ESTIMATE OF YIELD LOSS FROM THE CITRUS NEMATODE IN TEXAS GRAPEFRUIT

  • 1 January 1982
    • journal article
    • research article
    • Vol. 14  (4) , 582-585
Abstract
Chemical control of the citrus nematode, T. semipenetrans Cobb, has consistently increased yield of grapefruit on sour orange rootstock in Texas. Here, data from chemical control tests conducted from 1973-1980 were analyzed to determine the relationship between nematode counts and grapefruit yield, and fruit size. The correlation between yield and nematode counts was negative (r = -0.47) and highly significant (P < 0.01). The data best fit the exponential decay curve: y = 160.3e-0.0000429x, where y = yield in kg/tree and x = nematodes/100 cm3 of soil. The correlation between fruit size and nematode counts was not significant because yield and fruit size were inversely related. Yield loss in an average untreated orchard was estimated to be 12.4 tons/ha.