Pathogenic effects of Pratylenchus scribneri in maize root systems

Waudo, Stanley
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Plant Pathology and Microbiology

Feeding of the lesion nematode, Pratylenchus scribneri, in maize roots has detrimental effects on the health of hosts. Inbreds C123Ht, C103, and Mo17Ht inoculated with 8,500 (+OR-) 500 P. scribneri had dark brown discrete lesions on their roots, significantly (P = 0.50) reduced root size and weight, and extensively pruned root systems 90 days after inoculation in the greenhouse. Inbred B68Ht that was similarly treated gained root weight (29% gain) and had no visible symptoms;Pratylenchus scribneri also caused inferior root performance of most cultivars in the field. The nematode significantly (P = 0.50) reduced root weight, volume, size, number of crown roots, and fibrous roots of most cultivars as revealed by negative slopes from linear regression, negative correlations between numbers of P. scribneri and root parameters, and/or comparisons between aldicarb-treated and nontreated cultivars. For example, C123Ht, which supported the most P. scribneri, sustained losses in numbers of crown roots, root size, volume, dry weight, and fibrous roots of 5%, 6%, 28%, 31% and 37%, respectively, 51 days after planting;Cultivars C103, Mo17Ht, C123Ht x Mo17Ht, and C123Ht x C103, all related to C123Ht, also supported relatively high numbers of P. scribneri both in the greenhouse and in the field, and sustained damages in some instances;On the other hand, B37Ht supported relatively few P. scribneri and had the greatest performance in respect to root weight, size, volume, numbers of crown roots, and fibrous root intensity 51 days after planting in the field. In fact, comparisons between aldicarb treated and nontreated B37Ht revealed gains in numbers of crown roots, root volume, dry weight, fibrous root intensity, and size of 1%, 5%, 11%, 13%, and 17% respectively, of nontreated B37Ht.