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Linda S. Nelson, A.B. Stewart, and Kurt D. Getsinger

ABSTRACT

Growth chamber studies were conducted to evaluate the effectiveness of the aquatic herbicide fluridone for control of fanwort, and to assess the impact of treatment on the non-target plant, water marigold.  Treatments included static exposures of 0, 5, 7.5, 10, 15, 20 and 30g fluridone/L.  Changes in pigment concentrations within the plant (phytoene, B-carotene, and chlorophyll) and biomass were used to appraise treatment efficacy.  For fanwort, phytoene levels increased 82% and B-carotene decreased 88% when exposed to 5g fluridone/L for 14 days.  Effects on these two pigments persisted through 84 days after treatment (DAT) for fanwort.  In contrast, phytoene content was not affected in water marigold however, plants exposed to >10 ppb fluridone showed reduced B-carotene 84 DAT.  Leaf chlorophyll decreased with increasing fluridone concentration in fanwort whereas in water marigold, decreased chlorophyll was observed in plants treated with rates of 7.5g/L and higher.  Despite these observed differences in pigment response, all fluridone treatments significantly reduced shoot dry weight biomass.  Overall, the data showed that biomass and pigment levels of water marigold were minimally impacted following treatment of 5g/L fluridone.  However, the dose of fluridone required to control fanwort by >80%, severely inhibited water marigold growth.  We conclude that there is limited potential for selectively controlling nuisance fanwort populations with fluridone where water marigold must be protected.

For more information:

Nelson, Linda S.
USAERDC Vicksburg
CEERD-EP-P
3909 Halls Ferry Road
Vicksburg, MS 39180-6199
Email: nelsonl@wes.army.mil