Abstract
The objective of this study was to evaluate the effect of organic-matter incorporated into the soil on population densities of the causal agents of the dry rot disease of yam, under field conditions. The experiment was performed in a natural infested area with a mixed population of Pratylenchus coffeae and Scutellonema bradys, in Quebrangulo county (Alagoas state, Brazil) in a randomized block design with five treatments and five replicates. The sources of organic matter used as soil amendments were: coconut husk powder, castor bean cake, cattle manure and chicken manure. Non amended soil was used as a control. Nine months after planting, the tubers were harvested. No statistical differences were found among disease incidence, yam production and nematode population densities in the soil. However, the application of chicken manure reduced P. coffeae population in tubers. Key words: Dioscorea spp., Scutellonema bradys, Pratylenchus coffeae, nematode management.
Highlights
Yam (Dioscorea spp.) is a monocotyledonous plant of the family Dioscoreaceae, comprising more than 600 species in the genus, mostly grown in Africa (Dioscorea cayenensis), the Caribbean, Mexico and Southeast Asia (Dioscorea alata, Dioscorea esculenta, Dioscorea composita, Dioscorea dumetorum and Dioscorea rotundata) and South America (D. cayenensis) (Cazé, 2002).In 2014, African countries produced 65.7 million tons of tubers equivalent to 96.4% of the world production (68.2 million tons)
The sources of organic matter used as soil amendments were: coconut husk powder, castor bean cake, cattle manure and chicken manure
Among the constraints to yam production in Brazil, dry rot disease caused by Scutellonema bradys, Pratylenchus coffeae and Pratylenchus brachyurus causes the greatest damage to this crop (Moura, 2006)
Summary
In 2014, African countries produced 65.7 million tons of tubers equivalent to 96.4% of the world production (68.2 million tons). Among South American countries, Brazil ranks second, with 25.5 thousand hectares and an estimated production of 247 thousand tons (FAO, 2015). According to Santos et al (2011), the Northeastern region is the largest producer of yams in Brazil with approximately 15 thousand ha and production of 200 thousand tons (average yield of 10.5 t ha-1), mainly cultivated in the states of Paraíba, Pernambuco, Bahia and Alagoas. Among the constraints to yam production in Brazil, dry rot disease caused by Scutellonema bradys, Pratylenchus coffeae and Pratylenchus brachyurus causes the greatest damage to this crop (Moura, 2006).
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