Page 18>-Com Talk, Lancaster Farming, Saturday, April 17,1993 pennSTATE k(o®lM TPMJK MIWO Considerations for selecting com hybrids in Pennsylvania Selecting the best com hybrids can be a significant factor in the profitability of a com production enterprise. The differences in performance among commercially available com hybrids of the same maturity generally exceed 15 bushels per acre and frequently reach 50 bushels per acre. As a result, improving com yields by an average of 5 to 10 bushels per acre through careful attention to hybrid selection is not unrealistic. CHARACTERISTICS TO CONSIDER An effective hybrid selection strategy involves considering! a number of hybrid characteristics that are important for performance under your system and then using various sources of information to choose the most appropriate hybrids. Maturity is of primary importance in the hybrid selection process because it is critical to choose hybrids that can use as much of the available growing season and still have a minimal risk of being frosted before maturity. Hybrids that are too early will have a reduced yield potential and those that are too late may result in poor quality grain or silage. Com hybrids are rated in one of two systems; the relative maturity system and/or the growing degree day system. Of the two systems, the relative maturity system is more popular In the relative maturity (RM) system. hybrids are assigned a days-to-matunty rating based on the grain moisture at harvest compared to other hybrids As a result, a hybrid with a lower RM rating should have lower grain moisture levels at time of harvest than one with a higher RM rating. The rating is not a measure of the actual days required for maturity, since it is not uncommon for a 105-day hybrid to require 150 days from the dale it is planted to reach maturity The ratings also vary somewhat among companies, this makes comparisons of maturity more difficult One way to overcome the differences amonj the companies is to compare moisture contents of specific hybrids in perfoimance trials where they appeared to- gether—lower moisture contents translate into an earlier rating The second system is the growing degree day system In this system, the number of growing degree days is calculated between dates of planting and black layer or maturity The advantage of the growing degree day system is that n provides a link between hybrid maturity and local weather information Disadvantages of this system are 1) ODD ratings are not necessarily indicative of differences in gram moisture, because hybrids may differ in dry-down rates after black layer, and 2) growing degree day require ments of hybrids may change somewhat with location and season Hybrids in Pennsylvania frequently do not require as many growing degiee days as they will use in the Midwest states Also, growing degree day requirements of specific hybrids may be lower in cool seasons and late plantings A good rule of thumb is that com for grain should reach maturity one to two weeks before the first killing frost in the fall Other factors, such as harvest method, marketing plans, and timeliness considerations may also have a bearing on maturity selection The need for a field dry-down period with ear com and dry shelled corn means that maturity should not be pushed with these systems Where high-moisture corn harvest is planned, slightly longer season hybrids can be used Even longer season f 5 to 10 days) hybrids can be utilized for silage production provided wet soils will not interfere with harvest Earlier hybrids may provide some advantages for early com markets or more timely harvesting If you consider this approach, be sure to monitor yields of these earlier maturing hybrids to make sure this strategy is economical for your system A key to managing maturities in an area as diverse as Pennsylvania is to monitor crop development each year and use this information in selecting hybrid maturities for future years Appropriate maturities for gram production in Pennsylvania are shown in Figure 1 and Table 1 Figure 1. Pennsylvania corn maturity zones. MATURITY Hybrid selection is the main avenue for control of the the most predominant com diseases in Pennsylvania. Stalk rot, one of the most serious and common com diseases, is favored by environments where stress occurs during August. If stalk rot appears to be a persistent problem in your system, consider placing more importance on standability and stalk rot resistance in your hybrid selec tion. Gray leaf spot, northern leaf spot, and northern leaf blight are also common in Pennsylvania. ( Gray leaf spot is most severe in those fields of continu ous, no-till com where air drainage is poor. Fields that are along creeks and rivers are particularly vulnerable to gray leaf spot because of the extended periods of dew. The symptoms of the disease resemble a paper match—gray, rectangular shaped lesions that are restricted by the leaf veins. Where this disease is serious, gray leaf spot resis- Buy 10 Bags of Any NORTHROP KING RECEIVE ONE BAG OF MULTIKING I, VIKING I ALFALFA FREE! OR PURCHASE ONE OR MORE BAGS OF ANY NORTHROP KING BRAND ALFALFA VARIETY OR BLEND AND GET ONE BAG OF MULTIKING I, VIKING I or FORTRESS AGRONOMY CENTER Thompsontown, PA 717-535-5151 BEDFORD FARM BUREAU Bedford, PA 814-623-6194 LARRY BOWER Linden, PA 717-323-3546 BROOKLAND MILLS, INC. Me Veytown, PA 717-899-6772 BRUCE B. GAMBLE & SONS Concord, PA 717-349-2670 HAKES FARM & SEED SERVICE Rod Lion, PA 717-244-2754 ELWOOD HARER Montgomery, PA 717-547-6133 EDWARD HESSONG Greencastlo, PA 717-597-9534 HORRACE HEINDEL & SON York, PA 717-244-3780 HYDRO/KIRBY AGRI-SERVICES Lancaster, PA 717-299-2541 GORDON ISENBERG Alexandria, PA 814-669-9323 College of Agricultural Sciences • Cooperative Extension DISEASE RESISTANCE HYBRII CORN OR FORTRESS ALFALFA FREE! For Details See Participating Northrup JOHN D. CASSEL & SONS HERBERT MYERS Hummelstown, PA Lewisberry, PA 717-566-8022 717-697-8903 LYN-LEE FARMS State College, PA 814-238-1233 SCOTT MELLOTT RHOADS MILLS INC. Lancaster. PA Selmsgrove, PA 717-295-3470 717-374-8141 MENSINCER BROS. Nescopeck, PA 717-379-3388 GENE MILLER Calawissa, PA 717-799-5760 RALPH MILLER Womelsdorl, PA 215-589-2642 MIKE WASCOK Dunbar, PA 412-628-3993 NORTHRUP KING Both northern leaf spot and northern leaf blight occur most frequently in valley areas where heavy dews and early morning fog or mist are common. Northern leaf spot (race 3) symptoms are tan to brownish, linear, chain-like lesions. The northern leaf blight symptoms are elliptical, grayish green streaks that develop on the leaves and may extend the length of the leaves. Under severe infection, all leaves may die. Both diseases can cause early plant death. Resistant hybrids are the best means of control. Learn to identify the major com diseases in your area and select hybrids with specific resistance to these diseases. Be wary of hybrids advertised as having “good disease resistance”—instead ask your dealer about specific resistance to diseases that you know are common on your farm. OBERHOLTZER DAIRY FARM East Earl, PA 717-354-0832 RICHARD H. KAUFFMAN Columbia, PA 717-684-2683 RONALD SHAFFER & SONS Dalmatia, PA 717-758-6345 SCOn SHIPMAN SOMERSET MILLING CO. Turbotville, PA Somerset. PA 717-649-6133 814-445-7504 STEVE SHIPMAN District Sales Manager 717-726-6958 tance should be a primary consideration in your hybrid selection. (Turn to Page 19) Your King Dealer HYDRO-KIRBY AGRI SERVICE Richland. PA 717-866-5701 MASTER FARMER FERTILIZER Lancaster, PA 717-397-5152 PHILLIP PITZER Aspers, PA 717-677-7716 JOHN SNOOK Milllmburg, PA 717-966-0957 STEPHEN SNYDER Mdlersburg, PA 717-362-8735 RICHARD STONER Alverton. PA 412-887-8854 TWIN FIR FARM Centre Hall. PA 814-364-9270 WALNUT BARN & DAIRY EQUIP. Port Royal. PA 717-436-9429 WARRIORS MARK FEED CENTER Warriors Mark, PA 614-632-5490 WAYNE FEED SUPPLY Dillsburg, PA 717-432-9623 WAYNE FEED SUPPLY Chambersburg, PA 717-263-4121 KENNETH ZURIN Mt. Joy, PA 717-898-8736 ERTH-RITE, INC. Gap. PA 717-442-4171 ALAN HEFLIN Keymar, MO 301-898-7942 JACK HEFLIN Woodsboro, MD 301-898-5255 GORDON FLICKINGER Union Bridge, MO 410-775-7394
Significant historical Pennsylvania newspapers