Penetration, translocation, and metabolism of a fungicide guazatine-triacetate (TA), 1, 1'iminodi(octamethylene)diguanidine triacetate, in dwarf apple trees (Males pumila sp., cv. Inu-apple) were determined over a period of 12 weeks under laboratory conditions by using 14C-labeled guazatine-TA. Autoradiographic studies showed that (1) no observable movement of the radiocarbon in the apple leaves occurred following foliar application of 14C-guazatine-TA to either abaxial or abaxial surface of

more »

... leaves, and (2) the rate of penetration of 14C into the apple fruits was extremely slow and a major part of 14C was retained on the surface after surface application of 14C-guazatine-TA. The results of quantitative determination for 14C in 14C-guazatine-TA treated leaves indicated the following: (1) the rate of 14C-disappearance from the leaves was exceedingly slow (T112=67 weeks) with approximately 87% of the applied 14C being located in the treated leaves even after 12 weeks, and (2) the radiocarbon had poorly penetrated in the leaf tissues (21% of the applied 14C after 12 weeks). Quantitative determination of 14C in the fruits also confirmed the results of the autoradiographic observation for the fruits. The radioactive compounds dislodged from the surface of both leaves and fruits principally consisted of intact guazatine. Furthermore, several phototransformation products (a major product (Pm) and a few minor ones) were also detected, indicating the occurrence of photolysis of 14C-guazatine on the surfaces. The extracts from both the leaves and fruits also comprised intact guazatine as a primary radioactive component and photolysis products. Thus it appeared that guazatine and the photoproducts penetrated in the plant tissues were highly resistant to the plant metabolism. Translocation of the radiocarbon from the 14C-guazatine-TA treated leaves to symplasts (fruits and newly developed leaves after treatment) was negligible.