Vol. 54—2000 - NorthEastern Weed Science Society

EVALUATIONS OF PENNMULCH, WULPAK AND GEODISK
FOR WEED CONTROL IN CONTAINERS
R.E. Woolen and J.C. Neal'
ABSTRACT
Three studieswere conductedto evaluate-mulches·forweedcontrolin container
ornamentals.Wulpaj(R,pelletizedsweepingsfromthe shearingfloorsof sheepoperations,was
usedas a mulchor as a compresseddiskwhichwasshapedto fitthe topof the container.
PennMulch R is a pelletized newspaper product, wnh 1% nnrogen added, that is spread over the
top of the medium. Both the Wulpak and PennMulch pellets absorb water and swell to
approximately twice their volume. Geodisk", is a geotexlile disk wnh a coating of Spinout",
manufactured to fit different sized containers. In each test, the potting substrate was pine bar1<
+ sand (- 7:1 vlv) amended wnhfertilizer and lime; weed seed weresown before application of
mulches,disksor herbicides.
In the study at Castle Hayne, NC, PennMulch and Geodisk were compared to standard
preemergence herbicides. The test was conducted in a randomized complete block design wnh
4 replications and three pots per species per plot. The PennMulch was applied as a one-haff
inch deep mulch on top of the medium. The test waS inniated on 3/31199.Approximately 10
weeksafterinitialtreatment,allthe weedswere removedandon 6123199the chemical
treatments were reapplied. The weed species used in this stUdy were spotted spurge
(Euphorbia maculala), ecIipta (Eclipla alba), crabgrass (DigHaria sanguinalis), longstalk
phyllanthus (Phytlanlhus lennelus), doveweed (Muniannia nudiflora) and hairy bittercress
(eaniamine hirsuta).
Two tests were conducted at the Horticu~ure Field Laboratory (HFL) in Raleigh. One
test, to compare Geod,sk and Wulpak disk, was in a randomized complete block design wnh 3
treatmentsand5, single-potper speciesreplications.The secondtestwas a comparisonof
Pennmulch and Wulpak pellets each applied at twodepths, 0.25 and 0.5 inch. The test was
conduced in a randomized complete block design wnh6 treatments and 4 replications, with 3
pots per species per plot. The weed species used in both tests were spotted spurge, longstalk
phyllanthus crabgrass, horseweed (Conyza canadansis) and common groundsel (Senecio
vulgaris). Both studies were initiated on 7/13199.
In the Castle Hayne study, PennMulch and Geodisk controlled bittercress as well as
Scotts OH2 (oxyftuorfen + pendimethalin), the chemical check. In early ratings, crabgrass
control was good and phyllanthus control was moderate wnhthe mulch and disk treatments but
poor in later ratings. At 10 weeks aflertreatment (WAl), spurge control was excellent by all
three methods. Eclipta and doveweed were better controlled by the mulches than by OH2.
In the disk stUdy at HFL, Raleigh, both Geodisk and Wulpak disks controlled horseweed
and groundsel. Control of spurge was excellent wnh the Geodisk and fair wnh the Wulpak disk.
Phyllanthus was not controlled by either disk. At SWAT control had generally lessened but the
pattem of control did not. In the depth of mulch study, groundsel and horseweed were
controlled in all mulch treatments, but in the 0.25 inch Pennmulch plots groundsel control
dropped to 75% by 12 WAT. Spurge and phyllanthus were controlled by all treatments except
PennMulch at 0.25 inch. Only Wulpak at 0.5 inch controlled crabgrass.
, Department of Horticu~ural Science, N. C. State Universny, Raleigh, NC 27695
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