Long-term effect of Tylenchulus semipenetrans on citrus tree quality in reclaimed land of Egypt

Abstract Citrus fruit yield is considered a short-term response to the citrus nematode, Tylenchulus semipenetrans damage and therefore this study addressed parameters measuring overall appearance of the sampled trees. Soil and roots from 20 trees in each of three mature: 'banzaheer' lemon, 'Baladi' mandarin, and 'Navel' orange and one immature: 'Navel' orange orchards, all grafted on sour orange rootstock, in Egypt were sampled for the citrus nematode, T semipenetrans. in February 2011 to investigate their correlations with tree parameters (tree height and vigor, canopy diameter, and trunk circumference) that reflect long-term nematode damage of the sampled trees. The correlation between pairs of these four parameters were always positive and generally with high significant levels. Each of the four parameters was not significantly correlated with fruit yield of the mature trees but each of tree height and vigor, and canopy diameter was correlated with fruit yield of the immature Navel orange. The relationships between pairs of these biotic parameters and T semipenetrans population density in fibrous roots and soil were not consistent. Eleven edaphic factors in mandarin and mature orange orchards were measured and compared. Both soils were dominated by rough grainy particles of sand. Levels of potassium, calcium, phosphorus, ammonium and nitrate as well as soil solution pH, organic matter content and electric conductivity in the soil samples were significantly (P s 0.01) different between the mandarin and orange orchards. To achieve better economic revenue of citriculture, local tackling of T. semipenetrans problem in newly reclaimed areas of Egypt was discussed.