Vol. 54—2000 - NorthEastern Weed Science Society

exceeded 4. The success of training employees was greatest when leaf size differences were large;
using this size difference minimized the time wasted on teaching weed and crop identification.
However, it required knowledgeable or experienced personnel, usually owners, consultants or scouts
to successfully handweed plugs with identically sized leaves.
Handweeding at the time of transplant resulted in the greatest crop loss, Table 4. Delaying
handweeding for 1 week was not particularly advantageous; while crop regrowth occurred, it did not
outpace weed growth and identification remained difficult. Delaying handweeding for 2-4 weeks
greatly improved crop survival in large leaved crops; significant losses also occurred at 8 weeks with
small leaved crops. Weed growth obscured crops at 8 wat and crop sizedeclined; often to
unacceptable levels.
Herbicide use minimized crop damage but weed control was generally unacceptable. Where
most of the weed originated in the plug itself and resumed growth prior to or concomitant with the
crop; herbicides applied to surrounding soil proved ineffective. Control 4 wat for both Gallery and
Daethal ranged from excellent in large leaved aggressive plants such as Hosta and ornamental grasses
to poor in small leaved crops such as Veronica or lberis. Control at 8 weeks was superior to that
observed 4 wat; rapid expansion growth of the crop appears responsible for crowding or
overshadowing weeds. With the onset of branching and/or flowering and the decay of herbicides,
weed growth resumed and percent control declined. Using Roundup to selectively kin growing
weeds in dormant plugs proved damaging. Apparent dormancy was misleading, sufficient crop
regrowth had occurred and crop damage was substantial. Weed suppression was insufficient at 4 wat
and declined to very low levels thereafter. At 16 wat, no weed control was seen in Roundup treated
pots. Handweeding 4 weeks after Roundup application proved promising; much of the crop survived
phytotoxicity to resume growth and weed identification was markedly improved.
CONCLUSIONS
Handweeding perennial plugs upon receipt and at transplant resulted in substantial crop losses,
due principally to misidentification and small size. Categorizing weed and crop by leaf size improved
employee training and reduced crop loss due to handweeding errors only when knowledgeable
personnel could complete the removal of like-sized weeds. Handweeding and its damages highlighted
the frailty of herbaceous perennial plugs and the frequency with which weeds occur in imported plant
materials. The rapidity of weed growth and the damage that ensued could not be offset by
handweeding; rather those damages were exacerbated and crop loss was excessive. Applications of
two pre- and one postemegrent herbicides did not adequately control weeds actively growing in plugs
at the time of transplant. Postmergent Roundup proved damaging; preemergent applications were
helpful but did not result in a weed-free crop. Far greater crop cleanliness is necessary at the point of
propagation to ensure that distant exportation does not result in nursery-wide weed contamination.
While the responsibility for crop cleanliness rests with the whole sale producer; there remain few
options for local nurseries; to date; those options are both time-consuming and prone to damage. An
exploration of other herbicides with greater efficacies; incorporation of granular herbicides in soilless
mixes; drench or dip methods for ensuring weed to herbicide contact; the development of
Roundup-ready plant material and other suggestions deserve serious consideration as methods to
reduce the damage currently plaguing the herbaceous perennial industry.
23