Occurence and pathogenicity of rice root-knot nematode (Meloidogyne graminicola) and varietal reaction of onion (Allium cepa)

The distribution of the rice root-knot nematode, Meloidogyne graminicola, in major rice-onion farms in 4 provinces of Luzon in the Philippines (Ilocos Norte, Pangasinan, Nueva Vizcaya and Nueva Ecija), its pathogenicity, and the reaction of different onion (Allium cepa L.) cultivars to the nematode were assessed. The nematode was detected in all 17 ricefields surveyed in 4 barangays (villages) in San Jose City, Nueva Ecija and in 72% of the onion-growing areas in 78 barangays in four provinces. Galling in onion was more abundant in \u27Yellow Granex\u27 than in \u27Tanduyong\u27 and \u27Batanes\u27. Severely infected \u27Yellow Granex\u27 developed short roots with galls and no bulbs. All 30 cultivars or lines of Allium cepa evaluated for resistance in the greenhouse supported nematode reproduction. With gall index of 5.0 and reproductive indices higher than 5.0, \u27BSS-133\u27, \u271576 (lot 576 E5)\u27, \u27Dessex 38009\u27, \u27Henry\u27s special\u27, \u27LD 959 A05\u27, \u27Sunsweet (1504)\u27, \u27Primero 37053\u27, \u27Dehydrator No. 3\u27, and \u27Yellow Granex\u27 Improved (PRR) were found highly susceptible to M. graminicola

Effect of rice root-knot nematode on growth and yield of Yellow Granex onion

Rice root-knot nematode, Meloidogyne graminicola, infects all commercially grown onion cultivars in rice - onion cropping systems in the Philippines, but its economic importance has not been established. The effects of different preplant population levels (Pi) of M. graminicola on Yellow Granex onion in pots and of different percentages of galled roots in a naturally infested field were evaluated. Leaf weight and root length of \u27Yellow Granex 429\u27 seedlings decreased with increasing Pi, while low Pi mildly stimulated plant height at the vegetative growth stage. Age of transplant and Pi influenced growth and yield of onion at maturity. Onion yield and root and leaf weights decreased as the age of the transplants increased. Growth and yield decreased with increased Pi. Bulb weight was reduced by 7 to 82% and diameter by 10 to 62% when plants were inoculated with 50 to 10,000 second-stage juveniles. Onion bulbs from the field were reduced by 16, 32, and 35% in weight and by 6, 17, and 18% in diameter when the percentage of roots galled was 10, 50, and 100%, respectively. Management of M. graminicola populations at the start of the growing season must be part of onion culture in rice - onion systems to reduce onion yield losses and to prevent economic loss

Trap barrier system: a quick-selling intervention for rat management in the Ifugao rice terraces

Rat infestation in rice terraces clusters in the highlands of Ifugao appeared to be very serious during the 2001-02 cropping season. To validate this observation, a total of 60 farmer-owners of the terraced rice field in Banaue and Hungduan were surveyed in collaboration with the local government units. The survey showed that rats ranked first among the three major rice production constraints. Yield losses due to rat damage ranged from 38% to 75%. Most farmers considered sanitation and rodenticide baiting ineffective as rat management strategies due to untimely application. These strategies were applied individually in Banaue (83%) and Hungduan (100%). Rats were caught live through trap barrier system (TBS) and properly disposed. Thirty-eight rats have been collected in TBS in Hugduan with two rice croppings and 12 in Banaue with only one rice cropping over a span of three months. Testimonies from farmers near TBS have indicated low incidence of rat damage in their nurseries. The team is doing an active information campaign at community level for TBS

Rodent management and cereal production in Asia: Balancing food security and conservation

Rodents present a major problem for food security in Asia where smallholder farming families are particularly vulnerable. We review here recent developments in the biology and management of rodent pests in cereal cropping systems in Asia. The past decade has seen a strong focus on ecologically-based rodent management (EBRM), its adoption in field studies significantly increased rice yields (6–15%) and income (\u3e15%) in seven Asian countries. EBRM principles have also been successfully applied to maize in China. We provide case studies on EBRM in Cambodia, on interactions between rodent pests and weeds, and on the importance of modified wetlands for biodiversity and rodent pest management. Knowledge on post-harvest impacts of rodents is increasing. One research gap is the assessment of human health impacts from a reduction of rodent densities in and around houses. We identify 10 challenges for the next decade. For example, the need for population modelling, a valuable tool missing from our toolbox to manage rodent pests in cereal systems. We also need to understand better the interactive effects of cropping intensification, conservation agriculture and climate change. Finally, new management approaches such as fertility control are on the horizon and need to be considered in the context of smallholder cereal farming systems and mitigating health risks from zoonotic diseases associated with rodents. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry