Corn flea beetle and Stewart's wilt predictions for 2004

Transcription

1 Corn flea beetle and Stewart's wilt predictions for 2004 Mike Hoffmann & Jeffrey Gardner, Dept. of Entomology, Cornell University, Ithaca. John Gibbons, Ontario Co. CCE Stewart's wilt is an important disease of sweet corn in New York. The disease is caused by a bacterial pathogen that is vectored almost exclusively by the corn flea beetle. The bacteria overwinter in the gut of adult flea beetles. In the spring, beetles infest early plantings of corn and transmit the pathogen to the plant by feeding and defecating on leaves. Stewart's wilt is characterized by development of conspicuous streaks on the leaves and stalk due to plugging of vascular tissue. Early wilt infections cause reduction of yield in susceptible varieties by reducing stands due to death or stunting of infected seedlings. Seedlings, which survive early infections, remain stunted, tassel prematurely, and frequently produce no ears or nubbins. Disease severity is aggravated by high temperatures, which causes faster development and movement of the bacteria through the infected plants. Corn flea beetles spend the winter as adults near the soil surface in grassy areas in and around cornfields. Severe winter temperatures can kill most of the population and result in a very low incidence of Stewart's wilt disease the following summer. Thus, a winter temperature index is used to predict the likelihood of Stewart's wilt problems. One forecast (modified Stevens-Boewe) is based the sum of the mean monthly temperatures for December, January, and February. The Stewart's wilt index (likelihood of wilt problems) is as follows: Index (winter temperature) > 100 High 85 to100 Moderately High 75 to 84 Moderate Below 75 Absent Modified Stevens-Boewe Likelihood of early season Stewart s wilt 2004 forecast: This is the second cold winter in a row. Last winter ( ) killed many of the overwintering corn flea beetles but we did observe an increased number of beetles in August of We don t know if that represented a significant population heading into the winter. In general, the risk for 2004 is mostly absent across much of the state with some areas showing moderate risks. Risk maps generated using two different models can be accessed at The predictive models do not account for the insulating effect of snow cover. However, despite relatively heavy snow cover in , overwintering beetles suffered high mortality. Management options for Stewart's wilt disease control include: 1) planting resistant varieties 2) planting with treated seed for susceptible varieties 3) applying a foliar insecticide spray if needed to protect seedling corn

2 Below we have tabulated risk of Stewart s wilt for many locations in NY (using the modified Stevens-Boewe method). County Site Index Risk Albany ALCOVE DAM 63 Absent Albany ALBANY COUNTY AP 68 Absent Allegany WELLSVILLE 63 Absent Allegany ALFRED 64 Absent Allegany ANGELICA 65 Absent Broome WHITNEY POINT DAM 62 Absent Broome BINGHAMTON EDWIN A LINK FIELD 65 Absent Cattaraugus FRANKLINVILLE 60 Absent Cattaraugus LITTLE VALLEY 63 Absent Cattaraugus NEW ALBION 2 64 Absent Cattaraugus OLEAN 68 Absent Cattaraugus ALLEGANY STATE PARK 68 Absent Cayuga LOCKE 2 W 68 Absent Cayuga AURORA RESEARCH FARM 72 Absent Cayuga AUBURN 73 Absent Chautauqua JAMESTOWN 4 NE 70 Absent Chautauqua DUNKIRK CHAUTAUQUA CO AP 78 Moderate Chautauqua Fredonia* 80 Moderate Chautauqua SILVER CREEK 2 NE 80 Moderate Chautauqua FREDONIA 83 Moderate Chemung CHEMUNG 61 Absent Chemung ELMIRA CORNING REGIONAL AP 67 Absent Chenango NORWICH 62 Absent Clinton ELLENBURG DEPOT 44 Absent Clinton DANNEMORA 48 Absent Clinton PERU 2 WSW 55 Absent Columbia COPAKE 69 Absent Columbia VALATIE 1 N 72 Absent Cortland TULLY HEIBERG FOREST 57 Absent Delaware WALTON 2 58 Absent Delaware EAST SIDNEY 61 Absent Delaware DELHI 2 SE 62 Absent Delaware ARKVILLE 2 W 63 Absent Delaware DEPOSIT 70 Absent Dutchess RHINEBECK 4 SE 66 Absent Dutchess POUGHKEEPSIE 74 Absent Dutchess STORMVILLE 77 Moderate Dutchess POUGHKEEPSIE DUTCHESS CO AP 79 Moderate Erie WALES 67 Absent

3 Erie BUFFALO NIAGARA INTL AP 76 Moderate Essex NEWCOMB 39 Absent Essex LAKE PLACID 2 S 47 Absent Essex WILLSBORO 1 N 55 Absent Franklin TUPPER LAKE SUNMOUNT 41 Absent Franklin MALONE 42 Absent Genesee Elba 68 Absent Genesee Batavia 71 Absent Genesee BATAVIA 74 Absent Greene EAST JEWETT 58 Absent Greene PLATTE CLOVE 60 Absent Greene CAIRO 4 NW 72 Absent Hamilton INDIAN LAKE 2 SW 44 Absent Hamilton PISECO 44 Absent Herkimer OLD FORGE 41 Absent Herkimer BIG MOOSE 3 SE 48 Absent Herkimer LITTLE FALLS CITY RE 58 Absent Jefferson WATERTOWN AP 54 Absent Jefferson WATERTOWN 57 Absent Jefferson WELLESLEY ISLAND 61 Absent Kings NEW YORK 98 Moderately high Lewis HIGHMARKET 37 Absent Lewis LOWVILLE 47 Absent Lewis HOOKER 12 NNW 49 Absent Livingston HEMLOCK 71 Absent Livingston AVON 72 Absent Livingston DANSVILLE 74 Absent Livingston Groveland 76 Moderate Madison MORRISVILLE 6 SW 53 Absent Monroe ROCHESTER GREATER ROCHESTER IN 74 Absent Niagara NIAGARA FALLS INT'L 73 Absent Niagara NORTH TONAWANDA 77 Moderate Niagara North Appleton 79 Moderate Oneida BOONVILLE 2 SSW 46 Absent Oneida UTICA ONEIDA COUNTY AP 59 Absent Oneida CAMDEN 2 NW 61 Absent Onondaga SYRACUSE HANCOCK INT'L ARPT 68 Absent Ontario HONEOYE 72 Absent Ontario GENEVA RESEARCH FARM 72 Absent Ontario Farmington 75 Moderate Ontario CANANDAIGUA 3 S 76 Moderate Orange WALDEN 1 ESE 73 Absent Orange PORT JERVIS 74 Absent

4 Orange MIDDLETOWN 2 NW 81 Moderate Orange WEST POINT 83 Moderate Orleans Albion 64 Absent Orleans LYNDONVILLE 4 ESE 75 Moderate Orleans ALBION 2 NE 78 Moderate Oswego OSWEGO EAST 72 Absent Otsego CHERRY VALLEY 2 NNE 59 Absent Otsego COOPERSTOWN 59 Absent Otsego MARYLAND 6 SW 59 Absent Putnam CARMEL 75 Moderate Rensselaer TROY L & D 68 Absent Rensselaer WEST SAND LAKE 2 S 74 Absent Schoharie LANSING MANOR 58 Absent Schoharie COBLESKILL 2 ESE 62 Absent St. Lawrence MASSENA AP 42 Absent St. Lawrence GOUVERNEUR 3 NW 47 Absent St. Lawrence CANTON 4 SE 47 Absent St. Lawrence LAWRENCEVILLE 3 SW 49 Absent St. Lawrence COLTON 2 N 54 Absent Steuben HORNELL ALMOND DAM 62 Absent Steuben ADDISON 65 Absent Steuben Wayland 69 Absent Steuben Arkport 70 Absent Steuben BATH 71 Absent Steuben CORNING 71 Absent Suffolk BRIDGEHAMPTON 93 Moderately high Suffolk RIVERHEAD RES FARM 96 Moderately high Sullivan CLARYVILLE 63 Absent Sullivan LIBERTY 1 NE 65 Absent Sullivan ROCK HILL 3 SW 68 Absent Sullivan BLOOMINGBURG 2 SW 73 Absent Tioga SPENCER 1 NE 63 Absent Tioga OWEGO 3 WSW 65 Absent Tioga WAVERLY 71 Absent Tompkins FREEVILLE 1 NE 60 Absent Tompkins ITHACA CORNELL UNIV 67 Absent Tompkins Freeville 67 Absent Tompkins Ithaca 70 Absent Ulster SHOKAN BROWN SLIDE MOUNTAIN 56 Absent Ulster MOHONK LAKE 77 Moderate Warren GLENS FALLS AP 48 Absent Warren NORTH CREEK 5 SE 50 Absent Washington WHITEHALL 59 Absent

5 Wayne Sodus 75 Moderate Wayne Savannah 75 Moderate Wayne Williamson 75 Moderate Wayne SODUS CENTER 76 Moderate Westchester YORKTOWN HEIGHTS 1 W 79 Moderate Westchester DOBBS FERRY ARDSLEY 92 Moderately high Wyoming WARSAW 6 SW 61 Absent Wyoming Gainesville 65 Absent Yates Potter 70 Absent Yates Branchport 73 Absent Yates Dresden 75 Moderate *lower case indicates Northeast Weather Association (NEWA) station.