Weeds to watch out
1. Cyperus rotundus (Mutha, Sudsud, Onod-onod)
Adaptation of Cyperus rotundus from upland (dryland) to lowland (flooded condition)
Control/Management
- Flooding is no longer an option to control C. rotundus.
- Dry tillage during dry season will expose tubers to sunlight and tubers are killed through desiccation.
- Pre-plant glyphosate application. Allow C. rotundus tubers to emerge, then apply glyphosate 1-2 weeks after emergence (effect of glyphosate is not evident until 2 weeks after application).
2. Ischaemum rugosum (Bulo-?bulo, limba-limba, aguingay sa basak)
- Becoming abundant in wet direct-seeded rice
- A vigorous aggressive weeds
- Can tolerate 30-35% of full sunlight
- Very competitive (5 plants m-2 reduce rice yields 15% and 80 plants m-2 reduce yield by 82%)
- One of the commonest seed contaminants in rice seeds
- Alternate host of tungro virus and nematode
- Control measure: handweeding or herbicides
3. Leptochloa chinensis (Pawa, ikog kuring/iring, Palay maya, marapagaymaroy paroy )
- Increasingly important in wet-seeded rice.
- Not controlled by Nominee which is commonly used in rice.
- Generally multiply through seeds but can propagate vegetatively (cuttings of the culm or rootstocks.One of the contaminants in rice seeds.
- Seeds germinate well when fields are drained of flood water for a longer period.
Control/Management
- Use of uncontaminated seeds
- Continuous flooding
- Pre-emergence application of pendimethalin; early post-emergence application of cyhalofop butyl (0.1-0.15 kg a.i./ha) , butachlor + propanil mixture and fenoxaprop ethyl (0.06 kg a.i./ha 10 DAS
