Uptake and distribution characteristics of the novel fungicide pyraoxystrobin in cucumber plants

Abstract

The uptake and distribution characteristics of a novel fungicide, pyraoxystrobin, labeled with ¹⁴C on its pyrazol ring, were investigated in cucumber (Cucumis sativus) seedlings. Foliar applied pyraoxystrobin rapidly penetrated the treated leaf and reached a maximum uptake of 68% after 5 d. The translocation of absorbed ¹⁴C in cucumber seedlings was both acropetal and basipetal. However, over 74% of the absorbed ¹⁴C-pyraoxystrobin remained in the treated leaves. The order of its distribution in the plant was as follows: treated leaf > stalk above the treated leaf > leaves above the treated leaf > stalk below the treated leaf > leaves below the treated leaf > cotyledon > root. Seedlings grown in soils containing bound residues (BR) of pyraoxystrobin revealed that the BRs were not easily absorbed or translocated by the plant. Soil type had a large effect on root uptake, with the highest uptake among the three tested soils from red clay.

Fig. 1. Structure of ¹⁴C labeled SYP-3343.

Fig. 2. Total absorption of ¹⁴C SYP-3343 in cucumber seedling.

Fig. 3. Autoradiography of the cucumber with ¹⁴C-SYP-3343 leaf treatment (DAT = 8) (TL: treated leaf; LATL: leaves above treated leaf; LBTL: leaves below treated leaf, red color stands for high ¹⁴C concentration, following is yellow, then green).