Uptake of Triticonazole, during Imbibition, by Wheat Caryopses after Seed Treatment

The phenylpyrazole insecticide, fipronil, is used in seed coating against Agriotes larvae, which infest mainly corn and sunflower. Coating the seeds of the cultivated plants with fipronil has proven its effectiveness against Agriotes populations. In the case of sunflower or even corn, the possible root uptake of this insecticide may lead to a toxic effect against pollinators such as honeybees. In the present report, the uptake and transport of fipronil inside the sunflower seedling was studied in the laboratory. In a first study, sunflower was cultivated on an aqueous medium containing fipronil. An intense root uptake of fipronil occurred, leading to a transport into leaves depending upon transpiration. In a second study, plants were cultivated on a soil in which fipronil was uniformly distributed. Under our soil conditions (20% organic carbon), the partition coefficient between soil and water (K(d)) was found to be equal to 386 +/- 30. The average rate of fipronil transfer from soil water to seedlings was from 2 to 2.6 times lower than water transfer. During the 3 week experiment, 55% of recovered labeled compounds was in the parent form and 35% had been converted to lipophilic metabolites, with either a 4-CF(3)-SO(2) or 4-CF(3)-S substituant, which are also very potent lipophilic insecticides. This paper suggests that the possible uptake of fipronil by sunflower seedlings under agronomic conditions is mainly controlled by the physicochemical characteristics of the seed-coating mixture.

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“…The same was previously observed with numerous other pesticides and several different types of seeds (11,12).…”

Section: Fipronil Root Uptake By Sunflower Seedlingssupporting

confidence: 86%

Uptake and Xylem Transport of Fipronil in Sunflower

Aajoud

Raveton

Aouadi

et al. 2006

J. Agric. Food Chem.

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Uptake and fate of triticonazole applied as seed treatment to spring wheat (Triticum aestivumL.)

Quérou¹,

Euvrard²,

Gauvrit³

1998

Pestic. Sci.

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Following seed treatment of wheat (T riticum aestivum L.) with 14Clabelled triticonazole at a dose of 1É8 g kg~1 seed, the uptake of radioactivity by shoots and roots was investigated from the two-to three-leaf stage up to the beginning of the booting phase, 80 days after sowing. Triticonazole equivalents taken up by wheat plants reached 5É7% and 14É6% of the applied dose in the shoots and the roots, respectively. Between the two-to three-leaf stage and the beginning of the booting phase, the concentration of triticonazole equivalents in the shoots decreased from 2É5 to 0É15 lg g~1 fresh weight. This was attributed to uptake of triticonazole by roots not keeping pace with shoot growth and increased retention in the roots of triticonazole taken up. The main factor limiting the uptake of triticonazole by the roots may be the rapid growth of the uptake-active apical root parts out of the dressing zone which had formed in the soil. Distribution of triticonazole equivalents taken up by the main shoot showed a decreasing concentration gradient from the oldest to the youngest leaf. An increase in the seed treatment dose was investigated as a way to increase the concentration of triticonazole in the shoots, but its inÑuence remained limited.1998 SCI ( Pestic. Sci., 53, 324È332 (1998)

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