Integrated Weed Management Strategies in Rice-Onion Systems

CRSP:   |  Region:   |  Topic:   |  Database:

Project Code:
Not Available

Start Date:

End Date:

CRSP Phase:
Phase 2

Not Available



Lead University:

Other Partners:
UPLB, PhilRice, IRRI

Principal Investigator(s):

Co-Principal Investigator(s):
A.M. Baltazar (UPLB-PhilRice), J.M.Ramos, E.C.Martin, M.C. Casimero (PhilRice); A.M. Mortimer (IRRI); and S.K.De Datta (Virginia Tech


This project examined how tillage, in the form of stale-seedbedtechniques before planting onion, can reduce tuber and shoot populations and reduce the need for postplantweeding, which results in reduced weed control inputs,better crop growth, higher yields and net incomes.

Postplant herbicide treatments sprayed directly to weeds between crop rows, instead of handweeding, can also help reduce handweeding costs.


1. To quantify the yield losses due to purple nutsedge infestations in rice-onion cropping systems 2. Identify the best combination of tillage operations and chemicals in stale seedbed techniques combined with rice hull burning for reduction of purple nutsedge tuber and shoot populations 3. Assess the cost-effectiveness of stale seedbed treatments compared to farmers' practice 4. Quantify the population dynamics and fate of purple nutsedge tubers through five cropping seasons of the rice-onion rotation cycle 5. Determine selective postplant application methods of glyphosate for control of purple nutsedge and other weeds in onion grown after rice


Stale seedbed treatments reduced weed populations by 80 to 90%, weed control costs by as much as 60% in the onion crop and 80% in the rice crop compared to those of farmer's practice of rice hull burning and herbicides and increased net incomes by as much as 25% in onion and 31% in rice.A multi-season management approach of reducing tubersurvival through stale-seedbed treatment is more cost-effective than a single season approach using direct weed control inputs.Selective postplant herbicide application using a shielded nozzle increased weed control duration and reduced the amount of handweeding during mid to late season, thus reduced weed control costs by 88% and increased net incomes by 5 to 21% over those of farmer's practice.

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