Check of Amaranthus blitoides W. var. Reverchoni Th. - an Element of the Control of Cuscuta epithymum Murr in Lucerne (Medicago sativa L.)

Ts. DIMITROVA
Institute of Forage Crops, BG-5800 Pleven, Bulgaria

Abstract

DIMITROVA, Ts., 2004. Check of Amaranthus blitoides W. var. Reverchoni Th. - an element of the control of Cuscuta epithymum Murr in lucerne (Medicago sativa L.). Bulg. J. Agric. Sci., 10: 579-582

Cuscuta epithymum Murr is a weed parasitizing on lucerne and difficult to kill. The control of this parasite is impeded in addition by the spread the weed Amaranthus blitoides W. var Reverchoni Th. resistant to triazine herbicides that is also its host.
The objective of the studi was to investigate the control of Cuscuta epithymum in a Lucerne stand invested with Amaranthus blitoides that is a host to the parasite. During the period 2000 - 2002 a field trial was carried out field at the Institute of Forage Crops, Pleven, on a soil type of moderately deep chernozem. The trial was laid out by the block method with four replications at a size of harvest plot of 10 m2 and with the following variants : check - with weeds, without dodder; check - with weeds and dodder ; check - without weeds and without dodder ; imazethapyr 100 g/l - rate of 10 ml/da, three days after cutting of infected growth ; S - metolachlor 960 g/l - rate of 96 ml/da, after sowing, before emergcnce - imazethapyr 100 g/l - rate of 10 ml/da three days after cutting of infected growth; S - metolachlor 960 g/l - rate of 144 ml/da, after sowing, before emergence - imazethapyr 100 g/l - rate of 10 ml/da three days after cutting of infected growth.
As a result of the study it was found that: Cuscuta epithymum parasitizing on lucerne greatly reduced its biological potential which led to establishment of a stand with poor emergence and short persistence. The control of Cuscuta epithymum in a lucerne stand infested with Amaranthus blitoides was efficient by twofold treatment with herbicides applied in a system - S metolachlor 960 g/l at a rate of 96 ml/da after sowing before lucerne emergence and imazethapyr 100 g/l at a rate of 10 ml/da three days after cutting of infected growth.

Key words: lucerne, Cuscuta epithymum Murr., Amaranthus blitoides W. var. Reverchoni Th., herbicides