This study was conducted to address the problem of root-knot nematodes (Meloidogyne spp.) affecting semi-temperate vegetables cultivated by small-holder farmers in the highlands (Cordillera) in the northern part of Luzon, Philippines. Our general objective was to assist in the development of root-knot nematode management strategies suitable for small-holding farming that could result in improved crop productivity and quality. There are four experiments included in our study which started from the survey of plant-parasitic nematodes in the principal agricultural farms in Benguet Province. The objectives of this part of our study were to update the incidence of plant-parasitic nematodes associated with semi-temperate vegetables in Benguet Province and to identify the predominant plant-parasitic nematode species associated with semi-temperate vegetables in this province which is the major semi-temperate vegetables producing region of the Philippines. 
From the above mentioned experiment, the predominant plant-parasitic nematode Meloidogyne incognita was singled out for further experimentation in the greenhouse. The objective of this part of our study was to evaluate the host response (susceptibility and sensitivity) of six semi-temperate vegetables commonly grown today in the highlands of Benguet Province to M. incognita.  
A crop rotation scheme was designed to examine the host status for a local M. incognita population of the most commonly cultivated cash crops in the Cordillera Administrative Region (CAR) usually grown in rotation with carrot. Crops which were considered effective in suppressing root-knot nematode populations, such as marigold (Tagetes erecta), but are considered of no economic value in small-holding farming were not included in our study. A greenhouse experiment was conducted at Benguet State University, La Trinidad, Benguet, Philippines, during a 2-year-period (2006-2007). 
One promising practice is using silicon amendment to alleviate damage caused generally by fungi or bacteria. Until now, little had been studied for root-knot nematodes, therefore, the objectives of this part of our study were to: (1) investigate the effects of silicon on root-knot nematode, M. incognita; and (2) determine its consequent effects on plant growth and yield of carrot, celery, tomato and cucumber. This part of our study comprised of two experiments which were conducted in the greenhouse.