Uptake and translocation of imazethapyr in peas as affected by parasitism of Orobanche crenata and herbicide application methods

Abstract

[14C]‐Imazethapyr was applied as a seed treatment and at plant pre‐emergence and post‐emergence to peas (Pisum sativum L.) parasitized by Orobanche crenata Forsk. Herbicide uptake increased with time regardless of the application method. Uptake reached about 98%, 89%, 81% and 94% of the total herbicide applied for the seed coating, seed soaking, pre‐emergence and post‐emergence treatments respectively. Herbicide translocation within the host plants consistently differed between O. crenata‐infected and non‐infected plants. High levels of 14C activity were accumulated by parasitic plants from the host. In non‐infected pea plants, pods were stronger sinks for imazethapyr than the other parts of the plant, regardless of the application method. The herbicide distribution in the pea plant: O. crenata complex showed the same pattern regardless of the application methods. However, accumulation of radioactivity in the parasite was lower with pre‐emergence and post‐emergence application than with the seed treatments. In addition, radioactivity concentration in O. crenata plants was slightly higher when [14C]‐imazethapyr was applied to pea seeds by coating than by soaking.