Relationship between Crop Losses and Initial Population Densities of Root-Knot Nematode, Meloidogyne incognita in Soil of Sugarbeet Grown in West Nubariya District

• Gohar, I. M. A. And M. F. Maareg
• Sugar Crops Research Institute, Agricultural Research Center, Egypt.
• The Third International Conference onIPM Role in Integrated Crop management and Impacts on Environment and Agricultural Products. 26-29 November 2005, Giza, Egypt.

Abstract

Field experiment was carried out in naturally infested soil with the plant parasitic nematode, Meloidogyne incognita Kofoid &White (Chitwood), at West Nubariya Region throughout sugarbeet growing seasons of fall 1998 and summer of 1999. The objectives of this study were to determine the relationships between the yields (roots and Sugar) of sugarbeet and population density levels of M. incognita at planting time, and estimating the tolerance levels and damage function parameters necessary to optimize control costs. The initial population densities (Pi) in sugarbeet plots were determined before sowing time. The frequency distribution of population densities was made to classify them in density levels. Seeds of sugarbeet, Beta vulgaris saccarifera L. variety, Chems were planted. There was a negative linear relationship between roots and sugar yields of sugarbeet and levels of Pi of M. incognita and highly correlated value (r = -0.988, P > 0.01 and r = -0.937, P > 0.01, respectively) From the data it can be concluded that M. incognita larvae attack sugarbeet plants resulting in decreasing in root and sugar yields. The yield loss % proportion to the initial population density of this nematode at planting time, generally, the rate of decrease or loss % in sugar yield was greater than in the root yield. Tolerance limit for var. Chems (Polygerm) according to calculations was at Pi = 48.0 larvae of M. incognita per 250 gm soil. Damage or loss levels of root yield were compared using chi-square (X2) by analyzing frequency data to point out Economic injury level (EIL), which determined at Pi = 201 larvae of M. incognita per 250 gm soil