Weeds in Rice

Weed flora varies from place to place due to type of rice culture, soil type hydrology, tillage, cultural practices and irrigation pattern etc.

• Grasses are dominant in irrigated systems
• Sedges are dominant in rainfed system
• Weed problems are more severe in irrigated rice fields due to rotation at pattern of water issues
• Nearly 134 weed species identified from rice field in Sri Lanka belongs to 32 taxonomic families

  More than 70 species - grasses
  More than 50 species - sedges
  More than 20 species - broad leaves

However 10-20 species may be considered as economically important in rice culture Grasses are considered as the major weed group in rice fields in Sri Lanka.

Major Rice Weeds in Paddy Fields

Grasses	Sedges	Broadleaves	Ferns
Echinochloa colonum	Cyperus iria	Commelina diffusa	Marsilea quadrifolia
Echinochloa crusgalli	Cyperus difformis	Eclipta alba	Salvinia molesta
Panicum repens	Cyperus rotundus	Eichnornia crassipes
Ischaemum rugosum	Fimbristylis miliacea	Monochoria vaginalis
Isachne globosa	Linderina spp.	Murdannia nudiflora
Fimbristylis dichotoma	Scirpus supinus	Sphenoclea zeylanica
Paspalum distichum		SpLudwigia perennis
		Haeranthus africanus

 

Echinochola crusgalli is rated as the most trouble some weed in both well and poorly drained soils. Ischeamum rugosum and leptochloa chinensis are becoming important in rice fields due to continuous application of herbicides.