NEWARK, Del. - You can’t cure a tree once it gets wilt disease, but if the infection is mild, water not fertilizer may help it recover. This is the gist of research findings by plant pathologists at the Unviersity of Delaware Agricultural Ex periment Station. Results of work on wilt-infected yellow-poplars (tulip trees) by master’s degree candidate Carolyn Sanford and her advisor, Dr. Mien L. Morehart, challenge and present practice of fertilizing Verticillium infected trees to aid recovery. Typical symptoms of this fungus disease are yellowing (chlorosis) and browning (necrosis) of leaves. In very severe cases, Sanford says a tree may die within weeks after contracting the disease. There’s nothing the owner can do except cut the tree down and make sure tUSctSh FARM Si ix/ CENTER eatunng one piece steering rod all-welded construction rear hitch and pressure type grease fittings Bolster stakes can be set at 38 or 42 width Gear capacities are gross weight at farm tractor speeds All units comes less tires 6 Ton 80765-046 Reg 429 99 39999 8 Ton 44099 10 Ton CJQ99 80772 046 Reg 489 99 80780*046 Reg 589 99 iTKT Below gears standard with 3 longer reach Pole and kwik hitch safety tongue 1Q499 Reg 114 99 /SAVE 10 00 19461-243 Trailer Cart 10 Cu. Ft. Heavy steel body Quickly and eas ily hitches to a garden tractor or riding mower Removable sliding tailgate Large pneumatic tired wheels Body 42" long. 32 V wide. 12" deep Design may vary trom illustration 5 Panel Steel Gates 48 high gates with panels made of heavy 22 gauge galvanized steel Gates are 4 shorter than listed to compensate for hinges Complete with screw hooks and hinges 10’Gate 009* 14’Gate 0*99 17686 253 Reg 32 99 aO 17676 253 Reg 41 99 12' Gate 01 99 16' Gate 0099 17687 253 Reg 35 99 W I 17677 253 Reg 44 99 *9O Reg. prices may vary locally 7 BAR TUBE GATE IJ/«"l J /«" 7 Bar Round Tube Gate 10’Gate $0099 12'Gate $4.1199 17924 253 Reg 44 99 OO 17931 253 Reg 46 99 HU 14’Gate 0099 16'Gate $0099 17949-253 Reg 51 99 "W 9 17956-253 Reg 56 99 m Nitrogen helps wilt-diseased not to plant another susceptible species in the same place. With less severe infections, only a branch or two may be affected and the tree may spontaneously recover because it com partmentalizes or walls off the infection inside it. To increase the vigor of trees with Verticillium wilt, some authorities recommend fertilizing with nitrogen. Nitrogen comes in two basic forms, ammonium or nitrate, and some scientists say only the ammonium form should be used. But there is no universally accepted treatment. To see what would happen when infected trees were fertilized, Sanford decided to study the effect of both forms of nitrogen on the spread of Verticillium wilt through the vascular system of yellow poplars. She chose this species because « e 99 Forged I O Toplink 13415 063 Category 1 Adjustable from 20‘ thread 11/8 NC J 4 spockets Category 2 Forged Toplink 13642 063 1699 24670-282 Red Stripe Baler Twine This high quality twine is uniform in, thickness for guaranteed trou ble free operation, free replace ment of any defective twine 9000 ft. 290 Tensile strength. the tree is important both for timber and as a landscape specimen. Yellow-poplar is the major wood used in making drawers and backs of chests and other furniture. Because it grows quickly as well as tall and straight, it is the only hardwood species used for reforestation. A member of the magnolia family, it is also prized as a landscape specimen. The tree is very susceptible to Verticillium wilt, though otherwise_ it has few pests. Sanford’s advisor, Morehart, has been studying the yellow-poplar for some time because of its potential commercial value to Delmarva. Sanford’s experiment involved two greenhouse studies and two field studies. Some of the trees were fertilized and then inoculated with wilt disease. Others were inoculated first, then fertilized. Hurry! Sale prices good now thru Sat., July 21st Galvanized Steel Wire Smooth galvanized steel wire for use with electric fence chargers 17 ga. y 4 ml. 19102 150 17 ga. y 2 mi. 1499 14 ga. y 4 mi. 1C99 l5O I W 199" 43038-472 Truckbed& Tailgate Liner One piece rugged truckbed liner saves wear & tear on your pickup Resistant to gas oil acids & salts withstands ex treme impacts to 60* F Tailgate cover included to 29 19 99 19". 12656 040 Swivel Jack ' Flat bottom Assembly may be turned 90° horizontal or vertical Locking handle holds device m any position ALL RIDERS ARE SETUP AND SERVICED 99" 949" 2M79 Mfl 9 ' SAVE 10 °° Reg 999.99 / SAVE 50 00 0 u „ #5lBB-81 36" Side Discharge 23047-258 •S Mp. UynSftiarK #5lBB-80 36" Rear Discharge 23054-258 19" Push Mower 11 Hp. 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SjF/XRM & FAMILY CENTER CHAMBERSBURG LANCASTER 1351 Lincoln Way East Ph 717/264-8282 , 1570 Manheim Pike Ph 717/569-0111 Open 9-6 Mon -Thur / 9-9 Fn / 9-5 Sal Open 8 30-5 30 Mon Fn 8 30-5 Sat uKpßTnwu FLEETWOOD QUAKER lUWN weaver s hardware co Quakerlown Plaza Shopping Center RD 4125 Fleetwood PA 19522 RtS 309 & 313 Ph 215/538-2494 (on main road from Fleetwood to Toptonl 9-6 Mon-Wed / 9-9 Th &Fn / 9-5 Sal / 12-5 Sun PH 215 944 /486 215 944 9648 Hours Mon thru Fri BAMto 7 PM Sat 8 AM to 4 PM All items are sublet to stock on hand We reserve the right to limit quantities Sate ends on above date Not Responsible For Printing Errors Lancaster Farming, Saturday, July 14,1984—C3 trees recover She used four different forms of nitrogen in her studies; calcium nitrate, ammonium sulfate, am monium nitrate and urea. Most fertilized groups received a modest rate of 150 pounds per acre, though in field tests some trees received 600 pounds per acre (a level far in excess of the recom mended rate). After treatment, she assessed disease severity in fertilized groups compared with unfertilized checks. First she looked for leaf chlorosis and necrosis. Then she cut open tree trunks and branches and checked for vascular discoloration. The Verticillium fungus lives in vascular tissue and is spread by sap. The amount of discoloration is a measure of disease severity. Sanford found greater vascular discoloration in trees which had received a nitrate form of Reg 1199 99 /SAVE 100 00 36 Rear Discharge 22546 250 Dynamark 11 Hp. 6 Speed Tractor Synchro-balanced engine key ignition electric starting sealed beam headlights and a heavy duty Transaxle with disc brake & automotive differential section 6 forward speeds 1 reverse Available with either a 36 rear discharge twin blade cutting deck or a 42 side discharge triple blade deck In Carton nitrogen, indicating the wilt pathogen had spread further than when ammonia fertilizer was used. This bears out what other researchers have found. However, using ammonia nitrogen also spread the disease to some extent much more than in trees which had received no fertilizer at all. Based on these results, Sanford concludes that, contrary to some recommendations, it is wise to withhold fertilizer entirely from trees which are suspected of having Verticillium wilt. “I think the tree has a better chance of recovery if left alone,” she says. “I would give it water during dry periods because of fungus reduces the capacity of the tree to take up water. But although it’s recommended, I don’t think fertilizing yellow-poplars is a good idea, even with the ammonium form of nitrogen.” YOUR CHOICE 159999 Reg 1799 99 / SAVE 200 00 23061 258 Dynamark 18 Hp. 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