Preliminary Evaluation of Some Biological Control Agents for Controlling Trianthema portulacastrum L.

Abstract

The study was carried out to identify and evaluated some natural enemies as a bio-control agent of pigweed (Trianthema portulacastrum L.). One insects and two fungal diseases were found as major natural enemies of pigweed at chai Nat FCRC. Hymemia fascialis Cram. (Lepidopera : Oyralidae) feeded on the leave of pigweek at all development stages. Severe infestation made the plants stunted and died. However, this insect did not decrease the population of pigweed in the consecutive years very much. Leaf spot diseases caused by Drechslera sp. and Stemphylium sp. The leave and stems of pigweed were infected and turned brown within 3-5 days. Stemphylium sp. was dominated by Drechslera sp. both in the field and greenhouse. However, the insect was more effective than the two fungal diseases in term of biological control.