Effective pest management does not necessarily mean addressing all stressors affecting the crop.

Photo by Kathy June Fiel

These insights are based on Dr. Litsinger's broad background in international agricultural development and pest management. More specifically, his talk centered on research findings from on-farm research in the Philippines during his time as an entomologist and Farming Systems Program team member with the International Rice Research Institute (IRRI).

The studies were conducted in various research sites representing three ecosystems namely: dryland, rainfed wetland, and irrigated double cropped areas. Study results indicated significant differences in yield loss of untreated rice over those afforded with full protection. Yield loss incurred in each area varied due to differences in insect pests found in a particular site, characteristics of rice variety planted, and environmental conditions.

Low yields, as explained by Dr. Litsinger, are due to the many stresses acting on a crop in a synergistic fashion. Synergism is a state where the outcome of the whole is greater than the sum of individual component alternations. This means that the combination of field stressors could cause lower yield gain not obtainable by any of the stressors independently. In this case, field stressors do not only include insect pests but also cover disturbance caused by transplanting and, for young seedlings, competition with older ones.

Through these researches on crop stressors and their combined effect on rice, Dr. Litsinger and his team were able to identify which stresses and/or combinations of stresses have the greatest potential for causing yield loss. Likewise, the research results helped determine whether it was cost effective to address the field stressors individually and/or collectively for synergistic yield gain.

Dr. Litsinger served at IRRI from 1974 to 1992. He has over 30 years of overseas experience and over 30 consultancies through his work in both the US Peace Corps and with IRRI.

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Report based on Agriculture and Development Seminar Series (ADSS) presentation of Dr. James Litsinger entitled �Multiple pest infestation and yield loss on rice and other results from on-farm research in the Philippines� last April 22, 2010