Nematode distribution and damage to yam in central and eastern Uganda

Abstract

Yams (Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunately, nematodes are major pests to their production. A study was undertaken in major yam growing areas of Uganda to investigate the association of plant parasitic nematodes with damage symptoms. Nematodes were assessed from tubers, roots and surrounding soil for seven cultivars belonging to Dioscorea alata, D. bulbisiana, D. burkilliana and D. cayenensis at harvest. Pratylenchus sudanensis was found in the greatest density and was followed by Meloidogyne spp. Higher densities of both nematodes were observed in the tubers rather than roots. Although symptoms of cracking and galling were relatively low, P. sudanensis incidence was strongly associated with cracking and Meloidogyne spp. with galling. Pratylenchus sudanensis and Meloidogyne spp. incidence their associated damage were, however, negatively correlated, suggesting inter-species competition. Principal components analysis of data suggested that differences in susceptibility to P. sudanensis occur between yam cultivars and species.

Agricultural nematology in East and Southern Africa: problems, management strategies and stakeholder linkages

“…Research on the staple food crops of an area and awareness of nematode problems in the local farming communities are limited. However, the limited data available in ESA (addressing this weakness is one of the major keys to ameliorating the problem) indicate that PPN are widespread and cause significant losses in bananas, maize, yam, vegetables and fruit crops . The examples and discussions presented here have been selected to demonstrate that nematodes are frequently a limiting factor on a wide range of crops commonly grown in ESA, with particular focus given to Kenya, Tanzania, Uganda and Zimbabwe.…”

“…In Uganda, Pratylenchus sudanensis has been observed causing similar symptoms to S. bradys , while RKN are particularly prevalent and damaging, causing rotting and necrosis, especially during storage . Nematode‐damaged tubers used as planting material also reinfect the subsequent crop and so perpetuate the problem . It is possible to achieve control of Scutellonema bradys by hot water treatments of seed tubers, although resistance can be a potentially better way to manage this nematode …”

“…4,31 Nematode-damaged tubers used as planting material also reinfect the subsequent crop and so perpetuate the problem. 30,33 It is possible to achieve control of Scutellonema bradys by hot water treatments of seed tubers, although resistance can be a potentially better way to manage this nematode. 75…”

Screening of new yam clones (<i>D. alata</i> and <i>D. rotundata</i>) in nematode prone ecology of guinea savanna zone in West Africa.

“…The cracking symptoms caused by S. bradys were observed on D. alata and on D. rotundata tubers at the harvest. The damages were described in Uganda and in Nigeria as dangerous for roots and tubers as yam in African tropical soil (Mudiope et al, 2007;Amusa et al, 2003). They limit yam yield when they appear in the soil.…”

A survey of plant-parasitic nematodes of yam farms in Awka-North local government area, Anambra state, Nigeria.

“…In addition, International Institute of Tropical Agriculture (IITA, 2011) reported that Nigeria accounted for about 70% of the world production amounting to 17 million tonnes from land area of 2,837,000 hectares. It is a tropical tuber crop grown as a source of carbohydrate but also for use in ceremonial activities (Mudiope et al, 2007). Yam serves as staple food in many tropical and sub-tropical countries of the world and in Nigeria the principal source of carbohydrate.…”