Thou shalt not scalp seashore paspalum - GCSAA

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GCM April 2002 canopies therefore have a soft, silky feel com p a red to the sti f fer canopies of bermudagrass and zoysiagrass. The softer nature of the paspalum canopy means that the actual mowing height in the field is very close to the bench setting because the canopy does not slow down the mower as much.Any management factor that further softens the canopy (excess nitrogen, excess irrigation, poor drainage,low potassium or insufficient topdressing) can increase the potential for scalping. Scalping: causes and prevention Practices that minimize the potential for scalping in paspalum are the same as those for other grasses, but adjusted to paspalum’s specific requirements. 1. Fertility Fertility, especially excess nitrogen (which causes rapid shoot growth and excess su cc u l en ce) and inadequ a te potassium,is the most important factor in reducing paspalu m’s su s cepti bi l i ty to scalping. Excess nitrogen should not be applied to this grass at any time. SeaIsle 1 paspalum (www.seaisle1.com) maintains good color even at low nitrogen Tim Hiers, CGCS, mows a paspalum green at The Old Collier GC in Naples, Fla. Mower type, surface smoothness and firmness, and individual mower operator skills can all play a part in whether a green is scalped. levels, so nitrogen is seldom necessary for color retention. Nitrogen should be primarily applied to control or regulate shoot growth rates. Adequ a te ava i l a ble po t a s s ium is cri t- ical for high leaf tu r gor pre s su re mainten a n ce and root sys tem devel opm en t , m a i n ten a n ce and functi on a l i ty. It is also the first line of defense against many leaf s pot diseases. Se a s h ore paspalum has a h i gh requ i rem ent for po t a s s ium and is h i gh ly ef f i c i ent in using it. Th erefore , adopting a spoon - feeding ferti l i ty program (light ra tes app l i ed frequ en t ly or use of h i gh - percen t a ge slow - rel e a s e n i trogen produ cts) for both nitrogen and po t a s s ium is essen ti a l . Like other grasses,paspalum is most prone to scalping during the transition from grow-in fertility and topdressing programs to mature turf stand mainten a n ce progra m s . Se a s h ore paspalu m responds readily to available nitrogen (because of its high nitrogen uptake and use efficiency). Therefore, it is necessary to wean the grass off the aggressive nitrogen fertility program necessary for grow-in. Otherwise, the turf will be very prone to scalping during the tra n s i ti on peri od as the cut ti n g height is lowered. Dec rease the mowing hei ght gradu a lly for paspalu m , n orm a lly by 0.02–0.03- i n ch increm ents over 2–3-day peri od s once the nitrogen levels have been redu ced and shoot growth ra te is slowed . One indicator that the nitrogen fertility program is lean enough is when dollar spot (Sclerotinia) starts showing up on the paspalum. Then adequate nitrogen can be maintained by spoonfeeding without causing excess shoot growth. Nitrogen applications should be avoided until stolons start growing from the remaining shoots and the disease problem is under control. This grass responds rapidly to soluble nitrogen source s , wh i ch are ei t h er used immediately or stored for later use. Ch oi ce of ferti l i zer type (gra nu l a r, l i qu i d ), m et h od of a pp l i c a ti on (ferti gati on , foliar spray, gra nular) and solu bi l- i ty (percen t a ge slow rel e a s e , h i gh ly solu-
le) all must be determ i n ed in con cert with bu d get con s i dera ti on s . With pasp a lu m , adopti on of a lean-and-mean a pp l i c a ti on stra tegy in com p l i a n ce wi t h envi ron m ental stew a rdship issues is po s- s i bl e .Mac ronutri ents like nitrogen , po t a s- s ium and magn e s ium and spoon - fed m i c ronutri ents (espec i a lly manga n e s e ) a re important to maintain adequ a te , but not too ra p i d , s h oot growth ra te s . 2. Sand topdressing On paspalum (and bermu d a gra s s ) go l f green s , sand top d ressing du ri n g grow-in must be applied at frequencies and ra tes that maintain a thin mat (thatch with high levels of sand so that the sand provi des a firm su rf ace ) . In adequ a te top d ressing produ ces a s om ewhat puffy thatch layer, wh i ch results in a much less firm surface that is susceptible to scalping. The higher mowing heights and rapid turf growth rates required for grow-in make it easy to apply insufficient sand topdressing for true mat development. In the best-case scen a ri o, a firm su r- f ace is ach i eved du ring grow - i n . Devel oping this ideal su rf ace du ring the tra n s i ti on peri od is also accept a bl e , a l t h o u gh it is more difficult and requ i re s f requ ent light verti c ut ti n g. If a firm su r- f ace is not ach i eved by the time grow - i n has been com p l eted , it may take som e time to lower mowing hei ghts to playa bl e l evels in an ef fort to avoid scalping. Light verticutting aids in preventing scalping du ring the tra n s i ti on from grow-in to mature turf by allowing more topdressing sand to integrate into the turf surface. Heavy verticutting should be avoided, however. Good topdressing sand integrates easily into seashore paspalum surfaces even at close mowing heights and without verticutting when applied at light rates of 0.5 to 4.0 cubic feet of topdressing per 1,000 square feet. 3. Irrigation management Pa s p a lum is very re s pon s ive to irri gati on du ra ti on and frequ en c y. E m p l oyi n g f requ ent irri ga ti on events of s h ort du ra- ti on re sults in a shall ow root sys tem and grass that wi ll not ex h i bit its full po tential for dro u ght re s i s t a n ce and tends to grow ra p i dly, e s pec i a lly if ferti l i ty is h i gh . (“ Frequ ent irri ga ti on events of s h ort du ra ti on” means irri ga ting every 1-3 days at ra tes that on ly rewet the su r- f ace 4 inches of the root zone ra t h er than rech a r ging the whole roo t - zon e depth.) Un der these con d i ti on s , t h e grass also tends to be more su cc u l en t and ex h i bits too mu ch shoot growt h . In f requ ent irri ga ti on app l i c a ti ons of l on ger du ra ti on (irri ga ting every 4-7 days with su f f i c i ent water to rech a r ge the roo t zon e ,of ten abo ut 0.5 to 1.0 inch of w a ter on a sand green) wi ll train the root system deeper into the soil prof i l e ,while the s h a ll ower roots take adva n t a ge of ra i n f a l and irri ga ti on even t s .Hi gh eva po tra n s p i- ra ti on ra tes and dro u ght stre s s ep i s odes have little ef fect on grass with a deep root sys tem and a high rh i zome nu m ber. Periods of drought stress h a rden the grass to envi ronm ental stre s s e s . Excess irri ga ti on causes ad d i ti onal su cc u l en ce in the tu rf l e aves and a sof ter su r- f ace zon e ,wh i ch can also lead to scalping. The grass can t a ke excess water and prol on ged wet soi l - profile con d i- ti on s , but scalping po ten ti a l i n c reases accord i n gly, u su a lly because the tu rf su rf ace is less f i rm and is more prone to tra f f i c - rel a ted go u ging of the su rf ace . Poor dra i n a ge can also produ ce the same re sults in wet eco s ys tem s . The grower must balance the management of salts with supplying judicious quantities of water for the turf while complying with water conservation requirements. Use of highly saline water may alter the decision to verticut lightly, because the cut ends of the turf could be more prone to salt desiccation and injury. 4. Mower type Especially on greens, the type of Scalping predisposes seashore paspalum to diseases such as Helminthosporium, indicated by the reddish-brown color of the grass. April 2002 GCM
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Thou shalt not scalp seashore paspalum - GCSAA

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