Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

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EFFECT OF DEW AND GRANULAR FORMULATION ON MESOTRIONE EFFICACY
FOR LAWN WEED CONTROL. M.J. Goddard, S.D. Askew, J.B. Willis, Virginia Tech,
Blacksburg, R.J. Keese, Syngenta Crop Protection, Carmel, IN, and J.R. James,
Syngenta Crop Protection, Greensboro, NC.
ABSTRACT
Lawn weed control is typically achieved with granular herbicides. Scotts Turf
Builder Plus 2 (28-3-3 fertilizer plus 1.21% 2, 4-D, and 0.605% MCPP), the most
common granular herbicide for lawns, requires dew on leaf foliage for best results. With
dew present, granules stick to leaves instead of falling through the turf canopy. Granular
formulations of mesotrione are being developed for both consumer and professional
markets. Since mesotrione is absorbed though both foliage and roots, it may be less
dependent on dew than industry standards for consumer markets. Studies were
conducted at two sites in Blacksburg, VA to evaluate granular combination products of
mesotrione and fertilizer, compared to 2,4-D plus MCPP for consumer lawn care. Our
objective was to determine the effects of granular formulation and dew on efficacy of
mesotrione and 2,4-D plus MCPP for control of common lawn weeds.
We evaluated three mesotrione granular products including a 29-3-4 fertilizer
similar to Scotts Turfbuilder that contains mesotrione at 0.2% (EXC853), the same
fertilizer with mesotrione at 0.2% and prodiamine at 0.4% (EXC856), and a 29-3-4
fertilizer similar to Vigaro that contains mesotrione at 0.25% (EXC950). These
mesotrione products were compared to a commercial 28-3-3 fertilizer with 1.21% 2,4-D
and 0.61% MCPP (Scotts Turfbuilder Plus 2). All products were applied at 140
kg/ha. The study areas consisted of Kentucky bluegrass (Poa pratensis) containing
dandelion (Taraxacum officinale), corn speedwell (CSP) (Veronica arvensis), and white
clover (Trifolium repens). The four granular herbicides were applied in early AM while
foliage was still wet with natural dew and in the afternoon of the same day to dry turf. All
treatments received 0.4 cm irrigation within 48 h.
The presence of dew did not influence dandelion and white clover control by
mesotrione while dew increased CSP control by mesotrione with one of the three granular
products. Mesotrione on the fertilizer carrier similar to Vigaro did not control dandelion,
CSP or white clover as well as mesotrione on the fertilizer carrier similar to Scotts. For
example, Mesotrione controlled dandelion 90, 86, and 58% and white clover 90, 87, and
67% as EXC 856, EXC 853, and EXC 950, respectively 28 days after treatment (DAT)
regardless of dew presence. In contrast, 2,4-D + MCPP controlled dandelion and white
clover 88% when applied to wet foliage and 33 and 18%, respectively, when applied to
dry foliage. EXC 856 controlled CSP 88%, regardless of dew while EXC 853 controlled
CSP equivalently when dew was present but less (65%) when leaves were dry. In
contrast, EXC 950 controlled CSP 43% when dew was present and more (58%) when
leaves were dry. 2,4-D plus MCPP did not control CSP, regardless of dew. In this study,
mesotrione controlled weeds equivalent or superior to the commercial standard and could
be a viable product for consumer markets.
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