Incidence and Population Density of Plant-Parasitic Nematodes Infecting Vegetable Crops and Associated Yield Losses in Punjab, Pakistan

Plant-parasitic nematode population densities were determined from 325 root and soil samples collected from vegetable growing areas in Pakistan. Yield losses associated with nematode presence were quantified on 19 vegetable crops during 2007 and 2009. The most abundant plant-parasitic nematodes detected, in order of decreasing frequency of infestation (percentage of samples), were Meloidogyne incognita (90%), Pratylenchus penetrans (30.2%), Tylenchorhynchus clarus (29%), Hoplolaimus columbus (15%), Paratrichodorus minor (7.5%), Xiphinema americanum (7.1%), M. javanica (7%), Belonolaimus longicaudatus (5.6%), Longidorus africanus (5%), and Helicotylenchus dihystera (3.2%). We observed ca 23% yield losses ranged from 2% for cabbage to 45% for squash, which is 35%, 80%, and 46% higher compared to developed countries, USA, and India, respectively. The main reason for more losses in Pakistan might be related to incognizant growers about the presence of nematodes and the damage they cause. Another reason might be non-availability of resistant crop cultivars and nematicides. Another possibility is that on small-sized farms with varied cropping histories and inattention to the pest-host-status one result appears to be a larger list of available nematode species, compared to farming practices in USA where only one or two nematode species become dominant. This study provides important information for extension specialists and creates awareness among growers about these hidden crop enemies. It also suggests the need for improved management measures to avoid crop losses.