INTERRELATIONSHIPS OF MELOIDOGYNE SPECIES WITH FLUE-CURED TOBACCO

  • 1 January 1981
    • journal article
    • research article
    • Vol. 13  (1) , 67-79
Abstract
Microplot and field experiments were conducted to determine relationships of population densities of Meloidogyne spp. to performance of flue-cured tobacco. A 3 yr mircoplot study of these interactions involved varying initial nematode numbers (Pi) and use of ethoprop to reestablish ranges of nematode densities. Field experiments included various nematocides at different locations. Regression analyses of microplot data from a loamy sand showed that cured-leaf yield losses on ''Coker 319'' for each 10-fold increase in Pi were as follows: M. javanica and M. arenaria- 13-19%; M. incognita-5-10%; M. hapla-3.4-5%; and 3% for M. incognita on resistant ''Speight G-28'' tobacco. A Pi of 750 eggs and larvae/500 cm3 of soil of all species except M. hapla caused a significant yield loss; only large numbers of M. hapla effected a loss. M. arenaria was the most tolerant species to ethoprop. Root gall indices for microplot and most field nematocide tests also were correlated negatively with yield. Relationships of Pi(s) and necrosis indices to yield were best characterized by linear regression models, whereas midseason numbers of eggs plus larvae (pm) of field Pm and yield was also adequately described by the Seinhorst model. Degrees of root galling, root necrosis, yield losses and basic rates of reproduction on tobacco generally increased from M. hapla to M. incognita to M. arenaria to M. javanica.