Studies concerning the control of broomrape (Orobanche ramosa) in the tobacco fields of Romania
Broomrape represents one of the most damaging parasite weeds in the tobacco fields of Romania. The most frequent species is Orobanche ramosa . The tobacco plants attacked have distorted stems, a reduced number of leaves, which are very thin and breakable, and results in low quality tobacco after curing.
In the period 1997-2000, research conducted concerned the control of broomrape in Oriental tobacco fields (Experimental field Voicesti, on an alluvial soil) and tobacco of large consumption (Experimental field Urziceni, on levigated chernozem). The aim of the research was to observe the efficiency of certain herbicides in the control of broomrape, using products before and after transplantation, in different doses.
Pre-transplantation herbicides were:
- trifluralin 2 lts/ha;
- metolachlor gold 1 lt/ha;
- pendimetalin 4 lts/ha.
Post-transplantation herbicides were applied at 40 and 55 days respectively after the tobacco transplantation, when the weeds, including the broomrape, had emerged. The used products were:
- glyphosat 0.2 lts/ha at 40 days and 0.3 lts/ha at 55 days;
- ammonium gluphosinate (same doses as for gliphosat);
- imazametabenz (same doses as for gliphosat);
- imazetapis 0.4 lts/ha at 40 days and 0.5 lts/ha at 55 days;
- maleic hydrazide (check) 0.7 lts/ha at 40 days and 1 lt/ha at 55 days.
The herbicide imazetapir proved to be phytotoxic for tobacco (mark 5 on the scale EWRS).
The efficiency of the tested herbicides for the prevention and control of the species Orobanche ramosa was reflected by the frequency of the attacked tobacco plants, by the differences in yield and quality compared with the non-herbicide treated control.
The most efficient control of broomrape was assured in the variants with pre-transplantation treatments (any of the three herbicides), plus gliphosat used post-transplantation. Similar results were obtained also for ammonium gluphosinate and imazametabenz.
Maleic hydrazide, which was eliminated from the list of valid pesticides because of its toxicity for man and environment, was used only for comparison.
The yield and quality of the tobacco obtained in the herbicide variants was higher than that of the non-treated control, recording an increase of the soluble carbohydrates in the leaves by 20 - 30%, depending on the variant and the tobacco type.