 9 0 66 51 106 2.3 2.3 PAG 439 100.8 33.4 97 19 1 64 47 98 3.0 3.3 landmark C897XX 91.9 32.2 96 12 5 64 46 102 3.0 2.8 Wishnand 835 103.3 32.6 93 16 3 63 47 104 2.3 4.0 Wishnand 807 98.9 32.0 94 14 5 63 49 103 2.0 2.5 Wishnand 850 86.3 30.9 96 19 2 65 46 99 3.5 3.5 Mitchell Farms C/F95 61.5 32.0 94 23 1 65 41 95 5.0 7.0 '-.! Mitchell Farms C/Fl l 6 69.6 31.6 96 42 l 62 43 107 4.5 5.5 Mitchell Farms C/Fl 28 64.l 30.9 96 40 2 67 41 87 4.8 5.8 Mitchell Farms C/Fl 83W 77.4 37.1 93 17 l 65 47 96 3.0 4.0 Mitchell Farms C/F85 73.7 31.3 99 10 0 65 41 95 4.5 6.0 Crow's 825 88. l 30.4 97 25 2 65 46 95 2.8 3.0 Kenworthy K4 l l 87.2 32.4 95 13 2 63 44 99 3.3 3.8 Kenworthy K465 77.6 33.5 90 21 3 66 49 95 3.8 4.3 Kenworthy K500X 63.2 32.1 100 12 3 64 42 94 4.5 5.5 (Cl.388 x Va35) (Mo 12 x Oh78) 105.8 34.5 98 4 1 63 48 104 1.0 2.5 (N78 x Mol2) (837 x Oh514) 100.l 32.6 95 17 l 62 49 112 3.0 3.0 (N78 x Mol 2) {Va35 x Pa405) 103.0 29.8 99 15 0 63 47 109 2.0 2.3 (N78 x Oh5 l 4) (Va35 x Pa405) 97.2 29.2 93 13 8 62 42 114 2.0 2.5 Oh514 x N78 78.5 33.1 91 26 7 64 50 123 1.0 2.5 L.S.D. (5 % le;el) 10.5 1.41 l.16 Coefficient of Variation 8.72 7~ State '74 tk {3amft«a {o't J"/~tu'tat i<uea'td ad Z'~ofuuelet NORTHWESTERN • ' 1 • MUCK c.CROPS • MAHONING COUNTY COlUMBUS WOOSTER • CENTER HEADQUARTERS THE OH~ STATE EASTERN OHIO RESOURCE I WESTERN • UNIVERSITY DEVELOPM!NT CENTER I i I VEGETABLE CROPS I I "'""":"''" ,./ , "'"'~ JACKSONe f " SOUTHERN ' .... . '-.r~ . . "-Ohio's major soil types and cli-matic conditions are represented at the Research Center's 12 locations. Thus, Center scientists can make field tests under conditions similar to those encountered by Ohio farmers. Research is conducted by 13 de-partments on more than 6200 acres at Center headquarters in Wooster, ten branches, and The Ohio State Univer-sity. Center Headquarters, Wooster, Wayne County: 1953 acres Eastern Ohio Resource Development Center, Caldwell, Noble County: 2053 acres Jackson Branch, Jackson, Jackson County: 344 acres Mahoning County Farm, Canfield: 275 acres Muck Crops Branch, Willard, Huron County: 15 acres North Central Branch, Vickery, Erie County: 335 acres Northwestern Branch, Hoytville, Wood County: 247 acres Southeastern Branch, Carpenter, Meigs County: 330 acres Southern Branch, Ripley, Brown County: 275 acres Vegetable Crops Branch, Marietta, Washington County: 20 acres Western Branch, South Charleston, Clark County: 428 acres 

Maize dwarf mosaic virus in corn hybrids

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Maize dwarf mosaic virus in corn hybrids

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