Distribution and losses of Tylenchulus semipenetrans in citrus orchards on reclaimed land in Egypt

Four citrus orchards in Egypt were used in 2011 to study spread and losses of Tylenchulus semipenetrans based on a preliminary report of their infection in 2008. Soil and root samples indicated aggregated distribution and increase of nematode populations. The relationship between nematode number and lemon yield was described. When yield data of the mature groves were combined, we could construct other equations. The gain thresholds were 6.083 and 4.014 metric tons of lemon feddan(-1) (=4200 m(-2)) and the economic thresholds were 1810 and 141 second-stage juveniles (150 cm(3) soil)(-1) for cadusafos and oxamyl, respectively, based on the combined costs of nematode sampling and control to provide an actual estimate of a budget conscious choice. The use of healthy material is compulsory for tackling this problem in Egypt as a case in point. It entails setting up a citrus certification programme. Other phytosanitary measures to protect citriculture interests in Egypt are discussed.